Maxillonasal dysplasia (Binder's syndrome). A study of craniofacial morphology, associated malformations and familial relations.

The aims of the present thesis were to study the craniofacial morphology and growth pattern in individuals with maxillonasal dysplasia, to check the presence of associated malformations and to elucidate the etiological factors. The thesis was based on five investigations. A cross-sectional cephalometric study of the craniofacial morphology of 97 Binder-subjects was performed. Comparison of 36 variables measured was made between these subjects and a control material, consisting of children with orthognathic profile and normal occlusion, matched for sex and age. Highly significant differences were found in a number of variables, correlated to the maxillary retrognathia and associated with the very characteristic appearance of individuals with maxillonasal dysplasia. The growth and development was studied in two longitudinal groups: one consisting of 13 orthodontically untreated children and one consisting of 15 orthodontically treated patients at corresponding ages. The untreated children were compared with the same reference material as in the crossectional study. It was then shown that all linear dimensions changed with age, parallel with normal growth and to about the same extent, although on another level for some variables. Comparison between the two longitudinal groups was made in order to study the possible positive effect of orthodontic treatment on craniofacial growth in Binder-subjects. No such influence could be stated. However, the graphical description of the groups, by means of facial polygons, revealed marked divergences even at early ages, remaining throughout the growth period. In the more severe cases, the maxillary retrognathia was aggravated by the craniofacial morphology of the lower face, similar to that of Class III-anomalies. In these cases, the orthodontic treatment has to be combined with surgical correction after completed growth. Associated malformations of the cervical spine were radiographically examined in 43 Binder-subjects. Defects of varying severity were observed in 44.2% of the patients. No clinical symptoms were found at early ages. An etiological study of 50 patients with maxillonasal dysplasia was performed to elucidate possible genetic factors. The results indicated two possible hypotheses: either the syndrome is caused by an autosomal recessive allele or it is of a quantitative multifactorial character with a threshold. The results did not disprove the possibility of a genetic etiology, although it might not be the full explanation for the syndrome. In conclusion, individuals with maxillonasal dysplasia shall be subjected to a thorough treatment planning in collaboration between orthodontists and surgeons.(ABSTRACT TRUNCATED AT 400 WORDS)