Influence of dental implants on adjacent tooth survival and bone loss: a matched retrospective radiographic analysis.

OBJECTIVE

To evaluate the radiological bone loss and survival outcomes of teeth adjacent to dental implants (TAIs) in comparison to non-adjacent teeth (TNIs) of similar type and baseline condition, using a matched retrospective cohort design.

MATERIALS AND

METHODS

This retrospective study included 233 patients treated with 348 implants between 2013 and 2020 at the University of Freiburg. A total of 480 TAIs and 348 matched TNIs were observed over a mean follow-up of 54 months. Radiographic bone levels, survival rates, and restorative interventions were compared. Control teeth (TNIs) were matched by tooth type and jaw location. Statistical analyses included t-tests, Chi-squared tests, Kaplan-Meier survival analysis, and multivariate Cox-regression.

RESULTS

TAIs demonstrated significantly greater bone loss than TNIs (mean: 4.3 % (SD 6.8 %, median: 1.6 %, IQR: 0 - 6.1 %) vs. mean 3.1 % (SD 5.23 %, median: 0.9 %, IQR: 0 - 4.4 %), p = 0.005). New crown restorations were significantly more frequent in TAIs (14.4 %) than TNIs (7.3 %, p = 0.04), though differences in root canal therapy rates were not significant. Survival analysis showed higher 5-year survival rates for TNIs compared with TAIs (93.6 % vs. 88.6 %, p = 0.015). After adjustment for relevant covariates, implant adjacency showed only a limited association with tooth survival, and a stronger association with restorative factors. The most common causes of TAI loss were root fracture and caries.

CONCLUSION

Teeth adjacent to dental implants showed higher rates of bone loss and restorative interventions compared with TNI. This is the first investigation on TAI-survival with respect to preexisting restorative and site-specific conditions of both the TAI and the control teeth, indicating that restorative and endodontic conditions play a greater role than implant adjacency itself.

CLINICAL RELEVANCE: The findings indicate that implant adjacency has a limited effect on the survival of neighboring teeth when tooth-related factors are adequately controlled. Pre-existing restorative conditions, particularly crown restorations and root canal treatment, seem to play a more important role and should be considered in treatment planning and long-term follow-up.