Clinical wear of acrylic teeth in full and partial dentures

Objectives: Since in-vitro wear tests can only insufficiently simulate the large variety of parameters present in a real clinical situation, in-vivo data on the wear behavior of denture teeth are particularly valuable. This prospective study evaluated the clinical wear rate of posterior acrylic denture teeth used in removable partial dentures (RPD) and full dentures or overdentures (FD). Methods: 30 patients, provided with removable partial dentures (n=21) or complete dentures (n=15) were included in this study. Altogether, the wear rate of 204 posterior denture teeth (Vitapan, Vita Zahnfabrik, Bad Säckingen, Germany) was evaluated. Gypsum casts (GC Fujirock EP Pearl White, Leuven, Belgium) were made from preliminary polyvinylsiloxane impressions (Flexitime, Heraeus Kulzer, Dormagen, Germany) after denture insertion (baseline data) and after a period of 6 and 12 months. Wear measurements were carried out from gypsum replicas using a 3D Laser Scanner (Willytec, Munich, Germany). Wear was calculated as the difference between the replica surfaces at the recalls and at baseline. Statistical analysis was performed using Mann-Whitney-U-Test and ANOVA (Games-Howell). Results: The mean wear (µm) of all denture teeth was 20.5 (SD 14.6) after 6 months and 34.5 (SD 30.3) after 12 months. No significant differences in wear by gender and the antagonistic material were found. A separate analysis of the variable “type of denture” revealed slight differences. After 6 months the wear was 22.7 (SD 14.9) for RPDs and 18.5 (SD 14.0) for FDs (p=0,011). After 12 months a wear rate of 39.4 (SD 33.0) for RPDs and 30.9 (SD 27.8) for FDs was found. Conclusions: Acrylic denture teeth demonstrate continuous wear after 6 and 12 months in service. The results indicate that removable partial dentures retained on several abutment teeth are more susceptible to wear compared to full dentures.