Retrospective study on the prevalence and risk factors of proximal contact loss between implant-supported fixed restorations and adjacent natural teeth

doi:10.12337/zgkqzzxzz.2025.04.009

Abstract

Abstract: Objective This study aimed to observe the incidence of proximal contact loss (PCL) between implant-supported fixed prostheses and adjacent natural teeth in the posterior region and to analyze the risk factors. Methods A total of 103 patients who underwent ISFPs placement in the posterior regions were enrolled in this study, comprising 226 implants and 233 interproximal contact points. A 50 μm metal shim and dental floss were used to assess proximal contact tightness. Kaplan-Meier analysis, univariate log-rank test, multivariate Cox regression analysis, and Spearman rank correlation analysis were used to evaluate the association of patient characteristics, implant location, adjacent tooth bone support level, and opposing dentition status with PCL occurrence. Results The incidence of PCL was 68.0% at the patient level and 36.9% at the contact site level. The incidence of mesial PCL (46.6%) was significantly higher than that of distal PCL (15.3%). Multivariate Cox regression analysis showed that food impaction, marginal ridge height discrepancy, peri-implantitis, gingival inflammation, and an adjacent tooth bone support level >3/8 were independent risk factors for PCL. Kaplan-Meier analysis showed a progressive increase in PCL incidence over time, reaching 50.0% at the contact site level at the 6-year follow-up. Spearman rank correlation analysis showed that there was a positive correlation between the gap size of PCL and follow-up duration (rs=0.303). The mean PCL gap size was about 0.239 mm, and the maximum value was 0.800 mm. Conclusion This study found that food impaction was one of the most significant risk factors for PCL, although a bidirectional causal relationship may exist between the two. Over time, both PCL incidence and gap size increased progressively. Clinically, regular follow-up visits after implant placement are recommended to monitor and manage PCL. Risk-based interventions, including occlusal adjustment, restorative modifications, or crown replacement, may help prevent and treat PCL effectively.

Key words: Implant-supported fixed prosthesis, Proximal contact loss (PCL), Food impaction, Risk factors

Niu Yimeng, Zhong Weijian. Retrospective study on the prevalence and risk factors of proximal contact loss between implant-supported fixed restorations and adjacent natural teeth[J]. Chinese Journal of Oral Implantology, 2025, 30(2): 151-160.

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