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Objective: To evaluate the fracture behavior of human molars with extensive MOD restorations using short‐fiber‐reinforced resin composite of varying viscosities. Materials and Methods: Human molars were randomly divided into seven groups (n = 12): intact teeth (control); restoration using conventional high‐viscosity resin composite without (Filtek Z350XT, 3M) or with fibers (everX Posterior, GC); conventional low‐viscosity resin composite without (Filtek Supreme Flowable, 3M) or with fibers (everX Flow Dentin Shade, GC); bulk‐fill low‐viscosity resin composite (Filtek Bulk Fill Flow, 3M) or with fibers (everX Flow Bulk Shade, GC). Restorations were performed on extensive MOD preparations, following the manufacturers' recommendations for each material. Specimens underwent fracture strength testing (N) and fracture pattern (%) categorized as repairable, possibly repairable, or non‐repairable. Results were analyzed using a generalized linear model (N) and Fisher's exact test (%), with α = 0.05. Results: Restorations performed with high‐viscosity materials showed fracture strength values similar to the control and higher than those of restorations using low‐viscosity resin composites (p < 0.0001), except for the bulk‐fill low‐viscosity resin composite with fibers (p > 0.05). Teeth restored using low‐viscosity resin composite with fibers showed a higher % of repairable and possibly repairable fractures than the control (p = 0.0091). Conclusions: The viscosity of materials mediated the fracture strength, with restorations using high‐viscosity resin composites promoting values similar to the intact tooth; however, the presence of fibers influenced the fracture pattern. Clinical Significance: Teeth with MOD cavities restored with high‐viscosity resin composites showed similar fracture strength to intact teeth. Fiber‐reinforced low‐viscosity resin composite for the base of restoration resulted in a more repairable/possibly repairable fracture pattern. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of filled and unfilled modeler liquids on the cohesive strength and color stability when applied in between the resin composite layers in the stratification technique and on the uppermost surface layer. Methods: For the cohesive strength test (n= 10), 30 cylindrical samples were packed into a Teflon mold (6><2 mm) in 2 mm increments. Firstly, a dentin-shade resin composite (Empress Direct) was placed, followed by the accommodation of a body-shade resin composite (Filtek Z350 XT) and an enamel-shade resin composite (Estelite Omega. Before photoactivation of each increment, an unfilled (Signum Liquid) or filled (Modeling Resin) modeler liquid was applied between the first and second layers and on the uppermost surface layer. The control group (n= 10) did not receive modeler liquid. Cohesive strength was measured in a universal testing machine. For the color test (n= 10), the other 30 samples were fabricated for the cohesive strength test, except for the difference in the diameter (6)<6 mm). Before and after the staining of the samples, color was measured using the CIEL*a*b* system with a spectrophotometer (EasyShade). Data were submitted to ANOVA, Kruskal-Wallis test, or Mann-Whitney test (a= 5%). Results: Modeler liquids significantly increased cohesive strength (P= 0.008), while AEab'(P= 0.003) and AEoo (P= 0.005) values presented significantly lower changes for the groups that received modeler liquids, with no significant difference between unfilled and filled modeler liquids. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the impact of simplified or multi-step polishing techniques on the roughness, color, and susceptibility to staining of different resin composites.. Methods: Discs (Ø6 mm x 2 mm) were obtained from different resin composites [nanofilled (Z350XT), suprananofilled (Estelite Omega), and nanohybrid (Forma)]. The specimens (n= 15) were submitted to a simplified protocol using abrasive discs (Sof-Lex) and spiral discs (Diacomp Plus Twist), or a multi-step protocol using abrasive discs (Sof-Lex), abrasive points (Jiffy), silicon carbide brush and felt disc with diamond pastes (Diamond Polish). The specimens were evaluated initially for roughness (Ra) and color (CIEL*a*b*, CIEDE 2000), after completing the polishing protocol, and after exposure to a coffee solution (pH= 5.01). The data were analyzed according to the variables, using generalized linear models, and the Friedman, Nemenyi, Kruskal-Wallis, Dunn, and Mann-Whitney tests (α= 0.05).. Results: The nanohybrid resin composite showed an increase in Ra following use of both polishing methods (P= 0.038). Both techniques promoted an increase in L* values after polishing; however, the general color changes (Î"Eab and Î"E00) were greater after the multi-step polishing (P< 0.05). After immersion in coffee, the multi-step polished groups of the nanohybrid and suprananofilled resin composite showed higher L* values than the simplified polishing groups (P= 0.023), and the nanofilled resin composite showed higher Î"Eab and Î"E00 values than the other resin composites, regardless of the polishing technique (P< 0.05). [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of different varnishes on dentin permeability to erosive/abrasive challenges. Methods: 60 superficial dentin discs were randomly allocated to six groups (n =10): Duraphat, PRG Barrier Coat, Clinpro XT, Profluorid, Fluor Protector S and untreated (control). Permeability tests were carried out: after acid conditioning, after treatment, and after abrasive/erosive challenges. The abrasive-erosive challenges were performed for 5 days (citric acid and in remineralizing saliva), as well as abrasion with toothpaste slurry (Colgate Total 12). Scanning electron microscopy (SEM) images were obtained of the dentin surfaces (5,000×) after the treatments, and after the erosive/abrasive challenges. Results: Kruskal-Wallis and Dunn tests showed that all the varnishes promoted a decrease in dentin permeability directly after application, with Clinpro XT showing the highest percentage (69.52%) of dentin sealing (P = 0.0188). After the erosive/abrasive challenge, only PRG Barrier Coat varnish showed dentin sealing ability with reduced dentin permeability (42.16%) (P = 0.0014). However, none of the applied varnishes promoted a statistically significant difference in the percentage of dentin sealing, compared with the control group (P > 0.05). Clinpro XT showed a higher percentage of dentin sealing, while only PRG Barrier Coat showed reduced dentin permeability after the erosive/abrasive challenge. [ABSTRACT FROM AUTHOR]

Purpose: This study investigated the role of desensitising-only and desensitising/whitening versions of arginine and calcium carbonate-containing (ACC) and calcium sodium phosphosilicate-containing (CSPS) toothpastes on surface loss and permeability of root dentine.Materials and Methods: Slabs of human root dentine were embedded and exposed to citric acid solution to create a lesion resembling hypersensitive dentine. Sixty specimens were divided into six groups and exposed to slurries made with ACC (Colgate Sensitive Pro-Relief) and CSPS (Sensodyne Repair & Protect) toothpastes, in their desensitising or desensitising/whitening versions, an ordinary toothpaste (Crest Cavity Protection) or distilled water (DI). The other 60 specimens were brushed with either slurries or DI and assessed for surface loss. All specimens were analysed for dentine permeability. Data were subjected to analysis of variance (ANOVA) and Fisher's least statistically significant difference tests.Results: ANOVA (p = 0.018) showed that in the group brushed with DI surface loss was lower than in the groups brushed with toothpastes, but there was no statistically significant difference among the ordinary, desensitising-only and desensitising/whitening toothpastes. Dentine permeability was not influenced by brushing (p = 0.125). Toothpastes affected dentine permeability (p = 0.004), with the groups submitted to desensitising-only and desensitising/whitening toothpastes presenting significantly lower permeability than those submitted to DI, but no difference existed between the group treated with the ordinary toothpaste and DI.Conclusion: In comparison to desensitising-only, desensitising/whitening toothpastes neither accounted for increased surface loss nor impaired tubule occlusion of root dentine. [ABSTRACT FROM AUTHOR]

Purpose: To apply titanium tetrafluoride (TiF4) in an aqueous solution or incorporated into the primer of a self-etching adhesive (Clearfil SE Bond) as dentin pre-treatment and evaluate its antimicrobial effect, determine the minimum bactericidal concentraion (MBC) against Streptococcus mutans and Lactobacillus casei and analyse its potential to inhibit the development of carious lesions at the restoration interface.Materials and Methods: For MBC, an aqueous solution or primer with different concentrations (in %) of TiF4 were used (from 0.0 to 4.0). Also, 50 cavities were prepared at the enamel/dentin junction of third molars and received the following dentin pre-treatments (n = 10): Clearfil SE Bond (CL); aqueous solution of 2.5% TiF4 + CL (T2.5%); aqueous solution of 4% TiF4 + CL (T4%); 2.5% TiF4 incorporated into the primer (P2.5%); 4% TiF4 incorporated into the primer (P4%). Cavities were restored and submitted to pH cycling to create artificial caries lesions. Microhardness tests were performed after sectioning the restorations to assess the demineralisation at margins.Results: ANOVA and Tukey's tests showed that TiF4 in aqueous solution presented MBC against S. mutans and L. casei of over 2.0%. TiF4 in the primer of a self-etching adhesive presented MBC of over 1% for L. casei. For enamel, CL showed no significant differences in microhardness between the depths.Conclusions: The aqueous solution had an antimicrobial effect against Streptococcus mutans and Lactobacillus casei of over 2.0%. Pretreatment with the aqueous solution or primer did not inhibit demineralisation at enamel or dentin restoration interfaces. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the preventive effect of titanium fluoride (TiF4) gel and solution, in different concentrations, on dentin erosion. Materials and Methods: Of 140 root dentin slabs (3 x 3 x 1 mm) cut from 70 freshly extracted human third molars, 70 with intermediate Knoop microhardness and lowest surface curvature were selected and randomly divided into 7 groups (n = 10): G1: negative control (no treatment); G2: positive control (AmF/NaF/SnCl2 solution); G3: placebo gel (no fluoride); G4: 1% TiF4 solution; G5: 1% TiF4 gel; G6: 4% TiF4 solution; G7: 4% TiF4 gel. Samples were subjected to 10 days of erosive cycling, consisting of alternating exposures to citric acid (0.05 M, pH 2.3, 2 min, 6x/day) and remineralizing solution (pH 7.0, 90 min, between acid exposures). Each cycle consisted of a total of 6 immersions in acid per day. After 5 and 10 days of pH cycling, surface loss was assessed by optical profilometry (μm). Results: One-way ANOVA and Tukey's test (p < 0.05) showed that after 5 days, G7 revealed a significant reduction in surface loss compared to the other groups, while G4, G5 and G6 did not differ significantly from G1. After 10 days of erosive challenges, G7 did not differ significantly from G2 and there was no difference between G4, G5, G6 and G1. G3 showed the highest surface loss compared to all groups, except G1 and G5. Conclusion: The treatments tested were not able to prevent dentinal erosion, but the application of 4% TiF4 gel did reduce surface loss of dentin. [ABSTRACT FROM AUTHOR]