Fogorvosi szemle, 2005 (98. évfolyam, 1-6. szám)
2005-04-01 / 2. szám
FOGORVOSI SZEMLE 98. évf. 2. sz. 2005. 73 R. HOBSON, N. JEPSON, M. WRIGHT**, H. PETERS**, A. CURTIS**, A. JACOBS1 School of Dental Sciences , ‘Institute of Human Genetics, University of Newcastle upon Tyne, UK TRACING GENEALOGY OF HYPODONTIA The genetic control of tooth development in humans is poorly understood. Mouse models have shown the importance of the genes Msx1 and Pax9 and these genes are known to cause hypodontia in some familial human cases. 100 individuals with a family history of hypodontia and their families were asked to take part in a study into the inheritance of hypodontia. 44 families agreed to participate; comprehensive genealogies were recorded and DNA swabs of buccal mucosa collected from affected and unaffected family members. A limited linkage analysis was undertaken to compare DNA markers in affected and unaffected members. The majority of families showed dominant inheritance of hypodontia. 13 families indicated dominant inheritance with reduced penetrance or recessive inheritance. Some of these families only showed hypodontia in a single generation. Preliminary linkage data in 4 of the largest pedigrees (hypodontia over 3 generations) has been carried out using polymorphic markers close to the Msx1 and Pax9 genes. In one pedigree it has been possible to exclude one of these two genes which will enable direct mutation screening to be targeted to the non-excluded locus. In one further pedigree, for which there were 7 or 8 informative meioses, both loci were excluded making it a good candidate for a full genome linkage screen with the possibility of the identification of a new hypodontia locus. For all the remaining families the appropriate next stage of investigation is to screen for mutations in the candidate genes Msx1 and Pax9. Keywords: Hypodontia; genealogy Acknowledgements: The support of the RVI Special Trustees and Cost Action B23. I. KJAER Department of Orthodontics, School of Dentistry, Faculty of Health Science, University of Copenhagen, Copenhagen, Denmark INNERVATION AND TOOTH FORMATION The prenatal expression of NGFR in human tooth buds showed a spatio-temporal location of NGFR indicating the influence of peripheral nerves for tooth formation. In the present study, arrestment in tooth formation in children is demonstrated and related to anamnestic information on disruption in innervation pattern due to virus attacks and surgical incisions. Material and Method: Radiographic material from 12 children referred since 1995 to the Department of Orthodontics, School of Dentistry, University of Copenhagen, for diagnostics. All children had a severe mumps attack or ear surgery during early childhood. Results: The study showed that arrestment in tooth formation had a regional occurrence in the alveolar process, which corresponded to the pattern of innervation. This finding indicates that arrestment in tooth maturation occurs when the innervation to the root and surroundings is interrupted either by de-myelinization or by surgical incisions of peripheral nerves. This hypothesis will be discussed. References: Chavéz-Lomelí ME, Mansilla Lory J, Pompa JA, Kjaer I: (1996) J Dent Res 75: 1540-1544. Kjaer I: Neuro-osteology. (1998) Crit Rev Oral Biol Med 9:224-244. Kjaer I: (1998) Acta Odontol Scand 56: 326-330. Becktor KB, Bangstrup Ml, Rolling S, Kjaer I: (2002) Eur J Orthod 24: 205-214. Becktor KB, Hansen BF, Nolting D, Kjaer I: (2002) Orthod Craniofacial Res 5: 85-89. Keywords: Peripheral nerves, tooth formation Acknowledgements IMK Foundation and Cost Action B23. Y. KOZAWA, R.YOKOTA, Y. HANAIZYUMI, K. SUZUKI, H. MISHIIMA, H. YAMAMOMTO Department Anatomy, Nihon University School of Dentistry at Matsudo, Chiba 271-8587, Japan IMMUNOHISTOLOGICAL BASE ON HARNIBUIOUS MOVING OF ENAMEL ORGAN PRODUCES AMELOBLAST ‘GROUPING’ AND DANCING’ FORMING ENAMEL STRUCTURE The author showed an evolutional process of mammalian enamel structures that were cased by the ameloblast j moving of ‘dancing’ and ‘grouping’ (Kozawa2001).This I study reports on a cytological base of the amelobalst ‘dancing’ and ‘grouping’ are caused by the tooth germ harmony moving. Nishikawa (1992) reported ameloblast moving which formed Hunter-Schreger (H-S) bands with the immunohistology and the electronmicroscopy (EM) by in the rat, the pig, and the monkey tooth germs. He suggested that the junctional complex of ameloblast formed the moving. The boundaries of H-S bands were not so clear in these animals. On the other hand, it is clearly bordered zones of H-S bands in dog enamel, and Hanaizumi (1998) reported the arrangement of enamel prism in details. This report is to clarify the ameloblast dancing and grouping with the immunohistology and the EM in the puppy tooth germs. The actin, the keratin, Desmin, and Tublin are used for the study, because these play the cell attachment, the mobility, the secretion and maintain the cell form. The actin localized in the outer enam-
