Surface degradation of glass ceramics after exposure to acidulated phosphate fluoride

Abstract

ObjectiveThis study evaluated the surface degradation effect of acidulated phosphate fluoride (APF) gel exposure on the glassy matrix ceramics as a function of time.Material and methodsDisc-shaped ceramic specimens (N = 120, 10/per ceramic material) were prepared in stainless steel molds (inner diameter: 5 mm, height: 2 mm) using 6 dental ceramics: 3 indicated for ceramic-fused-to-metal (Vita Omega 900, Carmen and Vita Titankeramik), 2 for all-ceramic (Vitadur Alpha and Finesse® Low Fusing) and 1 for both types of restorations (IPS d.SIGN). The specimens were wet ground finished, ultrasonically cleaned and auto-glazed. All specimens were subjected to calculation of percentage of mass loss, surface roughness analysis and topographical description by scanning electron microscopy (SEM) before (0 min) and after exposure to 1.23 % APF gel for 4 min and 60 min representing short- and long-term etching effect, respectively. The data were analyzed using two-way ANOVA with repeated measures and Tukey`s test (α=0.05).ResultsSignificant effect of the type of the ceramics (p=0.0000, p=0.0031) and exposure time (p=0.0000) was observed in both surface roughness and percentage of mass loss values, respectively. The interaction factor between both parameters was also significant for both parameters (p=0.0904, p=0.0258). Both 4 min (0.44±0.1 - 0.81±0.2 µm) and 60 min (0.66±0.1 - 1.04±0.3 µm) APF gel exposure created significantly more surface roughness for all groups when compared to the control groups (0.33±0.2 - 0.68±0.2 µm) (p<0.05). There were no significant differences in percentage of mass loss between the ceramics at 4 min (p>0.05) but at 60 min exposure, IPS d.SIGN showed the highest percentage of mass loss (0.1151±0.11). The mean surface roughness for Vita Titankeramik (0.84±0.2 µm) and Finesse® Low Fusing (0.74.±0.2 µm) was significantly higher than those of the other ceramics (0.59±0.1 µm - 0.49±0.1 µm) and Vita Titankeramik (p<0.05) regardless of the exposure time. A positive correlation was found between surface roughness and percentage of mass loss for all ceramic materials [(r=0.518 (Vitadur Alpha), r=0.405 (Vita Omega 900), r=0.580 (Carmen), r=0.687 (IPS d.SIGN), r=0.442 (Finesse® Low Fusing), r=0.572 (Vita Titankeramik), Pearson`s correlation coefficient)]. The qualitative SEM analysis showed evidence of corrosive attack on all of ceramics at varying degrees.ConclusionsThe ceramics indicated for either metal-ceramic or all-ceramic restorations were all vulnerable to surface texture changes and mass loss after short-term and long-term APF gel exposure.

Bacterial Adhesion on Lithium Disilicate Ceramic Surface Exposed to Different Hydrofluoric Solutions

“…Acidulated fluoride gel is commonly used to prevent dental caries [25], with its professional application being recommended every three months in patients with a high index of caries [9]. However, this gel presents low pH, which could directly influence the longevity of ceramic restorations in the oral cavity.…”

“…However, the surface of these restorations can be susceptible to erosive solutions, or even those that fluoride-containing in their composition, which could damage the surface of such restorations, promoting an increase in roughness [9,10]. It is known that restoration surface integrity is related to the clinical success of the rehabilitation treatment [6].…”

“…However, literature is scarce when assessing the influence of such solutions on lithium disilicate ceramics and their influence on bacterial adhesion. Nonetheless, it is known that the accumulation of bacterial plaque is proportional to the surface roughness of the material, being a direct relationship with periodontal health, and consequently, the longevity of the restoration [1,9].…”

Effects of multiple firings on the microstructure of zirconia and veneering ceramics

“…The chemical property of ceramic materials, which consist mainly of various crystal phases, is affected by a variety of factors, such as the composition and microstructure of the ceramic materials, as well as temperature [10][11][12][13] . Firing protocols performed at high temperature (750-900°C) usually apply 2-5 successive firings in simple cases.…”

“…Firing protocols performed at high temperature (750-900°C) usually apply 2-5 successive firings in simple cases. However, in complicated cases, ten firings are sometimes required 11) . Previous studies have investigated the effects of the veneering firing protocol on the surface hardness of porcelain.…”