A predictive model of advancement genioplasty in Class III bimaxillary surgical cases.

INTRODUCTION: The aim of our study was to try to standardize the surgeon's clinical sense in order to avoid revision surgery. MATERIALS AND METHODS: Twenty-nine patients with skeletal Class III treated by bimaxillary surgery were selected according to inclusion and exclusion criteria. These patients were divided into two groups according to the type of surgery: Group 1 (G1): bimaxillary surgery alone, and Group 2 (G2): bimaxillary surgery with genioplasty. The study was conducted based on the presurgical (t0) and postchirurgical (t1) lateral cephalograms. The different changes were compared between the two groups using the Mann-Whitney Test. One way and multiple linear regression analyses were used to determine the variables influencing the amount of displacement of the chin fragment during the genioplasty procedure. The significance level was fixed at 0.05. RESULTS: The labiomental profile was significantly more improved in group G2 (bimaxillary surgery with genioplasty), the aesthetic changes included the thickness increase of the lower labial sulcus and soft tissue pogonion, and also the reduction of the labiomental angle (P<0.05). Only the presurgical value of the labiomental angle would influence the amount of chin displacement. Starting from the regression analysis, we suggested a predictive equation allowing to predict this amount of displacement, based on the presurgical value of the labiomental angle. CONCLUSION: The analysis of changes (specifically the aesthetic ones) between the two groups of patients, allowed the proposal of a model predicting the amount of chin displacement performed in genioplasty group, based on the presurgical parameters. This model could contribute to determine an indicative value for bimaxillary surgery with additional genioplasty.

Relationship between the curve of Spee and craniofacial variables: A regression analysis.

INTRODUCTION: The aim of this regression analysis was to identify the determining factors, which impact the curve of Spee during its genesis, its therapeutic reconstruction, and its stability, within a continuously evolving craniofacial morphology throughout life. MATERIAL AND METHODS: We selected a total of 107 patients, according to the inclusion criteria. A morphological and functional clinical examination was performed for each patient: plaster models, tracing of the curve of Spee, crowding, Angle's classification, overjet and overbite were thus recorded. Then, we made a cephalometric analysis based on the standardized lateral cephalograms. In the sagittal dimension, we measured the values of angles ANB, SNA, SNB, SND, I/i; and the following distances: AoBo, I/NA, i/NB, SE and SL. In the vertical dimension, we measured the values of angles FMA, GoGn/SN, the occlusal plane, and the following distances: SAr, ArD, Ar/Con, Con/Gn, GoPo, HFP, HFA and IF. The statistical analysis was performed using the SPSS software with a significance level of 0.05. RESULTS: Our sample including 107 subjects was composed of 77 female patients (71.3%) and 30 male patients (27.8%) 7 hypodivergent patients (6.5%), 56 hyperdivergent patients (52.3%) and 44 normodivergent patients (41.1%). Patients' mean age was 19.35±5.95 years. The hypodivergent patients presented more pronounced curves of Spee compared to the normodivergent and the hyperdivergent populations; patients in skeletal Class I presented less pronounced curves of Spee compared to patients in skeletal Class II and Class III. These differences were non significant (P>0.05). The curve of Spee was positively and moderately correlated with Angle's classification, overjet, overbite, sellion-articulare distance, and breathing type (P<0.05). We found no correlation between age, gender and the other parameters included in the study with the curve of Spee (P>0.05). Seventy five percent (75%) of the hyperdivergent patients with an oral breathing presented an overbite of 3mm, which is quite excessive given the characteristics often admitted for this typology; this parameter could explain the overbite observed in the hyperdivergent population included in this study. For the multivariate analysis, the overbite and the sellion-articulare distance remained independently related to the curve of Spee according to the breathing type, Angle's classification, and overjet. This regression model explains 21.4% of the changes in the curve of Spee.

Is systematic mandibular retention mandatory? A systematic review.

INTRODUCTION: Relapse in orthodontics, and particularly, mandibular anterior crowding is an unforeseeable phenomenon and a quite embarrassing situation for the orthodontist, as it may be interpreted by the patient as a treatment failure. Relapse may be inherent to various factors (periodontal, anatomical, muscular, occlusal, residual growth, third molars development…), which must be imperatively acknowledged in order to be managed during orthodontic treatment and therefore ensure an optimal control on the stability of the achieved final outcomes. The aim of this review was to determine, through a systematic analysis based on a Medline PubMed search, the scientific relevant factors involved in the relapse of mandibular anterior crowding. MATERIALS AND METHODS: A systematic research was performed based on an electronic search (between 2005 and December 2016) among various databases. The search was limited to the use of several specific search words expressed in two languages: English and French. Two investigators selected those meeting the exclusion/inclusion criteria. RESULTS AND DISCUSSION: Out of the 1055 references, only 19 studies met our inclusion criteria. The factors addressed by these studies are: extraction or non-extraction treatment, residual growth, facial divergence, periodontium, type of retainer, incisor morphology and quality of dental occlusion. Divergence in female patients, thin cortical bone and treatment using aligners were associated with a higher rate of mandibular anterior crowding relapse. However, due to the low level of evidence of the included studies, as well as the heterogeneity of protocols between the studies, it was not possible to determine factors truly involved in mandibular crowding relapse. Future reliable prospective studies are required to provide unbiased and quantifiable results.

Relationships between facial divergence and DMD parameters.

INTRODUCTION: The aim of this study was to examine the relationship between facial divergence and the parameters of dentomaxillary discrepancy (DMD), in particular crowding, the curve of Spee and the position of the incisors in the sagittal dimension. MATERIAL AND METHODS: A total of 90 young adult patients was selected from among the Moroccan orthodontic population attending the dentofacial orthopedic department and satisfying the following inclusion criteria: complete permanent dentition and a skeletal class I pattern with no previous orthodontic treatment, no crossbite, no periodontal disease, no mandibular asymmetry and no condylodiscal disunion. On cephalometric tracings, measurements were made of angles FMA, Go-Gn/SN, Occ/SN in the vertical direction, and of the values I/NA et i/NB in the sagittal direction. The curve of Spee and dental crowding were assessed using the one-way ANOVA test and the Bonferroni post-hoc test. Correlation analysis was performed between divergence and the different variables measured, using SPSS software with a 0.05 significance threshold. RESULTS: Patients recruited for the study had a mean age of 19.8±0.5 and were distributed as follows: 28 normodivergent, 31 hypodivergent and 31 hyperdivergent, 42 females and 48 males. Comparison showed that hypodivergent subjects had less crowding than hypo- or normodivergent individuals (P<0.05). Hypodivergent subjects had a more pronounced curve of Spee than the other two groups. This difference was not significant (P>0.05). Hyperdivergent subjects presented more labioversion and vestibular positioning of the incisors compared with the hypodivergent (P<0.05) and normodivergent (P<0.05) groups. Correlation analysis showed that crowding and the incisor positions in millimeters and in degrees were positively correlated to a moderate extent with facial divergence (r=0.3, r=0.5, r=0.4; P<0.05), while the curve of Spee was not (P>0.05). No correlation was found between age or sex and the DMD parameters (P>0.05).

Therapeutic efficacy of self-ligating brackets: A systematic review.

INTRODUCTION: Over the last few years, the use of self-ligating brackets in orthodontics has progressed considerably. These systems have been the subject of numerous studies with good levels of evidence making it possible to evaluate their efficacy and efficiency compared to conventional brackets. The aim of this study was to evaluate the therapeutic efficacy of self-ligating brackets by means of a systematic review of the scientific literature. MATERIALS AND METHODS: A systematic study was undertaken in the form of a recent search of the electronic Pubmed database, oriented by the use of several keywords combined by Boolean operators relating to the therapeutic efficacy of self-ligating brackets through the study of tooth alignment, space closure, expansion, treatment duration and degree of discomfort. The search was limited to randomized controlled studies, and two independent readers identified studies corresponding to the selection criteria. RESULTS AND DISCUSSION: The chosen articles comprised 20 randomized controlled trials. The studies analyzed revealed the absence of significant differences between the two types of system on the basis of the clinical criteria adopted, thereby refuting the hypothesis of the superiority of self-ligating brackets over conventional systems.

A systematic study of the release of bisphenol A by orthodontic materials and its biological effects.

INTRODUCTION: Bisphenol A (BPA) is a synthetic chemical substance used as a starting ingredient in the manufacturing process of a number or orthodontic materials. It is a well-known endocrine disruptor with low estrogenic properties. The aim of this investigation is to present a systematic review regarding the issue of bisphenol A release by orthodontic materials and its impact in orthodontics. MATERIALS AND METHODS: A systematic analysis was performed by electronic search (between 1936 and 2015) on several data bases. The search was limited by using several specific key-words in two languages, English and French. Two investigators selected the responses, which met the selection criteria. RESULTS AND DISCUSSION: Of the 376 studies found, only 21 met our selection criteria: 11 of these dealt with the release of bisphenol by orthodontic materials and 10 in vitro studies described the effects of BPA leaching from orthodontic materials on human and murine cells. The rate of BPA release was well below the daily tolerable intake (DTI) (50mg/kg/day in 2006, then 50µg/kg/day in 2015) according to the European Food Safety Authority (EFSA). Theoretical exposure to BPA was 11,000 times lower than recommendations. However, other studies have shown the presence of BPA and of monomers released in large quantities at very low doses. The effects of observed BPA varied significantly (toxic and carcinogenic potential) while some studies found no effects at all. The relatively small number of studies dealing with the release of Bisphenol A by orthodontic materials, apart from orthodontic materials and their significant biological effects, has led to the absence of standard protocols and has hindered precise determination of released BPA. Moreover, the lack of coherence between the various methodological approaches and variations in the experimental protocols have resulted in a low level of proof regarding the impact of BPA by orthodontic materials. RECOMMENDATIONS: Through this study, the authors encourage clinicians to observe the following recommendations designed to reduce the amount of BPA released by materials used in orthodontics: keep the tip of the light-curing lamp as close as possible to the composite and perform indirect rather than direct light-curing; Pumice-polish the composite after bonding so as to reduce the potential amount of BPA released; reduce exposure by brushing or rinsing with a mouthwash during the first hour after bonding; follow a standardized, reproducible and expert-validated research protocol aimed at better understanding of BPA release.

Cytotoxicity of elastomeric power chains in artificial saliva: an in vitro study.

INTRODUCTION: The main aim of this paper is to investigate the cytotoxicity of elastomeric power chains after stretching and immersion in a solution of artificial saliva. MATERIALS AND METHOD: Two brands of grey polyurethane power chains available from two different firms (GAC, G&H) were selected for cytotoxicity assay. Each segment was stretched up to an initial force of approximately 200 g. Then each segment was kept stretched using appropriate equipment. The samples were tested in artificial saliva at two pH levels, pH7 and pH4. Following incubation, the saliva was removed, filtered and placed in contact with cell culture media using the RD line. RESULTS AND DISCUSSION: At this supernatant dilution, no statistically significant difference was observed between the different groups of power chains studied in terms of cell viability. The GAC and G&H power chains, whether stretched or not and immerged in either pH7 or pH4 saliva, showed no toxic effect on RD cells (human cell line).

Surgical-orthodontic treatment of patients suffering from severe periodontal disorders - a clinical case study.

INTRODUCTION: Orthodontic or, more precisely, surgico-orthodontic treatment of patients suffering from periodontal disorders generally requires a multidisciplinary approach by a qualified dental team. Periodontal bone healing is an essential factor for successful orthodontic treatment in a compromised periodontal situation. CLINICAL CASE: We report on the case of an adult patient suffering from severe chronic periodontitis; he was a hyperdivergent skeletal Class III with dento-alveolar compensation, esthetic problems and a significant lack of dental material. A multidisciplinary approach was adopted. First of all, periodontal treatment was undertaken (root scaling and planing) accompanied by appropriate medical treatment and a bone graft to strengthen the area of the lower incisors. After that, surgical and orthodontic treatment to correct the malocclusion was begun. The difficulty lay in the significant absence of dental material to ensure proper intercuspation. A surgical repositioning splint was constructed on an articulator to ensure adequate mandibular retraction after maxillary advancement surgery. After treatment, the missing teeth were replaced by a prosthesis. RESULTS AND DISCUSSION: Following treatment, the periodontal bone resorption was stabilized; the bone deficit was improved and the malocclusion had been corrected; the missing teeth were replaced by appropriate dentures. Short- and medium-term follow-up confirmed the stability of the results obtained, which will be discussed. CONCLUSION: The right combination of properly managed orthodontic, periodontal and prosthetic treatment can contribute to effective elimination of chronic periodontitis, even at an advanced stage in an adult patient, while at the same time improving esthetic and functional parameters.

Elastomeric chain force decay in artificial saliva: an in vitro study.

INTRODUCTION: The main objective of this study was to reexamine the mechanical properties of elastomeric chains after stretching in various artificial saliva solutions and in air. MATERIALS AND METHODS: Five brands of elastomeric chain manufactured by different companies were selected. For each brand, four types were tested in different artificial media. A dismountable test kit was used to stretch the chains up to various initial force levels. They were then immersed in pre-prepared solutions, with control samples exposed to air only. Residual force was measured at multiple time points using a hand-held dynamometer. RESULTS AND DISCUSSION: The force delivered by the elastomeric chains decayed rapidly and differently over time. This decay varied depending on multiple factors, discussed here.

A systematic review of force decay in orthodontic elastomeric power chains.

INTRODUCTION: Elastomeric chains are one of several devices used to provide force for orthodontic tooth movement, but the force they exert diminishes over time and can thus be difficult to control. The objective of this investigation was to provide a systematic review of publications pertinent to force decay in orthodontic elastomeric chains. MATERIALS AND METHODS: A systematic review was performed via electronic querying of multiple databases for the period 1970-2011. Queries were limited to a set of specific keywords in two languages (English and French). Five main reviews were consulted manually to identify relevant publications. Two investigators sorted out those studies that complied with selection criteria. RESULTS AND DISCUSSION: A total of 53 studies were found to be relevant to force decay in elastomeric chains, including 22 on force decay over time, seven on the force consequences of pre-stretching, 12 on the impact of the environment on the force delivered, and 11 on clinical efficacy. CONCLUSION: The force delivered by elastomeric chains decays rapidly over time, affecting their mechanical properties and clinical efficacy when studied in either human saliva or laboratory test media.

Cleidocranial dysostosis: a case report / Disostosis cleidocraneal: reporte de caso

Cleidocranial dysostosis is a congenital condition that results from faulty development of membranous bones, mainly the clavicles and skull. The clavicular abnormality may range from a small defect in one clavicle to complete absence of both, but most frequently an absence of the central clavicular segment, as was seen in our patient. A review of the literature has revealed only one previous report a cleidocranial dysostosis syndrome...

La disostosis cleidocraneal es una condición congénita que resulta de un desarrollo defectuoso de los huesos con osificación membranosa, principalmente las clavículas y el cráneo. La anormalidad clavicular puede ir desde un pequeño defecto en una clavícula hasta la total ausencia de ambas, pero con mayor frecuencia se observa la ausencia del segmento clavicular central, como se observó en nuestro paciente. Una revisión de la literatura reveló sólo un caso previo con un síndrome de disostosis cleidocraneal de características similares...