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OBJECTIVE: To evaluate the effect of delayed light-curing of dual-cure bulk-fill composites on internal adaptation and microhardness (KHN) in depth. MATERIALS AND METHODS: Bulk-fill composites were placed in 35 box-shaped preparations and cured according to the following protocols (n = 5): Filtek Bulk-Fill light-cured immediately after insertion (FBF); Bulk-EZ light-cured immediately after insertion (BEZ-I); Bulk-EZ light-cured 90 s after insertion (BEZ-DP); Bulk-EZ self-cured (BEZ-SC); HyperFIL light-cured immediately after insertion (HF-I); HyperFIL light-cured 90 s after insertion (HF-DP); HyperFIL self-cured (HF-SC). After 24 h, the samples were axially sectioned, and the internal adaptation was evaluated using replicas under a scanning electron microscope. The KHN was evaluated at six depths (0.3 mm, 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm). The statistical analysis was performed using α = 0.05. RESULTS: The KHN significantly decreased with depth, except in self-curing mode, when it was similar at all depths. Delayed light-curing significantly increased the KHN at higher depths. The internal adaptation was material-dependent. Light-curing did not influence the internal adaptation of HyperFIL, whereas delayed light-curing significantly reduced the internal gaps (%) of Bulk-EZ. CONCLUSION: Delayed light-curing improved the depth of cure of dual-cure resin composites. Light-curing did not influence the internal adaptation of HyperFIL, but delayed light-curing improved the internal adaptation of Bulk-EZ. CLINICAL SIGNIFICANCE: Light-curing is fundamental for improving the mechanical properties of dual-cure resin composites. Moreover, depending on the dual-cure resin composite, the delay in light-curing can reduce the internal gaps.

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Context (Background): Resin composites are the most widely used material for restoring cervical defects. However, the high failure rate of these restorations is still a concern. Aims: The aim of this in vitro study was to evaluate, using microtomography (µCT), the interfacial gap and voids formation in Class V cavities in premolars restored with materials with lower polymerization shrinkage combined with different restorative techniques. Settings and Design: Cervical defects were created in 30 intact premolar and were randomly distributed to be restored by one of the following techniques (n = 6): Composite resin with two increments (CR), organic modified polymer (ORMOCER) with single (OR1) or two increments (OR2, or low viscosity bulk-fill composite resin with single (BF1) or two increments (BF2). Methods and Material: Each tooth was scanned before filling to determine the volume of interest (VOI) to be applied in the second µCT after restoration and to control the cavity volume among the groups. In the µCT after filling, the volume of interfacial gaps and voids was calculated for each group. Statistical Analysis: The groups were compared using one-way and Tukey HSD post hoc test (α = 0.05). Results: It was possible to identify higher gap formation in the OR1 group and higher void formation in CR group (P < 0.05). OR2 group showed better results than the group with one increment. BF2 showed the best filling capacity. Conclusions: It was possible to conclude that the material and the number of increments directly influenced the internal adaptation and voids formation of Class V restorations.

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Abstract This in vitro study aimed to evaluate the gaps length and depth of cure of dual-cure bulk-fill resin composites inserted in box-shaped preparations. Box-shaped preparations (4 mm deep) were made in fifteen human third-molars and divided into three groups according to the resin composites (n=5): Dual-cure bulk-fill BulkEZ (BEZ); Dual-cure bulk-fill HyperFIL (HF); and Tetric Evoceram Bulk-fill (TETRIC), as control. Gaps length (%) was evaluated in tooth-restoration interface with micro-computed tomography (µCT). The restorations were sectioned, and the degree of conversion (DC) and Knoop microhardness were evaluated at five depths (0.3, 1, 2, 3, and 4 mm). Microhardness data were statistically evaluated using absolute values (KHN) and relative values (microhardness percentages in relation to top). Gaps length (%) increased in the following order: BEZ=TETRIC<HF. The microhardness percentages in relation to top significantly decreased from 2 mm for TETRIC and 3 mm for HF. BEZ had constant microhardness and DC at all depths, while HF and TETRIC presented a significant decrease on DC at 4 mm. Dual-cure bulk-fill composites did not reduce gaps compared to light-cure bulk-fill, but they can improve depth of cure of bulk-filled restorations.

Resumo O objetivo neste estudo in vitro foi mensurar as fendas e a profundidade de polimerização de compósitos resinosos bulk-fill duais inseridos em preparos em forma de caixa. Os preparos em forma de caixa (4 mm de profundidade) foram realizados em quinze terceiros molares e separados em 3 grupos, de acordo com o compósito resinoso (n = 5): Bulk-fill dual BulkEZ (BEZ); Bulk-fill dual HyperFIL (HF); Tetric Evoceram Bulk-fill (TETRIC). O comprimento das fendas (%) foi avaliado na interface dente-restauração por meio de micro-tomografia computadorizada (µCT). As restaurações foram seccionadas e o grau de conversão (GC) e microdureza Knoop foram avaliados em cinco profundidades (0,3, 1, 2, 3 e 4 mm). Os dados de microdureza foram avaliados estatisticamente por meio de valores absolutos e relativos (porcentagens de microdureza em relação ao topo). O comprimento das fendas (%) aumentou na seguinte ordem: BEZ = TETRIC <HF. O percentual de microdureza em relação ao topo diminuiu significativamente a partir de 2 mm para TETRIC e 3 mm para HF. BEZ apresentou percentuais de microdureza e de GC constantes em todas as profundidades, enquanto HF e TETRIC apresentaram decréscimo significativo no GC em 4 mm. Os compósitos resinosos bulk-fill duais não reduziram as fendas formadas quando comparados a um compósito bulk-fill fotopolimerizável; entretanto, os mesmos podem melhorar a profundidade de polimerização em restaurações de incremento único.

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Objective: The aim of this study was to evaluate the internal and marginal adaptation of inlays fabricated from different types of impressions (conventional and digital) and different ceramics (feldspathic and lithium disilicate). Material and Methods: Forty premolars were prepared for all-ceramic inlay restoration and assigned to 4 groups (n=10), according to the impression method (conventional with addition silicone and digital impression) and ceramic type (lithium disilicate and feldspathic ceramic blocks). For each type of impression, 10 inlays were milled from lithium disilicate blocks and the other 10 from feldspathic ceramic blocks in a CAD-CAM facility. The internal adaptation was analyzed by the replica technique. The marginal fit was analyzed under a stereo microscope by directly measuring the gap formed between the inlay and the tooth in the proximal and occlusal regions. Results: The marginal or internal adaptations were not affected by type of impression (conventional = digital impression), irrespective of the ceramic type. Only the internal adaptation was affected by the material type, i.e., feldspathic ceramic had lower values than lithium dissilicate ceramic, when considering the digital impression. Conclusion: The conventional and digital impressions promoted similar marginal and internal adaptation for feldspathic and disilicate ceramic inlays. For the digital impression the feldspathic inlays showed better internal adaptation than lithium dissilicate inlays. (AU)

Objetivo: O objetivo deste estudo foi avaliar a adaptação interna e marginal de inlays confeccionadas a partir de diferentes tipos de moldagens (convencional e digital) e diferentes materiais cerâmicos (feldspática e dissilicato de lítio). Materiais e Métodos: Quarenta pré-molares foram preparados para inlay totalmente cerâmica e distribuídos em 4 grupos (n = 10) segundo o método de moldagem (convencional com silicone de adição e moldagem digital) e tipo cerâmica (dissilicato de lítio e blocos de cerâmica feldspática). Para cada tipo de moldagem, 10 inlays foram confeccionadas a partir de pastilhas de dissilicato de lítio e as outras 10 de blocos de cerâmica feldspática, por meio do sistema CAD-CAM. A adaptação interna foi analisada pela técnica da réplica. O ajuste marginal foi analisado com estéreo microscópio medindo diretamente o espaço entre a inlay e o dente nas regiões proximal e oclusal. Resultados: As adaptações marginais e internas não foram afetadas pelo tipo de moldagem (convencional = impressão digital), independentemente do tipo de cerâmica. Somente a adaptação interna foi afetada pelo material, sendo que a cerâmica feldspática apresentou menores valores que a cerâmica de dissilicato, considerando a moldagem digital. Conclusão: As moldagens convencional e digital promoveram adaptação marginal e interna semelhante de inlays de cerâmica feldspática e dissilicato testadas. Para moldagem digital, a cerâmica feldspática mostrou melhor adaptação interna do que a dissilicato de lítio (AU)

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OBJECTIVES: To evaluate the influence of various photoactivation techniques on the internal gap, Knoop-hardness, and polymerization depth of silorane- and methacrylate-based composites in Class II restorations. METHODS: Preparations were made in third molars (n = 10), according to composites (Filtek P60: methacrylate; Filtek P90: silorane) and photoactivation techniques (OC: occlusal photoactivation (control); OBL: occlusal+buccal+lingual photoactivation; and BLO: buccal+lingual+occlusal photoactivation (transdental)). Composites were inserted in two increments, both individually photoactivated for 20s. After 24h, specimens were sectioned and the ratio of internal gaps to interface length (%) recorded. Hardness was tested across the transversal section of restorations (1-4 mm below the surface). RESULTS: Silorane restorations showed significantly lower gaps compared with methacrylate, regardless of polymerization technique (P<.05). Supplementary energy dose in OBL and BLO protocols caused significant increase in gaps in silorane restorations (P<.05). For methacrylate restorations, OBL activation caused significantly higher gap formation (P<.05). Significantly lower hardness values were seen for silorane than for methacrylate composites (P<.05), regardless of depth and photoactivation. Significantly higher hardness values were seen in BLO activation for methacrylate restorations compared with control (P<.05); for silorane, no differences were observed. Significantly higher hardness values were observed at 1 and 3 mm compared to 2 and 4 mm for both composites. CONCLUSIONS: Internal gaps and hardness are affected by composite type and photoactivation. Despite the reduced values, hardness of silorane is not influenced by photoactivation or by depth. Internal gaps are dependent on the energy dose for both composites, with silorane showing lower internal gaps.