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This study aimed to evaluate volumetric polymerization shrinkage, degree of conversion and Vickers hardness of four bulk-fill resin composites light-activated with their dedicated light curing units (LCUs). Four groups were evaluated, according to the type of composite and curing mode: Tetric EvoCeram Bulk-fill (TEBO) and Tetric EvoFlow Bulk-fill (TEBF) were light-activated with Bluephase Style 20i (20s, in high-mode), while Tetric Powerfill (TEPO) and Tetric Powerflow (TEPF) were light-activated with Bluephase PowerCure (3s). Volumetric polymerization shrinkage test (n = 6) was performed in standardized box-shaped class-I cavities of extracted third molars (4 x 4 x 4 mm). Teeth were scanned before and after resin composite application by micro-computed tomography, and acquired data were evaluated with Amira software. Degree of conversion (n = 5) was evaluated at the top and bottom surfaces of composite cylindric samples (4 mm diameter, 4 mm thickness) using an FT-IR spectrometer (spectra between 1,500 and 1,800 cm-1, 40 scans at a resolution of 4 cm-1). Three Vickers indentations (50 g / 15 s), spaced 500 µm apart, were performed on the top and bottom composite surfaces and averaged. One-way ANOVA was used for data evaluation. TEPF showed the lowest volumetric polymerization shrinkage (p < 0.05), while the other composites were not significantly different within each other (p > 0.05). All materials presented a significant decrease in degree of conversion and Vickers hardness when compared top to bottom surfaces (p < 0.05). Bottom to top surface ratios for degree of conversion ranged from 0.8 (TEBO and TEPO) to 0.9 (TEBF and TEPF), and from 0.4 (TEPO) to 0.7 (TEBF and TEPF) for hardness. In conclusion, resinous materials present a decrease in hardness and degree of conversion from top to bottom even when a higher power is used, while the flowable material TEPF showed the lowest volumetric shrinkage values compared to the other materials.

Assuntos

RESUMO

Abstract This study aimed to evaluate volumetric polymerization shrinkage, degree of conversion and Vickers hardness of four bulk-fill resin composites light-activated with their dedicated light curing units (LCUs). Four groups were evaluated, according to the type of composite and curing mode: Tetric EvoCeram Bulk-fill (TEBO) and Tetric EvoFlow Bulk-fill (TEBF) were light-activated with Bluephase Style 20i (20s, in high-mode), while Tetric Powerfill (TEPO) and Tetric Powerflow (TEPF) were light-activated with Bluephase PowerCure (3s). Volumetric polymerization shrinkage test (n = 6) was performed in standardized box-shaped class-I cavities of extracted third molars (4 x 4 x 4 mm). Teeth were scanned before and after resin composite application by micro-computed tomography, and acquired data were evaluated with Amira software. Degree of conversion (n = 5) was evaluated at the top and bottom surfaces of composite cylindric samples (4 mm diameter, 4 mm thickness) using an FT-IR spectrometer (spectra between 1,500 and 1,800 cm-1, 40 scans at a resolution of 4 cm-1). Three Vickers indentations (50 g / 15 s), spaced 500 μm apart, were performed on the top and bottom composite surfaces and averaged. One-way ANOVA was used for data evaluation. TEPF showed the lowest volumetric polymerization shrinkage (p < 0.05), while the other composites were not significantly different within each other (p > 0.05). All materials presented a significant decrease in degree of conversion and Vickers hardness when compared top to bottom surfaces (p < 0.05). Bottom to top surface ratios for degree of conversion ranged from 0.8 (TEBO and TEPO) to 0.9 (TEBF and TEPF), and from 0.4 (TEPO) to 0.7 (TEBF and TEPF) for hardness. In conclusion, resinous materials present a decrease in hardness and degree of conversion from top to bottom even when a higher power is used, while the flowable material TEPF showed the lowest volumetric shrinkage values compared to the other materials.

RESUMO

The treatment of high-risk patients still is a challenge. The understanding and development non-invasive, non-destructive, and non-ionizing techniques, can help to guide the treatment and the diagnosis of primary and recurrent caries. The present study evaluated the behavior of enamel/restoration interface after a cariogenic challenge by Fourier domain optical coherence tomography (FD-OCT), scanning electron microscopy (SEM) examination, and the fluoride release of the different restorative materials. Cavities (1.5 × 0.5 mm) were performed in enamel surface and divided into groups (n = 8): glass ionomer cement (GIC), resin-modified glass ionomer cement (RMGIC), and resin composite (RC). The samples were submitted to pH-cycling, and the solutions analyzed for cumulative fluoride by ion-analyzer. The morphology was analyzed by SEM through replicas. The optical attenuation coefficient (OAC) was calculated through exponential decay from the images generated by FD-OCT. Data were analyzed considering α = 0.05. OAC values increased for all groups after pH-cycling indicating demineralization (p < .05). Considering the remineralizing solution, RMGIC presented higher fluoride release rate, followed by GIC, while RC did not release any fluoride. Yet for the demineralizing solution, RMGIC and GIC released similar fluoride rates, overcoming RC (p < .05). Micrographs revealed no changes on the restorations margins, although enamel detachment was observed for RC and GIC after pH-cycling.

Assuntos

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OBJECTIVE: To evaluate color matching of universal composite restorations performed in anterior teeth using two evaluation methods. MATERIALS AND METHODS: Sixty class III preparations were made on denture central incisors with different shades (A1-A3) and restored with multishade (Tetric Evoceram, Filtek Universal, and TPH Spectra Universal) and single-shade (Omnichroma) universal composites (n = 5). For photographic analysis, a digital photograph of each specimen was taken under standardized set-up. Color measurements were taken in the center of the restoration, and in the tooth surface 1.0 mm adjacent from the tooth/restoration margin. CIELab coordinates were recorded and color difference analysis (ΔE) was made using the CIEDE-2000 formula. For visual analysis, calibrated observers performed visual scoring of color matching and differences were graded as 0:excellent match; 1:very good match; 2:not so good match; 3:obvious mismatch; 4:huge mismatch. All data were statistically analyzed using a linear mixed model analysis with a confidence interval of 95%. RESULTS: For photographic analysis, Omnichroma showed the highest ΔE compared to the other composites for all shades (P < .05), without difference among experimental groups regarding tooth shade. For visual analysis, Omnichroma showed the highest scores (P < .05) for all teeth shades, without differences between the other groups. Furthermore, there were no differences between visual scores for different shades of a same resin composite group. CONCLUSIONS: Multishade universal composites presented higher color matching than the single shade universal composite. There were no differences of color matching for different tooth shades for all composites. CLINICAL SIGNIFICANCE: Universal composites with increased color matching may be helpful to simplify anterior restorations, minimizing clinical errors.

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OBJECTIVE: To describe the use of the injectable resin composite restorative technique with a flowable resin material, in a clinical case with esthetic problems associated with irregular tooth anatomies, allied with a finishing, and polishing protocol due to staining after 1 year of use. CLINICAL CONSIDERATIONS: The presented case report helped to achieve an immediate highly esthetic restoration with appropriate width proportions based on a previous wax-up. After 1 year of use, restorations presented staining; therefore, finishing and polishing procedures were required to re-achieve acceptable esthetic results and thus increase restoration's survival. CONCLUSIONS: The use of the presented technique allowed to obtain a simple and predictable workflow; however, care must be taken on the follow up of the restorations due to intrinsic characteristics of the flowable resin material. CLINICAL SIGNIFICANCE: The use of the presented injectable technique helped on obtaining a precise anatomy replicating a diagnostic wax-up, thus improving marginal precision and achieving a highly esthetic and functional immediate outcome, with an easy workflow when appropriately planned and executed. However, it also presented low color stability after 1 year of use only, thus, requiring attention from clinicians in regard to its maintenance over time.

Assuntos

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STATEMENT OF PROBLEM: Glass fiber post cementation procedures have undergone significant development. Relining the post with composite resin is a technique that aims to reduce resin cement thickness and consequently problems inherent to polymerization. Evidence is sparse regarding the efficacy of bonding procedures at increasing depths (from cervical to apical) using different adhesive cementation techniques. PURPOSE: The purpose of this in vitro study was to evaluate the push-out bond strength (PBS) of composite resin relined glass fiber posts cemented to bovine root dentin using different adhesive cementation protocols. MATERIAL AND METHODS: Eighteen bovine teeth (n=6) were embedded in polystyrene resin blocks, and the crowns were sectioned leaving a root portion of 20 mm in length. Root canals were prepared using rotary instruments provided by the post manufacturer (Whitepost DC #1), resulting in a uniform root canal preparation. The root canals were lubricated with a water-soluble glycerin gel. Silane (Prosil) was applied and the posts relined with a microhybrid composite resin (Filtek Z100) to conform to the root canal anatomy. Three adhesive cementation protocols were evaluated: a 3-step etch-and-rinse adhesive system (Adper Scotchbond Multi Purpose) in combination with a dual polymerizing resin cement (RelyX ARC); a universal adhesive system (Scotchbond Universal) associated with a dual polymerizing resin cement (RelyX Ultimate); and a self-adhesive dual polymerizing resin cement (RelyX Unicem 2). The roots were sectioned, resulting in four 2-mm segments at 4 different depths (cervical to apical) and evaluated by the PBS test, using a universal testing machine (Instron 4411) at 0.5 mm/min, until failure. Interfaces were evaluated by scanning electron microscopy, and failures were classified as cohesive failure in composite resin, cohesive failure in cement, cohesive failure in root dentin, adhesive failure, or mixed. Data were analyzed by 2-way split-plot ANOVA and the Tukey post hoc test (α=.05). RESULTS: No statistical differences were found for PBS when different cementation systems were compared (P=.253). Increased depths resulted in reduced PBS values for all cementation protocols evaluated (P<.001). CONCLUSIONS: Regardless the cementation system used, the lowest PBS values were at the apical region of resin relined glass fiber posts bonded to root dentin. Furthermore, the highest PBS is observed at the cervical portion of root dentin.

Assuntos