Comparison of Clinical and Histologic Outcomes of Zirconia Versus Titanium Implants Placed in Fresh Sockets: A 5-Month Study in Beagles

Purpose: This study evaluated the clinical and histomorphometric results of titanium (Ti) and custom-made zirconia (Zr) implants placed into fresh extraction sockets in beagles that did not receive oral hygiene attention or a softened diet during postoperative healing. Materials and Methods: The roughness of the Ti and Zr implant surfaces was assessed by confocal microscopy. In eight beagle dogs, four implants each (two Ti and two Zr) were placed in the distal sockets of the third and fourth premolars with the implant shoulder at the bone crest and subjected to submerged healing. Standardized radiographs were taken after placement and 5 months after placement (at sacrifice). Histologic and histomorphometric measurements were performed on nondecalcified histologic sections. The main outcome measures included implant survival, bone-implant contact (BIC), and bone loss on the buccal and lingual plates. Results: Topographic analysis showed significant differences between the Zr and Ti surfaces. Roughness was higher for Ti than for Zr implants, kurtosis was close to 3 for Ti, and skewness was negative for Zr. After 5 months, the mean BIC was similar for the Zr (57.0% ± 15.2%) and Ti (56.5% ± 14.4%) implants, and the most severe bone loss site was observed on the buccal wall. The risk of failure was significantly higher for the Zr (43.8%) than for the Ti (12.5%) implants. Conclusion: The implant failure rate for the Zr implants was 3.5 times higher than that of the Ti implants. This may be partially explained by the less favorable topography of the Zr implants, which had, on average, significantly lower roughness (Ra = 0.85 ± 0.04 μm), negative skewness of the surface profile (-1.56 ± 0.27), and higher kurtosis (7.88 ± 1.99). Keywords: histomorphometry, immediate implant, osseointegration, titanium, zirconia