Fogorvosi szemle, 2005 (98. évfolyam, 1-6. szám)

2005-04-01 / 2. szám

82

FOGORVOSI SZEMLE ■ 98. évf. 2. sz. 2005.

X-P. WANG, M. SUOMALAINEN, C.J. JORGEZ*, M.M. MATZUK“, S. WERNER***, I. THESLEFF

Developmental Biology Programme, Institute of Biotechnology, Viikki Biocenter, FIN-00014 University of Helsinki, Finland ‘Program in Developmental Biology and “Departments of Pathology, Molecular and Cellular Biology, and Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA “‘Institute of Cell Biology, ETH Zurich, Honggerberg, CH-8093 Zurich, Switzerland

BMP4 IS A MAJOR INDUCER OF AMELOBLAST DIFFERENTIATION AND ENAMEL FORMATION

The terminal differentiation of ameloblasts has generally been attributed to signals secreted by odontoblasts and trapped in predentin-dentin matrix, but the actual signals inducing ameloblast differentiation in vivo have not been identified. In this study we provide direct evidence that BMPs, in particular BMP4 from the odontoblasts induce ameloblast differentiation.

First, we showed that BMP-releasing beads induced strongly ameloblastin expression in cultured incisors and that noggin-releasing beads dramatically inhibited ameloblast differentiation. The comparison of BMP expression between the labial and lingual aspects of mouse incisors demonstrated that Bmp2, Bmp4 and Bmp7 were all expressed by odontoblasts underlying the labial side dental epithelium, but only Bmp4 was expressed also on the lingual side.

Secondly, we showed also that the TGFß inhibitor follistatin inhibits ameloblast differentiation in mouse incisors in vivo. In follistatin knockout mice, functional ameloblasts differentiated ectopically on the lingual surface of the incisors which normally is enamel free. Conversely, over-expression of follistatin in the dental epithelium by using the K14-promoter in transgenic mice resulted in the inhibition of ameloblast differentiation and failure of enamel formation on the labial side. Hence, both overexpression and loss-of-function of follistatin resulted in the loss of asymmetry in ameloblast differentiation and enamel formation, indicating that follistatin is required for the labial-lingual patterning of mouse incisors. Finally, we showed that follistatin specifically inhibits BMP function in the mouse incisors. We conclude that BMP4 is the major inducer of ameloblast differentiation in mouse incisors. Acknowledgement: The support of the COSTB23 program is acknowledged.

P. TREFNŸ, Z. SMAHEL*, M. PETERKA**

Institute of Dental Research, General Faculty Hospital, Prague, Czech Republic ‘Department of Anthropology, Faculty of Natural Sciences, Charles University, Prague, Czech Republic “Department of Teratology, Institute of Experimental Medicine, Academy of Sciences CR, Prague, Czech Republic

MAXILLOFACIAL GROWTH AND DEVELOPMENT IN UNILATERAL CLEFT LIP AND PALATE AFTER PRIMARY PERIOSTEOPLASTY

The most controversial issues in the management of cleft palate are the timing of surgical intervention, speech development after various surgical procedures, and the effects of surgery on facial growth. Analysis of lateral cephalograms is well established method for evaluating and predicting the maxillofacial growth in clefts, however, it provides only limited information on the palate itself. The aim of the study was to analyze three-dimensionally the size, shape and symmetry of the palate in patients with unilateral cleft lip and palate (UCLP) operated on by primary periosteoplasty. The sample of subjects with UCLP comprised dental stone casts of 30 males (mean age 14.8 years). The control group included dental stone casts of 28 healthy males (mean age 14.7 years) with the Angle Class I first molar and canine relationship. The maxillary dental stone casts were digitized using threedimensional laser scanner Roland LPX-250 (Roland DG Corp.). Using the reverse engineering software, the laser scan data were processed and converted into a NURBS surfaces. 3D computer models of dental casts were thereafter analyzed using newly developed measuring software 3D-DENT.

Compared with controls, patients with UCLP showed significantly smaller width of the palate in the transversal profiles, shallower palate in the area of upper premolars and molars and a marked asymmetry of transversal profiles. We also observed a distinct interindividual variability in both the maximum palate height and the shape of the transversal profiles. The data are a prerequisite for the evaluation of the outcomes of surgical and orthodontical procedures within the framework of the multidisciplinary treatment of clefts.

Keywords: unilateral cleft lip and palate, periosteoplasty, 3-D analysis Acknowledgements: This study was supported by Ministry of Education, Youth and Sports of the Czech Republic (grant COST OC B23.004) and Ministry of Health of the Czech Republic (grant 00002377901).