Effect of Ceramic Conditioners on Surface Morphology, Roughness, Contact Angle, Adhesion, Microstructure, and Composition of CAD/CAM Ceramics.

The objective of this study was to investigate the effect of surface treatments in maximum profile valley depth (Rv), surface roughness (Sa), contact angle (Ca), shear bond strength (SBS) of a light-cured resin cement, microstructure, and composition of two CAD/CAM ceramics: Cerec Blocs/Dentsply Sirona (feldspathic - FEL) and Empress CAD/Ivoclar Vivadent (leucite-reinforced - LEU). The ceramic specimens were submitted to six surface treatments: (1) 5% hydrofluoric acid (HF) - 20 seconds; (2) 5% HF - 60 seconds; (3) 10% HF - 20 seconds; (4) 10% HF - 60 seconds; (5) self-etching ceramic primer (MEP) - 20 seconds; and (6) MEP - 60 seconds. Specimens treated with HF received silane application for 1 minute. Rv and Sa were evaluated in a confocal laser microscope (n=10) and the Ca in a goniometer (n=6). For the SBS test, two resin cement cylinders were bonded to each specimen, one tested after 24 hours in distilled water storage (37°C) and the other after one year (n=10). The microstructures and compositions were analyzed by scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) (n=4). Rv, Sa, and Ca data were analyzed by two-way ANOVA, and the SBS data by three-way ANOVA, all followed by post-hoc Tukey's test (α=0.05). Results: Surface treatments with HF always produced higher Rv and Sa, and lower Ca than MEP 60s for both ceramics. After 1-year water storage, FEL ceramic treated with MEP for 60 seconds produced higher SBS values than HF treatments, whereas for LEU ceramic there were no differences among treatments. Application of MEP for 20 or 60 seconds produced no difference in Rv, Sa, Ca, and SBS for both ceramics. Surface treatments produced considerable differences in ceramic topography, but subtle ones in composition, for both ceramics. Conclusions: The results indicated that for FEL ceramic, MEP application for 60 seconds yielded higher SBS compared with HF etching, while for LEU ceramic the surface treatments did not influence the SBS results.

In Vitro Evaluation of Surface Properties and Wear Resistance of Conventional and Bulk-fill Resin-based Composites After Brushing With a Dentifrice.

OBJECTIVES: This study evaluated the effect of toothbrushing with a dentifrice on gloss, roughness profile, surface roughness, and wear of conventional and bulk-fill resin-based composites. METHODS AND MATERIALS: Gloss and surface roughness of resin-based composites (RBCs; Admira Fusion X-tra, Aura Bulk Fill, Filtek Bulk Fill Flowable, Filtek Bulk Fill Posterior Restorative, Filtek Supreme Ultra, Herculite Ultra, Mosaic Enamel, SDR flow+, Sonic Fill 2, Tetric EvoFlow Bulk Fill and Tetric EvoCeram Bulk Fill) were analyzed before and after brushing; the roughness profile and wear were also determined after toothbrushing. Representative three-dimensional images of the surface loss and images comparing the unbrushed and brushed surfaces were also compared. Analysis of variance and Tukey post hoc tests were applied (α=0.05) to the gloss, surface roughness, roughness profile, and surface loss data. Pearson's correlation test was used to determine the correlation between gloss and surface roughness, surface loss and percentage of gloss decrease after brushing, and surface loss and surface roughness after brushing. RESULTS: For all RBCs tested after 20,000 brushing cycles, the gloss was reduced and the surface roughness increased (p<0.05). However, the roughness profile and the amount of surface loss were dependent on the RBC brand. Admira Fusion X-tra, Aura, Tetric EvoCeram Bulk Fill, and Tetric EvoFlow Bulk Fill showed the deepest areas of wear (p<0.05). A significant negative correlation was found between gloss and surface roughness, and a weak correlation was found between the decrease in gloss and the extent of surface loss, and any increase in surface roughness and the surface loss. CONCLUSIONS: Toothbrushing with a dentifrice reduced the gloss, increased the surface roughness, and caused loss at the surface of all the RBCs tested. Considering all the properties tested, Mosaic Enamel exhibited excellent gloss retention and a low roughness profile and wear, while Admira Fusion X-tra exhibited the greatest decrease in gloss, the highest roughness profile, and the most wear.

An in situ investigation into the abrasion of eroded dental hard tissues by a whitening dentifrice.

This crossover study aimed to investigate abrasion of previously eroded hard dental tissues by a whitening dentifrice compared to a regular dentifrice. After a 3-day lead-in period, 14 volunteers were randomly assigned to use one of the toothpastes while wearing a removable appliance, containing 3 enamel and 3 root dentine slabs on each side. On the first day salivary pellicle was allowed to form. Twice daily for the following 3 days, one side of each appliance was immersed in an acidic carbonated drink ex vivo while the other side remained unexposed. Specimens were then brushed with the allocated dentifrice. After a 3-day washout period, new sets of enamel and dentine slabs were mounted in the appliances and the participants commenced period 2 using the alternative toothpaste. Acid-treated specimens always showed more wear than untreated specimens. The whitening dentifrice did not significantly increase the wear of softened enamel compared with the regular dentifrice. Brushing with the whitening toothpaste led to significantly greater wear of sound enamel and of both eroded and sound dentine than the regular dentifrice. The results suggest that whitening dentifrices may not increase the wear of acid-softened enamel but may have a more deleterious effect on dentine than regular toothpastes.