Measurement of wear on composites used to restore worn teeth

Objectives: The aim of this study was to measure the wear of extensive direct and indirect composite restorations in vivo. Method: 28 subjects participated in the study, having received ethical approval. 19 patients had tooth wear and the remaining nine without tooth wear acted as controls. All patients received at least 2 paired restorations. The tooth wear subjects had the restorations placed to provide an increase in the occlusal vertical dimension, mean 2.5mm (range 2-3mm). Each patient had restorations in both Heliomolar (Ivoclar, Liechtenstein) and a new indirect composite. The choice of restoration was decided by random selection. All restorations were placed by a single operator using the dental adhesive Syntac and the luting cement Variolink. Each premolar and molar restoration had an indent drilled into it to act as reference area for the wear analysis. Impressions were taken at 3, 6 and 9 month intervals using a elastomeric material. Impressions were scanned with a non-contacting laser profilometer and wear measured as step heights from the indents. Data was analysed using generalised estimating equations for cross-sectional time-series data (Stata version 8.2) with significance pre-determined at Ą=0.05. Results: A total of 64 restorations were placed. 31 teeth were restored with heliomolar and 33 with the new material. The longest recall period was 15 months and the shortest 3 months. A 9 months the median wear on the heliomolar for the tooth wear group was 0.57mm(IQR 1.64) and for the indirect composite 0.29 (IQR 0.9). For the controls the median wear of the heliomolar was 0.4 (IQR 0.9) and for the indirect composite 0.16 (IQR 0.3). There was no statistical difference in the wear between the two materials. Conclusion: the method to measure clinical wear showed no differences between the materials but some difficulties were observed in the technique. (*Ivoclar Plc Liechtenstein).