RESUMO
AIM: The aim of this study was the assessment of the anatomical thickness of danger zone in the cervical third of mesial canals of mandibular molars. MATERIALS AND METHODS: Fifty mandibular molars were selected and scanned with cone-beam computed tomography. Data were compared using a length tool provided by scanner software. The measured areas were the mesial and distal walls of the cervical third of the mesial roots, which correspond to the safety and danger zones, respectively. In addition, dentin thickness at the furcation was evaluated. RESULTS: Dentin thicknesses of the safety zone were higher than in the danger zone in all teeth examined. The thinnest dentin of the safety zone was found at a point located 4 mm below the canal orifice, with a mean value of 1.03 mm; conversely, in the danger zone, the thinnest point was located 3 mm below the orifice, with a mean value of 0.81 mm. As for the distance from the pulp chamber floor to the furcation, the average value was 2.23 mm. CONCLUSION: These results show that mean thicknesses at the danger zone of mandibular molar mesial roots were <1.0 mm. These data reinforce the importance of understanding anatomy and the need for conservative preparations when assessing and instrumenting these root canals.
RESUMO
Em canais de dentes com extração indicada, realizou-se cirurgia de acesso. Uma lima endodôntica acoplada a aparelho eletrônico foi introduzida no canal até que indicasse 1,Omm aquém do ápice. Essas medidas foram tabuladas. Em seguida, os dentes foram extraídos, limpos e identificados; reposicionaram-se as limas nos canais com as medidas obtidas e analisaram-se os ápices com o auxílio de uma lupa. Onde não se via a lima na saída do forame, acrescia-se a medida em 1,Omm, retomando para o canal, verificando se o instrumento aparecia no forame apical. Resultou que, para 80 por cento dos espécimes, o aparelho foi preciso. Em 10 por cento dos espécimes, houve extravasamento do forame e em 10 por cento, a lima foi posicionada aquém da medida indicada
