Metafounders are pseudo-individuals that act as proxies for animals in base populations. When metafounders are used, individuals from different breeds can be related through pedigree, improving the compatibility between genomic and pedigree relationships. The aim of this study was to investigate the use of metafounders and unknown parent groups (UPGs) for the genomic evaluation of a composite beef cattle population. Phenotypes were available for scrotal circumference at 14 months of age (SC14), post weaning gain (PWG), weaning weight (WW), and birth weight (BW). The pedigree included 680,551 animals, of which 1,899 were genotyped for or imputed to around 30,000 single-nucleotide polymorphisms (SNPs). Evaluations were performed based on pedigree (BLUP), pedigree with UPGs (BLUP_UPG), pedigree with metafounders (BLUP_MF), single-step genomic BLUP (ssGBLUP), ssGBLUP with UPGs for genomic and pedigree relationship matrices (ssGBLUP_UPG) or only for the pedigree relationship matrix (ssGBLUP_UPGA), and ssGBLUP with metafounders (ssGBLUP_MF). Each evaluation considered either four or 10 groups that were assigned based on breed of founders and intermediate crosses. To evaluate model performance, we used a validation method based on linear regression statistics to obtain accuracy, stability, dispersion, and bias of (genomic) estimated breeding value [(G)EBV]. Overall, relationships within and among metafounders were stronger in the scenario with 10 metafounders. Accuracy was greater for models with genomic information than for BLUP. Also, the stability of (G)EBVs was greater when genomic information was taken into account. Overall, pedigree-based methods showed lower inflation/deflation (regression coefficients close to 1.0) for SC14, WWM, and BWD traits. The level of inflation/deflation for genomic models was small and trait-dependent. Compared with regular ssGBLUP, ssGBLUP_MF4 displayed regression coefficient closer to one SC14, PWG, WWM, and BWD. Genomic models with metafounders seemed to be slightly more stable than models with UPGs based on higher similarity of results with different numbers of groups. Further, metafounders can help to reduce bias in genomic evaluations of composite beef cattle populations without reducing the stability of GEBVs. H) used in ssGBLUP was developed under assumptions that may not hold in practice and may result in biased genomic estimated breeding value (GEBV), especially when pedigree information is missing for genotyped animals (G) and pedigree (A) relationship matrices are observed  has been widely used for genomic evaluation in domestic species such as dairy and beef cattle, swine, and chicken . The mai animals . In suchobserved . Incompaquencies . Severalerations , scaling, post weaning weight gain , weaning weight , and birth weight . Phenotypic records deviating from the mean of contemporary groups ±3 standard deviations and contemporary groups with less than five records were removed. Contemporary groups for BW and WW were based on farm, year and season of birth, sex, and management group classes. Contemporary groups for SC14 and PWG were defined using farm, year of birth, and weaning management group classes. After data editing, a total of 49,541 phenotypic records for SC14, 96,994 for PWG, 325,014 for WW, and 264,981 for BW were available. The heritability estimates were 0.25 for SC14, 0.09 for PWG, 0.23 for WW, and 0.22 for BW. Heritabilities for all models were estimated using a BLUP model without UPGs or MFs because UPGs had a minor influence on estimated genetic parameters  commercial panel with approximately 30k SNP markers using the FImpute software . Subsequently, all genotypes were imputed to the software . After SA,G, and the pedigree relationship matrix for genotyped animals (A22) (ssGBLUP_UPG) or only for A and A22(ssGBLUP_UPGA); and single-step GBLUP with MFs (ssGBLUP_MF). The model without UPGs was as follows:Both UPGs and MFs were used to model the heterogeneous Montana base population. A four-trait model was applied to the pedigree BLUP (BLUP); pedigree BLUP with UPGs (BLUP_UPG); pedigree BLUP with MFs (BLUP_MF); ssGBLUP; single-step GBLUP with UPGs for y is the vector of phenotypes for each trait ; b is the vector of contemporary group and age of dam classes, and biological type composition covariates for models without UPGs or MFs, non-additive effects for total maternal heterozygosity (Hm), non-additive effects for direct heterozygosity , and age at recording for SC14; u is the vector of direct additive genetic effects for SC14, PWG, WW (WWD), and BW (BWD); m is the vector of maternal additive genetic effects for WW (WWM) and BW (BWM); c is the vector of maternal permanent environmental effects for WW and BW; e is the vector of residuals; and X, Z1,Z2, and Z3 are incidence matrices relating phenotypic records in vector y to effects in vectors b, u, m, and c, respectively.where Z1Qg term was added to the model, as follows:When UPGs were added to pedigree-based BLUP and ssGBLUP evaluations, a Q is an incidence matrix relating animals in vector u to UPGs in vector g. Traditional EBV and GEBV for UPG models were calculated as follows:where H . The H−1 for ssGBLUP_MF (HΓ−1) was computed as follows:A third approach used to model the heterogeneous Montana base population was MFs . The modAΓ−1 and A−1 and Γ, the matrix of relationships among MFs that accounts for similarities across base populations  approach . Intermediate crosses between base animals can also be used in different proportions to generate composites. The MFs and UPGs were assigned based on the biological type of the animals . The Montana composite beef cattle is formed by biological type clusters according to likeness, physiology, production, and reproduction levels using a combination of both Two genetic group definitions were used for both MFs and UPGs. Firstly, only four groups (GG4) that traced animals back to their N, A, B, and C founders were assigned. Missing parents of animals with a higher proportion of a particular biological type were assumed to be from that biological group. For example, a missing parent of an animal with a higher proportion of N was assigned to biological group N. Breed composition of almost all animals in the dataset was either known or estimated. Even when one parent was unknown, its breed proportion was inferred through the breed composition of its progeny. Further, when the two parents of an animal with known breed composition were unidentified, breed composition of the animal was assigned to both parents.In the second group definition, 10 groups (GG10) that traced animals back to their main biological type and their two-way, three-way, and four-way crossbreds were assigned. Initially, groups were represented by N, A, B, C, NA, AB, AC, BC, NB, NC, NAB, ABC, NAC, NBC, and NABC. However, the number of genotyped animals in the Montana population is small; thus, groups with only a few animals were merged to avoid computational problems when estimating group effects. Groups NA, AB, AC, and BC were merged into a single group, as well as NAB, NAC, and ABC. The breed proportion of an animal and its known parents were taken into account when assigning groups. Thus, if an animal of biological type NA had a known parent of biological type A, its missing parent was assigned to group N. When both parents were unknown, only the breed proportion of animal was taken into account for group assignments. For example, if the biological type of an animal with unknown parents was NA, one parent was assumed to come from group N and the other parent from group A. Numbers of animals in GG4 and GG10 are shown in r. The total number of phenotypic records per trait in the reduced dataset was 47,949 for SC14, 93,701 for PWG, 317,703 for WW, and 257,368 for BW. The complete dataset, identified with subscript c, included 49,541 phenotypes for SC14, 96,994 for PWG, 325,014 for WW, and 264,981 for BW. This dataset was used as a benchmark for validations. All evaluation models were run with both reduced and complete datasets, and all computations were done with programs from the BLUPF90 software suite (The linear regression (LR) validation method  was usedre suite .cov is the sample covariance, corc,r indicates that adding more data will result in few (G)EBV changes; thus, the reduced dataset is a good predictor of the complete dataset in this case. Inflation/deflation of (G)EBV was assessed as the deviation of the regression coefficient (b1) from 1, where b1 was obtained from the regression of The estimators of the LR method were calculated based on cr has an expected value of zero if the evaluation is unbiased.Another estimator used to measure the model performance was bias, calculated as A matrices (ssGBLUP_UPGA) were higher than those from models with UPGs in all relationship matrices (ssGBLUP_UPG).G and A22 with and without MFs. The inclusion of MFs in the pedigree-based relationship matrix and the assumption of allele frequencies equal to 0.5 causes an upward shift in the means of A22 and G. Noticeably, diagonal and off-diagonal element values for A22 and G were virtually identical when the number of MFs was increased from four to 10.Γ matrix) were smaller than one, and those between MFs  were different from zero in both scenarios (GG4 and GG10). Relationships within MFs in GG4 are presented in Γ4 below and ranged from 0.15 to 0.38, whereas the relationship across MFs ranged from 0.09 to 0.18.The relationships within MFs . Relationships across MF for GG10 ranged from −0.11 to 0.23 as opposed to all positive values for GG4. In particular, relationships between MFs1 and 3  and between 1 and 4  showed negative values in GG10. The relationship between MFs1 and 2  in GG10 was close to zero.Overall, relationships within MFs in GG10 were greater than those in GG4 and ranged from 0.15 to 0.65 (see A and A22 (ssGBLUP_UPGA) showed greater changes in accuracy for PWG when compared with other genomic models. The accuracy of (G)EBVs ranged from 0.38 to 0.50 for SC14, 0.10 to 0.79 for PWG, 0.35 to 0.51 for WWD, 0.30 to 0.64 for WWM, 0.47 to 0.58 for BWD, and 0.31 to 0.44 for BWM. Higher accuracies were observed when genomic information was added to the model, except for PWG that exhibited mostly minor changes. Inclusion of either four or 10 MFs in ssGBLUP models decreased accuracies (0.02 to 0.08); however, accuracies were still higher than corresponding values in BLUP models for all traits, except for PWG and ssGBLUP_MF10. Conversely, addition of UPGs to BLUP and ssGBLUP models yielded maternal (G)EBV accuracies that were either similar or higher than those from the original models, except for ssGBLUP_UPGA4 and WWM.1) of the regression of (G)EBVs from the complete dataset on (G)EBVs from the reduced dataset measures the degree of dispersion of (G)EBV estimated under a given model  for SC14, WWM, and BWD. Conversely, most of the genomic models showed a slight deflation  for SC14 and BWD. Overall, PWG showed similar dispersion in models with and without genomic information. Lastly, the inclusion of genomic information considerably reduced the inflation for WWD.The slope  showed only slight changes on inflation (0.01 to 0.04), regardless of the number of added UPGs. When UPGs were added only to A and A22 in ssGBLUP (ssGBLUP_UPGA4 and ssGBLUP_UPGA10), regression coefficients deviated from 1.0, especially for PWG that had b1 equal to 0.01 for ssGBLUP_UPGA4 and 0.65 for ssGBLUP_UPGA10. Those values were both 0.84 when UPGs were fit to A, G, and A22. Inflation values for ssGBLUP and ssGBLUP_MF models were very similar (differences of 0.01 to 0.07), except for WWD, which exhibited higher inflation in ssGBLUP_MF models. The MF models (ssGBLUP_MF4 and ssGBLUP_MF10) yielded the smallest dispersions among all ssGBLUP models for PWG, WWM, and BWD. Conversely, the dispersion for BWM was similar across models, except for BLUP_UPG10, which had the greatest inflation.Dispersion differences between pedigree-based models  were small for all traits . AdditioA, G, or A22 compared with ssGBLUP. The ssGBLUP_UPGA4 model tended to overestimate (G)EBV for direct traits shown positive bias for SC14, PWG, and WWD. The ssGBLUP_UPGA10 model produced the greatest biases for SC14, PWG, WWM, and BWD but no bias for BWM. The least biased models for WWM and BWM were ssGBLUP_MF4 and BLUP_MF4 or ssGBLUP_MF4, respectively. Overall, biases of genomic models with four MFs were similar to pedigree-based BLUP, lower than ssGBLUP models and genomic models with UPGs.Overall, genomic models were more biased than pedigree-based models for both direct and maternal traits; however, MF models tended to have similar biases without genomic information. Biases tended to increase when 10 UPGs were added to pedigree-based models. Slight differences in biases for direct traits were observed when four UPGs (ssGBLUP_UPG4) were added to A, G, and A22, biases increased for all direct traits, but BWD and the magnitude depended on the trait . Conversely, biases decreased for maternal traits (WWM and BWM). In contrast, models with UPGs in A and A22 showed almost no changes in biases for BWD, although bias decreased for WWD and BWM and increased for SC14, PWG, and WWM. Biases also increased when the number of MFs increased from four to 10, except for BWD.Increasing the number of UPGs from 4 to 10 in models without genomic information led to larger biases for almost all traits . AlternaPearson’s correlation coefficients between (G)EBVs of young animals predicted with various models are presented in Correlations between (G)EBVs from different models ranged from 0.40 to 0.98 for WWM . The corThe (G)EBV distribution of validation animals predicted with various models is presented in A matrices (ssGBLUP_UPGA4 or ssGBLUP_UPGA10) showed more thin distributions and higher median. Among all traits, higher variation of (G)EBV across models was observed for WWM (The (G)EBV for WWD  had simi for WWM . OverallSimilar distributions of (G)EBV across models were observed for BWD . AdditioAnimals in the Montana population must be composed of at least three breeds with a minimum of 12.5% of biological type A and a minimum of 25% of combined biological types N and A. In addition, the maximum percentage of each biological type allowed is 37.5% for group N, 87.5% for group A, and 75% for groups B and C .Currently, the genetic evaluation program for the Montana population does not account for missing pedigree. Unfortunately, unless missing pedigree is accounted for, animals with missing parents will have their breeding values regressed toward zero and will likely not be selected as parents of future generations. Unknown genetic groups and MFs can be used to account for missing pedigree and breed structure in base populations. Thus, it is important to assess the ability of UPGs and MFs to account for missing pedigree and breed structure in complex multibreed populations such as the Montana beef cattle population.Missing pedigree and uncertainty regarding the structure of the base population may be accounted for by adding genetic groups called UPGs based on criteria such as year of birth, generation, breed, line, sex, or a combination of these factors. Recently, Γ different from zero permit full consideration of MFs in genetic evaluation, whereas a zero Γ is equivalent to having UPGs for A and A22 . For instance, two unrelated individuals in A will be related through H if these animals are related through the G matrix, even if the pedigree does not show it . The number of UPGs appeared to have a higher impact on GEBV accuracies when they were not added to the G matrix. There is some evidence that it is not necessary to add UPGs to G in purebred populations because this matrix is not affected by missing pedigree. However, matrix G can be affected by line or breed differences EBV is a key component in selection schemes because it permits a fair comparison of (G)EBV among animals, and consequently proper selection decisions (When the slope of the regression of (G)EBV from the complete dataset on (G)EBV from the reduced dataset is equal to 1, both sets of (G)EBVs are on a similar scale. Inflation occurs when becisions . Inflatiecisions .A. Consequently, inflation/deflation can be reduced by a combination of pedigree truncation, incorporation of inbreeding in A, and accounting for inbreeding of unknown parents  or MFs (except for WWD) had only a small impact on GEBV dispersion across traits.  parents .G matrix (ssGBLUP_UPGA), especially for PWG regression coefficients that deviated from 1.0, especially for PWG that had b1 equal to 0.01 for ssGBLUP_UPGA4. This occurs because UPG solutions for PWG and ssGBLUP_UPGA4 from reduced and complete data are very different  and A11  are unrelated , H−1 will not contribute to the estimation of UPG effects EBV when UPGs were added to BLUP and ssGBLUP models, except when those were removed from ifferent . Convers effects . The incG, given that genomic relationships do not rely on pedigree missingness. Matrix G accounts for line and breed differences (G is important to obtain (G)EBVs with the smallest inflation/deflation in the Montana composite beef cattle population. However, this study was based on a small number of genotyped animals; thus, additional research witha larger Montana dataset would be needed to confirm our findings.The inflation/deflation of GEBVs from ssGBLUP_UPG was lower than that of GEBVs from ssGBLUP_UPGA. This raises the question of whether UPGs should be added to ferences ; thus, aBias is defined as the ability to correctly predict the mean breeding value of selection candidates . NonzeroA22 and A11, respectively), H−1 will not contribute to the estimation of group solutions, which is also equivalent to ignoring UPGs (Correlations between (G)EBVs from different models represent the degree of similarity between (G)EBVs across models. The high degree of similarity between EBVs from the various pedigree-based models for all traits indicates that the inclusion of UPGs and MFs produced minor changes in EBV values. Overall, correlations between GEBVs from genomic models were lower than correlations between EBVs from BLUP models, indicating larger changes in GEBV than in EBV. Correlations between (G)EBVs from BLUP and ssGBLUP_MF models were greater than between (G)EBVs from BLUP and ssGBLUP models with or without UPGs. The (G)EBV from UPGs and MF models included group effects; thus, changes in (G)EBV from these models depended on the accuracy of group effect estimates. The low correlations between (G)EBVs from ssGBLUP_UPGA and (G)EBV from other models, particularly for PWG and WWD, indicate inaccurate estimates of UPG effects for these traits. Additionally, when animals with and without phenotypes in the same group are unrelated, group effects are not estimable; thus, the ssGBLUP_UPGA model becomes equivalent to the ssGBLUP model without UPGs. Furthermore, if genotyped animals are not related to non-genotyped animals (animals in ing UPGs . Lastly,Genomic information helped improved the accuracy and persistence of predictions in the Montana composite beef cattle population. Addition of UPGs either to only the pedigree relationship matrix or to both the pedigree and genomic relationship matrices in ssGBLUP models to account for missing pedigree and base population heterogeneity did not improve accuracy, inflation/deflation, and bias of genomic predictions. Thus, addition of UPGs to relationship matrices in ssGBLUP models is not recommended in this population. Although the addition of MFs to ssGBLUP models was unable to increase the accuracy, this model yielded GEBV with lower inflation/deflation for some traits and the least biased genomic predictions. Therefore, this model could be recommended for genomic evaluation in small composite beef cattle populations.jbferraz@usp.br.The data cannot be made publicly available, because it is property of the Montana Tropical Composite breeders and this information is commercially sensitive. Reasonable requests for access to the datasets for research purposes can be e-mailed to JF, Animal Care and Use Committee approval was not obtained for this study because data set was provided by existing database.SK, YM, FB, and DL conceived and designed the project. JE and JF organized sample collection and genotyping. SK, YM, and DL analyzed the data. SK, YM, ST, and DL discussed the results. SK wrote the manuscript. DL and ST edited the manuscript. All authors contributed to manuscript revision and read and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewer AR declared a past co-authorship with one of the authors to the handling editor.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


The purpose of this study was to evaluate the clinical outcome of feldspathic ceramic laminate veneers over a 7-year period using minimally invasive techniques, such as vertical preparation (without prosthetic finish line), or no preparation (no-prep). A total of 170 feldspathic ceramic veneers were cemented in the anterior region, including 70 maxillary and 100 mandibular veneers, after special conditioning of the teeth and restorations. The veneers were evaluated using the FDI World Dental Federation criteria evaluation kit after recalling all the patients between February and June 2021. In total, 14 feldspathic veneers failed and were replaced with lithium disilicate because of core fracture, and 10 cases of chipping occurred on the ceramic surface and were polished. The overall survival rate was 91.77% for up to 7 years of function, with a failure rate of 8.23%. In this retrospective survival analysis, the failures, including the fracture of veneers and dental hard tissue, occurred both in prep and no-prep teeth. No failures were observed in veneers with a maximum thickness of 0.5 mm compared to those with a maximum thickness of 1 mm, 1.5 mm, 2 mm, and 2.5 mm. All dental restorations are liable to failure; even in metal–ceramic prosthetic restorations, fractures can jeopardize function and esthetics .Traditional metal–ceramic restorations have shown predictable strength, acceptable esthetic effects, and long-term survival in the oral environment ; howeverAll-ceramic systems have been developed to achieve the most pleasing esthetic effect and expand treatment options for patients, causing a major shift in clinical workflow .Abrasion and erosion are two increasingly common indications for dental treatment, and, if left untreated, may cause a loss of vertical dimension as well as diffuse and marked dentinal hypersensitivity ,6. To prOwing to their strength, longevity, conservative nature, biocompatibility, and esthetics, feldspathic porcelain veneers are suitable prosthetic restorations in the frontal area, considering the long-term survival rates they achieve ,16,17,18Several ceramic materials and fabrication methods are available for feldspathic porcelain veneers, including the platinum foil technique and the refractory die technique, which is the preferred technique in most laboratories ,18. FeldSeveral case reports present esthetic treatments that improve anterior tooth shape and alignment, size and proportions, and visibility of the teeth ,22,23,24Because of their high degree of translucency, feldspathic ceramics provide an excellent esthetic appearance that can optically approximate natural teeth ,15,25. PIn this retrospective study, we focused on the preparation of dental hard tissue by dividing patients into two groups: a vertical preparation group and a no-prep group. Owing to patient preferences, minimally invasive treatments currently provide the most impressive esthetic effect and excellent clinical performance with minimum thickness restorations ,29,30,31A vertical preparation ,34 is a Some clinical situations involve a minimal to no-preparation approach ,10,24, oApproaches such as additive-only as well as no-preparation ,41,42,43In the case of dental hard-tissue loss, conventional restorations (crowns) normally require endodontic therapy and crown lengthening, procedures that are unable to efficiently conserve pulp vitality and meet the desired objectives ,8,44. InThe combination of feldspathic ceramics and minimally invasive or noninvasive preparations provide clinicians with the option of a conservative approach in prosthodontic dentistry. In our study, we describe high-strength etchable ceramics that can be used at minimum thickness when the adhesive bonding methods of all-ceramic restorations are correctly used, as described by Ostermann .However, the literature offers insufficient data regarding the survival rate and the clinical performance of feldspathic ceramic veneers over extended periods of function.Accordingly, the aim of the present study was to evaluate the long-term clinical performance of feldspathic porcelain laminate veneers over a 7-year period, either using minimally invasive techniques such as vertical preparation without prosthetic finish line, or no preparation. The null hypothesis of the study was that there were no statistically significant differences between the clinical performance of feldspathic ceramic veneers with a maximum thickness of 0.5 mm, 1 mm, 1.5 mm, 2 mm, and 2.5 mm over a 7-year period.This retrospective study included 30 patients aged between 18 and 72 years, with a mean age of 36.7 ± 12 years. The patients (16 men and 14 women) visited our private dental clinic between 2013 and 2014; they were all treated by the same clinician (S.G.M.) and received 170 feldspathic ceramic veneers (70 applied on maxillary teeth and 100 on mandibular teeth). The study was approved by the Institutional Review Board of “Vasile Goldiș” Western University of Arad. All patients agreed to participate in the study and gave their written informed consent. Two methods were used: a minimally invasive/biologically oriented preparation (prep) technique for 108 veneers, and a no-preparation (no-prep) approach for 62 veneers. The veneers were also divided in five groups, according to their maximum thickness: 0.5 mm, 1 mm, 1.5 mm, 2 mm, and 2.5 mm. The biologically oriented preparation technique is a vertical preparation technique without a finish line, used to create a new anatomic crown with a prosthetic emergence profile. We opted for one of these two treatment options after carefully assessing several factors: tooth attrition, malocclusion, dental anomalies, and esthetic alteration.Vital teeth without endodontic treatment or major crown destruction were eligible to be included in the study. Patients who presented any parafunctional signs and symptoms of bruxism according to the International Classification of Sleep Disorders  were excAll patients were monitored periodically for at least 2 years after they received the veneers.All restorations were made following a case set-up protocol. First, the patients underwent an esthetic and functional analysis , and impIn the group in which we applied minimally invasive techniques, the objective was to obtain space for the future restoration, removing the maximum tooth convexity and any existing undercuts . The teeProvisional restorations were prepared to maintain tooth position, function, and esthetics using a mock-up as described previously. Using a double-mixing technique, a full-arch, polyvinylsiloxane  single impression was made for the opposing arch, and a type IV dental stone  was poured immediately.2. A glycerin gel was applied on the restorations and the polymerization procedure was performed for an additional 20 s to eliminate the oxygen inhibition layer. Any excess cement was removed with a scaler, dental floss, and a double-edged 12D surgical blade. The accessible restoration margins were further finished , washed and rinsed with water, and dried. Since etching with hydrofluoric acid leaves a significant amount of crystalline debris precipitate on the ceramic surface, the feldspathic restorations were also cleaned for 60 s using 36% orthophosphoric acid  c and ultfinished f and polAfter cementation, periodic evaluations were performed every 6 to 12 months  by two dentists who did not participate in the restorative procedure at the time of cementation (baseline). For the final re-evaluation, after at least 7 years of function, all the patients were recalled between February and June 2021.The restorations were evaluated for apparent changes in their external structural integrity and marginal integrity. Secondary caries, fracture of the restoration/tooth, debonding of the indirect restoration, severe periodontal breakdown, or pulpal necrosis were considered absolute failures. A clinical qualitative evaluation was performed using the FDI World Dental Federation criteria ,49 for ap < 0.05. The feldspathic ceramic veneers were analyzed starting at baseline and ending when the clinician determined that an irreparable failure of the restoration occurred. When a veneer failed, it was replaced with a new lithium disilicate restoration.Collected data were statistically analyzed using the SPSS Statistics platform . Nonparametric statistical tests  were used to analyse the categorical data sets. The survival rate of the indirect restorations was calculated using the Log Rank (Mantel-Cox) test. The tests were considered statistically significant for p = 0.814).No statistically significant differences were found between the maximum thickness (mm) of the veneers used in the no-prep and prep method , C6 and C10 (p < 0.001), and for C8 (p = 0.001), respectively.The Mann–Whitney U test results for comparing the prep and no-prep methods for each FDI criterion after a 7-year period showed that the scores for the no-prep method were significantly higher than the scores for the prep method for C3 (p < 0.001), C3 (p < 0.001), C4 (p < 0.001), C6 (p < 0.001), C7 (p = 0.004), C8 (p < 0.001), C9 (p = 0.001), and C10 (p < 0.001).The Kruskal–Wallis H test results for comparing the five groups of maximum veneer thickness  for each FDI World Dental Federation criterion after a 7-year period showed statistically significant differences for the following criteria: C1  after comparing the baseline scores (T1) and the scores after 7 years (T7) for each FDI criterion are presented in The Wilcoxon Signed Ranks test results .The functional properties on marginal adaptation were also very good (score 1).Regarding the biological properties, postoperative sensitivity and tooth vitality were rated as excellent (score 1) for the no-prep method, while the adjacent mucosa was rated as excellent (score 1) for both methods. No secondary caries or pulpal necrosis was observed in the natural teeth.Out of 170 veneers, 156 veneers (91.77%) survived after 7 years of function, with a failure rate of 8.23%. A total of 14 feldspathic veneers completely failed due to core fracture and were replaced with lithium disilicate restorations.p = 0.247), and for the five thickness groups (Log Rank (Mantel-Cox), p = 0.065).The failures were both on prep and no-prep teeth, but no failures were observed for the veneers with a thickness of 0.5 mm . No statWe observed that the veneers with a thickness higher than 1.5–2 mm were more susceptible to fracture b; the frIn this retrospective study, we evaluated the clinical outcome of feldspathic veneers placed in our private practice for up to 7 years. Feldspathic veneers had a survival rate of 91.77%, which is comparable with the results of previous studies ,35,50. TRegarding the esthetic objectives, we found similarities with other studies , which aWhen using minimally invasive or no-prep techniques, the vertical dimension of occlusion (VDO) can be safely increased for up to 5 mm in the anterior region without causing pain or discomfort ; the patThe accuracy of the new VDO can be verified with the phonetic test by analyzing the pronunciation of words, particularly the use of the “s” consonant , as wellAlthough the materials used in all-ceramic restorations have been recommended for fabricating inlays/onlays ,54,55 anGenerally, higher tensile and shear stress occurs when there are large areas of unsupported feldspathic ceramic (as in cases of diastema closure and teeth with chipping  or fractThe final color of the tooth is affected by the thickness of the restoration, substrate color, ceramic color, and cement shade ,60. FeldA photoshop assessment and functional evaluation, as well as a wax-up and mock-up, were used during pre-prosthetic planning. The esthetic properties of such restorations depend on the technician’s ability to properly replicate the anatomy, color, and translucency into the restoration; therefore, a strong collaboration between the patient, dentist, and technician is crucial ,14.An advantage to feldspathic ceramics is the absence of a core material, which allows increased space for characterization in the middle and incisal thirds; some of these materials showed excellent antibacterial performance owing to the 30% nanosized percentage of Ag ions . With thThe minimally invasive adhesive treatment is limited only to vital teeth without discoloration. The preservation of tooth structure and the remaining enamel should provide sufficient resistance strength, even in the presence of reduced thickness of the ceramic feldspathic material.In a quality assessment of dental treatments using en-face optical coherence tomography, Sinescu et al.  found miThe results obtained in this retrospective study showed that the use of feldspathic ceramic veneers in a private general practice, using minimally invasive preparation methods, achieved an overall success rate of 91.77% over a period of 7 years, on vital teeth without major crown destruction. The failures, including the fracture of the veneers and dental hard tissue, occurred both in prep and no-prep teeth. No failures were observed in the veneers with a maximum thickness of 0.5 mm, compared to those with a maximum thickness of 1 mm, 1.5 mm, 2 mm, and 2.5 mm. No statistically significant differences were found between the time-dependent survival curves for the two methods, and for the five thickness groups.No secondary caries or pulpal necrosis were observed. The postoperative sensitivity and tooth vitality were rated as excellent for the no-prep method. All the feldspathic ceramic veneers were rated clinically excellent for color match, translucency, marginal adaptation, and adjacent mucosa, both for the prep and the no-prep method.


To discuss the clinical application value of contrast-enhanced ultrasound (CEUS) in testicular occupied lesions.  Nine conventional-ultrasound-found testicular occupied lesions which underwent CEUS meantime were analyzed retrospectively. The CEUS perfusion pattern was compared with the surgical pathological result or follow-up findings.  Among all the 9 testicular occupied lesions, there were 5 testicular malignant tumors, 1 testicular benign tumor, 1 testicular tuberculosis, and 2 testicular hematomas. CEUS diagnosed 6 testicular malignant tumors, 1 testicular benign tumor, and 2 testicular hematomas, and its diagnostic accuracy was about 88.9%.  CEUS has high clinical application value in the differential diagnoses of benign and malignant testicular occupied lesions. Testicular tumors are relatively rare, typically speaking, which accounts for only 1% of all sorts of malignant tumors of the whole body, but they are the most common solid tumors in young men aging from 20 to 40 years old, almost all of which are malignant . In mostDue to its convenience and noninvasive advantages, ultrasound examination has been widely used in the diagnosis of testicular occupied lesions, and it has become an important method of distinguishing benign and malignant testicular tumors. Contrast-enhanced ultrasound (CEUS) is a safe, relatively cheap, and widely available imaging technology . It usesCollecting testicular occupied lesion cases during November 2013 and September 2020, which were detected by routine ultrasound examination in our hospital, we had 9 patients in all. Five cases had lesions in the right testicles and 4 cases in the left ones. Besides these, 2 cases had a history of testicular trauma. Patients were aged from 30 to 59 years old, 38 years old on average. The size of lesions was 52 mm × 25 mm × 25 mm maximum and 8 mm × 3 mm × 7 mm minimum. CEUS was performed in all 9 cases.Aplio 500  ultrasonic scanner with a 5~14 MHz linear transducer was used for an ultrasound examination. It was also equipped with color Doppler flow imaging (CDFI) and CEUS imaging software. The patients lay supine on the couch, fully exposing the scrotums. We scanned the scrotums from multiple sections and angles. First, the testicular scan was performed with conventional ultrasound, focusing on the observation of the location, size, number, morphology, boundary, and internal echo of the lesions. CDFI was then used to observe the distribution of blood flow in and around the lesions. After that, we switched it to CEUS mode. SonoVue was used as the contrast agent. 5 ml of normal saline (NS) was injected before use, and 2.4-3.0 ml of the mixture was extracted after shaking. After windowing the best image of the lesion, the extracted mixture was injected rapidly through the cubital vein, followed by 5 ml of NS, and a timer was set simultaneously. After contrast agent injection, real-time images were observed continuously for 3-5 mins. All images were archived for offline analysis. Two to three experienced senior sonographers repeatedly reviewed the playback clips, so as to dynamically observe the changing trend of contrast agent; summarized the perfusion pattern of contrast agent in terms of time and echo intensity; and analyzed the CEUS results. Finally, the medical history and pathological data were followed up for comparative analysis.CEUS descriptions: (1) the enhancement intensity of the mass was divided into hyperenhancement, isoenhancement, hypoenhancement, and no enhancement; (2) the homogeneity of enhancement was divided into homogeneous enhancement and heterogeneous enhancement; (3) compared with normal testicular tissues, the entering time and washout time of the contrast agent were observed, and the enhancement phase of mass was divided into fast-in and fast-out, fast-in and slow-out, slow-in and fast-out, slow-in and slow-out, etc.Testicular occupied lesions showed hypoechoic or heterogeneous echogenic regions in the testis on gray scale ultrasonography and weak or rich blood flow signals in some cases on CDFI . There wAll 9 patients with testicular occupied lesions were followed up or surgically treated.Six cases were suggested as malignant tumors by CEUS, and 5 of them were confirmed correct by surgical pathology (including 3 seminoma cases and 2 mixed germ cell tumor cases). The other one was testicular tuberculosis confirmed surgically. CEUS showed a benign tumor, and the surgical pathology was an adenomatoid tumor of the testis. Two cases of testicular hematoma were confirmed by follow-up observation. The CEUS diagnostic accordance rate of testicular occupied lesions was approximately 88.9% (8/9).Testicular tumors are classified into germ cell and nongerm cell types. Germ cell testicular tumors account for the majority of them, of which about 95% are malignant, and seminoma is the most common type . NongermEarly detection, diagnosis, and treatment are the keys to improve the cure rate of testicular tumors . UltrasoAmong the CEUS manifestations of all the 5 testicular malignant tumor cases, fast-in and fast-out enhancement was seen in 2 seminomas and 2 mixed germ cell tumors, and fast-in and slow-out enhancement was seen in 1 seminoma. Heterogeneous hyperenhancement was seen at their peak time. One testicular adenomatoid tumor presented fast-in and fast-out enhancement and slightly heterogeneous hyperenhancement at the peak time, which was similar to a testicular malignant tumor, indicating abundant blood supply inside. A testicular adenomatoid tumor is a kind of benign tumor without typical clinical manifestations. Substantially occupied lesions on gray scale ultrasound can usually be seen in the regional part of the testicle, which is with clear boundaries, homogeneous internal echo, and hypoecho or isoecho compared with the surrounding tissues . Since tThe reason why 1 case of testicular tuberculosis was misdiagnosed as a malignant testicular tumor in this study was that it had similar CEUS characteristics to testicular malignant tumors, which brought certain difficulties to the differential diagnosis. So, when we meet patients with diffuse nodules, details of TB history should be inquired about, because the exact clinical history data plays a suggestive role in the diagnosis of TB .Ultrasonic contrast agent SonoVue is the ideal contrast agent; its characteristics are listed as follows: (1) nontoxic; (2) possible to intravenously inject; (3) circulation through the lungs, heart, and capillaries; and (4) stability of recirculation. Ultrasound contrast agents can increase the reflective difference between the tumor and normal tissue and enhance the Doppler blood flow signals inside lesions. The vascular morphology, distribution, and blood supply status of tumors can be displayed more completely. It is possible to effectively improve the detection of tumor vessels, so as to evaluate them more accurately. When coming to combined diagnosis with CDFI, CEUS is hopeful to elevate the diagnosis rate and differential diagnosis rate .This study has limitations. The number of research cases is limited, and we call for further in-depth research with a larger sample size to improve the diagnostic accuracy of testicular space-occupying lesions. In future studies, I will collect more clinical samples for further verification. We will study the clinical application value of CEUS in the diagnosis, staging, and follow-up of testicular space-occupying lesions.In conclusion, as it is noninvasive, nonradiative, and possible to observe the real-time blood perfusion of testicular occupied lesions dynamically, CEUS has a high clinical application value of the diagnosis and differential diagnosis concerning benign and malignant testicular occupied lesions. We reported for the first time the application value of CEUS as a benign and malignant diagnosis and differentiation of testicular space-occupying lesions. It has important value in the diagnosis of testicular space-occupying lesions.


Cardiovascular diseases, cancers, chronic respiratory diseases, and diabetes are the 4 main noncommunicable diseases. These noncommunicable diseases share 4 modifiable risk factors . Short smartphone surveys have the potential to identify modifiable risk factors for individuals to monitor trends.We aimed to pilot a smartphone-based information communication technology solution to collect nationally representative data, annually, on 4 modifiable risk factors.We developed an information communication technology solution with functionalities for capturing sensitive data from smartphones, receiving, and handling data in accordance with general data protection regulations. The main survey comprised 26 questions: 8 on socioeconomic factors, 17 on the 4 risk factors, and 1 about current or previous noncommunicable diseases. For answers to the continuous questions, a keyboard was displayed for entering numbers; there were preset upper and lower limits for acceptable response values. For categorical questions, pull-down menus with response options were displayed. The second survey comprised 9 yes-or-no questions. For both surveys, we used SMS text messaging. For the main survey, we invited 11,000 individuals, aged 16 to 69 years, selected randomly from the Norwegian National Population Registry (1000 from each of the 11 counties). For the second survey, we invited a random sample of 100 individuals from each county who had not responded to the main survey. All data, except county of residence, were self-reported. We calculated the distribution for socioeconomic background, tobacco use, diet, physical activity, and health condition factors overall and by sex.The response rate was 21.9% . The median age for men was 52 years (IQR 40-61); the median age for women was 48 years (IQR 35-58). The main reported reason for nonparticipation in the main survey was that the sender of the initial SMS was unknown.We successfully developed and piloted a smartphone-based information communication technology solution for collecting data on the 4 modifiable risk factors for the 4 main noncommunicable diseases. Approximately 1 in 5 invitees responded; thus, these data may not be nationally representative. The smartphone-based information communication technology solution should be further developed with the long-term goal to reduce premature mortality from the 4 main noncommunicable diseases. Cardiovascular diseases, cancers, chronic respiratory diseases, and diabetes are commonly grouped as the main noncommunicable diseases as they are the world’s biggest killers -3. TheseIn 2013, the World Health Assembly, the decision-making body of the World Health Organization, adopted a Global Monitoring Framework for noncommunicable diseases with 25 key indicators to track progress in prevention and control of noncommunicable diseases . Before Statistics Norway performs annual surveys, with representative samples, on tobacco use . FurtherIn Norway, more than 95% of individuals aged 16 to 54 years, and between 74% to 88% of those aged 55 to 74 years, have smartphones . Short sThis pilot study, which included a smartphone-based solution, a website, and 2 smartphone surveys, was developed over a 2-year period and conducted during fall 2019.The details of the technical and architectural parts of the solution were developed by a private enterprise . For answers to the continuous questions, a keyboard was displayed for entering numbers ; there wThe information communication technology solution was intended for capturing sensitive data from smartphones and was developed in accordance with general data protection regulations . The cloWe developed a website to inform invitees and other interested parties about the study and survey . The webWe designed 2 mobile phone surveys—the first was sent to all invitees (main), and the second was sent only to a random sample of invitees who had not responded to the main survey. A total of 4 sets of SMS messages were sent: 1 request to participate in the main survey, 2 reminders, and 1 request to participate in the second survey . InviteeThe survey comprised 26 questions in Norwegian. There were 8 questions on socioeconomic background factors: year of birth, sex, education in years , marital status , number of persons in the household over and under 18 years , gross household income in Norwegian Kroner  during the previous year , and occupational status .There were 17 questions on the 4 main risk factors. The questionnaire contained 3 questions about cigarette, snus, and e-cigarette use  and 1 question about alcohol consumption . Consumers of alcohol were also asked the first 3 questions from the Alcohol Use Disorders Identification Test —frequencThere was 1 question asking if respondents have or have had any of the following conditions: high blood pressure, high cholesterol, atrial fibrillation, myocardial infarction, heart failure, stroke, chronic respiratory disease, cancer, diabetes, or none of these. In addition, there was an open box for comments. The estimated time for completing the main survey was approximately 5 minutes.The second survey comprised 9 statements that could be answered in the affirmative or negative: “I never answer such surveys”; “I did not want to answer several of the questions”; “I think the questions were difficult to answer”; “I was unsure who the SMS came from”; “I was expecting a login with BankID” (BankID is an electronic identification scheme in Norway for safe log in); “I was afraid that privacy was not taken care of”; “I had not heard of the Norwegian Centre for E-health Research”; “I had not heard of Healthcom”; “I thought the SMS I received looked like spam.” The estimated time for completing this survey was approximately 1 minute. There was also an open box for comments.The main survey was conducted on 11 consecutive days, with 2 reminders sent 5 and 10 days after the original invitation. The second survey was conducted 1 week after the main survey was completed.The Regional Committee for Medical and Health Research Ethics concluded that approval for this study was not necessary because the study fell outside the Norwegian Health Research Act. The study was approved by the Data Protection Section of the University Hospital of North Norway. All participants provided consented before answering any survey questions.A total of 11,000 individuals  aged 16 to 69 years, with 1000 from each of the 11 counties in Norway, were selected randomly from the Norwegian National Population Registry. All Norwegian residents have an 11-digit personal identification number in the National Population Registry. This registry contains the name, address, sex, age, and mobile phone number of each person. Persons who did not have a registered mobile phone number were replaced. For each person, name, personal identification number, phone number, sex, age, year of birth, and county of residence were retained. Subsequently, the system created a unique survey number for each participant. The Data Protection Section of the University Hospital of North Norway provided a server area specifically for this project where the linkage file could be stored. For the second survey, SMS text messages were sent to a random sample of 100 invitees who had not responded to the main survey from each of the 11 counties. The communication group at the Norwegian Centre for E-health Research sent a standard press release to each county before the launch of the survey. The press release was followed up with phone contact to selected local media in each county. The communication group used social media (Facebook and Twitter) to promote the survey. Several municipalities informed their residents about the survey on municipality website. The project leader also gave interviews on the local radio and to newspapers in some of the counties. In total, the survey was covered in various media channels 127 times.All data used in the analyses, except county of residence, consisted of self-reported data. We calculated means (with standard deviations) or medians (with interquartile range) and percentages for each health variable, overall and by sex, using STATA .Altogether, 25.2%  participants opened the survey, while 21.0%  submitted their responses. We excluded 2 participants reporting to be outside the targeted age groups. The remaining 2303 men and women constituted the respondents to the main survey.The response rate to the main survey was 21.9% . Among men and women, the response rates were 15.7% (866/5500) and 25.4% (1397/5500), respectively. The median age for men was 52 years (IQR 40-61), and the median age for women was 48 years (IQR 35-58). Trøndelag county had the highest response rate , and Vestland county had the lowest response rates .Of the 2303 respondents, 1419 (61.6%) answered all the questions; 15 of 29 variables were missing ≤3% values. Each of the questions on socioeconomic background factors had missing values, which ranged from 10.3% (238/2303) for marital status to 20.6% (474/2303) for number of persons under 18 years old in household. Tobacco and alcohol consumption variables had ≤3% missing values, physical activity variables had 1.8% (41/2303) to 9.7% (224/2303) missing values, and food variables had 1.5% (35/2303) to 5.9% (136/2303) missing values .Most respondents were in the oldest (50-69 years) age group , in the highest educational category , married , and employed full-time  .Daily use of cigarettes , snus , and e-cigarettes  was reported by respondents, and 32.2% (237/735) of men reported drinking alcohol more than once a week, of whom 7.1% (51/724) reported consuming ≥6 units on the same occasion weekly, and 22.7% (254/1119) of women reported drinking alcohol more than once a week, of whom 1.7% (19/1103) reported consuming ≥6 units on the same occasion weekly. Overall, 17.2% (378/2199) reported 0 days with moderate physical activity during the last 7 days .Only 44.5% 984/2209) of respondents were in line with national recommendations for BMI, and 42.0% 932/2219) of respondents were in line with national recommendations for tobacco or e-cigarette use [9 of resp9 of respAltogether, 18.1% (199/1100) of the invitees to the second survey opened it, but 8.2% (90/1100) did not submit a response, while 9.9% (109/1100) replied to some or all and submitted their answers. The latter group constituted the respondents of the second survey. The most common reason for not participating (in the main survey) was “I had not heard of Healthcom” , followed by both “I had not heard of the National Center for E-Health Research” and “I was unsure who the SMS came from” , then “I thought the SMS I received looked like spam” .This feasibility study is, to the best of our knowledge, the first successfully piloted smartphone-based information communication technology solution with technically, ethically, and regulatory functionalities for collecting annual data on the 4 main modifiable risk factors for the 4 main noncommunicable diseases. The primary reason reported for not participating in the initial survey was that the sender of the SMS was unknown. Due to the differences in response rates between men and women and between counties, our secondary objective to collect nationally representative data may not have been achieved. If the respondent sample has a similar distribution with respect to background characteristics, life style factors, and dietary intake variables, they may be nationally representative regardless of response rate.We are not aware of any previous work with the same overall objectives as ours.We chose to use SMS text messaging as the means of initial contact, instead of internet or email surveys, ordinary or computer-assisted telephone interviews, or interactive voice response because text messages are often perceived as personal forms of communication; they are more likely to be read quickly, understood, and responded to upon receipt ; and theIn 2017, Pariyo et al  suggesteIn addition to randomized selection of participants, response rate is often considered to be an important factor in obtaining representative data. Our response rate  was similar to those of 2 Norwegian eHealth research studies—a large population-based randomized controlled trial on smoking cessation with SMS text messaging or emails  and a weIt is common for researchers to use monetary incentives (such as gift certificates or lottery tickets) to increase participation -31. InstThere is, as far as we know, no commonly accepted minimal response rate. In the UK Biobank cohort , there wHealth and Disease—was too general.We assume that our response rate would have been higher if our university, a renowned entity, had been the sender. Instead, the Norwegian Centre for E-health Research, which was established in 2016 (a few years before the survey), and Healthcom both appeared as senders of the initial SMS. A systematic review  found thHelsenorge  services resulted in further selection problems.Another Norwegian eHealth study , which eOur survey was conducted in 2019 (before the COVID-19 pandemic) in Norway, and approximately 1 in 5 respondents  reported being obese. In fall 2020, after the first national lockdown, the Norwegian Institute of Public Health conducted a pilot study, collecting data on risk factors for the 4 main noncommunicable diseases and several other topics , which nSimilar to our findings, (1) the 3 previously described eHealth studies ,28,38 foIn our survey, 10.7% 240/2235) reported smoking daily. For 2019, Statistics Norway reported overall daily smoking to be 9% for both sexes [/2235 repIn our survey, 32.3% (237/735) men reported drinking alcohol more than once a week; the corresponding figure for Statistics Norway survey was 34%. In our survey, 7% (51/724) of men reported having consumed more than 6 units on the same occasion weekly; the corresponding figure for the 2019 Statistics Norway survey was 5%. In our survey, 23% (254/1119) of women reported drinking alcohol more than once a week; the corresponding figure for the 2019 Statistics Norway survey was 28%. In our survey, less than 2% reported having consumed more than 6 units on the same occasion weekly; the corresponding figure for the 2019 Statistics Norway survey was 3%.A recent review  found thFor a nationally representative study population, participants were sampled randomly from each of the 11 counties. Major assets were that our main survey could be answered in 5 minutes and comprised already validated questions.The main limitation of our study was the low response rate. Other limitations include the use of self-reported information and that only individuals who had a smartphone could participate; however, since smartphone ownership exceeds 80% in Norway , not beiShort smartphone surveys have the potential to be used to monitor trends annually to identify high-risk groups for the 4 main noncommunicable diseases. This knowledge can subsequently be used for better targeting of interventions and in policy making, to meet the United Nations Sustainable Development Goal to reduce premature mortality from noncommunicable diseases by 33% by 2030 [We encourage the further study of short mobile phone-based surveys regarding the modifiable risk factors for the 4 main noncommunicable diseases in high-, low-, and middle-income countries. Our study included only Norwegians, of whom the majority had more than high school level of education. Future studies should develop surveys that are easily recognized as research, have a well-known sender, and can be distinguished from spam. We recommend examining if an offer to the invitees for personalized feedback in response to their answers about the modifiable risk factors will increase overall participation.We successfully developed and piloted a smartphone-based information communication technology solution for collecting data annually on the four modifiable risk factors for the 4 main noncommunicable disease from a random sample of the Norwegian population; 1 in 5 responded, thus our secondary objective to collect nationally representative data may not have been achieved.


This paper provides the basis for understanding the preparation and properties of an old, but advanced material: activated carbon. The activated carbons discussed herein are obtained from “green” precursors: biomass residues. Accordingly, the present study starts analyzing the components of biomass residues, such as cellulose, hemicellulose, and lignin, and the features that make them suitable raw materials for preparing activated carbons. The physicochemical transformations of these components during their heat treatment that lead to the development of a carbonized material, a biochar, are also considered. The influence of the chemical activation experimental conditions on the yield and porosity development of the final activated carbons are revised as well, and compared with those for physical activation, highlighting the physicochemical interactions between the activating agents and the lignocellulosic components. This review incorporates a comprehensive discussion about the surface chemistry that can be developed as a result of chemical activation and compiles some results related to the mechanical properties and conformation of activated carbons, scarcely analyzed in most published papers. Finally, economic, and environmental issues involved in the large-scale preparation of activated carbons by chemical activation of lignocellulosic precursors are commented on as well. Since the last century, exorbitant growth in all aspects of human activity has taken place, in part due to the rise of the human population itself. Thus, the world’s population has boosted from 2.5 billion in 1950 to tripling up to 8 billion in 2021, with the projections for 2050 of about 9.6 billion people . ActivatIn view of all this, it is not surprising that the demand for AC materials will increase in the coming years, and also their price, in part as a consequence of the increasing use of ACs in water treatment. As an example, the world’s production of ACs was 1.7 million tons in 2020, and the predictions for the next five years point to an annual increase of 3%, standing at about 2 million tons . Thus, tACs have been prepared since pre-Egyptian times, although it was during the 19th century that numerous trials were carried out to improve ACs properties and performance. These studies were collected by Ostrejko (1900), who published the patents that later derived the two most widely used methods for the production of ACs at an industrial level: the so-called physical activation and chemical activation, British Patent 14,224, 1900; French Patent 304,867, 1901; German Patent 136,792, 1901, and US Patent 739,104, 1903 [Chemical activation is (wrongly) generally defined as a solid–solid reaction that involves intimate mixing of a carbonaceous precursor with a chemical (activating) compound , followed by heat treatment ,10,11,12In general terms, the published papers on the preparation of activated carbons by chemical activation have focused on different activating agents, different precursors, and different (activation) experimental conditions, which have led to a wide variety of porosities. In most cases, the achieved porosity has been the main concern, together with the final yield, whereas surface chemistry has been less studied.In parallel with studies devoted to the preparation of ACs, the use of these sorbents in a wide range of applications has been deeply investigated. Moreover, since the 2000s, the mechanism of chemical activation has also been analyzed with the aid of different experimental techniques ,23,24, b2 removal as examples, has received great attention [Recently, all the previous knowledge/background about chemical activation has been applied to the use of lignocellulosic sources as precursors ,19,25,26ttention ,32,33,34On one hand, little attention has been paid to the physicochemical transformations of the lignocellulosic biomass components during heat treatment. Also, the obtained yields and porosity developments require some revision, comparing them with those obtained by physical activation of similar precursors. Moreover, although the importance of the porosity development is undoubtful, little attention has been paid to the characterization of other features, which determine the use of these adsorbents in novel and important applications. For example, only a few studies have analyzed the surface chemistry of the activated carbons, and no clear conclusions have been extracted about the relationship between activation conditions and surface chemistry. Other features, such as density, granulometry-morphology, mechanical properties, electrical properties, or the presence of heteroatoms have been less analyzed. Very little attention has been paid, as well, to scaling up laboratory procedures or to the main economic and environmental issues and concerns, such as the possibility of recycling the activating agents for further activations. Therefore, this work aims to revise and comment on the published information devoted to some of those topics.Activated carbon is identified by the ACS registry number 7440-44-0 and from the point of view of chemical composition is mainly based on carbon (C). AC is macroscopically considered an amorphous structure derived from an allotropic modification of graphite; all forms of synthesized ACs contain heteroatoms  and, structurally, it can contain some crystalline domains and have different order degrees. The presence of heteroatoms is largely linked to the organic origin of each precursor and the activation process.As mentioned, the ACs′ total porosity, pore size distribution and the nature/content of their surface chemistry can be “easily” tailored ,18,25 byOne of the first advantages of chemical activation is its versatility in terms of the raw materials used as precursors for the production of ACs. Thus, any material and/or residue with a certain carbonaceous matter content can be used for the production of ACs ,13,25,35Thus, because of the high carbon content in coals see , they haData in 2SO4, ZnCl2, H3PO4, KOH, and NaOH, etc., showing from neutral to acid or basic character. It reacts in a controlled manner with carbon, consuming some of it, and creating porosity [2 and H3PO4 are the most suitable activating agents for low-ordered precursors , whereas alkaline hydroxides are more suitable for the activation of highly ordered ones  [The activating agent. It covers Hporosity ,11,21,25notubes) ,39.Heating treatment. Either pyrolysis followed by activation  and/or a single step chemical activation are required for preparing activated carbons, being the heating rate, the activation temperature, and the holding time at the activation temperature among the most influencing experimental parameters ,37. In aAtmosphere. The heating occurs in presence of a controlled gaseous atmosphere, commonly flowing gas ,25, whicThus, the preparation of activated carbons stands out for the wide variety of procedures used. Once the precursor is known/selected, three main preparation variables can be highlighted . The objective is to obtain a higher final carbon yield. Thus, temperatures between 400–900 °C can be used, although they are usually higher than 600 °C so that aromatization and condensation take place [2, CH4, H2, H2O, …) or tar , leaving a solid residue with a high carbon content, called carbonized solid or (bio)char [As a result of the temperature increase, some heteroatoms (other than carbon) are eliminated in the form of gaseous compounds. The exit of these gases leaves unsaturated parts of the molecules , which thus facilitate radical addition reactions , favorinbio)char ,17,18,25bio)char ,17,18,25bio)char ,17.When preparing ACs, one of the objectives of the carbonization stage is to maximize the char (carbonized) fraction. For that purpose, it is necessary to know which are the most appropriate features of the precursor so as to obtain high carbonization yields. The analysis of the pyrolysis process in lignocellulosic materials is extremely complex as a consequence of the chemical and structural complexity of the organic macromolecules that constitute them ,52,53. TParallel to the release of tar and volatile matter, a condensation process takes place due to bonding of unsaturated carbon atoms during the pyrolysis process ,57. The 2SO4, ZnCl2, H3PO4, KOH, and NaOH [3PO4 or ZnCl2, one of the main roles of the activating agent is to facilitate the dehydration of the carbonaceous macromolecular skeleton, which will influence the subsequent pyrolytic decomposition of the material, thereby reducing the production of tar and volatiles, and increasing the yield [As explained, an activation process is required to get a noticeable porosity and, for that purpose, the use of a chemical/activating agent is required. The most common activating agents are Hand NaOH ,11,22,25he yield ,24. Likehe yield .In the activation, intimate contact between the precursor and the activating agent is required. This confirms that the mixing procedure is important in the activation procedure. Thus, when using a solution of the activating agent, the precursor and the activating agent solution are mixed by stirring (impregnation) for several hours, up to 24 h, at temperatures ranging 60–150 °C depending on the chosen activating agent and precursor ,12,18,23As stated, other important factors are the activation atmosphere, the activation temperature, and the time. Chemical activation is carried out under an inert atmosphere, usually passing a nitrogen gaseous stream through the mixture ,19,25,37Another advantage of chemical activation, as a consequence of the chemical control in the precursors’ activation and the lower temperatures used, are the high yields generally achieved in chemical activation  ,9,63,64.With the idea of depicting and summarizing the general trends on the activation yields and specific surface areas achieved by chemical activation, 2 of a lignocellulosic precursor, walnut shell. In this case, two heating steps in different atmospheres are required, pyrolysis in N2 to get the biochar , and heat-treatment in CO2 for the proper activation (see the corresponding temperature ranges depicted in the figure). CO2 activation implies larger temperatures and results in the lowest yield, mainly due to the important weight loss during pyrolysis (at 300–500 °C) in order to develop a (bio)char. If these data are compared with the activation of lignocellulosic materials impregnated with phosphoric acid or zinc chloride, it can be concluded that although initially (up to 200 °C) H3PO4 or ZnCl2 activation show higher weight loss, in the temperature range of 200–500 °C the weight loss is lower, and hence in chemical activation the yields are generally larger than for CO2 activation.This figure also represents information about physical activation with CO3PO4, ZnCl2, KOH, and CO2 activation, respectively [With the aim of enlightening the role of each activating agent, ectively ,11,25,372/g range [2/g [These notorious differences are a consequence of different physicochemical processes involved in the activation with each activating agent, see summary in /g range ,18,25,37nge [2/g .2 activation is an endothermic process that needs temperatures higher than 800 °C to be initiated. The process kinetics is controlled either by the rate of the chemical reaction or by diffusion, depending on the temperature range. At lower temperatures , the rate of the chemical reaction (C + CO2 ⇌ 2 CO) is determinant, and CO2 molecules can penetrate the carbon structure before gasification [In the case of physical activation, commented for comparison purposes, porosity is mainly produced via carbon gasification ,25,37. Cfication . As a refication . At high2 evolved in the thermal decomposition of generated potassium carbonate takes place [For chemical activation, some differences are observed depending on the chosen activating agent. In the case of potassium hydroxide activation, as an example, porosity is produced by two processes. Potassium hydroxide reacts with carbon, producing potassium carbonate, hydrogen, and some potassium compounds, namely metallic potassium and/or potassium oxide, and, as a result of such reaction, some carbon is consumed, generating porosity in the carbon-rich matrix ,21,22. Aes place . Simultaes place . This exes place .3PO4 and ZnCl2 activation, combined chemical and physical processes are also involved in the porosity generation [3PO4 and ZnCl2 promote the degradation of biopolymers during the heat treatment, accelerating the condensation and aromatization reactions. Thus, comparison between the weight loss in H3PO4 activation of wood with that in a similar heat-treatment of wood in absence of activating agent, shows in the former a high weight loss in the 100–200 °C temperature range  ZnCl2 [4O10 from 400 °C, reacting with the carbonaceous material. Carbon gasification takes place, originating porosity, as well as widening any pristine porosity in the precursor. An adverse effect of the decomposition of phosphate linkages is the shrinkage of the macrostructure (at 350 °C), with some porosity reduction. In the case of ZnCl2, the shrinkage (with the same effects) takes place around 600 °C.In the case of Hl) ZnCl2 . For pho3PO4 (350–500 °C), ZnCl2 (500–700 °C), and KOH (700–900 °C).Thus, in general terms, The result of the detailed processes involved in chemical activation is a material, activated carbon, whose structure could, in principle, be described as disorganized. Even today, research is being carried out to get to a correct interpretation of the AC structure, and even some authors prefer to describe these materials as disorganized nanoporous carbons . In thisAs already commented, and as a result of their porous nanostructure, ACs are excellent adsorbents. An intensification of the weak physical interactions  between the surface (pores) of the carbon and the adsorbate molecules confined in these nanospaces occurs. Additionally, strong  interactions may appear between the activated carbon surface and the adsorbate molecules at specific sites, leading to strongly retained (chemisorbed) molecules . Under sThe study of the surface chemistry in activated carbons can be carried out by a wide variety of experimental techniques and parameters : chemicaWithin the structural heterogeneity of ACs, the active sites can roughly be located in two different sites: the basal planes of the polyaromatic sheets, which compose the micrographitic domains that constitute the structural framework of ACs, and the edges of these sheets. Structural (XRD) and microscopic (high-resolution transmission electron microscopy (HRTEM)) techniques provide information for such characterization. Henning highlighted, using TEM on graphite, the great difference in chemical reactivity of these two regions near lattice defects . The hig2SO4, HNO3, H3PO4, KOH, NaOH. So, these agents can favor the generation of oxygen surface complexes during the activation process, being the surface properties of activated carbons mainly associated with the oxygen functionalities contents, the subject matter of a large number of investigations [The presence of heteroatoms is largely linked to the organic origin of the precursors see . As previgations . Figure 2 are slightly acidic or neutral, whereas KOH produces groups with high basicity [3PO4, ZnCl2, and KOH with the same activating agent concentrations) with acidic (NO2) or basic (NH3) molecules [2 > H3PO4, whereas for acidity it is H3PO4 > ZnCl2 > KOH. Note that the different functional groups are significantly affected by the impregnation conditions, i.e., activating agent concentration and soaking time [3PO4 (400–500 °C), ZnCl2 (500–700 °C), and KOH (700–900 °C). Focusing on the absolute content of surface oxygen groups, it strongly depends on the preparation conditions, varying from 100 to 8000 μmol/g AC [The chemical properties exhibited by activated carbons can be approached within the context of their Lewis acidic, basic, or neutral character ,74,85. Obasicity ,86,87,88mol/g AC ,85,89.2 and KOH at the same activation temperature results in a similar content of surface groups [Nayak et al. has reported that the synthesis of activated carbons with ZnCle groups . This ise groups . Thus, tAs an example, Hasan Arslanoğlu has prepared activated carbons using potassium-rich wine stone precursor  and haveAll these examples have pointed out the importance and, in some cases, the difficulty of a correct assessment of surface chemistry in activated carbons, in general, and in biomass-derived ACs, in particular. Thus, if studies on the chemical activation of lignocellulosic precursors are taken into consideration, many of them perform a qualitative analysis (by FTIR) of such surface chemistry ,32,89,952-evolving groups are selectively transformed into CO-evolving groups [A careful analysis of the surface chemistry characterization for “aged” (previously heat-treated) samples, those treated some time ago, has revealed changes with respect to the “fresh” heat-treated ones, which should be taken into account. These changes occur as a result of several processes. The first process was reported many years ago by Puri et al. , and morg groups . It has g groups . All theThe surface chemistry of activated carbons can be modified, as previously stated, through various post-synthesis treatments ,105, whiAdditionally, other functionalities and/or heteroatoms can be incorporated to increase the surface’s basic character through heat treatment in the gas phase using nitrogen-containing compounds via surface amination process, ,110 or c2, …), which make the control of the generated surface groups difficult [2-plasma (avoiding N2) increases the amount of (acid) carboxylic groups on the surface of AC [3-plasma to modify the carbon surface [3/O2 –plasm has been used, resulting in an increase in acidic functional groups (–COOH) and basic groups (–NH2) [The mentioned methods have in common the use of a chemical compound and a thermal activation process to favor its interaction with the carbonaceous surface. In the last decade, other methods for the surface modification by activation of gaseous molecules have been analyzed, i.e., using microwaves , ultrasoifficult . In the ifficult . Contrarce of AC . Other a surface , observi surface . Recentls (–NH2) .In the case of lignocellulosic precursors, another approach has been tested in the last years to tailor the surface chemistry of ACs. Instead of the conventional pyrolysis used to obtain biochars, hydrothermal conversion of biomass has been an object of study, obtaining hydrochars ,42. Thes3g−1. They can be obtained by following two “opposite” procedures [In materials’ production shaping is very important. For most fields, materials are optimally subjected to a shaping process to get the desired shape and size with the least loss in other properties, especially those of interest for each selected use. In the case of ACs, they can be conformed in different shapes depending on the application : (i) Graocedures : soft teVery innovative papers regarding shaped activated carbons materials have been published using phosphoric acid as activating agent, such as the activation of lignin-based fibers  or the uRegardless their applications, the shapes and sizes of the ACs are of great importance from another operative point of view. ACs are used in continuous processes (treatment of gas or liquid flows), stirred processes (batch processes), or cyclic processes . After their use, a regeneration process of the AC is required involving, among others, cycles of downwards filtration and backwashing of the ACs, in the case of liquid applications, and thermal treatment with steam contraflow, or chemical regeneration, in gas applications ,135,136.Attrition or hardness measures the mechanical strength, it determines carbon’s ability to withstand normal handling operations and serves as an important parameter for understanding the relative loss during the transportation, handling, use, and regeneration ,23,40,672 of spherical activated carbons (SACs) with high mechanical strength, taking advantage of the retention of the spherical shape by the hard natural seeds precursors, and compare them with those of three commercial ACs, one of them activated from wood with phosphoric acid [3PO4 or ZnCl2, for example, derive in swelling of the precursor particles, with some loss in mechanical properties as well [One of the parameters that strongly determines the mechanical properties of an AC is the type of precursor used. In this sense, to get good mechanical properties it seems reasonable to select a precursor with high mechanical strength. This has justified the use of hard coals  to get hard ACs, since some authors remark the low strength and low attrition resistance of biomass waste-derived ACs . Paying ric acid . The mecric acid . In otheric acid . In thisric acid . However as well .The presence of fatty matter and pectin in the composition of a biomass precursor gives it self-binding properties, allowing it to be shaped into discs  without binding agents’ incorporation during compaction. Secondly, the lignocellulosic microstructure itself produces the formation of a carbon grid consisting of interwoven pleated laminae that persist during activation. This type of microstructure favors cohesion among the different microparticles of the carbonized material, endowing it with the appropriate mechanical properties .Another parameter that favors an increase in mechanical resistance is the use of high carbonization (and activation) temperatures. In two-step heat treatment activation, the higher the carbonization temperature, the greater the condensation and growth of graphitic sheets, which leads to an increase in the mechanical resistance of the resulting material ,58. Howe3PO4, KOH, and ZnCl2, that higher hardness percentages are obtained in one step procedure [3PO4 and KOH activation produces ACs with higher hardness than ZnCl2 [3PO4 and ZnCl2, obtaining such conclusions from the comparison between the crystallinity of the produced ACs [Regarding the influence of the type of activating agent used on the mechanical properties, its effect is less clear. P. Ravichandran et al. have paid attention to the influence of the activating agent and the preparation conditions (either one or two steps activation procedure) on hardness and attrition . Their srocedure . With rean ZnCl2 . Similaruced ACs . In contuced ACs .In respect to attrition, P. Ravichandran et al. highlighted that attrition results are dependent on the carbon density, precursor materials, and activating agents used ,23.Finally, another approach to obtain ACs with high mechanical properties is shaping activated carbons in a monolithic or pelletized form previously commented. This is usually carried out from a slurry of powdered activated carbon and a binder, which is compacted or extruded, and then carbonized and activated . Many stThe published results highlight that the mechanical properties of ACs depend on the precursor, the temperature of heat treatment, the chemical agent and also the shape, and these all together determine the most suitable uses for any prepared material.2 retention. As an example, Stavropoulos et al. have calculated the final costs of ACs prepared by chemical activation considering the raw material cost and the heating values [2 capture [3PO4/precursor impregnation ratio is optimum for their application, leading to 1506 m2/g—essentially microporous derived sorbents, and have analyzed in detail the annual operating costs for the synthesis of AC by H3PO4 activation [To emphasize the importance of activated carbon’s world in economic terms it should be recalled that the AC market was valued at 3.2 million USD in 2021 and was expected to reach USD 4.5 million by 2028, with an estimated compound annual growth rate of 5.4% in forecast period 2021–2028 . These ng values . They hag values . Asadi-S capture . These ativation . For suctivation . Compari2 post-combustion capture, Pramanik et al. have also studied in depth the cost of producing activated carbon by chemical activation 3·12H2O) by impregnation method [2/g), they accomplished a detailed techno-economic viability study of commercial-scale production, market size, costs, and revenues [Encouraged by the high cost of preparing solid adsorbents for COn method . A low-cn method . In theirevenues . Considerevenues . This corevenues .In close relationship with economic  concerns, Namazi et al. have studied the use of white liquor (containing NaOH) as an activating agent of pulp mill sludge, focusing on the influence of experimental conditions such as activation time and temperature, and NaOH/precursor ratio on the achieved surface areas and yields . Their s2 is not a desirable/preferred activating agent for those reasons) and any gaseous or liquid stream from the preparation procedure, and the possibility of recycling the chemical activating agent, strongly desirable. In this line, the investigation and use of mild conditions activation conditions is a tendency, with interesting approaches making use of different residues as carbon precursors [Environmental concerns in chemical activation are indeed important, keeping in mind the toxicity of the chemical activating agents (i.e., ZnClecursors ,13,18,25After a detailed literature survey about the possibility of recycling the chemical activating agents, it can be concluded that the number of related studies is really scarce, and mainly devoted to KOH activation. This is probably because potassium hydroxide is one of the preferred activating agents from several points of view, including high porosity, very narrow micropore size distribution, and high final activated carbon yield .Yuan et al. have tried to analyze if it is feasible to recover and reuse KOH in an activation process and, for that purpose, they have paid attention to the reaction mechanism and the prevalent reactions in two different temperature ranges, below and above 900 °C . They ha2CO3 is not stable and decomposes. Therefore, the prevalent activation reaction at this temperature range is:Above 900 °C, K2, which assures the activating agent recyclability [In both cases, K can react with water, producing KOH and Hlability . As theslability .Their study has aimed to conclude that ¾ of the potassium present in the activated product can be removed by water washing, and a majority of the potassium extracted with water is in the form of carbonate . This po2, synthesizing activated carbons with surface areas ranging 1190–3060 m2/g [Recently, Pramanik et al. proposed the recyclability of KOH during chemical activation by KOH + alum solution . In thei060 m2/g .These studies highlight the interest in green and sustainable procedures. However, much more effort is required for optimizing the production of “green” and sustainable activated carbons by chemical activation.The increase in the AC demand due to its extensive use in different applications, including water potabilization has led, especially in the last decade, to intensive research on the use of lignocellulosic precursors to produce activated carbons by chemical activation. In this review, the main features of biomass precursors and the physicochemical processes that take place during the preparation of ACs have been presented.3PO4 and ZnCl2 activation, in KOH activation the controlled carbon consumption reaction and the intercalation of metallic potassium prevail.The lignin content has shown to be an interesting parameter, with a strong influence on the AC yield. The different physicochemical interactions between the activating agents and the lignocellulosic components responsible for the porosity generation have been revisited. Thus, whereas dehydration and insertion/swelling are the most important steps in the generation of porosity for HAttention is paid not only to the optimal porosity development but to other key properties of the ACs produced, such as the generated surface chemistry using different chemical agents. The shapes, sizes, and mechanical properties of the ACs have also been commented on due to their importance in the uses of the ACs. This aspect is analyzed briefly, together with the mechanical properties of ACs.Finally, some economic and environmental concerns related to chemical activation are studied because of their interest in a feasible and sustainable use of lignocellulosic precursors to produce chemically activated carbons.


Gastric cancer is the 5th most common malignancy worldwide, representing ~5–10% of all new cancer cases. Although its incidence is declining, it is estimated that 1 in 98 Canadians will develop gastric cancer in their lifetime. The epidemiology and distribution of gastric cancer throughout Canada, however, remains poorly understood. A retrospective analysis of demographic data across Canada between 1992 and 2010 was performed using 2 population-based cancer registries. The incidence of gastric cancer was examined at the levels of provinces, cities, and postal codes. In addition, 43,955 patients were diagnosed with gastric cancer in Canada between 1992 and 2010; 66% were male and the average age of diagnosis was 68.4 years. The age-adjusted incidence rate was 5.07 cases per 100,000 individuals per year. The incidence decreased over the study period by 30%. High incidence rates were identified in rural areas of Newfoundland and Labrador, New Brunswick, and Quebec. Our study found a significant association between gastric cancer incidence rates and lower socioeconomic status, as well as Hispanic ethnicity. This is the first study to provide a comprehensive analysis of the incidence of gastric carcinoma in Canada, identifying high-risk populations that may benefit from increased primary and secondary prevention. H. pylori infection are strongly associated with gastric cancer development and mortality  was 0.9622; p = 0.002. The slope of the line is 0.148 cases per 100,000 individuals per year.The patients’ characteristics are presented in SES Q5 vs. Q1 = 0.39; 95% CI 0.35–0.42 p < 0.001). In addition, the average median income in FSAs with statistically significant higher incidence rates was CAD 18, 700, whereas it was CAD 27,200 in FSAs with statistically significant lower gastric cancer rates (p < 0.001). For ethnicity, incidence rates were significantly higher in quintiles with a higher percentage of Hispanic individuals compared to quintiles with a lower percentage of Hispanic individuals . In addition, the average percentage of Hispanic individuals in FSAs with statistically significant higher incidence rates was 1.34%, whereas it was 0.62% in FSAs with statistically significant lower cancer rates (p < 0.001). There was no significant association between gastric cancer incidence and East Asian ethnicity  nor African Canadian/black ethnicity (IRRBlackQ5 vs. Q1 = 0.93–1.13).Analyses by area based-SES and ethnic composition demonstrated a significant association between gastric cancer incidence rates, SES, and Hispanic ethnicity A,B. The The national ASIR was 5.07 cases per 100,000 individuals per year (95% CI: 5.02–5.13). Geographic maps illustrate age-standardized incidence rates of gastric cancer  relative to the national average based on the CCR/LRQC databases. On a provincial level, Newfoundland and Labrador, Nunavut, New Brunswick, Manitoba, Nova Scotia, and Quebec had significantly higher ASIR compared to the national average, with the highest being in Newfoundland and Labrador at 13.71  cases per 100,000 individuals per year B. In conCanadian cities with a population over >5000 individuals with differential (high or low) crude incidence rates are presented in Eleven FSAs had an ASIRs ≥ 3-fold that of the national average . The majH. pylori infection, decreased rates of tobacco use, and changes in food preservation [In this manuscript, we present the epidemiology of gastric cancer based on CCR and LRQS databases for all available years 1992–2010) at provincial, municipal, and FSA postal code levels. To the best of our knowledge, no previous study has assessed the distribution of gastric cancer across the entire country to identify the correlation with SES/ethnicity and identify communities where a focused intervention may be important. At the national level, we confirm a decreasing burden of gastric cancer, a male predominance, an average age at diagnosis ~68 years, and a national ASIR of 5.07 cases per 100,000 individuals per year. Similar trends are observed in other developed countries, with decreasing incidence attributed to the decline of ervation ,37. The ervation , age of –2010 at Our geographic mapping showed significantly higher ASIRs in Newfoundland and Labrador, mostly in rural areas and often affecting First Nation communities. Various modifiable risk factors are implicated in the pathogenesis of gastric adenocarcinoma such as obesity, and diets high in salt and processed foods ,39,40,41Among the 11 highest incidence FSA found in our study, 4 (36%) were home to First Nation communities. These included the Miawpukek (A0H), We’koqma’q (B0E), Gaspé (G0E), and Essipit (G0T) communities ,49,50 suOur findings of higher ASIR in Canadian immigrant population, particularly in areas with significantly higher Hispanic composition  is aligned with the previous literature demonstrating higher rates on gastric cancer among immigrants in Ontario . The StaH. pylori infection, as well as decreased consumption of nutritional and fresh foods due to decreased income, education, and access to resources [SES is often established from a combination of multiple variables with the 3 most prominently used being education, income, and occupation . The SESesources ,68,69.Given that annual income does not take into account how many people are supported by that income or if one is supported by someone else’s income, it may not be the most reliable indicator to use alone . When exOur study limitations include first and foremost the retrospective design and data years available (1992–2010). Data for the Canadian territories were sparse and not statistically significant. Due to confidentiality regulations, the data could not be presented in its entirety due to the mandatory rounding of frequencies of cases to the nearest 5 or 10, as well as the suppression of data exhibiting frequencies that were lower than 5. For the same reason, localities with less than 5000 inhabitants had to be excluded. For smaller cities/FSAs due to a relatively low number of residents and/or low number of gastric cancer cases, ASIR could not be calculated, and crude incidence rates were used. Detailed spaciotemporal information is not available through cancer registries and, hence, FSAs at inception were used. Given that the databases used did not include data concerning patient ethnicity, SES, and other health related risk factors, indirect comparison was used.The reported associations that were found when using area-based SES and ethnic composition analysis may not be applicable when examining individual-level factors such as SES and ethnicity, as these were indirectly correlated and could not be causally linked. Finally, given that the databases employed did not provide individual data concerning nutrition habits, income, and immigrant or First Nation composition of the populations with gastric cancer in each FSA, the interpretations discussed should be taken with caution in the context of ecological fallacy, as inferences about the nature and risk factors of gastric cancer cannot be made definitively based solely upon the aggregated data. More research is needed in order to define the geographical risk factors associated with gastric cancer with certainty.This is the first study to describe the strikingly unequal geographic distribution of gastric cancer in Canada. Importantly, localities with highest ASIR of gastric cancer are characterized by statistically higher than national average rates of known risk factors, notably low SES, and non-Caucasian ethnicity (notably Hispanic and First-Nation). The highest incidence rates in our country corresponded to rural/remote communities where high rates of food insecurity, obesity, and/or other risk factors  are well characterized. High incidence rates in First Nation communities were confirmed . IdentifWhile the incidence rates of gastric cancer are decreasing in Canada, incidence rates vary greatly on the geographic location favoring rural areas in Newfoundland and Labrador, New Brunswick, and Quebec. First-nation and highly multicultural (particularly Hispanic) communities were identified among high incidence regions. The association with low SES was confirmed. A total of 11 FSAs had an ASIR of gastric cancer >3-fold that of the national average. Since ~30% of gastric cancer cases are thought to be preventable, targeting high risk communities is of particular interest to improve disease burden and survival.