The Effect of Posterior Implant Restoration on the Survival, Coronal, Pulpal, and Periapical Status of Adjacent Teeth.

OBJECTIVES:This retrospective study evaluated the long-term effect of implant adjacency on the prognosis of adjacent natural teeth. MATERIALS AND METHODS:We included 345 patients who underwent posterior implant placement and prosthetic restoration between August 2007 and June 2025. In the experimental group, 502 implant-adjacent natural teeth were analyzed; contralateral teeth served as controls. Radiographic images and clinical records obtained at baseline (implant placement) and follow-up (minimum 24 months after prosthetic restoration; mean 70.98 months) were compared. Coronal status, pulpal status, and tooth survival were assessed, while periapical status was evaluated using the Periapical Index. RESULTS:Implant-adjacent teeth demonstrated significantly higher rates of coronal deterioration and periapical worsening than contralateral teeth, whereas changes in pulpal status did not differ significantly between groups. The survival rate of implant-adjacent teeth was significantly lower, with a 2.73-fold increased risk of extraction or loss. Subgroup analysis revealed that second molars exhibited a higher incidence of periapical deterioration, and mandibular premolars showed significantly reduced survival when implant-adjacent. CONCLUSION:Posterior implant restoration is associated with cumulative structural and radiographic alterations in adjacent natural teeth, which may compromise long-term tooth survival. The clinical success of posterior implant restoration should be evaluated by the preservation of structural and periapical integrity in adjacent teeth, not only implant survival.