Risk factors and reoperative survival rate of failed narrow-diameter implants in the maxillary anterior region

Background Narrow-diameter implants (NDIs) have been proposed to address the dilemma of implant installation in cases of insufficient bone volume. However, the potential risk factors of failed NDIs, and whether reimplants with reliable efficacy are still controversial. Purpose This study aimed to evaluate the survival/success rate of NDIs in the maxillary anterior region and that of reimplants at the same site, as well as to explore the potential risk factors of original and replaced implants. Materials and Methods From January 2015 to April 2019, patients receiving NDIs in the anterior maxilla were enrolled in the present study. Multiple variables were assessed to exploit the risk factor of failed NDIs, including age, sex, implant sites, length, surface characteristics, and healing abutment designs. The relationship between bone augmentation and the number of missing teeth was assessed. For failed NDIs, the reasons for NDIs removal and marginal bone loss (MBL) were analyzed. The details and outcomes of reimplants were evaluated. Results Cumulative survival rates (CSRs) and success rates of 1095 NDIs installed in 835 patients were 96.99% and 96.51%, respectively. In total, 33 of these NDIs failed. TiUnite (TU) surface was a risk factor and it affected the success rate (92.56%) and CSR (92.4%) of NDIs (P < .001). The single NDIs with bone augmentation have lower failure rate. The average MBL for 33 failed NDIs was 1.92 +/- 1.91 mm. Additionally, 22 patients with 23 NDIs accepted reimplantation of previously failed NDIs, and the success rate of reimplants was 95.65%. Conclusions Surface characteristic (TU surface) was a risk factor for failure of NDIs in the maxillary anterior region. Bone augmentation simultaneously performed during NDIs implantation was favorable for a single missing tooth. As an alternative plan, the reimplantation of failed NDIs was reliable and stable after successful bone reconstruction.