Christine Marchal-Sixou

[Three-dimensional cephalometry: applications in clinical practice and research].

A 3D cephalometric analysis method from scanner acquisition has been developed thanks to a long collaboration between Dr Treil and the Department of Orthodontics in Toulouse III University. It allows a perfect knowledge of maxillo-facial architecture using fourteen landmarks related to the neuromatricial axis of facial growth. These landmarks can be identified without ambiguity. The marking of each tooth relative to dental arches (gravity centre coordinates and torque and tipping of each tooth), and the location of arches relative to maxillo-facial frame are given by the analysis. Description and reconstruction of dental and maxillo-facial anatomy are possible with three levels: maxillo-facial frame, maxillar and mandibular bases and dentoalveolar level. The method not only gives more precise information than conventional cephalometrics in anteroposterior and vertical directions, but it allows transversal analysis and asymmetry measurement. Applications are numerous in research as well as in clinical medicine: analyses of cases border line surgery, surgical set-up, facial asymmetry, analysis of dentoalveolar compensations, definition of therapeutic aims, occlusal analysis and set-up, study of evolution in anthropology-primatology, study of growth etc. This method of description using a pattern of landmarks is perfectly adapted to the last developments of modern research techniques: morphometric geometry with Procustes superimpositions, EDMA, TPS, FEM.

Effect of fixed orthodontic appliances on salivary microbial parameters at 6 months: a controlled observational study

Objective The aim of this study was to assess the microbial changes in children with fixed orthodontic appliances compared with a control group of children without orthodontic treatment. Material and Methods Ninety-five children, aged between 12 and 16 years, participated in this study. Forty-eight subjects were fitted with fixed orthodontic appliances and forty-seven were free of any such appliances. The follow-up was 6 months for all children. The association between orthodontic appliances and high levels of Streptococcus mutans and Lactobacillus spp was assessed with logistic regression models, taking age, sex, pH and buffer capacity into account. Results Differences at baseline between the two groups were not statistically significant. We found that wearing a fixed orthodontic appliance was associated with high levels of Streptococcus mutans and Lactobacillus spp (adjusted OR: 6.65, 95% CI [1.98-22.37]; 9.49, 95% CI [2.57-35.07], respectively), independently of other variables. Conclusion The originality of the present epidemiological study was to evaluate the evolution of salivary microbial parameters in a population of children with fixed orthodontic appliances. Our results show an increase of Streptococcus mutans and Lactobacillus spp values during the follow-up. The whole dental workforce should be aware that preventive measures are of paramount importance during orthodontic treatment.

Cochrane systematic reviews in orthodontics

INTRODUCTION The Cochrane Collaboration is an international scientific not-for-profit organization the purpose of which is to produce and distribute systematic reviews of randomized clinical trials. The aim of this paper is to list the different existing Cochrane systematic reviews in the field of dentofacial orthopedics (DFO) and to analyse their main features. MATERIAL AND METHODS The choice of Cochrane systematic reviews based on dentofacial orthopedics was made from the exhaustive list published by the Cochrane Oral Health Group. RESULTS A total of 12 systematic Cochrane reviews related to dentofacial orthopedics were listed. All concluded on the need to conduct randomized clinical trials using more appropriate methodologies and comprising larger samples. None of these systematic reviews offered clear proof supporting any one form of treatment or treatment modality. DISCUSSION Despite the lack of relevant conclusions in the still meagre number of Cochrane systematic reviews related to DFO, it is essential for orthodontists to regularly consult the reviews in the framework of their daily evidence-based orthodontic practice. This is true too for orthodontic researchers as clinical DFO research needs to be extended with the setting up of methodologically unquestionable randomized clinical trials. However, there exist alternatives to randomized clinical trials offering a lower level of proof but which are better suited to the field of dentofacial orthopedics.

Centres de résistance des groupes dentaires et mécanique orthodontique: 2. Applications

Resume A l’heure ou l’orthodontie a de plus en plus recours aux ancrages « absolus », il semble neanmoins interessant de faire le point sur l’ancrage dentaire. En effet, l’ancrage stabile dentaire restera essentiel tant que les microvis ne seront pas un instrument systematique present dans toute therapeutique multiattache. Par ailleurs, l’ancrage dentaire controle seul les composantes non paralleles a la direction de la traction exercee par la vis Enfin, l’ancrage mobile conditionne toute la mecanique, avec comme sans microvis. L’utilisation du scanner 3D et des logiciels C2000-Cepha et Cepha3DT, a permis de calculer, a travers la notion de volume radiculaire, les ancrages des groupes dentaires classiquement mobilises en mecanique orthodontique. Nous etudierons la mecanique globale d’arcade, et les mecaniques sectorielles, avec ou sans liaison rigide entre les groupes stabile et mobile, ceci dans le cas d‘emploi de forces extraorales ou dans le cas d’emploi de microvis.

L’information de l’adolescent dans le cadre d’un traitement orthodontique multibague

Thoughts and questions are proposed on the reality of consent by adolescents. This reflection, ethical in nature, confronts the medico-legal facet of the care contract, which is specific when minors are concerned, with the psychological aspect, so particular when an adolescent is involved. How do we treat adolescents who have not reached their majority? Beyond this quasi-philosophical questioning on the inter-human care relationship, we put forward very practical elements towards answers.

Interest of decompression in orthodontics: Case report of a keratocyst during childhood

Keratocysts, also known as keratocystic odontogenic tumors (KCOT), make up 7% of all odontogenic cysts and develop asymptomatically in most cases. Enucleation is the benchmark treatment. However, there are surgical alternatives. Marsupialization and decompression are necessary in some cases, mainly when the KCOT is large, thus causing an increased risk of bone fracture, or if it has engulfed important elements such as the inferior alveolar nerve or teeth, consequently causing alveolar bone growth failure. The authors describe the case of a nine-year-old child treated for a large keratocyst situated in sector 4 (lower right jaw), impacting both premolars and the canine (45, 44 and 43). Surgical decompression associated with orthodontic multiband treatment were delivered to pull, and then place the three teeth in occlusion on the dental arch. With seven years hindsight since the first surgical procedure and three years since finishing orthodontic treatment, the cooperation between orthodontists and surgeons can be considered a success, from both the functional and esthetic points of view.

Posterior tooth size discrepancy

Despite having a correct anterior occlusal relationship between upper and lower teeth with canines in perfect Class I, some patients have imperfect posterior occlusal relationships with first molars in positions that are slightly Class II or Class III owing to an arch length discre pancy in the upper and lower buccal segments. From this study of 62 subjects treated with full banded appliances and no bicuspid extrac tions we were able to determine the ideal relationship of the widths of the lower bicuspid and molar teeth with their upper antagonists, one that make it possible for the attainment of Class I relationships of both canines and first molars. This ideal value is 1.062. We discuss the therapeutic implications of this finding, notably its influence on extraction decisions and propose solutions for cases of frank disharmony.