Peretz B, Nevis N, Smith P
Department of Pediatric Dentistry, Hadassah Faculty of Dental Medicine, Jerusalem, Israel.
Arch Oral Biol. 1998 Jul;43(7):525-33. doi: 10.1016/s0003-9969(98)00034-x.
The purpose of this study was firstly to characterize the changes occurring in size and form of the mineralizing maxillary second primary molar and first permanent molar crowns, and secondly to determine if similar changes in size and form characterize enamel apposition in the crowns of these teeth. Twenty-five primary second molars and 20 maxillary permanent first molars at various stages of development, found in archaeological excavations in Israel, were examined for a number of measured variables using image analyser software. Teeth were divided into two groups according to their stage of development: stage I included all teeth at an early stage of development in which mesiobuccal-cusp height was less than 5 mm for the primary molar and 5.9 mm for the permanent molar; stage 2 included all teeth in later stages of development where mesiobuccal-cusp height was greater than these values. In the primary molar, a significant increase was found between the two stages in almost all variables. Significant correlations were also found between all intercusp distances and the external variables. Strong correlations between height of the mesiobuccal cusp and all external and internal variables were noted in stage 1, but fewer in stage 2. In the permanent tooth, no increase was observed in intercusp distances and very few correlations were found between and among the variables. The results suggest that a change in the shape of the maxillary primary second molar occurs during formation, with the lingual cusp tips moving lingually and distally, and the distobuccal cusp tips moving distally. No change occurs in the shape of the maxillary permanent first molar during crown formation. Growth of the maxillary primary second and permanent first molar crowns occurs in 'bursts' of development.
本研究的目的，一是描述上颌第二乳磨牙和第一恒磨牙矿化牙冠在大小和形态上发生的变化，二是确定这些牙齿牙冠的釉质附着在大小和形态上是否有类似变化。在以色列考古发掘中发现的25颗处于不同发育阶段的乳磨牙和20颗上颌恒磨牙，使用图像分析软件对其进行了多项测量变量的检查。根据牙齿的发育阶段将其分为两组：第一阶段包括所有处于发育早期的牙齿，其中乳磨牙的近中颊尖高度小于5毫米，恒磨牙的近中颊尖高度小于5.9毫米；第二阶段包括所有发育后期的牙齿，其近中颊尖高度大于这些值。在乳磨牙中，几乎所有变量在两个阶段之间都有显著增加。所有牙尖间距离与外部变量之间也存在显著相关性。在第一阶段，近中颊尖高度与所有外部和内部变量之间存在强相关性，但在第二阶段则较少。在恒牙中，牙尖间距离没有增加，变量之间的相关性也很少。结果表明，上颌第二乳磨牙在形成过程中形状发生了变化，舌侧牙尖向舌侧和远中移动，远中颊侧牙尖向远中移动。上颌第一恒磨牙在牙冠形成过程中形状没有变化。上颌第二乳磨牙和第一恒磨牙牙冠的生长呈“爆发式”发育。
