Marginal bone-level alterations of loaded zirconia and @entity702 dental implants: an experimental study in the XXXX mandible.

@entity174 @entity235 @entity604 @entity72162 @entity702
OBJECTIVES: The aim was to test whether or not the marginal bone-level alterations of loaded zirconia implants are similar to the bone-level alterations of a grade 4 @entity702 one-piece dental implant. MATERIALS AND METHODS: In six @entity235 , all premolars and the first molars were extracted in the mandible. Four months later, three zirconia implants ( @entity72162 , VC, ZD) and a control @entity702 one-piece (STM) implant were randomly placed in each hemimandible and left for transmucosal healing (baseline). Six months later, CAD/CAM crowns were cemented. Sacrifice was scheduled at 6-month postloading. Digital X-rays were taken at implant placement, crowns insertion, and sacrifice. Marginal bone-level alterations were calculated, and intra- and intergroup comparisons performed adjusted by confounding factors. RESULTS: Implants were successfully placed. Until crown insertion, two implants were @entity174 (one VC, one ZD). At sacrifice, 5 more implants were (partly) @entity174 (one @entity72162 , four ZD), and one lost osseointegration (VC). No decementation of crowns occurred. All implant systems demonstrated a statistically significant (except VC) loss of marginal bone between baseline and crown insertion ranging from 0.29  mm (VC; P  =  0.116) to 0.80  mm (ZD; P  =  0.013). The estimated marginal @entity604 between baseline and 6  months of loading ranged between 0.19  mm ( @entity72162 ) and 1.11  mm (VC), being statistically significant for STM and VC only (P  <  0.05). The changes in marginal bone levels were statistically significantly different between zirconia implants and control implants (STM vs. @entity72162 P  =  0.007; vs. VC P  =  0.001; vs. ZD P  =  0.011). CONCLUSIONS: Zirconia implants were more prone to @entity174 prior to and after loading with implant-supported crowns compared to @entity702 implants. Individual differences and variability in the extent of the bone-level changes during the 12-month study period were found between the different implant types and materials.
