Interproximal contact loss at implant sites: a retrospective clinical study with a 10-year follow-up

Aim To assess the frequency and quantity of interproximal contact loss (ICL) between implant restorations and adjacent teeth after at least 10 years of follow-up (FU). Methods Thirty-nine patients (median age 57.3 years) with 80 implants were re-examined at least 10 years after insertion of final restorations (single crowns or fixed dental prostheses (FDPs)). Baseline (insertion of the restorations) and FU examinations encompassed the following: Stone casts were scanned and superimposed for metric assessment of tooth movements, radiographs, and clinical measurements. Outcome measures at implant sites were as follows: the extent of tooth movement and the frequency of interproximal contact loss [ICL], peri-implant marginal bone levels [MBLs], and clinical measurements (plaque control record [PCR], Bleeding on Probing [BOP], and probing depth [PD]). Data were analyzed statistically with generalized regression modeling with robust standard errors to account for within-patient clustering at 5%. Results Interproximal contact loss for at least one contact point after 10 years was observed in 50% of all implants (with open interproximal spaces up to 1.64 mm). Mesial contact points were significantly more prone to ICL than distal ones (relative risk [RR] = 1.79; 95% confidence interval [CI] = 1.07-2.99; p = .03). The type of restoration had a significant effect on ICL, with FDPs of 2 implants being significantly more prone to mesial ICL than single crowns (RR = 1.52; 95% CI = 1.02-2.25; p = .04). ICL was also associated with a significant increase in PD (+0.46 mm (95% CI = 0.04-0.88 mm; p = .03)) compared to implant sites without ICL. BOP, MBLs, and PCR were not significantly influenced by ICL. Conclusion Interproximal contact loss was a common finding in 50% of the implant sites and was significantly associated with an increase in PD.