Sui Zhongquan, Agrawal Kalpana R, Corke Harold, Lucas Peter W
Department of Botany, University of Hong Kong, Pokfulam Road, Hong Kong, PR China.
Arch Oral Biol. 2006 Jun;51(6):491-7. doi: 10.1016/j.archoralbio.2005.11.002. Epub 2005 Dec 22.
Previous studies suggest the orientation of the incisor teeth to the path of jaw movement pronouncedly affects their efficiency of action. To test this hypothesis, upper and lower incisal portions of a study model with ideal Asian occlusion were mounted on a mechanical tester and impressed into rectangular blocks made of 15.3% w/w starch gels or Cheddar cheese. At varying angulations of attack between the long axis of the teeth (defining the orientation of the tooth crown) and force direction, the teeth were driven into the blocks for 4-6mm until fractures had grown in the foods. Both the angle of attack and the work divided by fractured area produced in the food, termed 'work to fracture', were measured. The food type (cheese or gel), incisal type (upper or lower pair) and angle of inclination were significant effects on the works to fracture. The minimal work was for angles slightly proclined to the vertical, although only angles of proclination >40 degrees were significantly higher than all other angles. Retroclination or large angles of proclination made little difference to the work done, but produced markedly off-axis cracks. It is suggested that human incisors act most efficiently at small gapes and that orthodontic corrections will thus offer definite functional benefits.
先前的研究表明，切牙相对于颌骨运动路径的方向对其作用效率有显著影响。为了验证这一假设，将具有理想亚洲人咬合关系的研究模型的上下切牙部分安装在机械测试仪上，并压入由15.3% w/w淀粉凝胶或切达干酪制成的矩形块中。在牙齿长轴（定义牙冠方向）与力的方向之间不同的攻击角度下，将牙齿压入块中4 - 6毫米，直到食物中出现裂缝。测量攻击角度以及食物中产生的功除以断裂面积（称为“断裂功”）。食物类型（奶酪或凝胶）、切牙类型（上牙对或下牙对）和倾斜角度对断裂功有显著影响。最小的功出现在略微向垂直方向倾斜的角度，尽管只有倾斜角度>40度时才显著高于所有其他角度。向后倾斜或大角度的向前倾斜对所做的功影响不大，但会产生明显的偏轴裂缝。研究表明，人类切牙在小开口时作用效率最高，因此正畸矫正将带来明确的功能益处。
