Kurita Takeshi, Mizuhashi Fumi, Sato Toshihide, Koide Kaoru
Functional Occlusal Treatment, The Nippon Dental University Graduate School of Life Dentistry at Niigata, Japan.
Department of Removable Prosthodontics, The Nippon Dental University School of Life Dentistry at Niigata, Japan.
J Adv Prosthodont. 2020 Dec;12(6):338-343. doi: 10.4047/jap.2020.12.6.338. Epub 2020 Dec 28.
The present study aimed to investigate the relationships between the crown form of the upper central incisor and their labial inclination, overbite, and overjet.
Maxillary and mandibular casts of 169 healthy dentitions were subjected to 3D dental scanning, and analyzed using CAD software. The crown forms were divided into tapered, square, and ovoid based on the mesiodistal dimensions at 20% of the crown height to that at 40%. The degree of labial inclination of the upper central incisor was defined as the angle between the occlusal plane and the line connecting the incisal edge and tooth cervix. The incisal edges of the right upper and lower central incisor that in contact with lines parallel to the occlusal plane were used to determine the overbite and overjet. One-way ANOVA was performed to compare the labial inclination, overbite, and overjet among the crown forms.
The crown forms were classified into three types; crown forms with a 20%/40% dimension ratio of 1.00±0.01 were defined as square, >1.01 as tapered, and <0.99 as ovoid. The labial inclination degree was the greatest in tapered and the least in square. Both overbite and overjet in tapered and ovoid were higher than those in square.
Upper central incisor crown forms were related to their labial inclination, overbite, and overjet. It was suggested that the labial inclination, overbite, and overjet should be taken into consideration for the prosthetic treatment or restoring the front teeth crowns.
本研究旨在探讨上颌中切牙的牙冠形态与其唇倾度、覆合覆盖之间的关系。
对169例健康牙列的上下颌模型进行三维牙科扫描，并使用CAD软件进行分析。根据牙冠高度20%处与40%处的近远中尺寸，将牙冠形态分为锥形、方形和卵圆形。上颌中切牙的唇倾度定义为咬合平面与连接切缘和牙颈部的直线之间的夹角。使用右上颌和下颌中切牙与平行于咬合平面的线接触的切缘来确定覆合覆盖。进行单因素方差分析以比较不同牙冠形态之间的唇倾度、覆合覆盖。
牙冠形态分为三种类型；20%/40%尺寸比为1.00±0.01的牙冠形态定义为方形，>1.01为锥形，<0.99为卵圆形。唇倾度在锥形中最大，在方形中最小。锥形和卵圆形的覆合覆盖均高于方形。
上颌中切牙的牙冠形态与其唇倾度、覆合覆盖有关。建议在修复治疗或修复前牙牙冠时应考虑唇倾度、覆合覆盖。
