Long-term retrospective study of narrow implants for fixed dental prostheses

OBJECTIVE The objectives of this study were to analyze retrospectively the long-term survival and success rates of Narrow implants (NIs) placed with various implant systems, and the association with biological and technical complications. MATERIAL AND METHODS In total, 338 patients (men = 45.6%, women = 54.4%) who received 541 NIs (≤3.5 mm in diameter) for fixed prostheses were enrolled in this retrospective study. The mean marginal bone level (MMBL) change was calculated. Life table analysis with the cumulative survival rate and success rate was calculated, and biological and technical complications were evaluated. RESULTS The annual MMBL change was 0.07 ± 0.20 mm. The 12-year cumulative survival (success) rates of NIs were 98.1% (91.8%) and 98.5% (93.8%) for the implant- and subject-based analysis, respectively. During the observation period up to 12 years (mean 4.9 years), six implants were lost in the maxilla, whereas three implants were lost in the mandible. Technical complications were more frequent than biological complications. Infection was the most common underlying cause of biological complications and the most frequent technical complication was decementation. CONCLUSION In conclusion, the findings of this study suggest that NIs could be used safely for narrow alveolar ridges or narrow mesiodistal spaces on the basis of their high survival rate.