Normal torque of the buccal surface of mandibular teeth and its relationship with bracket positioning: a study in normal occlusion

Abstract

This study evaluated the degree of buccolingual inclination of mandibular tooth crowns relative to torque. For such purpose, mandibular and maxillary stone casts from 31 Caucasian Brazilian adults with normal occlusion, pleasant facial aspect and no history of previous orthodontic treatment were examined. A custom device was developed for measuring the degree of inclination (torque) of bracket slots of orthodontic appliances relative to the occlusion plane, at three bonding height: standard (center of clinical crown), occlusal (0.5 mm occlusally from standard) and cervical (0.5 mm cervically from standard). Except for the mandibular incisors, which presented a small difference in torque from one another (lingual root torque for central incisors and buccal root torque for lateral incisors), the remaining average values are close to those found in the literature. Due to the convexity of the buccal surface, the 1-mm vertical shift of the brackets from occlusal to cervical affected the values corresponding to the normal torque, in approximately 2 degrees in central and lateral incisors, 3 degrees in canines and 8 degrees in premolars and molars.

Labio-lingual root control of lower anterior teeth and canines obtained by active and passive self-ligating brackets

“…The play between bracket and wire can be calculated knowing the slot and the wire dimension, yet variation in curvature of the crown, bracket positioning, and variation in the thickness of the adhesive will affect the final buccolingual inclination as well. [4][5][6][7] The influence of bracket material, dimensional precision, and wire-slot interaction have been studied in vitro. [8][9][10][11] Type of ligation and consistency in ligation have been assigned importance for the torque obtained.…”

Tooth Inclination in Elderly with Many Remaining Teeth Observed by 3-D Imaging

“…Therefore, it is difficult to determine the center on a clinical crown in such teeth. Figures 8-1, 2 show a comparison of our results with those of Andrews [1][2][3] , Sebata 21) and Mestriner et al 14) (Mandibular teeth only). Andrews [1][2][3] reported six significant characteristics observed in a study of 120 casts of young non-orthodontic normal occlusion.…”

“…This is in the middle of the labial or buccal long axis of the clinical crown. The clinical parameter for assessing the labio or bucco-lingual inclination of each tooth is the angle formed by its labial or buccal surface in relation to the occlusal plane 1,2,6,14,21) . A plus reading is given if the gingival portion of the tangential line (or of the crown) is lingual to the incisor portion in Fig 1; a minus reading is recorded when the gingival portion of the tangential line (or of the crown) is labial to the incisor portion.…”

“…Sebata 21) observed tooth inclination in 41 young Japanese by computer calculation using the same concept as Andrews. Mestriner et al 14) measured the degree of inclination at the center of the clinical crown relative to the occlusal plane using mandibular plaster casts from 31 young Caucasian Brazilian adults with normal occlusion. Tooth inclination showed a progressive decrease from anterior to posterior.…”

Analysis of mesiodistal angulations of preadjusted brackets

“…In contrast, the conventional "edgewise" mechanical technique uses nonprogrammed, or standard, brackets, in which the orthodontist must bend the wires to achieve the desired tooth movement. 5,6,7 Andrews maintained the use of a rectangular wire in a rectangular bracket slot to allow three-dimensional movement.…”