Effect of toothbrushing on surface roughness and gloss of CAD-CAM versus conventional interim materials with different surface treatments

Statement of problem: Characterizing interim restorations promotes esthetics. However, studies on the effects of characterization materials on the surface roughness and gloss of interim materials after toothbrushing are lacking. Purpose: The purpose of this in vitro study was to evaluate the surface roughness and gloss of 5 different interim materials with different surface treatments after 1 year of simulated toothbrushing. Material and methods: Cuboid specimens (10x12x2 mm) were fabricated from each interim material: autopolymerized polymethyl methacrylate (UNIFAST Trad), autopolymerized bis-acryl composite resin (Protemp 4), light-activated composite resin (REVOTEK LC), milled polymethyl methacrylate block (DD provi P HI), and 3-dimensionally printed methacrylate oligomer (Nextdent C&B MFH). Each material was divided into 3 groups based on surface treatment (n=10): polishing, application of Lite Art and Resin Glaze, and application of OPTIGLAZE color. The specimens were subjected to 5000 and 10000 cycles of toothbrushing. The surface roughness and gloss were measured and separately analyzed by using 3-way repeated measures ANOVA (alpha=.05). Results: Significant interactions of the surface roughness and gloss among interim materials, surface treatments, and toothbrushing durations were found (P<.001). After 5000 and 10000 cycles, each polished material showed no significant difference in surface roughness compared with baseline: Protemp 4 (P>.999), REVOTEK LC (P>.999, P=.922), and Nextdent C&B MFH (P>.999), except for UNIFAST Trad and DD provi P HI (P<.001). Coating with Lite Art and Resin Glaze, as well as OPTIGLAZE color, significantly reduced surface roughness after both 5000 and 10000 cycles for all materials (application of Lite Art and Resin Glaze with UNIFAST TRAD (P<.001), Protemp 4 (P<.001), REVOTEK LC (P<.001), DD provi P HI (P<.001), and Nextdent C&B MFH (P<.001, P=.002), and application of OPTIGLAZE color with UNIFAST TRAD (P<.001), Protemp 4 (P<.001), REVOTEK LC (P<.001, P=.002), DD provi P HI (P<.001), and Nextdent C&B MFH (P<.001, P=.008)). Specimens with these treatments also exhibited significantly better gloss compared with the polished specimens (P<.001). Conclusions: After 5000 to 10000 cycles of toothbrushing, Protemp 4, REVOTEK LC, and Nextdent C&B MFH, interim materials containing fillers, exhibited smoother surfaces compared with UNIFAST Trad and DD provi P HI, interim materials without fillers. Coating of all materials reduced surface roughness and increased gloss. After 5000 to 10000 cycles of toothbrushing, the surface roughness of each material remained stable; while the gloss decreased slightly, it remained within clinically acceptable levels.