传统模型与三维数字化模型在平整牙弓间隙分析中的比较研究

目的 比较传统模型与三维数字化模型在间隙分析中的差异，并且应用数字化模型来准确计算平整牙弓所需间隙。验证传统模型分析中对平整牙弓所需间隙的方法是否正确。方法 随机选择30个正畸治疗前的石膏模型，用激光扫描的方法制作这30模型的数字化模型。在数字化模型上比较Spee曲线深度与平整牙弓所需间隙的差异，判断是否可以用Spee曲线深度来代替平整牙弓所需间隙；为了验证在正畸治疗中，Spee曲线深度的变化与由此带来的牙弓长度的变化的关系，选择另外22个正畸病例，比较在实际治疗正畸治疗前后Spee曲线深度的变化值与牙弓长度的变化值是否一致。结果在数字化模型上，Spee曲线深度的．测量值大于平整牙弓所需间隙的测量值，正畸治疗前后Spee曲线深度变化值要大于因此产生的牙弓长度变化值，且差异都具有显著性，因此临床上所认为的每平整牙弓1mm则需要1mm的牙弓间隙过多估计了平整牙弓所需间隙，二者的关系不是1：1。而是2：1。甚至3：1的关系。结论临床上传统的模型测量所认为的每平整牙弓1mm则需要1mm的牙弓间隙是错误的：在正畸临床上，三维的数字化模型测量分析方法比传统的模型测量分析方法有更多的优越性。

The arch length for levelling the curve of Spee in three - dimensional analysis of digital model

Objective Aim of this study was to calculate the space for levelling the curve of Spee in digital models,and compare with the traditional method used in orthodontic practice.Methods The study sample consisted of 30 randomly selected after treatment patients with full dentition.The actual space needed to level the curve of Spee's line is measured in digital models.To study and test the relationship of change of arch length and change depth of Spee in actual orthodontic treatment,we also measured the change of arch length and depth of Spee of the other 22 patients before and after orthodontic treatment.Results The depth of Spee's line is significantly greater than the actual space needed to level the curve of Spee's line.It was showed that the change of the depth of Spee before and after treatment was significantly greater than the change of arch length.Clinical practice of allowing 1mm arch length for levelling each millimetre of curve of Spee about two times overestimates the amount of arch length needed to flatten the curve of Spee.Conclusion It was showed that the change of the depth of Spee during the orthodontic treatment was significantly greater than the change of arch length.Clinical practice of allowing 1mm arch length for levelling each millimetre of curve of Spee about two times overestimates the amount of arch length needed to flatten the curve of Spee.analysis,which takes the depth of Spee's line as the space needed to level the curve of Spee.