Nozaka K, Itoh M, Ono R, Satoh T, Amari E, Nozaka Y, Hongoh T
Iwate Medical University.
Bull Tokyo Dent Coll. 1990 Nov;31(4):309-19.
This study was designed to devise configuratively ideal cavity formations using 49 second deciduous molars, consisting of 25 extracted from the maxilla and 24 from the mandible. A cavity having at least 1 mm subcavitary (below the cavity) dentin thickness at any point of measurement and having an appropriately formed and positioned retention was defined as an ideal cavity. The same methods were used as in our previous study of first deciduous molars. The following results were obtained: 1. In upper second deciduous molars, the subcavitary dentin thickness was thin at the mesiobuccal side of the cavity; it measured 0.9 mm. In lower second deciduous molars, the subcavitary dentin thickness was thin at the mesiobuccal, distolingual sides of the cavity, and central fossa, where the retentional groove was provided; it measured 0.8-0.9 mm. The other measured values exceeded 1.0 mm. All thickness measurements were very close to the values considered as ideal. 2. In upper second deciduous molars, the margins of the cavity were positioned medially to the summits of respective cusps, 1.8-2.0 mm at the buccal side and 1.5 mm at the lingual side. The entire cavity was located lingually. 3. In lower second deciduous molars, the buccal margin of the cavity was positioned 1.7 mm medially to the summit of the distobuccal cusp and 1.2-1.3 mm medially to the summits of the other buccal cusps. The lingual margin was positioned 1.4-1.5 mm medially to the summits of respective cusps. medially to the summits of respective cusps. 4. The buccolingual width of the cavity amounted to 1/3 of the distance between the summits of the buccal and lingual cusps in both upper and lower second deciduous molars. 5. At the mesial side, the depth of cavity was 1.4 mm at the buccal wall and 1.5 mm at the lingual wall in upper second deciduous molars, and 1.4 mm at the buccal wall and 1.6 mm at the lingual wall in lower second deciduous molars. 6. The width of gingival wall in the proximal box measured 1.0 mm in both upper and lower second deciduous molars.
本研究旨在利用49颗第二乳磨牙设计出形态理想的洞形，其中25颗取自上颌，24颗取自下颌。将在任何测量点处洞下（洞下方）牙本质厚度至少为1mm且具有适当形成和定位的固位形的洞定义为理想洞形。采用与我们之前对第一乳磨牙研究相同的方法。获得了以下结果：1. 在上颌第二乳磨牙中，洞的近中颊侧洞下牙本质厚度较薄，为0.9mm。在下颌第二乳磨牙中，在洞的近中颊侧、远中舌侧以及设有固位沟的中央窝处，洞下牙本质厚度较薄，为0.8 - 0.9mm。其他测量值超过1.0mm。所有厚度测量值都非常接近被视为理想的值。2. 在上颌第二乳磨牙中，洞的边缘位于各牙尖顶点的内侧，颊侧为1.8 - 2.0mm，舌侧为1.5mm。整个洞位于舌侧。3. 在下颌第二乳磨牙中，洞的颊侧边缘位于远中颊尖顶点内侧1.7mm处，位于其他颊尖顶点内侧1.2 - 1.3mm处。舌侧边缘位于各牙尖顶点内侧1.4 - 1.5mm处。4. 在上颌和下颌第二乳磨牙中，洞的颊舌宽度均为颊尖和舌尖顶点之间距离的1/3。5. 在近中侧，上颌第二乳磨牙洞的颊壁深度为1.4mm，舌壁深度为1.5mm；下颌第二乳磨牙洞的颊壁深度为1.4mm，舌壁深度为1.6mm。6. 在上颌和下颌第二乳磨牙中，邻面盒形的龈壁宽度均为1.0mm。
