Sotos syndrome is a well-known overgrowth syndrome caused by haploinsufficiency of NSD1 gene located at 5q35. There are two types of mutations that cause NSD1 haploinsufficiency: mutations within the NSD1 gene (mutation type) and a 5q35 submicroscopic deletion encompassing the entire NSD1 gene (deletion type). We investigated detailed craniofacial, dental, and oral findings in five patients with deletion type, and three patients with mutation type Sotos syndrome. All eight patients had a high palate, excessive tooth wear, crowding, and all but one patient had hypodontia and deep bite. Hypodontia was exclusively observed in the second premolars, and there were no differences between the deletion and mutation types in the number of missing teeth. Another feature frequently seen in common with both types was maxillary recession. Findings seen more frequently and more pronounced in deletion-type than in mutation-type included mandibular recession, scissors or posterior cross bite, and small dental arch with labioclination of the maxillary central incisors. It is noteworthy that although either scissors bite or cross bite was present in all of the deletion-type patients, neither of these was observed in mutation-type patients. Other features seen in a few patients include enamel hypoplasia (two deletion patients), and ectopic tooth eruption (one deletion and one mutation patients). Our study suggests that Sotos syndrome patients should be observed closely for possible dental and oral complications especially for malocculusion in the deletion-type patients.
The effects of childhood masticatory function loss and soft foods on the mandibular condyle have been the subject of much research. However, the corresponding bone turnover is not fully understood. The purpose of the present study was to clarify the effects of a lack of teeth and a soft food diet during the growth period on bone turnover in the mandibular condyle. We divided 3-week-old Wistar rats into the following three groups: 1) Extraction group: The maxillary molars were extracted at the age of 4 weeks, and animals were fed powdered standard feed. 2) Powder group: Animals were fed powdered standard feed without tooth extraction. 3) Control group: Animals were fed solid standard feed without tooth extraction. Non-decalcified thin-slice specimens of sagittal sections of the mandibular condyle were obtained at the age of 20 weeks for histological analysis. We used micro-CT analysis and bone histomorphometry to measure bone volume (BV), bone mineral content (BMC), bone mineral density (BMD), bone microstructure, bone resorption, and osteogenesis in the mandibular condyle, and we compared the results among groups. In the extraction and the powder groups, we found deformation and disruption of the arrangement of chondrocytes, coagulation of chondrocytes, and duplication of the tidemark in the cartilage. We also found an increase in multinuclear osteoclasts in the cancellous bone. We found a reduction in BV, BMC, and BMD in the extraction and powder groups compared to the control group, as well as a reduction of bone volume, a lowering of osteogenesis parameters, and an increase in bone resorption parameters in the secondary cancellous bone. These results suggest that a lack of teeth and a soft food diet during the growth period cause a decline in bone microstructure, a decrease in osteogenesis, and an increase in bone resorption.
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