Implant–Prosthetic Rehabilitation of Maxillary Lateral Incisor Agenesis with Narrow Diameter Implants and Metal–Ceramic vs. All-Ceramic Single Crowns: A 16-Year Prospective Clinical Study

The main objectives of the present prospective clinical study were to evaluate the marginal bone resorption and the peri-implant soft tissue conditions around narrow diameter implants, as well as the clinical performances of metal–ceramic and all-ceramic single crowns in the implant–prosthetic treatment of maxillary lateral incisors agenesis. Seventy-two patients affected by monolateral or bilateral agenesis of the maxillary lateral incisors were included in the study, and a total of 105 narrow diameter implants were inserted. The final single crowns were fabricated 4 months after the surgical procedures by means of either titanium abutments with Auro-Galvan Crowns (AGC) veneered with feldspathic ceramics or zirconia abutments with all-ceramic (alumina or zirconia) crowns layered with dedicated veneering ceramics. Both marginal bone resorption and soft tissue quality were evaluated after a maximum period of 16 years. Two independent survival curves for patients wearing AGC or all-ceramic crowns were calculated by means of Kaplan–Meier analysis, and a log-rank test was performed in order to compare these curves (p < 0.05). After 16 years of clinical function, a mean marginal bone resorption of 1.2 ± 0.61 mm and good response of peri-implant soft tissues were observed. Descriptive statistics resulted in 80% and 87.1% cumulative success rates for patients provided with AGC prostheses onto titanium abutments and all-ceramic crowns on-to zirconia abutments, respectively. The cumulative survival rate calculated for AGC group was 93.3%, whereas all-ceramic group showed a cumulative survival rate of 95.7%. No statistically significant differences were found with the log-rank tests. The overall success and survival rates calculated were 85% and 95% for all the restorations, respectively. Mucositis, abutment unscrewing, loss of retention, chipping, core fracture, and esthetic failure were the major complications reported. The implant–prosthetic approach can be considered an effective and viable solution to treat cases of maxillary lateral incisor agenesis in the long term.