Early changes in interproximal contact and tactile sensitivity around implant-supported restorations: An 18-month...

To longitudinally assess the frequency and magnitude of interproximal contact loss (ICL) between implant crowns and adjacent teeth, and changes in tactile sensitivity thresholds around single implant restorations compared with contralateral natural teeth over 18 months.

A prospective cohort study was conducted on 20 participants who were restored with a single posterior implant crown. Each restoration used a custom-milled titanium abutment and a screw-retained monolithic zirconia crown. Occlusion was standardized to light centric contacts on the implant crowns, and follow-ups were conducted at 1, 3, 6, 12, and 18 months. Interproximal contact tightness was quantified with a digital force gauge using 0.22-mm floss and open contact was measured at 0 N. Frictional forces were analyzed with repeated-measures and between-subjects ANOVA. Tactile sensibility was tested with foils with a thickness of 8-100 µm at implant and control sites, and detection of tactile sensitivity was modeled by logistic regression to estimate 50% detection thresholds. Peri-implant indices, modified Plaque Index, probing depth, and bleeding on probing were recorded to assess the health of the peri-implant soft tissue.

All contacts were closed at baseline; ICL occurred in two implant crowns (10%), confined to the mandible, and did not progress after 6 months. Interproximal frictional forces showed a nonsignificant time trend (p = 0.06) with no mesial-distal or tooth-group differences. For tactile sensitivity, controls outperformed implants at 24 µm (p = 0.02) at 3 months; by 18 months, group differences were nonsignificant. Detection thresholds improved from ∼39-40 µm at 3 months to ∼20 µm at 18 months (p = 0.045). At ≥80 µm, all participants detected contacts at all sites and timepoints. Peri-implant health remained stable; no implants demonstrated clinical signs consistent with peri-implantitis.

Within the 18-month observation period, single posterior implant restorations under controlled occlusion demonstrated early adaptive proximal contact stability and functional tactile adaptation. Most contact changes occurred within the first 6 months, primarily in mandibular sites, emphasizing the importance of early monitoring. Peri-implant clinical parameters remained stable during follow-up. Clinically, maintaining occlusal contacts and regular follow-up can support proximal stability during the early phase of function.