Incidence of missed canals during endodontic treatment of maxillary first and second molars.

Untreated canals are a primary cause of persistent apical periodontitis, and the inability to identify and adequately treat canals has been considered a major cause of failure of root canal therapy in maxillary molars. The purpose of this retrospective study was to use cone beam computed tomography (CBCT) to quantify the number of missed canals in maxillary first and second molars needing endodontic retreatment after treatment by general dentists. A total of 401 CBCT scans of maxillary first and second molars were examined. A total of 214 scan sets (53.37% [95% CI, 48.48%-58.25%]) showed evidence of an untreated canal, with the highest rate (49.38%; n = 198) observed in the second mesiobuccal canal. Imaging revealed that multiple canals were missed in some patients, for a total of 225 missed canals. The examinations showed untreated first mesiobuccal canals in 2.99% of CBCT scan sets (n = 12), untreated distobuccal canals in 2.99% of CBCT scan sets (n = 12), and untreated palatal canals in 0.75% of CBCT scan sets (n = 3). Preoperative CBCT imaging should be considered prior to initial root canal treatment of maxillary molars. When the risks and limitations of CBCT are taken into consideration, the additional information it provides can improve diagnostic accuracy, increase confidence in decision-making, and positively impact treatment planning.

Avaliação do sistema WaveOne Gold e ProTaper retratamento para remoção de guta-percha clínico / Evaluation of WaveOne Gold system and ProTaper retreatment for gutta-percha removal

Objetivo: avaliar ex vivo a quantidade de guta-percha remanescente no retratamento de canal de dentes pré-molares inferiores com único canal utilizando o sistema WaveOne Gold em comparação com o sistema de retratamento ProTaper R. Materiais e métodos: foram selecionados 52 pré-molares inferiores humanos extraídos, distribuídos aleatoriamente em 2 grupos (n=26), em função das técnicas de retratamento: sistema WaveOne Gold (grupo 1) e sistema de retratamento ProTaper R (grupo 2). Após os canais radiculares serem instrumentados e obturados com guta--percha, foram submetidos à de sobturação e ao procedimento de retratamento. Os dentes foram seccionados confeccionando uma canaleta nas faces proximais dos dentes obtendo-se duas hemi--secções radiculares, expondo, portanto, a luz do canal preparado. Todas as amostras foram codificada se fotografadas por máquina Cânon A640 acoplada ao microscópio Zeiss, com aumento de 5 vezes. As fotos foram transportadas para o programa de software Image Tool 3.0. Foi feita medição das áreas de remanescentes de material obturador no interior do canal e a medição da área total do interior do canal através das imagens da secção no computador. As medidas foram comparadas em relação a cada sistema utilizando o programa BioEstat 4.0 (teste de Mann-Whitney). Resultados:A menor porcentagem de material obturador remanescente ocorreu no sistema ProTaper Rcom diferenças significantes em relação ao sistema WaveOne Gold (p<0.01). Conclusão: o sistemaProTaper R foi mais eficaz na remoção de guta-percha em comparação com o sistema WaveOne Gold, entretanto nenhum dos sistemas removeram totalmente o material obturador do canal.

Objective: This ex vivo research study aims to evaluate ex vivo the amount of remaining gutta -perchaduring canal retreatment of lower premolars single-rooted using WaveOne Gold system compared with Protaper R system. Materials and methods: 52 mandibular premolars were selected and randoml y divided into 2 groups (n = 26), according to the retreatment techniques, which are: WaveOne Gold system(group 1) and ProTaper R system (group 2). After the root canals were instrumented and filled withgutta-percha, they underwent removal procedure. After retreatment procedure, the teeth were sectioned in the proximal surfaces resulting in two hemi-sections exposing the interior of the root canal. Allsamples were coded and photographed by A640 Canon machine attached to the microscope Zeiss withzoom in 5 times, and the photos were transported to the Image Tool 3.0. software. The evaluation wasdone by measurement of areas of remaining filling material and the total area of the interior of root canal through the images on the computer. The measurements were compared for each system using Bio-Estat 4.0 program and Mann-Whitney test. Results: The smallest percentage of remaining gutta-perchaoccurred in ProTaper Retreatment system with significant differences from the WaveOne Gold system(p <0.01).Conclusion: ProTaper R system was more effective in removing gutta-percha compared withWaveOne Gold system. However none of the both systems completely removed the filling material.