Nozaka K, Ono R, Itoh M, Satoh T, Amari E, Nozaka Y
Iwate Medical University.
Bull Tokyo Dent Coll. 1990 Aug;31(3):217-28.
Using a total of 60 human extracted first deciduous molars (30 upper molars and 30 lower molars), we contrived a variety of ideal cavities having dentin thicknesses below the cavity (subcavitary dentin) that measure approximately 1 mm in thickness from the pulp chamber at any point of measurement and also having a retentional groove prepared in such a way that detachment of a filling material is prevented. The transparent specimens prepared from the cavity-containing teeth were cut into serial sections of 93 microns. These sections were reconstructed using a personal computer. The thickness of dentin below the cavity was measured in randomly selected sections. Results obtained were as follows: 1. An ideal thickness of the subcavitary dentin was preserved for upper first deciduous molar by preparing a retentional groove lingually or by providing a dovetail-like shape to mesio-distolingual sides in the cavity; for lower first deciduous molar, any form of cavitation worked. 2. In the upper first deciduous molars, the margins of the cavity were displaced medially to the summits of the respective cusps 1.9 mm at the buccal side and 1.2 mm at the lingual side. In the lower first deciduous molars, the buccal margin medially measured 0.9 mm and the lingual margin measured 0.6 mm at the mesial side. At the distal side, the buccal and lingual margins measured 1.2 mm and 1.0 mm, respectively. 3. The ratio of cavity width to the distance between the summits of the buccal and lingual cusps was 1/3 in upper deciduous first molars and 2/5 in the lower first deciduous molars. 4. In the upper first deciduous molars, the depths of the buccal and lingual walls of the cavity at the center of the central groove were both 1.1 mm. In the lower first deciduous molars, the cavity formed with its center at the middle of the transverse ridge had a depth of 1.5 mm at the buccal wall and a depth of 1.7 mm at the lingual wall. The cavity formed with its center at the central fossa had a depth of 1.2 mm at the buccal wall and 1.1 mm at the lingual wall. 5. The width of the gingival wall in the proximal box measured 0.6-0.7 mm in upper and lower first deciduous molars.
我们使用总共60颗人类拔除的第一乳磨牙（30颗上颌磨牙和30颗下颌磨牙），制备了各种理想的窝洞，这些窝洞下方的牙本质厚度（窝洞下牙本质）在任何测量点距髓腔的厚度约为1毫米，并且制备了固位沟以防止充填材料脱落。将含有窝洞的牙齿制备成的透明标本切成93微米的连续切片。这些切片使用个人计算机进行重建。在随机选择的切片中测量窝洞下方牙本质的厚度。得到的结果如下：1. 对于上颌第一乳磨牙，通过在舌侧制备固位沟或在窝洞内近远中舌侧提供燕尾状外形来保留理想厚度的窝洞下牙本质；对于下颌第一乳磨牙，任何形式的窝洞制备方式都可行。2. 在上颌第一乳磨牙中，窝洞边缘在颊侧内侧移位至各牙尖顶1.9毫米处，在舌侧移位至1.2毫米处。在下颌第一乳磨牙中，颊侧边缘在内侧近中侧测量为0.9毫米，舌侧边缘测量为0.6毫米。在远中侧，颊侧和舌侧边缘分别测量为1.2毫米和1.0毫米。3. 上颌第一乳磨牙窝洞宽度与颊舌牙尖顶之间距离的比值为1/3，下颌第一乳磨牙为2/5。4. 在上颌第一乳磨牙中，中央沟中心处窝洞颊壁和舌壁的深度均为1.1毫米。在下颌第一乳磨牙中，以横嵴中部为中心形成的窝洞，颊壁深度为1.5毫米，舌壁深度为1.7毫米。以中央窝为中心形成的窝洞，颊壁深度为1.2毫米，舌壁深度为1.1毫米。5. 上下颌第一乳磨牙近中盒内牙龈壁的宽度为0.6 - 0.7毫米。
