Purpose To evaluate the effect of multiple firings on the optical and mechanical properties of two dental CAD/CAM glass‐ceramics. Materials and Methods A total of 45 specimens of each lithium disilicate‐LD (IPS E.max CAD, Ivoclar Vivadent) and zirconia lithium silicate‐ZLS (Vita Suprinity, Vita Zahnfabrik) material were prepared in a disk shape. These specimens were divided into three groups according to two factors: “type of ceramic” (LD and ZLS) and “numbers of firings” (Control 2F‐two firings, 5F‐five firings and 7F‐seven firings). The firing cycles were performed according to the manufacturer's recommendations. X‐ray diffraction was additionally performed to determine crystalline phases in each group, spectrophotometry was used to determine color and translucency variation, and biaxial flexural strength (BFS) evaluated the mechanical behavior. The data were analyzed individually using two‐way ANOVA tests and Tukey's test at α = 0.05. Results The crystalline phases did not present any change after multiple firings for either of the analyzed materials. Both commercial materials showed a significant difference regarding translucency at 7F (p = <0.01), and ZLS presented a difference in color higher than one (ΔE > 1) at 5F and 7F. Regardless of the number of firings, LD presented a higher BFS compared to ZLS (p = <0.001), and a significant increase in BFS comparing 2F and 7F (p = <0.024). Conclusion The use of multiple firings can significantly alter the color, translucency, and mechanical strength of CAD/CAM ceramics.

Owing to their adequate adhesive, esthetic, and mechanical properties resin-based cement has been widely used in dental practice to bond metallic, ceramic, or polymeric indirect restorations (crowns, veneers, inlays, onlays, or fixed partial dentures) in mineralized dental tissues. 1-3 Compared to conventional types of cement, like zinc phosphate and glass ionomer, resin-based cement has improved adhesive and mechanical properties and it is less soluble. 2-4 However, because of their potential cytotoxic effect on pulp-dentine complex 5-7 and the possible occurrence of postoperative hypersensitivity owing to the absence of hermetical sealing on the tooth/cement interface provoked by a

Objective: To determine the time required for pH buffering by saliva after use sugary(S), sugar-free (SF) and probiotic (P) chewing gums. Material and Methods: Saliva was collected from 12 volunteer dental students at UNESP São José dos Campos / SP, in order to determine salivary flow (SR) rate and initial buffering capacity (BC). Participants presenting BC>4.0 were invited to continue the research. Participants chewed different types of gum for 3 consecutive days, and saliva was collected at 0-1min, 1-5min, and 5-10min intervals. The time required to neutralize saliva pH after chewing the different types of gum was analyzed by RM ANOVA and Tukey's test (5%). Results: RM ANOVA revealed significant influence on the interaction effect (chewing gum and time) (statisticFdf(4.66) = 4.027, p = 0.0055 <0.05). According to Tukey's test, differences were observed in the following circumstances: for the 0-1 interval, BC of S differs from SF and P; BC of S differs from SF at 1-5 min and 5-10 min intervals; and, 0-1min interval differs from 1-5 min and 5-10 min intervals for both S and SF. Conclusion: Dentistry students showed no increased predisposition to dental caries with a specific type of chewing gum. Although time for pH recovery differed according to gum type, they were all above the critical range for enamel demineralization.

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(1) Background: to propose a new approach for crown veneers, with the use of an aesthetic porcelain coating, only in part of the zirconia infrastructure, and to analyze its biomechanical behavior to minimize chipping failures. (2) Methods: a maxillary molar was modeled using CAD software, preparing for traditional crowns and veneer crowns with various lengths. Five groups were formed: M—control group (monolithic crown of ultra-translucent zirconia); B—conventional (bilayer crown of ultra-translucent zirconia and ceramic covering); V—veneer (ultra-translucent zirconia crown with reduction only in the buccal and application of covering ceramics); V1—ultra-translucent zirconia crown with buccal reduction and 1 mm occlusal extension for covering ceramic application); V1.5—ultra-translucent zirconia crown with buccal reduction and 1.5 mm occlusal extension for application of covering ceramics. A load of 600 N was performed axially to a fossa bottom to simulate parafunction, and 300 N to the cusp tip to obtain the maximum principal stress results. (3) Results: group B showed a higher stress concentration in the occlusal region of the restorations, while the other groups absorbed the stress and dissipated it throughout the crown, presenting a higher stress concentration in the interface region with the tooth. (4) Conclusion: the highly translucent zirconia ceramic only associated with buccal covering ceramic could add aesthetic gain and rigidity to the system and could be a good option to restore maxillary molars in patients who do not have parafunction.