Germane N, Bentley B, Isaacson R J, Revere J H
Dept. of Orthodontics, MCV Station, Richmond, VA 23298.
Angle Orthod. 1990 Spring;60(1):49-54. doi: 10.1043/0003-3219(1990)060<0049:TMOCIR>2.0.CO;2.
The canine occupies the transition from anterior to posterior occlusion. Following orthodontic treatment the canine's incisal edge occlusion demonstrates the tip and torque present in the appliance that was used. The effective torque of the bracket, however, is influenced by the tooth morphology at the bracket's base. The morphology of the facial surface can be described by an angle formed between the tangent at the point of bracket placement and the long axis of the crown. In this study, tangent angles at four millimeters and five millimeters from the cusp tip of 100 maxillary and 70 mandibular canines were determined. There was a significant difference between tangent angles at the same location on different canine teeth and also at different locations on the same canine tooth. Proximal collum angles were also measured in this study and there was a significant negative proximal collum angle in maxillary canines and a significant positive proximal collum angle in mandibular canines. The presence of these normal biologic variables will either enhance or minimize the torque supplied by preadjusted appliances, depending on a combination of prescription used and biologic variable present.
尖牙处于前牙咬合至后牙咬合的过渡位置。正畸治疗后，尖牙的切缘咬合情况显示了所使用矫治器中的转矩和扭矩。然而，托槽的有效转矩受托槽基部牙齿形态的影响。牙面形态可用托槽放置点处切线与牙冠长轴所形成的角度来描述。在本研究中，测定了100颗上颌尖牙和70颗下颌尖牙距牙尖4毫米和5毫米处的切线角度。不同尖牙同一位置以及同一尖牙不同位置的切线角度存在显著差异。本研究还测量了近中颈部角度，上颌尖牙近中颈部角度显著为负，下颌尖牙近中颈部角度显著为正。这些正常生物学变量的存在将根据所使用的处方和存在的生物学变量的组合，增强或最小化预调整矫治器提供的转矩。
