Wear behavior and abrasiveness of monolithic CAD/CAM ceramics after simulated mastication

Abstract

Objectives To evaluate the wear resistance and abrasiveness of monolithic CAD/CAM ceramics. Materials and methods Rectangular-shaped specimens (12 mm × 6.5 mm × 1.5 mm) were sectioned from the following CAD/CAM blocks (n = 10); partially crystallized lithium disilicate (PLD), experimental fully crystallized lithium disilicate (FLD), zirconia-reinforced lithium silicate (ZLS), super-translucent monolithic zirconia (SMZ), and ultra-translucent monolithic zirconia (UMZ). Silicon carbide papers were used to mechanically flatten and polish the surfaces. PLD specimens were subjected to a combined crystallization/glazing firing cycle. Ceramic specimens were mounted to the wear device and tested for 200,000 cycles against human premolars at 20 N force and 2 mm sliding distance. Artificial saliva was used as a lubricant. The teeth were scanned using micro-CT before and after the wear test and the generated models were overlapped to determine the volumetric tooth loss. Before and after the test, specimens’ weights and surface roughness (Ra) values were measured, and the differences were calculated. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) were utilized for microstructural and chemical analysis. Statistical analysis was performed using one-way ANOVA or an equivalent test for non-parametric results. Significance level was set at P ≤ 0.05. Results The type of ceramic material affected the ceramic and antagonist wear rates (P < 0.001). PLD and ZLS had the highest ceramic and antagonist wear, whereas UMZ and SMZ demonstrated the lowest wear values. The FLD group showed comparable antagonist wear and significantly less ceramic wear than PLD and ZLS. Conclusions Monolithic zirconia demonstrated the best wear resistance and least abrasiveness to the antagonist. The experimental lithium disilicate was more wear-resistant than other glass–ceramic groups. Clinical relevance Monolithic zirconia is wear-resistant and gentle on the antagonist. In contrast, glass–ceramics are more abrasive to enamel.

An investigation on fatigue, fracture resistance, and color properties of aesthetic CAD/CAM monolithic ceramics

“…The FLD crowns were milled from new fully crystallized lithium disilicate CAD/CAM blocks. These new blocks have been advertised as needing only polishing after milling and no subsequent crystallization firing is required [ 14 ]. No sufficient data is yet available in the literature about the microstructure of FLD to compare it to the conventional PLD.…”

“…LD CAD/CAM blocks are supplied in a “soft” intermediate phase to facilitate the machining process and preserve edge stability, then the milled restoration must be fired in a special ceramic oven to achieve the ultimate flexural strength [ 12 , 13 ]. Fully crystallized lithium disilicate (FLD) restorations were recently developed that can be milled directly from fully crystallized blocks without further crystallization [ 14 ]. However, it is not yet known how such a material will perform mechanically and aesthetically.…”

Wear Behavior of Monolithic Zirconia after Staining, Glazing, and Polishing Opposing Dental Restorative Materials: An In Vitro Study

“…This fact can be attributed to zirconia's ability to retain the initial surface smoothness after polishing for the P group, and the weak interface between zirconia and glaze paste related to the G group. Additionally, polishing offers the dental clinician the advantage of finishing the restoration chairside without the need for an expensive firing furnace or glazing cycles [29].…”

“…Although the wear behavior of 3Y-TZP has been widely investigated [14][15][16][18][19][20][21][22][23][24][25][26][27], a few studies investigated the wear behavior of 5Y-TZP [23,24,[28][29][30][31]. Among these studies, some compared the wear behavior of polished 3Y, 4Y, and 5Y-TZP opposing steatite antagonists [23,24], while others investigated the wear behavior of polished 5Y-TZP opposing bovine enamel [28], human enamel [29,30], composite resin [30,31], and lithium disilicate [30,31], but the effects of staining and finishing procedures on the wear behavior of 5Y-TZP opposing dental restorative materials were not evaluated. Therefore, the purpose of this in vitro study was to evaluate the effect of staining, glazing, and polishing on the wear behavior of 5Y-TZP opposing 5Y-TZP, leucite-reinforced ceramic, lithium disilicate, and microhybrid composite resin.…”

Biomimetic approaches and materials in restorative and regenerative dentistry: review article

“…In 2000, Holland et al were able to develop an apatiteleucite glass ceramics that are made of needle-like apatite building blocks similar to those found in the living dental tissues. The needle-like apatite crystals improved the esthetic and mechanical properties of the material [26][27][28].…”