Histological analysis of loaded zirconia and titanium dental implants: an experimental study in the dog mandible

Abstract Objective To assess whether or not peri‐implant soft tissue dimensions and hard tissue integration of loaded zirconia implants are similar to those of a titanium implant. Materials and methods In six dogs, two one‐piece zirconia implants ( VC , ZD ), a two‐piece zirconia implant ( BPI ) and a control one‐piece titanium implant ( STM ) were randomly placed. CAD / CAM crowns were cemented at 6 months. Six months later, animals were killed and histomorphometric analyses were performed, including: the level of the mucosal margin, the extent of the peri‐implant mucosa, the marginal bone loss and the bone‐to‐implant contact ( BIC ). Means of outcomes variables were calculated together with their corresponding 95% confidence intervals. Results In general, the mucosal margin was located coronally to the implant shoulder. The buccal peri‐implant mucosa ranged between 2.64 ± 0.70 mm ( VC ) and 3.03 ± 1.71 mm ( ZD ) (for all median comparisons p > 0.05). The relative marginal bone loss ranged between 0.65 ± 0.61 mm ( BPI ) and 1.73 ± 1.68 mm ( ZD ) (buccal side), and between 0.55 ± 0.37 mm ( VC ) and 1.69 ± 1.56 mm ( ZD ) (lingual side) ( p > 0.05). The mean BIC ranged between 78.6% ± 17.3% ( ZD ) and 87.9% ± 13.6% ( STM ) without statistically significant differences between the groups ( p > 0.05). Conclusions One‐ and two‐piece zirconia rendered similar peri‐implant soft tissue dimensions and osseointegration compared to titanium implants that were placed at 6 months of loading. Zirconia implants, however, exhibited a relatively high fracture rate.