Contact areas increase in size with age Functions:
– Stabilizes dental arch – Prevents food impaction – Aids in food flow pattern
Proximal contact area
Height of contour (HOC) = greatest extent of curvature of a crown surface
Some general rules regarding height of contour:
Facials all teeth - cervical third Lingual surfaces
Incisal (occlusal) embrasures increase in size from anterior to posterior
Cervical embrasures decrease in size from anterior to posterior
Labial & lingual embrasures are nearly equal in anteriors
Contact areas:
Distal contact more cervical than mesial
Location of contact areas:
More incisal in anterior teeth Becomes more cervical from anterior to
Lingual embrasures are larger than buccal embrasures in posteriors
Interproximal embrasures are symmetrical
Functions of embrasures:
Spill-way for food Aids in self-cleansing process Esthetics in anterior teeth
Embraact areas
– Incisal/occlusal – Cervical (gingival) – Buccal (labial) – Lingual
Some general rules regarding embrasure form:
2）牙移位
2．经功能性磨耗---小斜面接触 生理意义：1）咀嚼食物
2）稳定
（二） 轴面
1. 唇颊舌面的凸度
形态：前牙
后牙
生理意义：
1）正常凸度使排溢的食物
凸度过小—创伤牙龈
凸度过大—废用性牙龈萎缩
牙颈部龋
2）唇颊颈1/3凸度扩展牙龈
中老年牙龈退缩
Facial and Lingual Heights of Contour
posterior
Contact areas:
Contacts centered F-L in anteriors Contacts are buccal to the midline in
posteriors
3. 楔状隙(embrasures) 又称外展隙 概念：（接触区周围）
唇，颊楔状隙 舌楔状隙 切，牙合 楔状隙 邻间隙
二.牙根形态的生理意义
牙根的形态与牙的受力及功能相关 牙根的数目、粗细、长短、长形凹陷、分
叉度与位置
前牙：功能简单，单根 切牙（上，下颌） 尖牙
后牙： 前磨牙 磨牙
2.邻面的凸度 接触点—接触区 位置：
形态：前牙 切龈径>唇舌径，长椭圆形 后牙 颊舌径>牙合 龈径，扁椭圆形
生理意义：初萌邻牙间是点接触—接触点 磨耗后成为小面接触—接触区
接触不良：过紧 过松 位置不正确
Proximal Contact Areas
Where two adjacent teeth contact each other (mesial and distal height of contour)
牙体形态的生理意义
牙冠形态的生理意义
（一） 切缘和牙合面 切嵴 牙合 面各结构的生理意义
1 牙尖 功能尖 非功能尖 牙尖—牙窝、牙尖—边缘嵴
2 牙合 面窝 3 边缘嵴 4 发育沟 颊舌沟 牙合面发育沟 5 牙尖三角嵴
形态： 1．初萌切缘与牙合 面是曲线、曲面--点线接触。 生理意义：1）咀嚼食物
– Anterior teeth – cervical third – Posterior teeth – middle third
Distal HOC more cervical than mesial HOC
Aids in protection and stimulation of gingiva