Relationship Between Upper Dental Arch Shape and Second Molar Rotation in Primary Dentition

乳齒列上顎第二乳臼齒旋轉度與牙弓型態之關係

蔡恆惠(Hung-Huey Tsai)

《Mid-Taiwan Journal of Medicine》 8卷4期 (2003/11) Pp. 192-198

https://doi.org/10.6558/MTJM.2003.8(4).2

摘要

目的　由於第二乳臼齒在決定牙弓型態與大小上扮演重要角色，本研究比較了A、B、C三種不同牙弓型態群(A群牙弓寬大、B群牙弓適中、C群牙弓狹窄)間上顎第二乳臼齒的大小與旋轉度之差異。
方法　使用116個正常咬合兒童之上顎乳齒列牙弓石膏模型咬合面照片，測量11個直線與5個角度項目。
結果　三群間第二乳臼齒的大小無統計上之差異。A群與C群的比較顯示；A群牙弓長度較小、牙弓寬度較大、第二乳臼齒向近心顎側的旋轉度較大。B群的所有測量項目之平均值皆介於A與C群的平均值之間。三群的上顎第二乳臼齒的近心顎側咬頭的平均位置大部分位於上顎第二乳臼齒遠心面中心點至切齒乳頭中心點的連線上。
結論　本研究的結果有利於了解正常乳齒列上顎第二乳臼齒旋轉度之變異性並判斷各種牙弓形態的上顎第二乳臼齒旋轉度是否在於正常範圍內。

關鍵字

牙弓型態 ； 乳齒列 ； 旋轉 ； 上顎第二乳臼齒

並列摘要

Objectives. Because the primary second molars play such an important role in determining dental arch type and size, the author compared the size and rotation of the upper primary second molars among three groups of children.
Methods. The occlusal surfaces of the upper primary dental casts of 116 children with untreated normal occlusions were measured from standardized photographs (11 linear measurements of tooth size and 5 angular measurements of primary second molar rotation). The children were divided into groups according to their upper dental arch shape: group A, a wide arch, group B, a round arch, and group C, a slender arch.
Results. There were few significant differences in the sizes of the upper primary second molars among the three groups. Children in group A had significantly smaller arch lengths, larger arch widths, and more mesiopalatal rotation of the upper primary second molars compared with children in group C. The arch lengths, arch widths, size of the upper primary second molars, and degree of mesiopalatal rotation of the upper primary second molars in children in group B were between those in group A and those in group C. The mean positions of the mesiopalatal cusp of the upper primary second molars were almost on the lines connecting the midpoint of the distal surface of the upper primary second molar to the midpoint of the incisive papilla in each group.
Conclusions. These findings may be helpful in understanding the variations in upper primary second molar rotation in normal primary dentition and in determining whether the teeth are in ideal rotations in their dental arch shapes.

並列關鍵字

dental arch shape ； primary dentition ； rotation ； upper primary second molar