3D hard tissue palatal size and shape in 6-year old subjects affected by hypohidrotic ectodermal dysplasia

Introduction. Hypohidrotic Ectodermal Dysplasia (HED) is a rare inherited disorder that share primary defects in the development of two or more tissues derived from ectoderm. Individuals affected by HED present a classical triad of hypotricosis, hypohidrosis and hypodontia. Clinical management of oligodontia presents the prosthodontist with aesthetic and functional peculiar needs: loss of removable prosthesis retention, sore points and occlusal changes caused by erupting teeth or jaw growth should be carefully monitored by the dentist. Moreover, in the craniofacial complex structures derived from the meso-ectodermal layer of the neural crest are involved quite often, thus producing an abnormal morphology with maxillary and mandibular hypoplasia. To date, no quantitative analyses on palatal shape were performed in HED subjects. In the present study, the morphology and the dimensions of hard tissue palate of eight Italian HED six-years-old boys were analyzed. Reference quantitative data on palatal morphometry in subjects with HED could be useful for a better assessment of patients. Methods. Four HED children were completely edentulous and four were partially dentate. Palatal landmarks were identified on stone casts and digitized with a three-dimensional computerized electromagnetic instrument. Palatal length, slope, width, maximum palatal height in both sagittal and frontal planes were measured. From the coordinates of palatal landmarks, a mathematical equation of palatal shape, independent of size was constructed. HED palatal data were compared with reference data obtained in 12 healthy boys with a complete deciduous dentition. Results. Palatal length and height in both sagittal and frontal planes were significantly reduced in the HED than in control individuals (Wilcoxon rank-sum test, p < 0.05). A less steep (not significant) palatal slope was found in HED than in reference subjects, while similar palatal width values were observed. All palatal measurements were larger in partially dentate than in edentulous patients (p*0.05). Both HED and edentulousness influenced palatal shape: HED boys had a relatively lower palate than the reference boys. In the edentulous HED boys the hard tissue palate was relatively lower than in partially dentate HED subjects. Conclusions. Palatal size and shape were significantly modified by the presence of Hypohidrotic Ectodermal Dysplasia and the major alterations were found in edentulous HED subjects. Further studies in larger samples are needed to determine mean dimensions and shape of the palate in older HED patients thus providing useful information to the clinicians during oral treatment planning.