Prevalence of Dentinogenesis Imperfecta in a French Population.

BACKGROUND: Dentinogenesis imperfecta is a genetic disorder of the dentin occurring during the tooth development. It leads to many structural changes that can be identified clinically (brownish colored teeth, cracked enamel) and radiologically (globular crown, cervical constriction, short roots, and obliterated pulp chamber and/or root canals). The aim of this study was to determine by panoramic radiographs assessment the incidence of dentinogenesis imperfecta in a group of patients attending a specialized maxillofacial imaging center in Paris, France. MATERIAL AND METHODS: A retrospective observational study was conducted using panoramic radiographs of 8830 patients (3723 males and 5107 females), which were used to search the radiological criteria of dentinogenesis imperfecta. RESULTS: In our sample, the prevalence of dentinogenesis imperfecta was 0.057%. Out of the 8830 subjects, 0.080% of the males presented the radiological signs of the dentinogenesis imperfecta against 0.039% of the females. CONCLUSION: In our study, we found that dentinogenesis imperfecta is a relatively rare dental anomaly in France, with a rate different from the rates reported in other studies and with no disparity in prevalence among genders.

[Imagery and orthodontics: trends, present and future]. / Imagerie et orthopédie dento-faciale: évolution, présent et avenir.

From the first dental image in 1895 and the first image of the head in 1896 by Otto Walkhoff to 3D modern cephalic assessment there has been a continuous evolution in imaging techniques. Digital cephalic volume data processing allows 2D and 3D reformations in accordance with morphologic, topographic and biodimensional anatomic needs. In France, Jacques Treil demonstrated its application in cephalometry through his CT scan research. The transcription of European Directives to national laws leads to rigorous radioprotection measures. The worldwide spread of cone beam technique devoted specifically to dentomaxillofacial imaging should now reduce the reluctance of orthodontists to provide radiological examinations to children by significantly reducing radiation exposure. This is certainly the technique of the future.

Eruption of third molars: relationship to inclination of adjacent molars.

The purpose of this study was to determine the relationship between the sagittal inclination of the first and second maxillary molars and the eruption of the third molars. The sample consisted of 2 groups. The subjects in the first group (n = 28) had complete normal dentitions including third molars; those in the second group (n = 32) had impacted right and left third molars. The sagittal inclinations to the palatal plane of the first and second maxillary molars were measured on computed tomography sagittal images obtained with multiplanar reconstructions. The Mann-Whitney U test was used to compare mean angular values between the 2 groups. Spearman correlation coefficients were calculated to assess the relationship with age. A multivariate analysis was used to evaluate the relationship between the eruption of the third molars and the sagittal inclination of the first molar, the second molar, sex, and age. Maxillary first and second molars were more mesially inclined in the first group, particularly in the younger subjects (16-25 years). This inclination increased with age. The logistic regression showed that the sagittal inclination of the first molar is a predictor of the eruption of the third molar. This finding suggests that a more mesially inclined maxillary dentition is likely to be associated with third molar eruption. The absence of data on space requirements in the maxillary arch and interarch relationships warrants further exploration in an orthodontic population.