An evaluation of the surface changes in denture base of toothbrush/dentifrice abrasion

Objectives: The objective of this study was to evaluate the abrasion resistance and surface roughness of poly(methylmethacrylate) denture base materials by simulating toothbrushing.
Methods: According to manufacturers’ instructions, an autopolymerizing resin (Heraeus Kulzer GmbH, Hanau, Germany) were fabricated in 25×25×3mm. Ten specimens divided into 2 groups according to the cleaning method used. The simulated toothbrushing included a control group (without dentifrice, WD) and a toothbrush/dentifrice group (the ratio of dentifrice and water is 1:2, TD). Toothbrushing was performed 60Hz with using 50,000 strokes of brush by reciprocating abrasive machine (PAT-2012, PROyes, Taiwan) at a load of 200g. A profilometer (Surftest SJ-410, Mitutoyo Corporation, Japan) was used to determine the surface roughness (Ra) before and after toothbrushing. The surface characteristics were evaluated by SEM, and the weight loss was also measured.
Results: The cumulative values for weight-loss of each 10,000 strokes in the TD showed the reduction in the weight of the specimens to be a fairly linear loss in character. On the contrary, the WD specimens showed constant during toothbrushing. The mean values of initial/finial roughness (Ra, m) were as follow: WD (0.024/0.064); TD (0.024/20.11). The micrograph of abraded specimens showed that the grooves be scraped, and the phenomenon of denture base material flaked from the surface in microcosmic.
Conclusions: Brushing with water alone produced no detectable wear on any of the materials. Dentifrice played a significant role in abrasion that increased surface roughness and resulting in the intense vertical wear.