Periapical Bone Loss as a Signal of Risk for Prosthetic Screw Loosening in Full-Arch Implant-Supported Fixed Complete Dentures: A Multicenter Retrospective Pilot Study.

PURPOSE: Prosthetic screw loosening is among the most prevalent mechanical complications in full-arch implant-supported fixed complete dentures (FCDs). This multicenter retrospective pilot study aimed to detect a preliminary signal of association between periapical bone loss (PBL) characteristics and prosthetic screw loosening in All-on-4 and All-on-6 FCDs and to generate effect-size estimates for planning future confirmatory studies.

MATERIALS AND

METHODS

Forty-three arches from 32 patients at three private dental clinics in Bangkok, Thailand (2017-2025) were retrospectively analyzed. PBL was assessed on panoramic radiographs; intraexaminer reliability was evaluated using the intraclass correlation coefficient (ICC). Eleven predictor variables were examined by univariate logistic regression. Firth's penalized logistic regression was performed as the primary multivariable analysis, with Kaplan-Meier survival analysis as a supplementary time-to-event analysis.

RESULTS

Screw loosening occurred in 10 of 43 arches (23.3%). The intraexaminer ICC was 0.990. The number of PBL-affected implants showed a significant signal of association with screw loosening in univariate analysis (OR=2.539, 95% CI:1.200-5.371, P=.015). Kaplan-Meier analysis demonstrated significantly shorter time to first screw loosening in arches with ≥3 PBL-affected implants versus 1-2 (19.5 vs 30.0 months; log-rank P=.002).

CONCLUSIONS

Among PBL-affected arches, the number of PBL-affected implants per arch showed a signal of association with prosthetic screw loosening across multiple analytical approaches. These exploratory, hypothesis-generating findings warrant confirmation in adequately powered prospective studies.