Longevity of frictional telescopic crowns in the severely reduced dentition: 3-year results of a longitudinal prospective clinical study

Objectives: The longevity of frictional telescopic crowns (FTC) in severely reduced dentitions with 1 to 3 remaining teeth per jaw has not yet been studied prospectively and exclusively. Aims of this study were to estimate risks of telescope loss and abutment tooth loss and to determine abutment tooth mobility over time. Method and Materials: A total of 74 patients with severely reduced dentitions received 82 telescopic removable partial dentures (TRPDs) retained with 173 FTCs. Dentures were reexamined after 1 week and 3, 6, 12, 18, 24, 30, and 36 months. Tooth mobility was monitored with Periotest values. Adjuvant therapies were carried out if necessary. Survival probabilities of telescopes and abutment teeth as well as the influence of clinical factors (age, sex, jaw, vitality, opposing dentition, axis inclination, end Periotest value, crown length, crown margin quality, wearing mode, tooth types, abutment distribution, number of telescopes) were calculated with Kaplan-Meier estimators. The relative risks for telescope loss were calculated with Cox regression. Results: The survival rate was 93.9% for abutment teeth and 87.5% for telescopes. Number of telescopes, abutment distribution, vitality, and gender as factors influenced the survival rates (Kaplan-Meier). In combination with the jaw as a factor, these affected the risk for telescope loss (Cox regression). Periotest values (mean of abutment teeth per examination) decreased significantly (P .0001). Altogether, 11% of teeth fractured and 4.6% of teeth were extracted. Patients were mostly very satisfied. Conclusion: TRPDs proved to be a favorable treatment concept for severely reduced dentitions. FTCs can be considered as elements with a good benefitmaintenance relation. A general increase of abutment tooth mobility could not be verified. Keywords: abutment tooth mobility, frictional telescopic crowns, Periotest values, prospective clinical study, severely reduced dentition, survival probability