Wear of a dental composite in an artificial oral environment: A clinical correlation

The study objective was to correlate wear between an in vitro method for simulating wear and in vivo wear of a posterior dental composite. Ten subjects (12 restorations) were selected from a five-year clinical study (University of North Carolina, School of Dentistry) that assessed wear of SureFil composite (Caulk, Dentsply). Subject casts were digitized and changes in volume and mean depth with time were calculated from the 3D digital models for contact and contact-free wear. SureFil composite disks were mounted in the University of Minnesota's Artificial Oral Environment, opposed by natural enamel, subjected to mandibular-like movements for 150 K, 300 K, 600 K, 1.2 M, and 1.5 M cycles, and loaded with peak forces of 13 N (n = 7) or 30 N (n = 3). Wear rates were calculated as the slope of the linear regressions fitting the wear data. Data were analyzed using one-way ANOVAs and post hoc t-tests where appropriate (p = 0.05). Clinical restorations included contact wear on seven restorations and contact-free wear on all restorations. Contact-free wear was less than contact wear (p < 0.01). SureFil clinical wear rates were 0.012 mm/year (mean depth) and 0.023 mm(3)/year (volume). Clinical restorations expanded slightly during the first year. Using a conversion rate of one year equals 3 × 10(5) cycles, there were no significant differences between the clinical and simulated data except depths at Year 5 and 13 N volume at Year 4. The 30 N simulation reproduced the clinical data if contact-free wear was taken into account. Good agreement between simulated and clinical wear implies that in vitro simulation can screen new composite formulations.