Effects of Malocclusion on Maximal Aerobic Capacity and Athletic Performance in Young Sub-Elite Athletes.

Oral pathologies can cause athletic underperformance. The aim of this study was to determine the effect of malocclusion on maximal aerobic capacity in young athletes with the same anthropometric data, diet, training mode, and intensity from the same athletics training center. Sub-elite track and field athletes (middle-distance runners) with malocclusion (experimental group (EG); n = 37; 21 girls; age: 15.1 ± 1.5 years) and without malocclusion (control group (CG); n = 13; 5 girls; age: 14.7 ± 1.9 years) volunteered to participate in this study. Participants received an oral diagnosis to examine malocclusion, which was defined as an overlapping of teeth that resulted in impaired contact between the teeth of the mandible and the teeth of the upper jaw. Maximal aerobic capacity was assessed using the VAMEVAL test (calculated MAS and estimated VO2max). The test consisted of baseline values that included the following parameters: maximum aerobic speed (MAS), maximal oxygen uptake (VO2max), heart rate frequency, systolic (SAP) and diastolic arterial pressure (DAP), blood lactate concentration (LBP), and post-exercise blood lactate assessment (LAP) after the performance of the VAMEVAL test. There were no statistically significant differences between the two study groups related to either anthropometric data (age: EG = 15.1 ± 1.5 vs. CC = 14.7 ± 1.9 years (p = 0.46); BMI: EG = 19.25 ± 1.9 vs. CC = 19.42 ± 1.7 kg/m2 (p = 0.76)) or for the following physical fitness parameters and biomarkers: MAS: EG = 15.5 (14.5-16.5) vs. CG = 15.5 (15-17) km/h (p = 0.47); VO2max: EG = 54.2 (52.5-58.6) vs. CG = 54.2 (53.4-59.5) mL/kg/min (p = 0.62) (IQR (Q1-Q3)); heart rate before the physical test: EG = 77.1 ± 9.9 vs. CG = 74.3 ± 14.0 bpm (p = 0.43); SAP: EG = 106.6 ± 13.4 vs. CG = 106.2 ± 14.8 mmHg (p = 0.91); DAP: EG = 66.7 ± 9.1 vs. CG = 63.9 ± 10.2 mmHg (p = 0.36); LBP: EG = 1.5 ± 0.4 vs. CG = 1.3 ± 0.4 mmol/L (p = 0.12); and LAP: EG = 4.5 ± 2.36 vs. CG = 4.06 ± 3.04 mmol/L (p = 0.60). Our study suggests that dental malocclusion does not impede maximal aerobic capacity and the athletic performance of young track and field athletes.

[Tongue retraining and occlusal stability in a young adult. Case report]. / La rééducation linguale et la stabilité occlusale chez le jeune adulte. A propos d'un cas clinique.

The clinical observation describes the case of a 20-year-old woman who has consulted for aesthetic and functional reasons. She presents a skeletal class III normodivergent, an occlusal class III with a lower proalveoli quite marked. In addition, a lingual dysfunction which manifests itself by important anterior diastema and dento-dental disharmony at the upper jaw complicates the case. The undertaken therapeutic project starts with a first step of a lingual praxis rehabilitation, followed by an orthodontic step and upper lateral incisors-plasty. The purpose of those results is the evaluation of the stability two years later, which was reported positive.

[Impact of incisor repositioning on the cephalometric position of points A and B]. / Le repositionnement incisif: quel impact sur la position céphalométrique des points A et B?

Introduction: points A and B are bony landmarks used in cephalometric studies to assess sagittal ratio between maxilla and mandible. The purpose of this study is to assess the reliability of points A and B as bony landmarks, by investigating the role of incisor repositioning on their cephalometric position. Method: superposition of cephalometric tracings at beginning and end of treatment of 30 patients without bone growth disorders, presenting with biproalveolia and having undergone orthodontic treatment with extraction of four first premolars was carried out to estimate changes in points A and B position. The significance threshold was set at 0.05. Results: our study showed that the influence of orthodontic treatment on point A position was not statistically significant, while its influence on point B position was statistically significant (p= 0,01). Indeed, for every 1mm of incremental repositioning, point B moved back by 0.17mm. Conclusion: incisor repositioning in the mandibular arch induces a change in the position of point B backwards.

[Self-ligating brackets and friction in vivo : micro-morphological and chemical assessment of active slot surface]. / Brackets autoligaturants et friction in vivo : évaluation micro-morphologique et chimique de la surface active.

The use of self-ligating brackets has largely developed in orthodontic practice thanks to numerous advantages, including the reduction of frictional forces during sliding orthodontic mechanic. Faced with scientific evidence, this advantage still seems to be debatable. Our objective was to evaluate in vivo the frictional force of self-ligating brackets by searching for micro-morphological and chemical effects on the active slot surface, after phase of alignment-leveling and after a period in the mouth. 16 brackets from four commercial brands were selected (Damon®, In-Ovation®, Smart-clip® and Carriere®). These brackets were visualized using a scanning electron microscope (SEM) and dispersive energy spectroscopy to study their surface and initial chemical composition. After a period in the mouth, these brackets were debonded and evaluated with SEM, to search topographic and chemical changes in relation to the frictional forces. After a period of three months used for dental alignment, all the brackets show considerable changes in topographic and chemical properties related to frictional forces, with deposit of organic debris whose importance is related to the initial surface different from one manufacturer to another.

In vivo enamel stripping: A macroscopic and microscopic analytical study.

INTRODUCTION: Interdental stripping is often used in orthodontics to correct discrepancies of tooth shape or size. However, this procedure involves significant risks for the enamel. The roughness of the enamel surface might depend on the instruments used; it can lead to the accumulation of cariogenic plaque and periodontal problems. The main objective of our study was to evaluate the enamel surface condition after interproximal stripping in the mouth, by comparing different manual and mechanized enamel reduction protocols; on the other hand, the topography of the stripped area was observed to specify its location on the stripped proximal surfaces. MATERIALS AND METHODS: An in vivo study was carried out: interdental stripping was performed in the mouths of patients undergoing orthodontic treatment and on healthy teeth intended for extraction for orthodontic or periodontal reasons. The sample was divided into four groups: in group 1, the distal faces were stripped with conventional single-sided diamond abrasive strips and non-stripped mesial faces (control faces); in group 2: the distal faces were stripped with the manual ContacEZ IRP Kit (single-sided abrasive files of different grain sizes) and non-stripped mesial faces (control faces); in group 3: the faces were stripped with ContacEZ IRP diamond discs attached to a handpiece and the mesial faces were not stripped (control faces); in group 4: the distal faces were stripped with the Intensiv Ortho-Strips mechanized system and the mesial faces were not stripped (control faces). RESULTS: Our study showed that regardless of the type of stripping material used, the enamel surface showed some roughness with the presence of striations and grooves of different widths and depths. Our observations objectivised more regular and less roughened enamel surface conditions when using the Intensiv oscillating files. Manual instruments (abrasive strips and files) have shown rougher and more irregular surface conditions that may constitute a real risk of carious and periodontal disease. The macroscopic evaluation of the topography of the stripped area showed that there is great variability in the situation and extent of the stripped area in relation to several parameters. CONCLUSION: The current mechanized instruments (oscillating files) provide enamel stripping with more comfort for the patient and the practitioner, and seem to produce a more regular and less harmful surface condition for the tooth and periodontium.

Enamel protection after stripping procedures: An in vivo study.

INTRODUCTION: Interproximal enamel reduction (IPR) is a clinical procedure that has been in use since the advent of non-extraction orthodontic techniques. However, such a procedure affects the surface condition of the enamel and may predispose patients to cavities and hypersensitivity. The use of a remineralizing agent is recommended to prevent these side effects. The objective of our study was to evaluate the evolution of stripped proximal dental surfaces after exposure to the oral environment for 4 months with and without fluoride protection. MATERIALS AND METHODS: Our sample consisted of 14 premolars (PM) from 6 patients of the Dentofacial Orthopaedics Department of the Consultation and Dental Treatment Centre of Rabat (CDTC) who required orthodontic treatment with PM extraction and had given their informed consent. The teeth were divided into 5 groups: group 1: intact enamel; group 2: intact enamel+fluoride varnish+4-month oral exposure; group 3: IPR (manual and mechanized)+extraction; group 4: IPR (manual and mechanized) without varnish+4-month oral exposure; group 5: IPR (manual and mechanized)+fluoride varnish+4-month oral exposure. Proximal surfaces were subjected to qualitative analysis by scanning electron microscopy and quantitative analysis by Dispersive Energy Spectroscopy (DES) to quantify the percentage of mineral elements. RESULTS: Exposure of stripped dental surfaces to the oral environment for 4 months with or without fluoride protection showed the persistence of surface irregularities caused by stripping. We noted an improvement in the percentage of mineral elements for both groups with and without fluoride protection. However, the percentages of calcium (Ca) and phosphorus (P) were close to that of intact enamel in the fluoride varnish group. CONCLUSION: Protecting stripped surfaces with fluoride varnish could help preserve the integrity of the enamel surface by restoring some of the mineral elements lost during stripping.

Fluoride induced corrosion affecting Titanium brackets: A systematic review.

INTRODUCTION: A number of studies have been published regarding the behaviour of titanium inside the oral cavity or in a similar environment. Very often the results converge although they may on occasion be divergent. There appears to be a strong need for a systematic review because of this disparity, with a view to designing an experimental working method. Our study will attempt to analyse the various aspects of this problem. It will therefore focus on fluoride and its impact, as well as on the role it plays in corroding titanium orthodontic brackets (Ti) according to the synthesis and critical analysis drawn from literature. METHODS: An exhaustive bibliography search was conducted in the following databases: PubMed, Science Direct and Cochrane Library using a search equation based on the following key-words: corrosion, titanium brackets and fluoride. RESULTS: Out of 459 identified references, only 5 matched our inclusion criteria. CONCLUSION: Although very few articles look into the impact of fluoride on titanium orthodontic brackets, one may conclude that in the presence of fluoride ions, resistance to corrosion of Ti attachments decreases in the presence of high fluoride concentrations and lengthy exposure to fluoride ions and an acid pH.

A systematic review of orthodontic retention systems: The verdict.

INTRODUCTION: Retention during both the active and passive phases of treatment has given rise to numerous publications concerning its efficacy, the range of systems available and its variability over time. There are currently many different retention protocols regularly used by orthodontists; however, their efficacy and duration are still subject to debate. There is as yet no consensus as to which retention protocol is the most effective or for how long the retention device needs to be worn. The aim of this research was to perform a systematic review of the scientific literature in order to evaluate the efficacy of the different retention systems and clinical protocols among those most widely used, so as to make recommendations beneficial to both patient and practitioner. MATERIALS AND METHODS: A search of the literature was performed in the following databases: PubMed (MEDLINE), ScienceDirect and Cochrane Library. The search was limited to publications in English and French during the period 2006-2016. RESULTS: Out of 1952 references initially identified, 17 articles corresponded to our inclusion criteria. The results show that: fixed retention is more effective than removable retainers for the maintenance of incisor alignment during the first six months of retention; there is no significant difference in efficacy between the different fixed retention systems; there is no significant difference in efficacy between the vacuum-formed systems and the Hawley retainer; part-time use of removable retainers (between 8-10h/day) is sufficient; the most widely used retention protocol combines a vacuum-formed splint or Hawley retainer in the upper arch with mandibular fixed retention. CONCLUSION: Despite the large number of studies devoted to orthodontic retention only a few articles corresponded to the methodological criteria of bio statistical analysis. Also, on account of the variations in experimental protocols, the levels of proof relating to the efficacy of different systems are very weak. Research into this topic should first seek to normalize methods of analysis and then perform randomized controlled long-term trials to shed light on this problem.

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.

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.

Orthodontic aligners and root resorption: A systematic review.

INTRODUCTION: Root resorption is one of the leading problems in orthodontic treatment. Most earlier studies have assessed the incidence and severity of root resorption following orthodontic treatment using fixed appliances as well as associated factors. However, few studies have assessed these parameters in the context of orthodontic treatment using thermoplastic splints or aligners. The aim of this systematic review was to assess the incidence and severity of root resorption following orthodontic treatment using aligners and associated factors. A comparative analysis was also made with fixed multi-bracket treatments. MATERIALS AND METHODS: The data bases consulted were: Medline, Embase, EBSCO Host, Cochrane Library and Science Direct. Our search included meta-analyses, randomized and non-randomized controled trials, cohort studies and descriptive studies published before December 2015 and evidencing a connection with the incidence and severity of root resorption following orthodontic treatment using aligners alone or compared with fixed multi-bracket treatments. RESULTS: Among the 93 selected references, only 3 studies met our selection criteria. The incidence of root resorption ranged between 0 and 46%, of which 6% were severe cases. Relative to fixed multi-bracket non-extraction treatments to correct the same malocclusions, the incidence of resorption ranged between 2% and 50%, of which 22% were severe cases. In both techniques, the incidence of resorption was higher for the maxillary incisors and was not influenced by either age or sex. CONCLUSION: In malocclusion cases not requiring extractions, orthodontic aligner treatment is possibly associated with a lower incidence of resorption than fixed multi-bracket treatment. Further research encompassing extraction cases is needed to better assess the incidence and severity of root resorption following the use of these removable appliances.

[Timing of alveolar bone graft and sequences of canine eruption in cases of cleft lip and palate: a systematic review]. / Calendrier de la greffe osseuse et séquences d'éruption canine dans les cas de fentes labio-alvéolo-palatines : revue systématique.

INTRODUCTION: The alveolar bone graft (ABG) is an important phase in the surgical treatment of cleft lip and palate (CLP). The purpose of alveolar bone grafting is to eliminate oronasal fistulas, restore the continuity of the maxilla and provide optimal periodontal support for spontaneous eruption of permanent canines adjacent to the cleft. The purpose of this systematic review was to determine the ideal timing of the ABG that would achieve these goals. MATERIAL AND METHODS: Databases consulted were MEDLINE, Embase et EBSCOhost, using keywords present in the MeSH: [cleft lip and palate] and [alveolar bone graft] and [tooth eruption]. Selection criteria included retrospective studies, prospective studies and meta-analyzes dating from January 2005, with available full text. RESULTS: Among 105 references, 9 articles met our selection criteria. ABG carried out before or just after the eruption of permanent canines adjacent to the cleft, between 8 and 12 years old, has the best success rate of the transplant (71% to 89%) and the lowest risk of canine inclusion (5% to 19%). CONCLUSION: According to literature data, the optimal timing of ABG that provide best results is located between 8 and 12 years, before or just after the eruption of permanent canines adjacent to the cleft. However, this timing could be modified by the multidisciplinary team according priorities, particularly aesthetic, defined for each child.

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).

Topographic and chemical surface modifications to metal brackets after a period in the mouth.

INTRODUCTION: In the current state of our knowledge, the effects of corrosion on the performance of orthodontic appliances and on patient health are far from clear. Awareness of these problems has led to a growing demand for nickel-free products. Titanium brackets were recently launched on the market as an alternative to stainless-steel brackets. However, the use of fluorides for caries prevention creates a risk of corrosion of these titanium appliances. The aim of this study is to examine the corrosion of stainless-steel and titanium brackets in clinical orthodontic use, focusing on the impact of fluorine. METHODS: After approval by the ethics committee and the informed consent of the patients, 30 candidates for multi-bracket treatment were selected on the basis of certain exclusion criteria. The patients were divided into 4 groups: group 1: titanium brackets and fluorine protection; group 2: titanium brackets without fluorine protection; group 3: stainless-steel brackets and fluorine protection; group 4: stainless-steel brackets without fluorine protection. RESULTS: Analysis of the brackets removed after 4months in the mouth, using scanning electron microscopy (SEM) with phase contrast, revealed a difference in the surface topography of the metal brackets and the presence of chromium coating on the surface of the titanium appliances.

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.

Resorption of maxillary incisors after orthodontic treatment--clinical study of risk factors.

INTRODUCTION: External apical root resorption (EARR) is one of the major problems associated with orthodontic treatment. Such lesions represent an iatrogenic risk that must be detected as early as possible, with regular radiological follow-up and appropriate therapeutic precautions. The causes and mechanisms leading to susceptibility to root resorption following the application of an orthodontic force are often not clear and are generally said to be of multifactorial origin. The aim of this clinical study was to analyze the factors linked to the occurrence of moderate to severe resorption (MSR) of upper incisors during orthodontic treatment in a group of Moroccan patients treated in the Dento-Facial Orthopedic Department of the Dental Consultation and Treatment Center (Centre de consultation et de traitements dentaires [CCTD]) in Rabat. MATERIAL AND METHODS: A total of 82 patients (28% males, 72% females) aged between 12 and 27, with various malocclusions, who had been treated with fixed appliances for at least 1 year and for whom panoramic X-rays at the start, during and at the end of treatment were available, were selected randomly. The reduction in maxillary incisor root length was evaluated using resorption scores. The factors studied in relation to the risk of occurrence of MSR were: age, sex, treatment duration, extraction or non-extraction, type of malocclusion (Class I arch-length discrepancy, Class II, Class III), the vertical diagnosis (normal, supraocclusion, open bite), presence of dysfunction, impacted canines and root morphology. Statistical analysis was performed using SPSS software, version 18.0. Statistical tests used were: Kaplan-Meier analysis and the univariate and multivariate Cox models for the study of factors associated with MSR. The threshold of significance adopted was 0.05. RESULTS: The factors that were significantly associated with the occurrence of MSR at the level of the upper incisors were: tooth type, with a greater risk for the lateral incisor (HR=3.2 95% CI [2.3-4.5] P<0.001), treatments with extraction (HR=1.64 95% CI [1.16-2.33] P<0.05), the presence of supraocclusion (HR=2.17 95% CI [1.33-3.53] P<0.05) or open bite (HR=3.12 95% CI [1.66-5.86] P<0.001) and root malformation (HR=1.5 95% CI [1.09-2.07] P<0.05). Age, sex, type of malocclusion, dysfunction and impaction of canines were not associated at a statistically significant level with the risk of occurrence of MSR of the upper incisors. CONCLUSION: EARR is difficult to avoid; the orthodontist's role remains crucial in identifying risk factors so as to adopt a treatment strategy taking these factors into account. In our population, the risk of MSR in the upper incisors appeared to increase in treatments with extraction, situations of supraocclusion or open bite, and in the presence of root abnormalities. Finally, clinical recommendations for the prevention of the occurrence of MSR of the maxillary incisors are proposed, taking into account all the risk factors identified.

Cervico-facial irradiation and orthodontic treatment.

Cancers during infancy and childhood affect 1 to 3% of children under the age of 15. Among these cancers the most frequent are malignant hemopathies, and in particular, acute lymphoblastic leukemia, which represents 80% of infant leukemias, with a peak of incidence around the age of 3-4. The overall prognosis for infant malignant hemopathies has improved significantly thanks to progress made in chemotherapy and radiotherapy. However, these anti-cancer treatments, particularly radiotherapy, when performed early, generally before 5 years of age, can have harmful effects that interfere with overall growth and particularly cranio-facial growth, and also with the child's oro-dental development. Some effects such as mandibular retrognathia, macrodontia, microdontia, agenesis and delayed eruption could increase the need for orthodontic treatment, while other complications, particularly the reduced height of the alveolar processes, short thin roots and modification of the superficial and profound periodontium, are likely to make such treatment more difficult. The aim of this review of the literature is to identify the essential factors that must be analyzed before orthodontic treatment is proposed for subjects who have undergone radiotherapy at an early age, and the precautions to be taken before and during orthodontic treatment.

Orthodontics and enamel demineralization: clinical study of risk factors.

UNLABELLED: The appearance of white spots on the vestibular surface of teeth fitted with brackets has been described as one of the potential iatrogenic effects of orthodontic treatment. These enamel demineralizations, more commonly known as "white spot lesions" (WSL), lead in some rare cases to the creation of true cavities, causing both esthetic and functional problems. The aim of our retrospective clinical study was to evaluate the incidence of the appearance of these WSL in a Moroccan orthodontic population and to determine possible associations with a number of risk factors. PATIENTS AND METHODS: The study was based on intraoral photographs of a pool of 69 patients who underwent orthodontic treatment with or without extractions in the DFO unit of the Rabat CCDT (Center for dental consultation and treatment). Patients with prostheses or WSL before the beginning of the study were excluded. Digital start- and end-of-treatment photos for each patient were compared by a single operator looking for the appearance of WSL on the vestibular surfaces of the incisors, canines, premolars and first molars. WSL were classed according to three degrees of severity: slight, severe and cavitation. Data were processed using SPSS 13.0 software. RESULTS: The results of the study showed that the prevalence of WSL in the sample was 66.7%, with a highly significant predominance of localization in the premolar/molar segment and in patients with poor oral hygiene. CONCLUSION: Poor oral and dental hygiene was identified as the most important risk factor for the development of white spots during multibracket orthodontic treatment.