多年来,预测成人牙弓大小的方法都是根据于统计学、百分率和可能数字,但只能适用于大部份儿童而不是全部。一般常用预测牙弓周径的方法是在混合牙列时安置固定舌弓,用以维持可利用的间隙以保证提供因不良的萌牙顺序、不良习惯、肌张力不正常或龋病等丧失了的位置。但这种方法是不准确的且有时又因固定舌弓保存了过量的位置而 Over the years, methods of predicting adult dental arch sizes have been based on statistics, percentages, and possible numbers, but only for most, if not all, of the children. The commonly used method for predicting the circumference of a dental arch is the placement of a fixed lingual arch during compounding of the dentition to maintain the available clearance to provide for the loss of dental implants due to poor adorable order, bad habits, abnormal muscle tone or caries s position. However, this method is inaccurate and sometimes retains an excessive amount of space due to the fixed lingual arch