Maxillofacial morphological characteristics in growing orthodontic patients with non-syndromic oligodontia.

OBJECTIVE: Patients with oligodontia frequently show different types of malocclusions. However, how oligodontia affects the maxillofacial growth remains uncertain. This study aimed to investigate the maxillofacial morphological characteristics in growing patients with oligodontia. SETTING AND SAMPLE POPULATION: The study subjects included 33 Japanese children with non-syndromic oligodontia (14 boys and 19 girls; mean age: 10.2 years) who visited the orthodontic clinic of Fukuoka Dental College Medical and Dental Hospital from 1999 to 2019. MATERIALS AND METHODS: Cephalometric analyses were performed, and the variables measured in each subject were converted into Z scores in relation to the mean and standard deviation of the Japanese norms matched for growth stage. The one-sample t-test or Wilcoxon signed-rank test was performed to compare the mean scores in the patients with oligodontia with those of the Japanese norms. RESULTS: Compared with the Japanese norms, patients with oligodontia showed a smaller convexity and larger A-B plane and SNB angles. The Frankfort-mandibular plane and gonial angles were smaller, whereas the height of the ramus was larger. The vertical height of the alveolar bone in the maxillary and mandibular incisors and molar areas was smaller in patients with oligodontia. CONCLUSIONS: Patients with oligodontia showed Class III skeletal tendency with mandibular prognathism and flattened mandibular plane with a smaller gonial angle. These maxillofacial morphological features can be induced by a deficiency in the vertical growth of the alveolar bone in the maxillary and mandibular molar areas due to the lack of tooth germs.

Differentiation of rat dermal mesenchymal cells and calcification in three-dimensional cultures.

Three-dimensional (3D) cultures are known to promote cell differentiation. Previously, we investigated the differentiation of rat dermal fibroblasts to α-smooth muscle actin (α-SMA)-positive myofibroblasts through transforming growth factor (TGF)-ß production using a 3D culture model. Here, we investigated the phenotypic change from dermal mesenchymal cells (mostly fibroblasts) to osteoblast-like cells, being inspired by the roles of smooth muscle cells or fibroblasts during vascular calcification. Spindle-shaped cells that grew in heterologous populations out of dermal explants from 2-day-old Wistar rats were cultured within a collagen matrix. α-SMA and alkaline phosphatase (ALP) meßsenger RNA (mRNA) levels initially increased, followed by a rise in Runx2 and osteocalcin (OCN) mRNA levels without calcification. Calcium deposits were produced in the presence of a high concentration of inorganic phosphate (2.1 mM) or ß-glycerophosphate (ßGP, 10 mM) after 2 weeks of culture, and both were sensitive to an inhibitor of type III phosphate transporters. An ALP inhibitor decreased only ßGP-induced calcification. Inhibition of TGF-ß type-I receptors attenuated ALP mRNA levels and ßGP-induced calcification, suggesting that endogenous TGF-ß stimulates ALP activity and then ßGP breakdown. An increase in the number of cells embedded in the collagen gel enhanced the mRNA levels of Runx2 and OCN, but not of ALP. Collectively, several factors are likely to promote the differentiation of dermal mesenchymal cells into osteoblast-like cells and ectopic calcification in a 3D collagen matrix, implying the utility of these cells as a potential autologous cell source for tissue engineering.