Does Calcium Phosphate Peri‐Implant Grafting Improve Osseointegration of Dental Implants? An Experimental In Vivo Study

This in vivo study aimed to evaluate the osseointegration of dental implants with a nanostructured hydroxyapatite (HAnano) coating or a double acid-etched (DAA) surface, grafted with or without calcium phosphate in the peri-implant gap, in low-density bone in a sheep model. Thirty implants (15 HAnano and 15 DAA) were installed in the iliac crest of five sheep (2-4 years old). Six implants were placed per animal: two with a xenograft biomaterial, two with an alloplastic biomaterial, and two without grafting (control). Microtomographic analyses evaluated the percentage of bone and biomaterial for all groups. Histomorphometric analysis assessed bone-implant contact (BIC), bone occupied area fraction (BAFo), and biomaterial presence after an 8-week healing period. Data were analyzed using repeated-measures ANOVA or mixed-effects models with a significance level of 0.05. No complications were observed during the healing period. The average BIC across all groups was 55%, ranging from 4.6% to 67.7%. BAFo averaged 30%, with biomaterial occupying 22% and connective tissue 44% of the interface area. There were no statistically significant differences between grafted and non-grafted groups for BIC (p = 0.413), BAFo (p = 0.097), connective tissue presence (p = 0.192), and for the percentage of bone and biomaterial (p = 0.959), bone percentage (p = 0.283), or biomaterial percentage (p > 0.0959). Peri-implant grafting with xenograft or alloplastic biomaterials did not significantly enhance osseointegration compared to ungrafted implants in small peri-implant defects. These results suggest that spontaneous healing may suffice in such cases.