EFFECT OF GLASS INSERTS ON RESIN COMPOSITE WEAR

Purpose: To determine the in vitro wear resistance and microstructural stability of composites in which the beta quartz insert was used. Mat erials and Methods: Three different sized inserts were used in conjunc tion with P-50 and Herculite XR posterior resin composites. The study was designed to create varying gap dimensions between the insert and w all 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 o ther half rested on 1.0 mm of composite. The controls consisted of rei n composite only. Using an in vitro wear testing device, all specimens were subjected to 400,000 cycles of masticatory loading. Upon complet ion of testing, profilometric tracings and SEM were used to determine relative wear, patterns of wear and microstructural changes. Differenc es in wear values were analyzed by two-way ANOVA. Results: The wear va lues for P-50 and Herculite XR controls were 24.8 and 31.3 mu m, respe ctively. No significant differences were detected (P<0.05) in amount o f wear between the control specimens and the insert specimens, regardl ess of size, The same results were obtained regardless of whether the insert rested on dentin or resin composite. SEM evaluations however, r evealed excellent interfacial continuity after wear testing. While the inserts did not influence the wear resistance, they may provide an ex cellent means for maintaining functional occlusion.