Ten-Year Proof of Non-precious Metal Double Crowns With Spark-eroded Friction Pins

Objectives: Double crowns with spark-eroded friction pins (DCP) perform comparable clinical long-term success compared to other double crown systems. Clinical data for this type of double crown are available for a period of 5 years. The aim of this follow-up study is the investigation of severely reduced dentures (SRD) compared to non-severely reduced dentures (NSRD) after a wearing period of 10 years.
Materials and Methods: A total of 158 participants (71 female, 87 male) aged 24.5-87.0 years (mean age 62.5±12.7 years) with 182 prostheses on 520 abutment teeth were followed up in the period from 2006 to 2021. The SRD group included 144 dentures (RPD) supported on 314 abutment teeth. The 10-year survival rates of dentures and abutment teeth were determined according to the Kaplan-Meier method, the log-rank test was performed, and a Cox regression was calculated. Participant age, gender, jaw, localization (according to the Steffel classification), and vitality were considered as relevant factors.
Results: The 10-year cumulative survival rate of all abutment teeth was 65.6% (CI: 59.0-72.2), with significantly lower values in the SRR (53.5%; CI: 43.9-63.1; log rank: p < 0.001). The survival rate for all DCP-dentures was (64.6 %, CI: 52.2-77.0 %). The SRD group showed significantly lower survival rates of (56.7%, CI: 41.7-71.7%; p = 0.006). The number, location and vitality of the abutment teeth had a significant influence on survival rates.
Discussion and Conclusion: DCP showed an acceptable clinical survival rate after 10 years. These results are comparable to other double crown systems described in the literature. The age of the patient, sex, and the distribution and vitality of the abutment teeth showed a significant influence on the survival rates of the abutment teeth. Consideration of these factors could prove helpful in the prognostic evaluation of abutment teeth in the context of clinical treatment planning.