• The Journal of the Korean dental association
• /
• v.12 no.2
• /
• pp.113-118
• /
• 1974

The importance of light and stress as factors in growth has not previously been clearly delineated. As the result of using experimental environments on growth rate of incisors in 24 young rats with body weight ranging 58 Gm to 62 Gm., the author obtained following conclusions. 1) The eruption rate of normal rats incisors was 0.421mm in upper incisors and 0.592mm in lower incisors per a day respectively. 2) In light environment, growth rate of incisors in rats and body weights were found to increase more rapidly during the 8-week experimental period in comparison with any environments. 3) In stress environment, growth rate of incisors in rats and body weight were found to decrease in comparison with amy environments during the 8-week experimental period.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.31 no.4
• /
• pp.651-658
• /
• 2004

Runx2 is a transcription factor in homologous with Drosophila runt gene and it is essential for bone formation during embryogenesis and a critical gene for osteoblast differentiation and osteoblast function. Runx2-haploinsufficency causes cleidocranial dysplasia (CCD). CCD is an autosomal-dominant inherited disorder characterized by hypoplastic clevicle and delayed ossification in fontanelles and wormian bones. Dental defects are possibly shown to CCD patients : multiple supernumerary teeth, irregular and compressed permanent tooth crowns, hypoplastic and hypomineralized defects in enamel and dentin, an excess of epithelial root remnants, the absence of cellular cementum, and abnormally shaped roots. In addition, delayed eruption of the secondary dentition is a constant finding. The aim of this study is to evaluate the role of Runx2 in the tooth development and eruption through analyzing the expression pattern of Runx2 by in situ hybridization during crown (late bell stage) and root formation of tooth, using postnatal day 1, 4, 7, 14 and 21 mice mandibular molar teeth. mRNA of Runx2-full length is expressed in dental follicle and surrounding tissue at postnatal day1 and 4. At postnatal day 7, it is expressed in ameloblasts of occlusal surface of enamel and bone area surrounding the tooth. In comparison with previous stage, at postnatal day 14, it is expressed in ameloblasts of proximal surface of enamel. At postnatal day 21 it's expression is observed only in bone area. mRNA of Runx2-typeII is not expressed. At postnatal day 1 and 7. At postnatal day 14 and 21, it's expression is observed in the bone area. In this study, we suggest that Runx2 have a relation of ameloblasts differentiation and an important role to tooth eruption made by dental follicle during intraosseous eruption stage. Also we can confirm that Runx2 has a role to bone formation.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.30 no.3
• /
• pp.459-464
• /
• 2003

Dentigerous cyst is a cyst arising by tissue fluid accumulation between the enamel and the residual enamel epithelium. It includes the crown of the impacted tooth and excludes the root. The treatments of the dentigerous cyst are enucleation, marsupialization, decompression, surgical excision and etc. In these cases children were evaluated for the chief complaints of the remained mandibular primary second molar. Each cases showed swelling on the buccal side of the primary secondary premolar. In the radiologic evaluation a radiolucent lesion including the crown of the mandibular secondary premolar was found, and it was diagnosed as dentigerous cyst. And the histopathologic examination showed the same result. Marsupialization was operated through alveolar socket and the alveolar socket was protected with vaseline gauze, the obturator combined with space maintainer was followed by the operation. After the operation, the impacted permanent tooth was showing faster eruption speed than the other normal teeth.