Cahill D R, Marks S C
J Morphol. 1982 Feb;171(2):213-8. doi: 10.1002/jmor.1051710208.
Exfoliation of third deciduous mandibular premolars and their replacement by the third permanent premolars were compared in young dogs of purebred beagle and mongrel stock. Radiographic and histologic studies showed that eruption of the permanent premolar begins during the 16th postnatal week and is completed in 7 weeks. Root elongation proceeds with eruption, but fibers of the periodontal ligaments are not anchored in alveolar bone and do not attain their final orientation with respect to the long axis of the tooth until final phase of the eruptive period. These data define a predictable system in which various stages in the mechanism of eruption of noncontinuously erupting teeth may be examined experimentally. Furthermore, the observation that these processes are identical in timing and sequence in beagle and mongrel dogs suggests that less expensive, more readily available mongrel dogs can be used for these studies.
对纯种比格犬和杂种犬幼犬的下颌第三乳前磨牙脱落及其被第三恒前磨牙替代的情况进行了比较。放射学和组织学研究表明，恒前磨牙在出生后第16周开始萌出，并在7周内完成。牙根随着萌出而伸长，但牙周韧带的纤维在牙槽骨中未锚固，直到萌出期的最后阶段才达到相对于牙齿长轴的最终方向。这些数据定义了一个可预测的系统，在该系统中，可以通过实验研究非连续萌出牙齿萌出机制的各个阶段。此外，在比格犬和杂种犬中，这些过程在时间和顺序上相同的观察结果表明，价格较低、更容易获得的杂种犬可用于这些研究。
