Standardized Rat Model Testing Effects of Inflammation and Grafting on Extraction Healing.
BACKGROUND
Loss of alveolar ridge width and height after tooth extraction is well documented, but models to evaluate ridge preservation are neither standardized nor cost-effective. This rat model characterizes the pattern of bone turnover and inflammation after extraction and bone grafting with or without local simvastatin (SIM).


METHODS
Fifty retired-breeder rats underwent extraction of the maxillary right first molar and standard surgical defect creation under inhalation/local anesthesia. The left side of each animal served as unmanipulated control. Untreated groups (n = 8 to 9 per group) were compared (analysis of variance, t test) at days 0, 7, 14, and 28 for alveolar ridge height and width and for markers of inflammation and bone turnover by microcomputed tomography, histology, and enzyme-linked immunosorbent assay. Seventeen additional specimens had defects grafted with either bone mineralized matrix (BMM) or a BMM+SIM conjugate.


RESULTS
Extraction-induced bone loss (BL) was noted on buccal, palatal, and interproximal height (P <0.05) and ridge width (P <0.01). Week 1 inflammation positively correlated with ridge height; thereafter, a more intense inflammatory reaction corresponded to reduction in alveolar bone height and density (r = 0.74; P <0.05; Spearman). BMM+SIM preserved the most interproximal bone height (P <0.01), increased ridge width and bone density (P <0.01), enhanced 7-day prostaglandin E2 (P <0.01), and reduced 28-day inflammation density (P <0.05).


CONCLUSIONS
The standard defect used in the current study paralleled human postextraction alveolar BL. Defect grafting, especially BMM+SIM, reduced inflammation and preserved bone.
['Willett|Emily S|ES|', 'Liu|Jingpeng|J|', 'Berke|Molly|M|', 'Giannini|Peter J|PJ|', 'Schmid|Marian|M|', 'Jia|Zhenshan|Z|', 'Wang|Xiaobei|X|', 'Wang|Xiaoyan|X|', 'Samson|Kaeli|K|', 'Yu|Fang|F|', 'Wang|Dong|D|', 'Nawshad|Ali|A|', 'Reinhardt|Richard A|RA|']
D016301:Alveolar Bone Loss D000818:Animals D016723:Bone Remodeling D016025:Bone Transplantation D004195:Disease Models, Animal D004797:Enzyme-Linked Immunosorbent Assay D008437:Maxilla D008963:Molar D051381:Rats D019821:Simvastatin D014081:Tooth Extraction D020390:Tooth Socket D014945:Wound Healing D055114:X-Ray Microtomography
rats inflammation tooth extraction Bone remodeling