Effect of glass inserts on resin composite wear

To determine the in vitro wear resistance and microstructural stability of composites in which the beta quartz insert was used.

Three different sized inserts were used in conjunction with P-50 and Herculite XR posterior resin composites. The study was designated to create varying gap dimensions between the insert and wall of the preparation (0.75, 1.25 and 1.50 mm). In addition, one half of the inserts contacted the dentin floor of the cavity whereas the other half rested on 1.0 mm of composite. The controls consisted of resin composite only. Using an in vitro wear testing device, all specimens were subjected to 400,000 cycles of masticatory loading. Upon completion of testing, profilometric tracings and SEM were used to determine relative wear, patterns of wear and microstructural changes. Differences, in wear values were analyzed by two-way ANOVA.

The wear values for P-50 and Herculite XR controls were 24.8 and 31.3 micrometers, respectively. No significant differences were detected (P<0.05) in amount of wear between the control specimens and the insert specimens, regardless of size. The same results were obtained regardless of whether the insert rested on dentin or resin composite. SEM evaluations however, revealed excellent interfacial continuity after wear testing. While the inserts did not influence the wear resistance, they may provide an excellent means for maintaining functional occlusion.