The Measurement Of The Height Of Normal Occlusion Cusp And The Bonded Height Of Bracket Positioning

Objective: In order to afford the reference for clinically positing the height of bracket bonded, the cusp height of normal occlusion model and the height of bracket bonded be measured. Methods: 35 Images of normal occlusion model are taken by digital camera. The marginal ridge plane of three back teeth in the same dentition is taken as reference plane. The distance between the each buccal cusp (or incisor ridge) in the same dentition or the central point of clinical crown(FA point)to the reference plane is measured by the orthodontic cast measuring software(taking the distance from cusp or incisor ridge to the reference plance as the cusp height) Finally, the height of bracket bonded of each tooth is calculated through count these data. Results: 1. the height of the cusp maxillary: the height of canine cusp is biggest, which is 2.76mm, and it is gradually decreased from the central incisor to first bicuspid, lateral incisor, second bicuspid, first molar, which are 2.62mm, 2.32mm, 2.04mm, 1.85mm and 1.29mm, respectively.Mandibular: the height of canine cusp is biggest, which is 2.65mm; and next to incisor, which are 2.27mm and 2.26mm. Then, it is gradually decreased from first bicuspid to second bicuspid, first molar, which are 2.09mm, 1.74mm and 1.07mm, respectively. 2. the height of bracket bondedmaxillary: the height of canine bracket bonded is biggest, which is 4.53mm. Then it is gradually decreased from the central incisor to first bicuspid, lateral incisor, second bicuspid, first molar, which are 4.39mm, 4.10mm, 3.81mm, 3.72mm and 3.07mm, respectively.Mandibular: the height of canine bracket bonded is biggest, which is 4.53mm. Next to incisors, which are 4.15mm and 4.14mm, respectively. Then, it is gradually decreased from first bicuspid to second bicuspid, first molar, which are 3.96mm, 3.62mm and 2.95mm, respectively. 3.The cusp height and the height of bracket bonded are gradually decreasing from canine to backward in the same array by 0.5mm. 4.The size of tooth is different in different patients, and the 0.5mm is taken as the criteria. Then, five groups data are acquired by accordingly increasing or decreasing the height of bracket bonded, and these data can be taken as a reference clinically bracket positioning.Conclusions: 1.For the height of each tooth in the same dentition is different, The height of bracket positioning is different position, which is gradually decreased from canine to molar.2.the approach on positioning the bracket on the basis of marginal ridge plane is advisable.