Up to 30 years of clinical performance of double-crown-retained removable dental prostheses with spark-eroded friction pins placed in a general dental practice

PURPOSE: The purpose of this retrospective cohort study was to investigate the clinical performance and longevity of double-crown-retained removable-dental-prostheses (DCR-RDP) with spark-eroded friction pins inserted in a general dental practice and followed up over a period of 30 years. MATERIALS AND METHODS: This retrospective cohort study observed the influence of various factors on the longevity of the DCR-RDPs with spark-eroded friction pins and the abutment teeth using Kaplan-Meier estimation (log-rank test, p < .05) estimation and Cox regression (α = 0.05). RESULTS: During a mean follow-up of 14.07 ± 7.89 years (max 31.66 years), 196 prostheses and 563 abutments were observed. 30.61% (n = 60) of the prostheses and 39.43% (n = 222) of the abutments failed. The mean survival time for the prostheses was 22.66 ± 0.86 years (95% CI:20.97 to 24.24 years), and for the abutments, 20.29 ± 0.51 years (95% CI: 19.29 to 21.29 years). The following factors had a significant influence on the performance of either the prostheses or the abutment teeth: Kennedy class, number of replaced teeth, opposing dentition, number of abutments, crown-root ratio, probing depth, location, and vitality (p<.05). CONCLUSIONS: The highest survival rates were shown by Kennedy Class III DCR-RDPs and abutment teeths, while the lowest were seen with prostheses with 11 or more replaced teeth. The number of abutment teeth, pocket depth, vitality, and crown/root length ratio should also be considered in terms of the abutment teeth's longevity.