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 titanium one‐piece dental implant.
Materials and methods
In six dogs, all premolars and the first molars were extracted in the mandible. Four months later, three zirconia implants (BPI, VC, ZD) and a control titanium 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 fractured (one VC, one ZD). At sacrifice, 5 more implants were (partly) fractured (one BPI, 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 bone loss between baseline and 6 months of loading ranged between 0.19 mm (BPI) 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. BPI P = 0.007; vs. VC P = 0.001; vs. ZD P = 0.011).
Conclusions
Zirconia implants were more prone to fracture prior to and after loading with implant‐supported crowns compared to titanium 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.