Anchorage in Orthodontics: Three-dimensional Scanner Input.

AIMS AND OBJECTIVES: The aim of this article is to re-evaluate anchorage coefficient values in orthodontics and their influence in the treatment decision through the usage of three-dimensional (3D) scanner. MATERIALS AND METHODS: A sample of 80 patients was analyzed with the 3D scanner using the C2000 and Cepha 3DT softwares (CIRAD Montpellier, France). Tooth anatomy parameters (linear measurements, root, and crown volumes) were then calculated to determine new anchorage coefficients based on root volume. Data were collected and statistically evaluated with the StatView software (version 5.0). RESULTS: The anchorage coefficient values found in this study are compared to those established in previous studies. These new values affect and modify our approach in orthodontic treatment from the standpoint of anchorage. CONCLUSION: The use of new anchorage coefficient values has significant clinical implications in conventional and in microimplants-assisted orthodontic mechanics through the selection and delivery of the optimal force system (magnitude and moment) for an adequate biological response.

Predictability of Craniofacial Skeletal Age with Geometric Morphometries.

AIM: This study aims to estimate skeletal age of craniofacial shape obtained from cone beam computed tomography (CBCT)-defined facial and basicranial landmarks using geometric morphometrics method in a random sample of growing patients, and explore the correlation between craniofacial shape and skeletal age as determined from hand and wrist radiograph. MATERIALS AND METHODS: Generalized Procrustes analysis (GPA) of craniofacial shape with estimation of centroid size was performed on CBCTs of 48 growing patients (mean age 11.7 ± 1.5 years). Greulich and Pyle method for skeletal age assessment were used for correlation with centroid size. Correlation among the variables relied on Pearson's coefficient and its 95% confidence interval was estimated. The model's R2 was calculated, (Cook's distances, Mahalanobis distances, leverage values, and studentized residuals) and multiple regression analysis performed using the Statistical Package for the Social Sciences (SPSS) version 22. RESULTS: Mean skeletal age was 11.9 ± 2.4 years. Centroid size (151.5 ± 7.2) was significantly correlated with chronological age (R = 0.616, 95% CI 0.355-0.789, p < 0.01) and skeletal age (R = 0.605, 95 % CI 0.331-0.794, p < 0.01). CONCLUSION: A new equation for determining craniofacial skeletal age was developed, using the centroid size of the craniofacial frame, gender, and the known chronological age. CLINICAL SIGNIFICANCE: A CBCT may be used for skeletal age assessment without additional hand wrist radiograph.

Dental and Skeletal Age Estimations in Lebanese Children: A Retrospective Cross-sectional Study.

AIMS AND OBJECTIVES: Assessing dental and bone ages is frequently required in a wide range of fields such as odontology, forensic science, as well as orthopedics. The aim of this study was to evaluate applicability of two methods of bone age assessment and two methods of dental age (DA) assessment for Lebanese children. MATERIALS AND METHODS: Skeletal age (SA) of 260 orthodontic patients (124 males, 136 females divided into four groups each) was consecutively assessed using Greulich and Pyle and Fishman's SMI methods. DA was evaluated using both Demirjian's and Willem's methods. Mean age was 11.89 ± 1.38 years for males and 11.75 ± 1.58 years for females. Data were collected and statistically analyzed using the SPSS software (IBM SPSS Statistics, version 21, USA). The differences between estimated DA, estimated SA, and chronological age (CA) were compared by gender and age group. RESULTS: Greulich and Pyle method showed nonsignificant difference with CA in male sample, while in both assessment methods, the difference between skeletal and CAs is significant in female sample. Results of Willem's method in the whole sample suggested a statistically nonsignificant difference, when compared to CA. Demirjian's method delivered higher mean value than Willem's assessment in both genders. CONCLUSIONS: Greulich and Pyle method is accurate for SA assessment in males and only in one group of females, while it significantly overestimates age in all other female groups. Willem's method is more suitable to assess DA in both genders. A strong correlation exists between both dental and skeletal assessment methods and CA.

Orthodontics and Dental Anatomy: Three-dimensional Scanner Contribution.

AIMS AND OBJECTIVES: The objective of this article is to focus on the dental anatomy, its influence on therapeutic choices, and decision in orthodontics. MATERIALS AND METHODS: A sample of 80 subjects was selected and analyzed. Through the usage of the three-dimensional scanner with the C2000-Cepha and Cepha3DT software, it is now possible to calculate the volume and the dimensions of both crown and root of each tooth and compare them to the literature. Data were collected and statistically evaluated with the StatView software (version 5.0). RESULTS: These references values were compared with those known in the literature redefining our approaches to treatment in orthodontics. CONCLUSION: The individual anatomical data either unique or in a group of teeth give new insights on the orthodontic therapeutic options.

[Influence of trigeminal nerve lesion on facial growth: study of two cases of Goldenhar syndrome]. / Influence de l'atteinte trigéminale sur la croissance faciale : étude de deux cas de syndrome de Goldenhar.

INTRODUCTION: This cases report confirms the hypothesis that embryonic and maxillofacial growth are influenced by the peripheral nervous system, including the trigeminal nerve (V). So, it's interesting to use the stigma of the trigeminal nerve as landmarks to analyze the maxillofacial volume and understand its growth. The aim of this study is to evaluate the validity of the three-dimensional cephalometric analysis of Treil based on trigeminal landmarks. CASE PRESENTATION: The first case is a caucasian female child with Goldenhar syndrome. The second case is a caucasian male adult affected by the same syndrome. In both cases, brain MRI showed an unilateral trigeminal nerve lesion, ipsilateral to the facial dysmorphia. CONCLUSION: The results of this radiological study tend to prove the primary role of the trigeminal nerve in craniofacial growth. These cases demonstrate the validity of the theory of Moss. They are one of anatomo-functional justifications of the three-dimensional cephalometric biometry of Treil based on trigeminal nerve landmarks.

[Invisible and almost invisible orthodontic appliances]. / Les appareils orthodontiques invisibles et presque invisibles.

Patient demand for invisible esthetic orthodontic appliances is steadily increasing. Two types of orthodontic appliances have a high rate of patient acceptance. The lingual technique has continually evolved by offering both prefabricated brackets or custom-made brackets. The various techniques have been improved over time, and the results are better than ever. Thermoplastic aligners are an alternative to lingual devices and their use is rapidly growing. Their specific properties make it easier to assess their indications and limitations. A review of the literature, the development of these systems and a presentation of some clinical examples of treated cases will help us to provide some of the basics for understanding each of these two types of appliances and to demonstrate the advantages and disadvantages of each system.

Asynchronous dentofacial development and dental crowding: a cross-sectional study in a contemporary sample of children in France.

BACKGROUND: The causes of dental crowding are not fully understood, but it may result from an evolutionary trend towards reduced facial volume, without a proportional reduction in tooth sizes. Most previous studies conducted among modern humans have revealed a very low or non-existent correlation between tooth size and jaw size. Cross-comparison between dental age and facial skeletal age could help to provide better knowledge of the dynamic process of dental crowding. The primary objective of this research was to study the synchronism of dental maturation and skeletal facial growth in a sample of modern children living in France. The secondary objective was to assess the link between dentofacial asynchronism and dental crowding. RESULTS: The random sample comprised 28 subjects (16 girls, 12 boys). Mean chronological age was 13.5 years (± 2.1; range 9.2-17.6). Mean dental age was 14.2 years (± 2.8; range 7.5-17) and mean facial skeletal age was 12.8 years (± 2.6, range 7-22). In the estimations of dental age and facial skeletal age, there was no evidence of systematic bias. There were 10 subjects (9 girls, 1 boy) with asynchronous dentofacial development. Finally, there were 13 subjects (8 girls, 5 boys) with dental crowding. A significant association was found between delayed facial skeletal growth/advanced dental maturation and dental crowding (P = 0.01). CONCLUSIONS: Dental maturation and facial growth are not necessarily synchronous. Further understanding of the interactions between dental maturation and facial growth could have crucial implications in biological anthropology, as well as for the clinical practice of orthodontists. From an anthropological perspective, this study suggests that asynchronous dentofacial development could, at least partially, explain the frequency of dental crowding in modern populations.

[Study of asymmetries in the severe antero-posterior disharmonies]. / Etude des asymétries dans les grandes dysmorphies antéro-postérieures.

Using the Treil 14 points cephalometric model orthodontists can prepare a complete cranio-facial anatomic assessment at three analytic levels: the framework or envelope, the basal bone and the alveolo-dental arcade. The assessment of border-line surgical antero-posterior dysmorphosis can elucidate interesting depictions of asymmetries, their relation to other malformities, and their genesis. Asymmetry arises from over-growth of one side of the face in all three dimensions of space even if, clinically, it often appears that one dimension is predominately affected. The ortho-morphic cases of Angle Class I present a little right excess or "natural" asymmetry. The Class III cases present a severe excess on the right side, while the Class II cases present an excess on the left side comparing with reference sample.

Posterior growth and forecasting the development of mandibular third molars.

The inter-dependence of overall orthodontic treatment and the development of the third molars requires the entire dentition to be taken into consideration ab initio and for the patient to be fully informed as to the extractions involved. The anatomical conditions in which the development of the wisdom teeth can occur are studied using comparative samples, with and without third molar retention, followed up to the age of 20 years. Posterior growth observed between the beginning of multiband treatment and adulthood amounted to 11/16mm (girls/boys). The initial difference in forecasting the space between the groups with retained third molars and without was slight (5.5mm). However, this difference was maintained throughout the growth period and was sufficient to guide the final choice whether to extract these teeth or allow them to erupt.

[Three-dimensional 14 point-cephalometric analysis: compensation of maxillofacial dysmorphisms]. / Analyse céphalométrique tridimensionnelle à 14 points: compensations des dysmorphies maxillo-faciales.

The eight points cephalometric Treil model and the alveolodental parameters already allows an initial description of the maxillofacial framework and the teeth. Added six points allows taking into consideration an intermediate level: the maxillary and mandibular skeletal basis. So, the 14 points complete model allows a complete craniofacial anatomy description in three analysis levels: the framework or envelope, the osseous bases, the alveolodental arch. The correlation study between the 3D parameters at different levels defines the compensation notion. It allows understanding how skeletal disharmony may be distributed among the different levels. Only vertical direction compensations are analysed here.

[Correlations between the volume of the sinuses and the facial bones and parameters of 3D cephalometry]. / Liaisons entre volumes des cavités aériennes et des bases osseuses maxillaires et paramètres de céphalométrie 3D.

The goal of this work is to study, using a sample of 95 persons, the parameters of the 14 points of the 3D Treil cephalometric analysis and to compare them to the facial volumes of these subjects. The 3D parameters are described on three levels and for all three dimensions of space; they are also defined statistically for each class of occlusion, and indications are given for sagittal two-dimensional variables. The correlations between all these variables and facial bones and air cavity volumes are also analyzed. The antero-posterior and vertical variables showed more statistically significant relationships with volumes than with transverse parameters. It appears that a Class III occlusion is primarily related to the vertical and antero-posterior position of the mandible and its morphology and not to its size, while Class II Division 1 types are associated with increased size of the maxillary sinuses. It also appears that facial hyper-divergence is related to a decrease in the size of the maxilla and the mandible.

[Orthodontic approach to asymmetry]. / Approche orthodontique des asymétries.

From an orthodontic point of view, asymmetries can be gathered in three great clinical entities: mandibular lateral deviations, dental asymmetries without skeletal involvement, skeletal asymmetries. Once the therapeutic aims and the principles of the orthodontic approach of these dysmorphoses have been recalled, the authors present the various orthodontic means implemented in this type of treatment. Four cases treated illustrate those types of treatment. Vertical non-surgical asymmetry may have an obvious local origin, for instance, a unilateral damage to a nerve. but usually, there is no evident origin. Frequently the occlusal slippage of a severe sagittal or a vertical malformation, which may evolve as a borderline surgery case, is suspected to be the real cause. In these cases, the diagnosis is always late, with the ending growth. The treatment needs peculiar strong asymmetric mechanics and, sometimes, unilateral mixed extractions. The post-treatment occlusion can be unstable; for this reason, the finishing steps must be carefully conducted. Four clinical case reports develop these points ov view. Multidisciplinary treatments prove very useful to solve three types of clinical situations. In the adult patient, facial esthetics are indicated in severe dentofacial asymmetries. Esthetic improvements of dental nature are still required in deviated smiles, or frontal tippings of the occlusal plane. In addition, asymmetrical intermaxillary relationships will lead to functional anomalies: TMJ disorders, dental wear or lingual dysfunctions. Finally, multidisciplinary treatments in the adult concern the occlusal transverse anomalies, the lateral crossbites, the Class II subdivisions, the deviations of the inter-incisor midlines or unilateral edentulousness. The various plans of treatment, as well as the orthodontic mechanics used, are illustrated in the following development by clinical cases.

[3-dimensional cephalometry in orthodontics. The current possibilities of Cepha 3DT software]. / Céphalométrie tridimensionnelle en orthopédie dento-faciale. Les possibilités actuelles du logiciel Cépha 3DT.

A 3D cephalometric analysis method from a scanner acquisition, has been developed thanks to a long collaboration between the CIRAD modeling Laboratory and Jacques Treil. The model of skeletal description is based on eight landmarks related to the neuromatrical axis of facial growth (heads of the mallei, supraorbital, suborbital, submental points); it has been abundantly described. The purpose of this work consists in presenting the dentoalveolar level of the analysis. The description and the marking of the arches and the teeth mainly rest on the systematic use of a mathematical tool, the calculation of the central matrix of inertia, and on three fundamental choices: the identification of the dental arches from their constituting teeth leaving aside any alveolar marking, the marking of each tooth relative to the arch, as it can be observed by the orthodontist's eye, and not relative to the craniofacial architecture, the definition of the position of each tooth by the orientation of its coronoradicular axis and not its sole buccal side, Their uses in orthodontics are numerous: diagnosis, choice of the mechanics, therapeutic simulation, therapeutic follow up, analysis of the findings... Clinical applications illustrate the theoretical presentation.