Toothbrushing Wear Resistance of Stained CAD/CAM Ceramics

Abstract

Aim: To investigate the effect of toothbrushing on different stained Computerd Aided Design/Computer Aided Manufacturing CAD/CAM ceramics. Materials and Methods: Fifty specimens (high translucency zirconia, YZHT; zirconia-reinforced lithium silicate, ZLS; feldspathic, FDL; hybrid ceramic, HC; all from Vita Zahnfabrik) were divided into five groups according to their staining technique. ZLS allowed the composition of two groups: ZLS1 with crystallization and staining together; ZLS2, with the stain firing after the crystallization. YZHT received a stain firing after the sintering process, and FDL received stain firing directly. The HC was stained with acrylic staining, and was light-cured on its surface. The specimens were brushed in total for 150,000 cycles at 2.45 N with 180 strokes/min. Surface measurements to obtain Rz were performed after 50,000, 100,000 and 150,000 cycles, with five evaluation lines (5 mm) per specimen orthogonal to the brushing direction, covering brushed and unbrushed areas. The wear was analyzed using two-way ANOVA and Tukey tests (α = 5%). Scanning electron microscopy (SEM) was performed to access the surface profile. The wear was affected by material (p < 0.001) and time (p = 0.139). Superior wear (µm) was observed for HC (6.6 ± 4.4; 6.8 ± 4.0; 9.2 ± 3.5) compared to ZLS2 (1.0 ± 0.3; 1.2 ± 2.2; 1.3 ± 0.3), YZHT (1.0 ± 0.1; 1.2 ± 0.3; 1.2 ± 0.3), ZLS1 (0.9 ± 0.1; 1.1 ± 0.5; 1.2 ± 0.3) and FDL (0.9 ± 0.1; 0.9 ± 0.1; 1.0 ± 0.2) after 5, 10 and 15 years of simulation, respectively. SEM showed different wear patters for HC with the removal of the glaze layer. HC showed a higher staining wear rate compared to the glass-based and polycrystalline ceramics after 15 years. The extrinsic characterization of feldspathic ceramic showed its superior longevity compared to the evaluated high-translucency zirconia, zirconia-reinforced lithium silicate, and hybrid ceramic.

Influence of Toothbrush Abrasion and Surface Treatments on Roughness and Gloss of Polymer-Infiltrated Ceramics

“…According to Trauth et al [25], polishing the final product relieves the voids and flattens the final layer for better light reflection. In another study by Dal Piva et al, staining of CAD-CAM ceramics was employed for assessing comparative wear resistance [29]. It was observed that hybrid ceramic showed a higher wear rate compared to feldspathic ceramic.…”

Wear of dental ceramics

“…Toothbrushing simulation is widely used to evaluate the abrasion wear of ceramic materials, as well as, the wear of the glaze or the extrinsically stain layer [79][80][81][82][83][84]. However, depending on how and when toothbrushing is performed, as well as the type of dentifrice and toothbrush used [85], toothbrushing frequency and force of brushing, dental wear may increase [14].…”

“…For the toothbrush simulation, a slurry of the toothpaste and deionized water should be prepared in a ratio of 1:3 (w/w) [83,84,97] (Figure 10). The main purpose of the slurry is to obtain a consistency that better simulates the conditions in the oral cavity.…”

“…This procedure will remove surface debris, allowing comparison between specimens. The amount of wear in micrometers can be obtained by contact profilometer by using the Rz parameter [83,84,99] or a dedicated software [97]. In addition, the wear values can be obtained by 3D lasermeasuring microscopy [102] and vertical loss of dental cusp [103].…”

“…To standardize the method, two parallel grooves can be marked at the lateral area of the specimen's surface as reference, allowing the superimposition of the initial and final surface profiles (Figure 9C). A metal strip containing an orifice can be used to protect these grooves, so only the central area will be brushed [83,84,97] (Figure 9B). A custom-made device is used to place the specimens in the same position before and after brushing.…”