Ligature-Induced Peri-implant Bone Loss Around Loaded Zirconia and Titanium Implants

Purpose: To radiographically investigate ligature-induced peri-implant bone loss around loaded titanium (Ti-SLA) and zirconia (ZrO₂-ZLA) implants using a canine model. Materials and Methods: Forty sandblasted and acid-etched titanium and zirconia implants were alternately placed in the mandibles of five canines (20 Ti-SLA, 20 ZrO₂-ZLA). Implants were restored after 6 weeks of unloaded healing. After 4 weeks of functional loading, oral hygiene procedures were stopped and experimental peri-implant bone loss was initiated by placing cotton ligatures. After 8 weeks of active progression, ligatures were removed and plaque was allowed to accumulate for another 16 weeks of spontaneous progression (without ligatures). Standardized radiographs were taken at implant placement, at functional loading, and every 2 weeks during active and spontaneous progression of bone loss. Results: Before ligature placement, all implants were successfully osseointegrated and no clinical or radiographic signs of peri-implant infections were detectable. Two weeks after ligature removal, one titanium implant was lost; however, no zirconia implant failures were observed during the study. Radiographically, zirconia implants revealed statistically significantly less crestal peri-implant bone loss compared to titanium implants at the end of the active progression period (Ti-SLA: 3.92 mm; ZrO₂-ZLA: 2.65 mm; P .01); however, no significant differences occurred after the spontaneous progression period (P = .6). Combining the active and spontaneous progression periods together, zirconia implants demonstrated significantly reduced peri-implant bone loss compared to titanium implants (Ti-SLA: 3.76 mm; ZrO₂-ZLA: 2.42 mm; P .01). Conclusion: These results demonstrate a significantly reduced ligature-induced inflammation and bone loss for ZrO₂-ZLA implants compared to Ti-SLA implants in the canine model. Keywords: bone remodeling, dental implants, peri-implantitis, titanium, yttria stabilized tetragonal zirconia, zirconium oxide