Biometric study of the width, length and depth of the root trunk groove of human lower second molars

Foram obtidos 100 dentes, segundos molares inferiores (51 esquerdos e 49 direitos) extraídos de humanos quando diagnosticados como condenados (extração indicada). Por meio de um aparelho Contracer foram traçados, em papel milimetrado, os perfis das faces vestibulares e linguais dos 100 dentes em estudo. Estes perfis foram registrados a partir do limite amelocementário, de milímetro em milímetro, até que atingíssemos a entrada da furca. Foram realizadas medidas da largura, comprimento e profundidade da região da pré-furca, assim como o comprimento do tronco radicular. Após a análise estatística (p < 0,05), conclui-se que: a) a largura da pré-furca, na face vestibular, é de 3,6 mm e na face lingual 3,3 mm; b) a profundidade da pré-furca foi de 0,88 mm na face vestibular e 0,77 mm na face lingual; c) o comprimento da pré-furca na face vestibular foi de 2,93 mm e de 3,61 mm na face lingual. O comprimento do tronco radicular foi de 3,09 mm na face vestibular e de 3,91 mm na face lingual (p < 0,025). Houve uma coincidência do comprimento do tronco radicular e da pré-furca em 90,2% da amostra para a face vestibular no lado esquerdo e 77,5% no lado direito; para a face lingual, a coincidência ocorreu em 77,5 % dos casos no lado esquerdo e 88,3% no lado direito.One hundred human lower second molars, 51 from the left side and 49 from the right side, extracted due to their poor clinical and radiographic conditions were utilized in this study. Using a Contracer apparatus, the profiles of the buccal and lingual root surfaces of these teeth were traced on a millimeter-scaled paper. The profiles were registered from the cementoenamel junction (CEJ), millimeter by millimeter, up to the entrance of the furcation. The width, length and depth of the root trunk groove, as well as the length of the root trunk, were studied. After statistical analysis (p < 0.05) it was possible to conclude that: a) the mean width of the root trunk groove on the buccal surface was 3.6 mm and, on the lingual surface, 3.3 mm; b) the mean depth of the root trunk groove on the buccal surface was 0.88 mm and, on the lingual surface, 0.77 mm; c) the mean length of the root trunk groove on the buccal surface was 2.93 mm and, on the lingual surface, 3.61 mm. The mean length of the root trunk on the buccal surface was 3.09 mm and, on the lingual surface, 3.91 mm (p < 0.025). There was a coincidence between the length of the root trunk and that of its groove in 90.2% of the buccal surfaces of the samples from the left side, and in 77.5% of the samples from the right side; on the lingual surface, the coincidence occurred in 77.5% of the teeth from the left side, and on 88.3% of the teeth from the right side. This work revealed that there is a concavity on the root trunk region of the lower second molar, whose depth and width were greater on the buccal surface and whose length was greater on the lingual surface. The depth of the root trunk groove increased in the apical direction, with maximum depth in the last millimeter of the root trunk. The root trunk was longer on the lingual surface than it was on the buccal surface