Chlastakova Ivana, Lungova Vlasta, Wells Kirsty, Tucker Abigail S, Radlanski Ralf J, Misek Ivan, Matalova Eva
Laboratory of Animal Embryology, IAPG v.v.i., Academy of Sciences, Brno, Czech Republic.
Eur J Oral Sci. 2011 Aug;119(4):265-74. doi: 10.1111/j.1600-0722.2011.00838.x.
The mouse third molar (M3) develops postnatally and is thus a unique model for studying the integration of a non-mineralized tooth with mineralized bone. This study assessed the morphogenesis of the mouse M3, related to the alveolar bone, comparing M3 development with that of the first molar (M1), the most common model in odontogenesis. The mandibular M3 was evaluated from initiation to eruption by morphology and by assessing patterns of proliferation, apoptosis, osteoclast distribution, and gene expression. Three-dimensional reconstruction and explant cultures were also used. Initiation of M3 occurred perinatally, as an extension of the second molar (M2) which grew into a region of soft mesenchymal tissue above the M2, still far away from the alveolar bone. The bone-free M3 bud gradually became encapsulated by bone at the cap stage at postnatal day 3. Osteoclasts were first visible at postnatal day 4 when the M3 came into close contact with the bone. The number of osteoclasts increased from postnatal day 8 to postnatal day 12 to form a space for the growing tooth. The M3 had erupted by postnatal day 26. The M3, although smaller than the M1, passed through the same developmental stages over a similar time span but showed differences in initiation and in the timing of bone encapsulation.
小鼠第三磨牙（M3）在出生后发育，因此是研究非矿化牙齿与矿化骨整合的独特模型。本研究评估了与牙槽骨相关的小鼠M3的形态发生，将M3的发育与第一磨牙（M1）的发育进行比较，M1是牙发生研究中最常用的模型。通过形态学以及评估增殖模式、凋亡、破骨细胞分布和基因表达，对下颌M3从起始到萌出进行了评估。还使用了三维重建和外植体培养。M3在围产期开始发育，是第二磨牙（M2）的延伸，M2生长到M2上方的软间充质组织区域，此时仍远离牙槽骨。出生后第3天，无骨的M3牙蕾在帽状期逐渐被骨包绕。出生后第4天，当M3与骨紧密接触时，首次可见破骨细胞。从出生后第8天到出生后第12天，破骨细胞数量增加，为生长中的牙齿形成空间。M3在出生后第26天萌出。M3虽然比M1小，但在相似的时间跨度内经历相同的发育阶段，但在起始和骨包绕时间上存在差异。
