Effect of nickel-titanium alloys on root canal preparation and on mechanical properties of rotary instruments

Abstract The aim of this study was to evaluate the quality of curved root canal preparation, torsional fatigue, and cyclic fatigue of rotary systems manufactured with different NiTi alloys. Ninety single-rooted canals with curvatures of 15° to 30o were scanned and divided into three groups according to the rotary system used: BT-Race (BTR) - 10.06, 35.00, 35.04; SequenceRotaryFile (SRF) - 15.04, 25.06, 35.04; and ProDesignLogic (PDL) - 25.01, 25.06, 35.05. Each system was used on three specimens. The teeth were prepared, scanned, and analyzed to assess increase in volume, transportation, and centering ability of the root canal. Torsional fatigue of glide path instruments (BTR 10.06, SRF 15.04 and PDL 25.01) and cyclic fatigue of the finishing instrument (BTR 35.04, SRF 35.04 and PDL 35.05) were obtained by analyzing completely new instruments (n = 10) and instruments after they had been used three times (n = 10). After the torsional and cyclic fatigue tests, the fractured surface of the new and used instruments were examined by scanning electron microscopy. Increase in volume, canal transportation, and centering ability showed no significant differences among the groups (p > 0.05). The torsional test showed that SRF 15.04 produced the highest torque values for both new and used instruments, followed by PDL 25.01 and BTR 10.06 (p < 0.05). PDL 25.01, both new and used, exhibited higher values of angular deflection followed by SRF 15.04 and BTR 10.06 (p < 0.05). As regards cyclic fatigue, use of PDL 35.05, both new and used, required a longer time and larger number of cycles than did SRF 35.04 and BTR 35.04 (p < 0.05). Clinical use affected the torsional fatigue of BTR; however, cyclic fatigue was not significantly affected (p < 0.05). All rotary systems were able to prepare the curved canals satisfactorily and were used safely on the three specimens. Relative to torsional fatigue, SRF 15.04 exhibited a higher torque, and PDL 25.01, higher angular deflection. BTR 10.06 was the most affected by clinical use. PDL 35.05 showed greater resistance to cyclic fatigue.

Laboratory study of tissue repair of resin-based endodontic sealers in critical surgical defects

Abstract Filling materials should be restricted to the root canal space. However, sometimes it is impossible to control the apical extrusion, in this case, the fate of the filling material and the result of the treatment will depend on its physicochemical properties and biocompatibility. Objective To evaluate the tissue response and bone repair capacity of endodontic sealers that were implanted in the calvaria of Wistar rats, forming the groups (n=16): AH Plus and Sealer Plus, compared to the clot group. Methodology On days 30 and 60, the animals were euthanized, the calvaria was removed and processed for hematoxylin-eosin, immunohistochemistry for collagen type I, Picrosirus red and microtomographic analysis. Data were subjected to ANOVA and Tuckey tests (p<0.05). Results At 30 days, all groups showed an intense inflammatory reaction (p>0.05). At 60 days, the AH Plus and Sealer Plus maintained an intense inflammatory infiltrate compared to the clot group (p<0.05). We observed immunopositive areas for type I collagen in all groups at 30 days and 60 days (p>0.05). We observed more red collagen fibers for the Sealer Plus compared to the clot group at 30 days (p<0.05). Considering the total fibers, the clot group at 30 days compared to 60 days after surgery showed an increase in the amount of matrix (p<0.05). There were no statistical differences between groups for green and yellow fibers (p>0.05). Regarding morphometric parameters, at 30 days, the newly formed bone volume and number of bone trabeculae were higher in the groups with sealers compared to the clot group (p<0.05). At 60 days, AH Plus and Sealer Plus showed greater bone neoformation compared to the clot group (p<0.05). Conclusions Despite AH Plus and Sealer Plus induced an intense inflammatory reaction, they can be considered biocompatible materials, since they allowed bone repair.

Padronização do modelo experimental da insuficiência renal aguda para estudo bidirecional com a periodontite apical / Standardization of the experimental model of acute renal failure for bidirectional study with an apical periodontitis

Introdução: A insuficiência renal aguda (IRA) ocorre em cerca de 5% das hospitalizações e até 30% das internações em UTI, possuindo taxas de mortalidade entre 15% e 60%. Objetivo: O objetivo do presente trabalho foi analisar diferentes protocolos de indução da IRA em modelo animal, buscando a padronização do modelo para o estudo da relação bidirecional com a periodontite apical (PA). Métodos: Foram utilizados vinte e quatro ratos divididos em três grupos (n=8): G1) administração de gentamicina na dosagem de 80mg/Kg/dia durante cinco dias; G2) administração de gentamicina na dosagem de 100mg/kg/dia durante oito dias; e G3) administração de gentamicina na dosagem de 100mg/kg/dia durante dez dias. A PA foi induzida em todos os grupos por meio da exposição pulpar dos primeiros e segundos molares superiores e inferiores do lado direito. Após trinta dias da exposição pulpar, os animais foram eutanasiados; os rins, coletados para análise histológica em HE; e as maxilas e mandíbulas, removidas para análise radiográfica. Resultados: A presença da PA foi confirmada em todos os espécimes pelo exame radiográfico. O grupo G3 apresentou índice de mortalidade de 75%, enquanto G1 e G2 não apresentaram mortalidade. Histologicamente, o tecido renal do grupo G2 apresentou alterações teciduais, como dilatação e necrose tubular mais severa, quando comparado ao grupo G1 (p<0,05). Conclusão: Diante do alto índice de mortalidade observado em G3 e dos achados histológicos observados em G1 e G2, o protocolo indicado para o estudo da relação bidirecional com a periodontite apical é o de 100mg/kg/dia durante oito dias (AU).

Introduction: Acute Renal Failure (ARF) occurs in about 5% of hospitalizations and up to 30% of ICU admissions, with mortality rates between 15% and 60%. The objective of this study was to analyze different protocols for the induction of IRA in an animal model, seeking the standardization of the model for the study of bidirectional relationship with apical periodontitis (AP). Methods: Twenty-four rats were divided into three groups (n = 8): G1 - Administration of Gentamicin at a dose of 80mg/ kg/day for 5 days; G2 - Administration of Gentamicin at the dose of 100mg/kg/day for 8 days; G3 - Administration of Gentamicin at the dosage of 100mg/kg/day for 10 days. The AP was induced in all groups by means of pulp exposure of the first and second upper and lower molars from the right side. After 30 days, the animals were euthanized, the kidneys collected for histological analysis, and the jaws removed for radiographic analysis. Results: The presence of AP was confirmed in all specimens by radiographic examination. The G3 group had a mortality rate of 75% while G1 and G2 had no mortality. Histologically, the renal tissue of the G2 protocol presented tissue changes such as dilation and more severe tubular necrosis when compared to the G1 protocol (p <0.05). Conclusion: In view of the high mortality rate observed in G3 and the histological findings observed in G1 and G2, the indicated protocol is 100mg/kg/day for 8 days to study the bidirectional relationship with apical periodontitis (AU).

Cytotoxicity, biocompatibility and biomineralization of a new ready-for-use bioceramic repair material

Abstract New mineral trioxide aggregate (MTA) formulations are constantly introduced in the market, usually in a powder-and-liquid form. Bioceramic (Bio-C) Repair is a ready-for-use material suggested as substitute for MTA, but its properties need to be studied. This study evaluated the cytotoxicity, biocompatibility and biomineralization of Bio-C Repair compared to MTA Repair High-Plasticity (MTA-HP) and white MTA-Angelus (MTA-Ang). L929 fibroblasts were exposed to material-extracted (undiluted, ½ and » dilutions; 6, 24 and 48h). Polyethylene tubes with material or empty (control) were implanted in the subcutaneous tissue of rats. After 7 and 30 days (n=8), the specimens were removed for analysis (hematoxylin-eosin, von Kossa and polarized light). Cytotoxicity data were statistically analyzed by two-way ANOVA, and biocompatibility data by Kruskal-Wallis and Dunn tests (p<0.05). The cells exposed to the materials had greater viability at most of the periods compared with control (p<0.05). The undiluted and ½ dilutions of MTA-HP extract showed higher cytocompatibility than Bio-C Repair at 6 h and with the » dilution at 24 h (p<0.05); the white MTA-Ang showed higher cytocompatibility than Bio-C Repair at most of periods (p<0.05). The undiluted white MTA-Ang extract had higher cytocompatibility at 6 and 24h than MTA-HP, and with ½ dilution at 24h (p<0.05). The materials' cytocompatibility was similar at 48h for most dilutions (p>0.05). At 7 and 30 days, the groups had moderate and mild inflammation, respectively (p>0.05). All materials showed positive structures for von Kossa and polarized light. In conclusion, Bio-C Repair had similar cytocompatibility to MTA-based materials is biocompatible and induces biomineralization.

Resumo Novas formulações de agregado de trióxido mineral (MTA) são constantemente introduzidas no mercado, geralmente em forma de pó e líquido. O Biocerâmico (Bio-C) Reparador (Repair) é um material pronto para uso sugerido como substituto do MTA, mas suas propriedades precisam ser estudadas. Este estudo avaliou a citotoxicidade, biocompatibilidade e biomineralização do Bio-C Repair comparado ao MTA-High Plasticity (MTA-HP) e MTA branco da Angelus (MTA-Ang). Fibroblastos L929 foram expostos a extratos dos materiais (não diluído, ½ e » diluições; 6, 24 e 48 h). Tubos de polietileno contendo os materiais ou vazios (controle) foram implantados no tecido subcutâneo de ratos. Após 7 e 30 dias (n=8), os espécimes foram removidos para análises (hematoxilina-eosina, von Kossa e luz polarizada). Os dados da citotoxicidade foram analisados estatisticamente pelo teste de two-way ANOVA, e os dados da biocompatibilidade pelos testes de Kruskal-Wallis e Dunn (p<0,05). As células expostas aos materiais apresentaram maior viabilidade celular na maior parte dos períodos, comparados com o controle (p<0,05). O extrato não diluído e ½ diluição do MTA-HP apresentaram maior citocompatibilidade do que Bio-C Repair às 6h, e com » diluição às 24h (p<0,05); o MTA-Ang branco apresentou maior citocompatibilidade do que o Bio-C Repair na maior parte dos períodos (p<0,05). O extrato não diluído do MTA-Ang branco apresentou maior citocompatibilidade às 6 e 24 h comparado ao MTA-HP, e com ½ diluição às 24h (p<0,05). A citocompatibilidade dos materiais foi semelhante às 48 h para a maior parte das diluições (p>0,05). Aos 7 e 30 dias, os grupos apresentaram inflamação moderada e leve, respectivamente (p>0,05). Todos os materiais mostraram estruturas positivas para von Kossa e luz polarizada. Em conclusão, o Bio-C Repair teve citocompatibilidade semelhante aos materiais à base de MTA, é biocompatível e induz à biomineralização.