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Introduction: Recent observations performed in the orthodontic department of La Pitié-Salpêtrière hospital in Paris reported an increase of non-familial eruption defects of permanent molars. Our recent data have evidenced the involvement of osteoclasts (OC) in both the eruption and the dental retention processes through the RANKL/RANK/OPG signaling pathway. These facts are at the origin of the hypothesis of the existence of an environmental etiology for those eruption defects that would correspond to the perturbation of cellular autocrine/paracrine signaling pathways as the RANKL/ RANK/OPG., Materials and Methods: C57BL/6 mice were submitted to repeated injections with anti-RANKL neutralizing antibody during the nine days following birth. A phenotypic comparison with transgenic mice overexpressing RANK was performed for the functional characterization of the RANKL/RANK/OPG pathway. The dento-alveolar complex was analyzed using micro-CT for bone density and Masson's trichrome staining for histological examination., Results: The RANKL transient invalidation of RANKL stopped the molar root development and tooth eruption contrary to transgenic mice overexpressing RANK. The recruitment and the OC activity were strongly impacted., Discussion: This research is of direct clinical interest in understanding the pathology of eruption as indirect in establishing orthodontic treatment protocols for particular cases., (© EDP Sciences, SFODF, 2019.)

Pulpotomy is the most performed and controversial therapeutic in pediatric dentistry. Formocresol is known to have a toxic effect on living tissues, a mutagenic and carcinogenic potential with a systemic uptake of formocresol via pulpotomized teeth, other alternative products have been investigated. 40 molars were pulpotomized using Micro Mega Mineral Trioxide Aggregate (MM-MTA), which eliminates the need for the use of formocresol. The effects of this material were evaluated both clinically and radiographically. Post-operative control examinations were performed at 1, 6, 12, and 18 months trying to detect spontaneous or stimulated pain, pathological tooth mobility, abscesses or fistulas, internal or external pathological tooth resorption, periapical bone destruction, or canal obliteration. Pain was absent at 18 months post operatively. Thirty six molar treated with the MM-MTA didn't show any mobility or pain, one molar presented a pathological resorption and one molar presented an abscess without a fistula at 12 month. The observations were compared to others related to formocresol, ferric sulfate, MTA, and laser pulpotomies, using the Chi-square test x2. The abundance of positive result strongly demonstrate that the MM-MTA pulpotomy on carious temporary molars is a promising technique.

Objective: Determine the differences in skeletal and dental maxillary expansion as evidenced by the degree of dental tipping and if this is symmetrical or not., Methods: Sixty-two patients who were diagnosed as requiring maxillary expansion treatment were recruited over an 18-month period. Patients were randomly allocated into three groups where a total of three to four cone-beam computerized tomographies (CBCT) were obtained throughout a one-year period depending on the group allocated. Landmarks used were from the first and second molars and premolars of the maxilla. For each of the eight teeth, three landmarks were identified: the root apex, alveolar bone and pulp chamber. Statistical analysis consisted in the use of MANOVA and after significant overall effects were detected, the univariate repeated measures results were analyzed along with separate ANOVA for each variable at each of the four time points., Results: There was strong overall significance for time, group, and time*group. The first and second molars saw both bone- and tooth-anchored treatment groups with significantly different dental inclination than the control group. For the second premolars, only the tooth-anchored group was significantly different from control. The tooth-anchored group was also significantly different than the control group in the first premolar measurements. For the analysis of asymmetry in dental inclination, no significant time, group, or time*group effects were seen overall., Conclusion: The analysis provided evidence that dental tipping does occur in the molars for both RME treatments, while the premolars showed increased tipping in the tooth-anchored, but not the bone-anchored group., (Copyright © 2012. Published by Elsevier Masson SAS.)

Introduction: The aim of our study was to investigate the prevalence of root resorption during and at the end of orthodontic treatment and to assess its relationship with age, sex and treatment with or without extractions., Patients and Methods: Our study included 82 patients (51 women and 31 men) aged between 6 and 38 years, who received orthodontic treatment. Evaluation of root resorption was performed on panoramics at the beginning and at the end of orthodontic treatment. All the teeth were observed. The degree of root resorption was increased respectively by the standards in four ordinal levels (4). Data analysis was performed by Epi Info 6.0., Results: Root resorption was present in all the teeth and maxillary incisors are the most affected. The correlation between age and root resorption was significant (p = 0.008). Women were more affected by resorption (P = 0.002). Patients treated with extraction showed more root resorption (p = 0.12)., Conclusion: Our results suggest that orthodontic treatment is involved in the development of root resorption. The most often teeth resorbed are maxillary incisors. Age, sex and orthodontic extractions can be considered as risk factors for root resorption.

The occluso-proximal restorations should restore a coronary morphology permitting a normal physiology. The radiological evaluation of 55 occluso-proximal restorations with the amalgam done by 4th and 5th years students at the Odonto-Stomatology Institute, and judged clinically acceptable, has shown 63,63% of incorrect restorations with faults: of inter-dental contact (absence of contact or large contact area) and of cervico-proximal limit (hiatus or excess. The identified iatrogenic faults come from choice of matrixing material in accordance with the clinical situation, to use of separators or inter-dental wedges. The radiographic control of these restorations has permit an immediate correction of excesses and some big areas of contacts, by improving appreciably the success score (up to 20% without re-doing the obstrusion with the amalgam). The retro-alveolar radiography is a clinical evaluation instrument for a better periodontal integration of occlusoproximal restorations in the biological space and inter-proximal space.

This study was done to establish the prevalence of taurodontism using the criteria of SCHIFMAN and CHANANNEL, the first and second molars on the panoramic radiograph of 150 consecutive 15-19 year-old Senegalese people were assessed. Results have shown that taurodontism was present in 48% of patients (18.8% of teeth). Taurodontism was greater in females (% compared % in male) but the difference was not significantly, it was found that was significantly greater in the maxillary and in the second molar.

This study was done to establish the prevalence of taurodontism and pyramidal molars in Senegalese people using the criteria of SCHIFFFMAN and CHANANNEL for taurodontism and the criteria of BRABANT for pyramidal molar, the first and second molars on the panoramic radiograph of 150 consecutive 15-19 year-old Senegalese people were assessed. Results have shown that taurodontism and pyramidal molars were present in 48.6% of patients (20% of teeth). Taurodontism was present in 48% (18.8% of teeth) of patients whereas prevalence of pyramidal molar was 4.6% (1.6% of teeth). Taurodontism was alone in 91.6% of case while pyramidal molar was alone in 8.6% of case.

Dentigerous cysts, also called follicularor corono-dental cysts, are malformative odontogenic cysts in the WHO classification of odontogenic tumors. We review the general characteristics of these frequent odontogenic tumors which always occur in associated with an included tooth. Diagnosis is based on clinical features, X-ray findings and pathology results. We report the evolutive aspect in three patients of different ages.

The purpose of the present study was to investigate the radiological results of 40 autotransplantations (20 molars and 20 premolars) performed in the Orthodontic Department of the University of Geneva between 1979 and 1990. The sample demonstrated persistence of pulp vitality and continuous root growth, followed however in most cases by ankylosis and replacement root resorption. The data were in accordance with previous published studies and point out an ideal developmental stage for molar and premolar transplantation to ensure pulpal and periodontal survival.

The goal of this research was to evaluate the conventional means of clinical (mirror and probe examination) and radiological diagnosis (bitewing radiographs) of occlusal caries of first permanent molars during the post eruptive period. These teeth showed colored or non-colored fissures, and none of them had conservative or preventive obturations, or dentinal caries. Four experienced dentists independently evaluated the trials, diagnosed the lesions and advised a treatment. The effective lesions were shown by opening minimal preventive cavities, which were then obturated with amalgam. The results showed the lack of precision for the early diagnostic means of initial pit- and fissures-caries, and differences and errors of evaluation performed by the dental professional with respect to their diagnosis and proposed therapeutic choice. The effective lesions demonstrated the high incidence of pit- and fissure-caries in permanent molars during the post eruptive period.

101 children, each of them with two teleradiographies, were selected. The first X-ray was taken at the time of the mixed dentition, the second one, when the permanent dentition was established. The purpose of the research is to show the oscillations of the palatine and mandibular planes, and their link to the movements of the first permanent molars. The palatine plane is found to swing between -7 degrees and +5 degrees with an average of -0.97 degree. The posterior part of that plane rocks downwards in 51% of the children. The limits are -7 degrees and -1 degree, with an average of -3.2 degrees. In 22%, the plane rocks upwards between +1 degree and +5 degrees with an average of +3.1 degrees. In 27% it moves parallel to itself. The posterior part of the mandibular plane varies between -6 degrees and +5 degrees, with an average of -1.1 degrees. It rocks downwards in 48% of the cases, between -6 degrees and -1 degree with an average of -3.9 degrees. In 22% of the children, this plane rocks upwards between +1 degree and +5 degrees with an average of +2.5 degrees. In 30%, it moves parallel to itself. The overall result is that the more the posterior part of the palate, or of the mandible moves downwards, the more the first permanent molars get straight or move forwards.

The purpose of this study was to assess clinically and radiographically at mid-term the anchoring of custom posts in flat and curved roots. The results were compared to those of a similar study done in vitro (Brustlein-Rathle et al. 1988). 342 root canals from 143 premolars and molars were treated with standardized procedures by undergraduate students at the "Section de Médecine dentaire" of the University of Geneva. The results, which corroborated the above-mentioned in vitro observations, confirmed that the endodontic preparation as well as the canal widening for the post insertion straightens and thins the canal walls in 60% of the round and curved roots and in 25% of the flat and curved roots, also named root at risk. The study also demonstrated the difficulties of estimating and visualizing radiographically the weakening and possible cracks within the root wall because of radicular and osseous radiographic superimposition.

Many lower wisdom teeth are impacted. Various authors advocate systematic and prophylactic removal of all third molars. The reasons for such procedure are not always clear, and often, radiological evaluation is missing. A study of over 200 patients was carried out to determine whether systematic extraction of wisdom teeth is justified. Another study was undertaken, to observe the development of 42 lower impacted third molars. It was tried to find conclusions which might justify the radiological criteria for such an extraction. The factors, leading to diagnosis and radiographic analysis were discussed and four radiological criteria were finally established. In conclusion, it seems that early radiological evidence (age 16--17) is very important.

Physiological mesiodistal inclinations of the permanent first molars are now well recognized. These inclinations can be measured without difficulty on a lateral teleradiographic image of the head. Several cases are reported where anatomical normality of articulation of the molars did not correspond with physiological normal limits.

Scanning electron microscopic observations of pulp calcifications in deciduous molars were correlated with microradiographic findings. Numerous spherical calcifications were found in appearance similar to those in the permanent dentition. In a second type, mineralization took the form of diffuse deposits of calcium. The discrete diffuse foci coalesced into large islands of mineralized connective tissue. A third type of calcification was observed in which rhombic crystals were associated in a spherulitic pattern. The exact cause of the crystal formation is unknown. Moreover, as we are aware, the spherulitic calcifications have never been previously reported in this location. The preliminary results indicated that mineralization in the pulp of deciduous molars, takes a variety of forms, suggesting that calcium deposition can occur by different processes.