Calibration of an Artificial Oral Environment with Clinical Data

Objective:  Correlation of in-vitro estimates of masticatory wear with clinical experience is of first importance. Therefore, this study calibrates the University of Minnesota artificial oral environment (ART) wear using clinical wear of a posterior composite.  Methods: Casts of ten patients with SureFil (Caulk Dentsply) composite restorations, rated for wear at 0.5, 1, 2, 4 and 5 year intervals ( Bayne et al. J Dent Res 84; Special Issue A: #583, 2005), were mapped using a contact profiler.  Baseline and recall images were fit together and analyzed using AnSur (Copyright Regents University of Minnesota).  Seven restorations (5 patients) had contact wear for comparison to the ART contact wear.  Seven SureFil disks 12.5 mm diameter and 2 mm thick were prepared following manufacturer's directions and stored for 24 hrs in 37º C deionized water.  Each disc was mounted in ART and opposed by a natural enamel cusp. ART mandibular-like movement parameters: 0.5 mm lateral movement, haversine force profile, peak force of 13N, force duration of 0.2 sec, lubrication deionized water at 37º C.  Wear was calculated following 150K, 300K, 600K, 1.2M, and 1.5M cycles using the same method used for the clinical samples.  The test was repeated on three samples using a peak force of 31N.  Results: Linear regressions forced through zero for the clinical and ART 13N and 31N peak force data sets were expressed as Volume Loss (mm³) = k (mm³/year) x Time (Years) where k = 0.080 (r²=0.49), 0.049 (r²=0.58), and 0.077 (r²=0.92), respectively.  Pearson correlations between the clinical and the ART data sets were r=0.65 (13N) and r=0.93 (31N).  Conclusions: The artificial oral environment with a peak force of 31N and 300,000 cycles equal to one year reproduces the SureFil clinical contact wear.  This work was supported by the Minnesota Dental Research Center for Biomaterials and Biomechanics.