Effect of Brushing on Surface Properties of Subtractively and Additively Manufactured Resin-based Materials for Permanent Restorations.

Abstract

This in vitro study evaluates the impact of simulated toothbrushing on the surface roughness, gloss, and color stability of subtractively and additively manufactured resin-based materials intended for permanent dental restorations. Six materials were tested: two CAD/CAM pre-polymerized resin blocks, a ceramic material, a composite resin for direct and indirect use, and a newly FDA-cleared 3D-printed resin material designed for permanent crowns. To simulate clinical conditions, specimens were subjected to a controlled brushing protocol for up to 50,000 cycles, equivalent to approximately five years of brushing. Measurements of surface roughness (Ra), gloss (GU), and color stability (ΔE) were measured at baseline and after 10,000, 30,000, and 50,000 cycles. Surface roughness was assessed with a non-contact optical profilometer, gloss with a glossmeter, and color stability was with a spectrophotometer. Additionally, scanning electron microscopy (SEM) was used to analyze surface morphology post-brushing. The results showed significant differences in surface properties among the tested materials (p < .001). Ceramic materials, particularly the lithium disilicate glass-ceramic blocks, exhibited superior resistance to surface roughness and gloss loss, maintaining high aesthetic properties even after extensive brushing. In contrast, the 3D-printed resin material experienced a notable increase in surface roughness and significant gloss reduction, indicating higher susceptibility to wear. Resin composites varied in their performance, with direct-use resin composites performing worse in terms of gloss retention and color stability compared to their CAD/CAM counterparts. Color stability assessments indicated that ceramic materials remained within clinically acceptable color change thresholds, while resin-based materials generally exceeded these limits, suggesting potential long-term aesthetic challenges. Statistical analysis confirmed these findings, with ceramic materials showing minimal changes across all parameters, while the 3D-printed and direct-use resin materials demonstrated the most significant changes.