Quantification of taurodontism: interests in the early diagnosis of hypohidrotic ectodermal dysplasia.

OBJECTIVE: The aim of this study was to provide a quantification of taurodontism in Hypohidrotic Ectodermal Dysplasia (HED) and to report its occurrence in a cohort of HED patients to assess phenotypic-genotypic correlations. PATIENTS AND METHODS: Of 68 HED patients retrospectively reviewed, 16 patients aged 7-51 years were selected and compared with a control sample (n = 351). The pulp surface index of the first lower permanent molar was calculated from the panoramic radiograph of each individual, and statistical comparisons between the HED patients and the control sample were performed. RESULTS: Whatever the genetic disorder, 81.25% of the HED patients exhibited a relative enlargement (>or=1 s.d.) of the pulp. Major deviations (>5 s.d.) were respectively related to men affected by large deletion of the EDA gene or missense mutation. The autosomal recessive form was linked to a relative moderate pulp enlargement (3.44 s.d.). In NEMO forms, the increase of pulp size in men appeared to be less marked than in EDA mutations. CONCLUSION: This study provides for the first time an objective assessment of pulp enlargement in HED patients, and the various degrees of taurodontism depicted could be interesting dental phenotypic markers of HED forms.

Dento-craniofacial phenotypes and underlying molecular mechanisms in hypohidrotic ectodermal dysplasia (HED): a review.

The hypohidrotic ectodermal dysplasias (HED) belong to a large and heterogeneous nosological group of polymalfomative syndromes characterized by dystrophy or agenesis of ectodermal derivatives. Molecular etiologies of HED consist of mutations of the genes involved in the Ectodysplasin (EDA)-NF-kappaB pathway. Besides the classic ectodermal signs, craniofacial and bone manifestations are associated with the phenotypic spectrum of HED. The dental phenotype of HED consists of various degrees of oligodontia with other dental abnormalities, and these are important in the early diagnosis and identification of persons with HED. Phenotypic dental markers of heterozygous females for EDA gene mutation-moderate oligodontia, conical incisors, and delayed dental eruption-are important for individuals giving reliable genetic counseling. Some dental ageneses observed in HED are also encountered in non-syndromic oligodontia. These clinical similarities may reflect possible interactions between homeobox genes implicated in early steps of odontogenesis and the Ectodysplasin (EDA)-NF-kappaB pathway. Craniofacial dysmorphologies and bone structural anomalies are also associated with the phenotypic spectrum of persons with HED patients. The corresponding molecular mechanisms involve altered interactions between the EDA-NF-kappaB pathway and signaling molecules essential in skeletogenic neural crest cell differentiation, migration, and osteoclastic differentiation. Regarding oral treatment of persons with HED, implant-supported prostheses are used with a relatively high implant survival rate. Recently, groundbreaking experimental approaches with recombinant EDA or transgenesis of EDA-A1 were developed from the perspective of systemic treatment and appear very promising. All these clinical observations and molecular data allow for the specification of the craniofacial phenotypic spectrum in HED and provide a better understanding of the mechanisms involved in the pathogenesis of this syndrome.

Biochemical study of whole saliva from children with chronic renal failure.

The biochemical composition of unstimulated whole saliva was studied on ten children suffering from chronic renal failure and who, at the same time, displayed a very low caries activity. Various salivary components were studied before (T) and after (To) dialysis and were compared with similar elements of a control group, as well as with blood values. A mean salivary urea concentration of 513 +/- 210 mg/100 ml was found prior to dialysis, whereas after treatment this value dropped to 241 +/- 82 mg/100 ml, about twice as much as in the control group, 110 +/- 48 mg/100 ml. The mean urea concentrations in blood at T and To were respectively 196 +/- 38 mg/100 ml and 53 +/- 22 mg/100 ml. The various free amino acids in the whole saliva of these patients showed different changes in their concentrations as a result of dialysis, with the basic amino acids being considerably increased. Blood electrolytes remained close to the normal range, although calcium was depleted and magnesium lowered by a factor of 10 when compared before and after dialysis, as well as versus the control group.

[Low caries activity and salivary pH in youngsters dialyzed for chronic renal failure]. / Fiable activité carieuse et pH salivaire de jeunes dialysés rénaux chroniques.

Caries experience was studied in 18 young patients dialyzed for chronic renal failure and aged 7 to 17 years. The mean plaque index (Silness and Löe, 1964) was 1.89 +/- 0.15. Beside abundant plaque, these patients presented with poor oral hygiene and a food intake rich in sugars. Despite these unfavourable factors, caries experience was low. Of a total of 18 patients, ten (56%) had a DMF of 0. In addition, 11 subjects presented dental hypoplasias on more than two teeth. In these patients, the pH of whole saliva was determined at the beginning of the dialysis at time T and at the end of the dialysis at time To. The values at time T were always higher than those of time To. The mean pH at time T was 8.58 +/- 0.01 and the mean pH at time To was 8.09 +/- 0.01. These high salivary pH values are related to the low caries experience noted in these patients.