This study was performed to investigate the detailed morphological growth and development of dentition in postnatal suncus (house musk shrew, Suncus murinus).
X-ray micro-computed tomography was used to observe the mineralization pattern of the lower dentition at various postnatal ages. At birth, mineralized tissues were detected in the crowns of several tooth types, followed by the formation of enamel layers and root mineralization. Mineralization of all tooth types was completed by 15 days of age. Additionally, the mineralization pattern of the three major cusps of the lower molars—protoconid, metaconid, and hypoconid—progressed in that order, consistent with previous studies regarding the onset calcification during the embryonic period in suncus.
The crown height and crown area index (indicating crown thickness) of lower molars M1 and M2 peaked at 11 days of age, after which the index decline. However, no change was observed in the crown width-thickness index (representing crown shape), suggesting that although the crowns thickened and then thinned, their shape remained consistent.
Alveolar eruption was noted at birth for most tooth types, except I2-3, C1, P3, and M3. Subsequently, I2-3, C1, and M3 erupted, but P3 eruption was delayed until 15 days of age. Gingival eruption began with I1 and I1 at approximately 10 days of age and was completed by 17 days of age for all tooth types except P3. Tooth types that did not show occlusion between the upper and lower jaws tended to erupt later, suggesting that gingival eruption is likely influenced by feeding-induced friction on occlusal surfaces.
