Individual variations of root morphology in the post-canine teeth of squirrel monkeys

研究了赛敏松鼠后尖牙的牙根形态特征。材料为98个颅骨及其拔除的牙齿，上颌磨牙有三个牙根，两个颊根和一个舌根，均由一个普通牙根长出。牙根通常融合在远中磨牙中，而颊根最常相互融合。当上颌磨牙有三个牙根时，牙根间牙本质突呈Y形或T形，当有两个牙根时，呈直线。M3的牙根结构较M1和M2明显缩小。下颌磨牙有近远中牙根。这两个根有时在M3中完全融合。当两根融合轻微时，出现在舌侧，而不发生在颊侧，呈沟沟状。当下颌磨牙有两个分离的牙根时，根间牙本质突呈直线状。上颌永久前磨牙最常见的是两个牙根，一个颊根和一个舌根，而P2有超过一半的病例只有一个牙根。在上颌乳牙中，DP2只有一个牙根，而DP3和DP4有三个牙根，两个颊根和一个舌根。DP4牙在牙冠和牙根结构上与M1相似，但DP4的喇叭状和细长状牙根多于M1。大多数下颌恒前磨牙只有一个牙根。在P4牙中，31.6%的牙根分叉位于近远中，距骨发育良好。下颌近中乳前磨牙只有Dne根，其继承者也是如此。DP4的牙根既有近中根，也有远中根，其模式与M1相同。

The morphological characteristics of the roots of the post-canine teeth of squirrel monkeys (Saimin) were investigated. Materials used were 98 skulls and their extracted teeth.Maxillary molars had three roots, two buccal and one lingual, which arose from a common root.trunk. The roots were often fused in the distal molars, with the buccal roots most often fused to each other. When the maxillary molars had three roots, the interradicular dentine process running between them was Y- or T-shaped ; when they had two roots, it was a straight line. The root structure of M3 had a more reduced pattern than those of M1 and M2.The mandibular molars had mesial and distal roots. These two roots sometimes fused completely in M3. When the fusion of the two roots was slight, it occurred on the lingual side, but not on the buccal side, and it was gutter-shaped. The gutter-shaped root was most frequently found in M2.When the mandibular molars had two separated roots, the interradicular dentine process was a straight line. Maxillary permanent premolars had the most commonly two roots, one buccal and one lingual, while in more than half of the cases P2 had a single root. Of the maxillary deciduous teeth, dp2 had a single root, but dp3 and dp4 had three roots, two buccal and one lingual. The dp4 teeth resembled M1 in both crown and root structures, but dp4 had more flared and slenderroots than Ml. Most of the mandibular permanent premolars had a single root. Of the P4 teeth, 31.6% had bifurcated roots situated mesiodistally and had a well-developed talonid. The mesial mandibular deciduous premolars had only dne root, as did their successors. The dp4 teeth had both mesial and distal roots, a pattern identical to M1.