1992 Volume 34 Issue 1 Pages 173-178
This study was designed to evaluate the transverse root form of the mandibular second molar of permanent teeth in Japanese subjects. After an impression of these teeth had been taken: they were replicated into a plaster model: which had been embedded in a block of polyurethane resin. The replica was cross-sectioned at 1 mm intervals from the reference surface. Traces of each cross-section were made at X 10 magnification with a projector. The traced form was examined for the frequency of concavity: the distance from a tangent line to the concavity 1 mm coronal and 2 and 4mm apical to the furcation area. The results illustrate: 1. The degree and distribution of concavity 1mm coronal to the furcation area: a buccal surface area of 1.00±0.35 mm (100%) : lingual surface; 0.70±0.25mm (100%) : mesial surface ; 0.15±0.05 mm (73.8%) : distal surface ; 0.15±0.05 mm (16.7%). 2. The degree and distribution of concavity 2mm apical to the furcation area: mesial surface of the mesial root ; 0.25±0.20mm (90.5%) : distal surface of the mesial root ; 0.60±0.20mm (100%) : mesial surface of the distlal root; 0.35±0.15mm (100%) : distal surface of the distal root; 0.10±0.05mm (52.4%). 3. The degree and distribution of concavity 4 mm apical to the furcation area: mesial surface of the mesial root; 0.20±0.15mm (90.5%) : distal surface of the mesial root; 0.60±0.20mm (100%) : mesial surface of the distal root; 0.35±0.20mm (100%) : distal surface of the distal root ; 0.10±0.05mm (42.9%). 4. Morphological differences between the right and left molars were not statistically significant.
