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To evaluate the influence of the restorative approach and aging time on dentin bond strength (BS), failure mode (FM), and bottom/top microhardness ratio (B/T) in a large dentin cavity model. A total of 102 bovine incisors were used to produce models of conical dentin cavities (4.0 mm thickness × 4.8 mm top diameter × 2.8 mm bottom diameter), which were restored using semi-direct filling (SDF) (Filtek™ Z250 XT + Scotchbond™ Universal/RelyX™ Ultimate luting system), direct bulk filling (DBF) (Filtek™ One Bulk Fill), and direct incremental filling (DIF) (Filtek™ Z250 XT) techniques. B/T, BS, and FM (n = 17) were analyzed in a microhardness tester, a universal testing machine, and a stereomicroscope, respectively, after 24 h and 6 months of water storage. BS and B/T data were analyzed using two-way ANOVA/Tukey post-hoc test (p < 0.05), while FM data were analyzed descriptively. There was a statistically significant difference in BS between the restorative techniques, and BS was influenced by aging time in the DBF and SDF groups. Mixed failure was predominant for the SDF technique in both aging times. There was no statistically significant difference in B/T among the restorative approaches regardless of the aging time (p > 0.05). Although all restorative approaches provided similar B/T, the semi-direct technique showed better performance on the material bond strength to dentine in large cavities.

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INTRODUÇÃO: As técnicas restauradoras desempenham um papel fundamental na longevidade clínica das restaurações, sobretudo em cavidades profundas em resina composta. OBJETIVO: O objetivo do estudo foi avaliar a influência da técnica restauradora (direta incremental, direta de incremento único e semidireta) e do tempo de envelhecimento (24 horas e 6 meses) na resistência ao cisalhamento por extrusão, nanoinfiltração e profundidade de polimerização em cavidades profundas. MÉTODO: Foram utilizados 120 incisivos bovinos (n=20), onde a coroa foi separada da raiz e na porção coronária, foi realizado um preparo cavitário com 4,8mm de diâmetro superior, 2,8mm de diâmetro inferior e 4,0mm de profundidade. As amostras foram divididas em 6 grupos de acordo com a técnica restauradora e com o tempo de envelhecimento: BF 24hs, SD 24hs, CONV 24hs, BF 6 meses, SD 6 meses e CONV 6 meses. Os testes realizados foram: Profundidade de Polimerização (PP), Nanoinfiltração (NI) e Resistência ao cisalhamento por extrusão (RU). Os dados foram analisados através de estatística descritiva e inferencial utilizando ANOVA Two Way com Post Hoc de Tukey (p<0,005). RESULTADO: Para RU, houve diferença estatisticamente significativa entre as diferentes técnicas restauradoras (p<0,005), onde a técnica semidireta apresentou melhores resultados. Ainda nesta análise, não houve diferença significativa no tempo de envelhecimento (p>0,005) para cada técnica. Para PP não houve diferença estatisticamente significativa entre as técnicas restauradoras em nenhum tempo de análise (p>0,005). Na NI a técnica semidireta não apresentou concentração de cristais de prata na interface adesiva, demonstrando assim, melhores resultados em relação à técnica convencional e de preenchimento único. CONCLUSÃO: A técnica semidireta, pelo bom comportamento mecânico e por apresentar menor incidência de nanoinfiltração na interface adesiva, pode ser indicada em cavidades profundas de dentes posteriores (AU).

INTRODUCTION: Restorative techniques make a fundamental role in the clinical longevity of restorations, especially in deep composite resin cavities. OBJECTIVE: The aim of this study was to evaluate the influence of the restorative technique (direct incremental, direct single fill and semi-direct) and aging time (24 hours and 6 months) on extrusion shear strength (push-out), nanoleakage (NK) and depth of polymerization (DP) in cavities deep. METHODS: A total of 120 bovine incisives (n=20) were used to separate the root and the coronary portion, with a cavity preparation of 4.8mm in diameter, 2.8mm in diameter and 4.0mm in depth. . As examples were divided into 6 groups according to the restorative technique and working time: BF 24hs, SD 24hs, CONV 24hs, BF 6 months, SD 6 months and CONV 6 months. The tests performed were depth of polymerization (DP), nanoleakage (NK) and extrusion shear strength (push-out). Data were applied using descriptive and inferential statistics using Two Way ANOVA with Tukey Post Hoc (p <0.005). RESULT: For push-out, there was a statistically significant variation between restorative variables (p <0.005), where the semidirect technique presented better results. Still in this analysis, there was no significant difference without aging time (p> 0.005) for each technique. For DP there was no statistically significant difference between restorative techniques at any time of analysis (p> 0.005). At NK, the semidirect technique did not show concentration of silver crystals at the adhesive interface, thus demonstrating better results than the conventional and single fill technique. CONCLUSION: The semidirect technique, due to its good mechanical behavior and the lower incidence of nanoleakage at the adhesive interface, can be indicated in deep posterior teeth cavities (AU).

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OBJECTIVES: To study the intensity of inflammatory infiltrate and production of interleukin-1ß (ll-1ß), tumor necrosis factor-ß (TNF-ß), fibroblast growth factor-2 (FGF-2), glutathione peroxidase (GPX), and osteocalcin in response to in-office tooth bleaching in rats. MATERIAL AND METHODS: Twenty male Wistar rats were randomized into four groups (n=5) according to the received treatment (tooth bleaching or no treatment - control) and the period of euthanasia after treatment (24 h or 10 days). We performed tooth bleaching using a 38% hydrogen peroxide gel on maxillary and mandibular incisors. After euthanasia, incisors (20 per group) were processed for histological analysis, immunohistochemistry staining of ll-1ß, TNF-ß, FGF-2 and GPX and osteocalcin by immunofluorescence. We analyzed data using the Mann-Whitney and Kruskal-Wallis/Dunn tests (p<0.05). RESULTS: The bleached groups presented statistically significant differences regarding the pulp inflammation stage compared with the control groups. Bleached teeth showed moderate/severe inflammatory infiltrate and control groups presented absent inflammatory cells or a negligible number of mononuclear cells (p<0.001) at two times (24 h and 10 days). There was strong staining for ll-1ß, TNF-ß, and GPX in bleached groups at 24 h and strong staining for ll-1ß, TNF-ß, GPX and FGF-2 at 10 days. After 10 days of tooth bleaching, the bleached group showed a statistically superior amount of osteocalcin than the other groups (p<0.01). CONCLUSIONS: Tooth bleaching with 38% hydrogen peroxide causes severe pulp inflammation, but characteristics of tissue repair after 10 days.

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