Evaluation in the danger zone of mandibular molars after root canal preparation using novel CBCT software

Abstract: This study measured the thickness of cementum/dentin in the danger zone of the mandibular molars after root canal preparation using novel cone-beam computed tomography (CBCT) software. Eighty-four teeth were distributed into four groups: ProTaper Next, BioRace, Reciproc Blue, and WaveOne Gold. E-Vol DX® CBCT software was used to measure initial and final remaining cementum-dentin thicknesses after root canal preparation of the mesial root of mandibular molars at 1 and 3 mm from the furcation. The Kolmogorov-Smirnov test was used to test variable symmetry. The variables were described as mean and standard deviations, compared among the groups using analysis of variance (ANOVA), and within the groups using the Student t test. A generalized estimating equation model was used to compare the variation before and after root canal preparation. The level of significance was set at 5%. Differences between mean initial and final thicknesses of the mesiobuccal (MB) and mesiolingual (ML) canals were not statistically significant. The mean initial thickness was 3 mm (0.900 mm ± 0.191), considering that a mean lower than 1 mm (1.035 mm ± 0.184) indicates the danger zone. Although cementum/dentin is thinner at 3 mm from the furcation (0.715±0.186) after root canal preparation, the greatest amount of dentin removed was found at 1 mm (0.734 ± 0.191). The cementum-dentin remaining after preparation was thicker than 0.715 mm in root canals prepared using #35 (WaveOne Gold®) and #40 (ProTaper Next®, BioRace® and Reciproc Blue®) instruments. This confirms the safety of canal preparation in the danger zone using these systems.

Reparo pulpar frente ao Mineral Trioxide Aggregate / Pulp repair with Mineral Trioxide Aggregate

Avaliou-se estudos longitudinais relacionados ao reparo biológico do tecido pulpar frente ao Mineral Trioxide Aggregate, por meio de revisão sistemática. Utilizou-se pesquisa manual e fontes de catalogação bibliográfica identificadas eletronicamente por MEDLlNE, EMBASE e Cochrane Library - CENTRAL, a partir de 1966 até 30 de julho de 2008, com o termo mineral trioxide aggregate. De 180 estudos in vivo, apenas seis estudos satisfizeram os critérios de inclusão. Em todos os estudos in vivo, em animais e humanos, observou-se que o MTA favorece o processo de reparo do tecido pulpar após o tratamento conservador.

It was evaluated longitudinal studies of the biological repair of the pulpal tissue front to the Mineral Trioxide Aggregate, through systematic revision. It was used of handsearching and sources of bibliographical cataloguing identified electronically by MEDLlNE, EMBASE and Cochrane Library - CENTRAL, starting from 1966 until July 30,2008. As search strategy was used the terms - mineral trioxide aggregate - as word-key. Of the 180 studies in vivo, six studies satisfied the inclusion criteria. In all of the studies in alive, in animals and humans, and in those that satisfied the inclusion criteria, it was observed that MTA favors the repair process of the pulpal tissue after the conservative treatment.

Microbial microleakage in temporary restorative materials after post space preparation / Infiltração microbiana em materiais restauradores temporários após preparo para retentores intrarradiculares

Purpose: This study investigated the microbial microleakage through temporary restorative materials (Coltosol, IRM, Vidrion R) after post space preparation.Methods: Forty-two maxillary anterior human teeth were prepared and obturated with guttapercha and Sealapex using the lateral condensation technique, with 4mm of apical obturation remaining. Calcium hydroxide paste was used to fill the post space preparation, and 4mm of the coronal portion was restored with the temporary filling materials. Six specimens were totally sealed (negative control) and six specimens were not filled (positive control). An in vitro microbial leakage test (MLT) with a split chamber (upper/lower chambers) was used. Microbial microleakage was observed daily for 90 days. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests.Results: Coltosol, IRM, and Vidrion R allowed microbial microleakage after 19 to 89 days. Conclusion: All temporary fillings and intracanal dressings did not prevent the penetration of microorganisms to the root apex.

Objetivo: Este estudo investigou a infiltração microbiana em materiais restauradores provisórios (Coltosol, IRM, Vidrion R) após preparo para retentores intrarradiculares. Metodologia: Quarenta e dois dentes humanos anteriores superiores foram preparados e obturados com guta-percha e Sealapex utilizando a técnica da condensação lateral, mantendo 4mm de remanescente apical de obturação. Foi usada pasta de hidróxido de cálcio para preencher o espaço criado para os pinos, deixando um espaço de 4mm na cervical a ser preenchido pelos materiais testados. Seis espécimes foram totalmente impermeabilizados (controle negativo) e seis espécimes não foram obturados (controle positivo). Um teste de infiltração microbiana (MLT) com uma câmara dividida em duas partes foi usado neste ensaio. A infiltração microbiana foi verificada diariamente durante 90 dias. Os dados obtidos foram analisados pelos testes de Kruskal-Wallis e de Mann-Whitney. Resultados: Coltosol, IRM e Vidrion R permitiram infiltração microbiana após 19 a 89 dias. Conclusão: O material restaurador temporário e a medicação intracanal não preveniram a penetração de microrganismos até o ápice radicular.