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The extraction of maxillary first premolars is usually the treatment of choice to resolve crowding, alveolar protrusion, or Class II malocclusion. The demand for a lingual orthodontic treatment is increasing because of its esthetic value; therefore, understanding lingual biomechanics is essential to every clinician. This study compared the 3-dimensional (3D) effects of sliding mechanics in labial and lingual orthodontics using the finite element method.Twelve 3D finite element models were created with different power arm heights and miniscrew positions. A 150 g of retraction force was applied from the head of the miniscrew to the power arm. The 3D displacement of the original nodes was measured, and the stress distribution on defined element zones of the periodontal ligament.Different force directions led to different movement patterns and stress distribution. The lingual models showed a more important lingual crown tipping, extrusion, and higher stress values than the labial models. Results were not affected by the vertical position of the miniscrew.Bodily en-masse retraction was not achieved in all models. Adding extra torque to the archwires is essential to prevent excessive lingual crown tipping. The lingual appliance induced more lingual tipping and extrusion of the anterior teeth. Expanding the archwire is important to minimize the risk of intercanine width reduction. The vertical position of the miniscrew does not affect the results of en-masse retraction.

Summary Objective The aim of this in vitro study was to evaluate the effects of enamel deproteinization on the shear bond strength of a self-etching primer Transbond Plus™(TBP), with different application times of sodium hypochlorite (NaOCl 5.25%), primarily and secondarily on the adhesive remnant index score. Materials and methods One hundred twenty-five freshly extracted human premolars were randomly and blindly divided into five groups according to the enamel surface preparation, as follows (n = 25): group 1(control): Etching with 37% phosphoric acid for 15 seconds + Bonding; group 2 (control): TBP™ without NaOCl, group 3: 60 seconds NaOCl + TBP™, group 4: 30 seconds NaOCl + TBP™, group 5: 15 seconds NaOCl + TBP™. The same composite resin was used (Transbond XT™) to bond the orthodontic metal brackets. After the immersion of the teeth in distilled water at 37 °C for 24 hours the shear bond strength was measured using the universal testing machine and the adhesive remnant index score (ARI) was evaluated under an optical microscope (25 × ). Results The mean SBS values (in MPa) of the groups were respectively: group 1: 13.03 ± 5.36; group 2: 12.28 ± 3.06; group 3: 12.38 ± 4.55; group 4: 12.98 ± 5.76; and group 5: 11.73 ± 5.67. Enamel deproteinization increased the SBS for groups 3 and 4, but no statistically significant difference was found between the five groups (P = 0.883). Group 1 showed the highest ARI scores, with 52% of the teeth retaining all the adhesive (score 3). However, for all the other groups, scores 0 and 1 were predominant, with less than half of the adhesive or no adhesive at all remaining on the teeth. Conclusions Enamel deproteinization with sodium hypochlorite (5.25%) and the variation of its application time has no effect on the SBS of the self-etching primer Transbond Plus ™.

The aim of this in vitro study was to determine if there is a significant difference in the excess adhesive flash between the metallic APC™ Flash-Free adhesive system, the APC™ pre-coated adhesive system and a conventional uncoated system.One hundred eighty-six freshly extracted human premolars were randomly and blindly divided into three groups according to the type of brackets. Group A (control group n=60): The conventional uncoated metallic bracket (Victory, 3M Unitek®) with a Transbond XT™ Light Cure Adhesive Paste was used. Group B (n=60): The APC™ II metallic maxillary precoated premolar brackets was used. Group C (n=66) : The metallic APC™ Flash-Free adhesive system without flash clean up was used. Images were taken at 40 magnifications in a dental microscope (Leica M320 for dental, Wetzlar, Germany) then analyzed with the ImageJ software and the area of excess adhesive flash was measured.The mean percentage was significantly different between the three groups (p0.001; ANOVA). It was significantly smaller for brackets in the APC Flash-Free group (p0.001), and the difference was not significant between conventional brackets and APC (p=0.224).The new technique seems to reduce the amount of excessive adhesive around orthodontic brackets.L’objectif de cette étude in vitro était de présenter une évaluation comparative et objective de l’efficacité d’une nouvelle technique d’attaches métalliques préencollées APC™ Flash-Free fabriquées par 3M Unitek®, éliminant l’étape de nettoyage grâce au système de fibres non tissées.Cent quatre-vingt-six prémolaires humaines saines fraichement extraites sont réparties en trois groupes de façon randomisée. Groupe A : 60 dents sont collées avec des attaches conventionnelles à encoller avec du Transbond XT™ (3M Unitek®). Groupe B : 60 dents sont collées avec des attaches préencollées APC™ II préenduites du même type de pâte adhésive. Groupe C : 66 dents sont collées avec des attaches APC™ Flash-Free (3M Unitek®), puis observées avec un microscope (Leica M320 for dental, Wetzlar, Germany) sous un agrandissement x40. Les photographies sont analysées à l’aide du logiciel ImageJ.Les comparaisons multiples de Tukey ont montré que le pourcentage moyen était significativement plus petit au niveau des attaches du groupe C, APC™ Flash-Free (p-value0,001), mais la différence n’a pas été significative entre les attaches conventionnelles du groupe A et celles préencollées du groupe B (p-value=0,224).La technique de pointe adoptant un matériau non-tissé a l’air de réussir à réduire l’excès d’adhésif périphérique.

Summary Objective The aims of this retrospective study were, first to evaluate the distance between the root apices of the upper first molars and the palatal plane (PP), and second to determine the validity (accuracy) of the use of cephalometric radiographs or panoramic X-rays compared to cone beam computed tomography (CBCT) in determining this distance. Material and methods The distance was calculated from the root apices of the first molars to PP, on the cephalometric radiographs of 204 subjects and then 57 measurements were compared to those obtained on panoramic X-rays and CBCT images, in order to find a statistically significant difference according to age, sex, side, vertical and sagittal skeletal patterns, and to determine if 2D radiographs are suitable for this task. Results The distance increased significantly in subjects after 20 years of age and in hyperdivergent patients, but was not influenced by sex, side or anteroposterior position of the mandible. No statistical significance was found between the calculated measurements on cephalometric and CBCT radiographs, but both were different from those taken on panoramic X-rays. Conclusions Cephalometric radiographs are reliable in the assessment of the distance between the roots of the upper molars and the PP. In hyperdivergent and adult patients, posterior teeth have enough space between their roots and the upper limit of the hard palate to undergo intrusion mechanics using miniscrews, but care must be taken while planning and managing these movements in order to minimize the unwanted side effects.

BackgroundThe aim of this study was to find the best surface treatment for provisional crowns made in the laboratory (CAD/CAM) allowing optimal bond strength of brackets.MethodsThe sample consists of 30 lower bicuspids and 180 provisional teeth. The provisional teeth were randomly divided into 6 different groups. The orthophosphoric acid etching (37%) was applied to the 30 lower bicuspids. The provisional teeth had undergone different surface treatments. Group 1: No treatment (Control Group). Group 2: Diamond bur. Group 3: Sandblasting. Group 4: Plastic Conditioner. Group 5: Diamond bur and Plastic Conditioner. Group 6: Sandblasting and Plastic Conditioner. The brackets in all groups were identically placed using the Transbond XT® Primer and the Transbond XT® Paste. Then, the entire sample underwent an artificial aging procedure and a measurement of the bond strength was done. After debonding, the surface of the teeth was examined to determine the quantity of the adhesive remnant.ResultsNatural teeth recorded the highest average followed by the averages of groups 5 and 6. However, group 1 recorded the lowest average. Groups 2 and 4 had very close averages as well as groups 5 and 6. A statistically significant difference between the averages of all groups was recorded (pDiscussionThe bonding of brackets on provisional teeth is considered as a delicate clinical procedure. In fact, unlike natural teeth, the orthophosphoric acid usually used, does not have any effect on the surface of provisional restorations. Several surface treatment techniques were proposed to enhance the bond strength between the orthodontic brackets and the surface of the provisional restorations.Moreover it is difficult to simulate the exact intra-oral environment conditions.ConclusionUsing a diamond bur combined with the Plastic Conditioner and sandblasting combined with that same product resulted in a bond strength close to natural teeth.

The aim of this in vitro study was to compare the shear bond strength (SBS) and the adhesive remnant index (ARI) of the metal APC™ Flash-Free adhesive system, the APC™ pre-coated adhesive system and a conventional uncoated system.One hundred eighty-six freshly extracted human premolars were randomly divided into 3 groups and bonded by a single operator. Group A/Control Group (60 teeth): the manual bonding group treated with Transbond™ XT Light Cure Adhesive Paste (3M™ Unitek). Group B (60 teeth): treated with APC™II metal maxillary premolar precoated brackets. Group C (66 teeth): treated with metal maxillary premolar APC Flash-Free brackets. The teeth were then stored in distilled water at 37̊C for 24hours, and five hundred cycles of thermocycling were performed. The Shear Bond Strength (SBS) test was performed using an Instron Universal Testing Machine, and the adhesive remnant index (ARI) was determined using a dental optical microscope at ×25 magnification.The mean shear bond strength values showed differences between the three types of brackets (P=0.016; Anova). It was significantly higher with APC™II and lower with APC Flash-Free brackets; however, no significant differences were found between conventional and APC Flash-Free brackets (P-value=0.574). The distribution of the dichotomized ARI score was significantly different between the three brackets (P-value=0.049). The ARI score for APC Flash-Free brackets was higher with no significant difference between the conventional system and APC brackets (P-value=0.361).The mean SBS values were not significantly different between APC Flash-Free metal brackets and uncoated metal brackets. The APC Flash-Free metal system's bond failure occurred at the bracket-adhesive interface, with the highest percentage of teeth having more than 50% of the residual composite on the enamel after debonding.

The aim of this study was to determine among young orthodontic patients the relation between the spheno-occipital synchondrosis (SOS) fusion and the cervical vertebral maturation (CVM) and to look for an eventual impact of gender, skeletal class and vertical pattern on their association.CBCT scans and lateral cephalometric radiographs of 117 patients, aged between 8 and 18 years, were selected. SOS fusion was assessed on a mid-sagittal cut of the CBCT scans. CVM was evaluated on the lateral cephalograms as well as ANB and GoGn-SN angles. Spearman correlation test was used to assess the relationship between SOS and CVM. Fisher's exact test was performed at every CVM stage to analyse the association between SOS and other variables (gender, skeletal class, and vertical pattern). Cohen's kappa analysis was used for reliability.A strong correlation was found between SOS maturation and CVM (r=0.852, P001). Fisher's exact test indicated significant association only between gender and SOS in CVM stage 2 group, and between vertical pattern and SOS in CVM stage 4. Cohen's kappa analysis showed moderate inter and intra-rater reliability for CVM index (k=0.50 and 0.53 respectively, P.001), strong inter-rater reliability (k=0.80, P.001) and almost perfect intra-rater reliability (k=0.85, P.001) for SOS index.SOS fusion correlates well with CVM and might be a reliable tool for skeletal maturation assessment. Girls seem to have an earlier fusion of SOS in relation to their respective CVM compared to boys, and the vertical pattern could influence the association between SOS and CVM stages.

Maintenance of the intercanine and intermolar distances reduces the risk of relapse and increases the chance of stability; these values represent the limits of the arch, resulting from the muscular balance of each patient. The ideal would be to reproduce the patient's arch form individually. The Ricketts pentamorphic arch forms allow the clinician to choose among 5 shapes, the one that best fits the patient's arch form. The objective of this study was to evaluate the effect of orthodontic treatment without extraction according to the pentamorphic arch forms on mandibular arches of different forms.Fifty patients were included in the study. For each patient, the pretreatment and end-of-treatment models were scanned by 3Shape Trios (3Shape, Copenhagen, Denmark) and transferred to the OrthoAnalyzer software (3Shape) version 2017-11.7.1.3 for measurements and superimpositions. The following measurements were made on the mandibular arches for both initial and final digital models: arch depth; intercanine distance, the distance between the first premolars, the distance between the second premolars, the distance between the first molars, and the distance between the second molars. Three superimpositions were made: superimposition between the initial arch and the corresponding form of the pentamorphic arch forms, superimposition between the final arch and the corresponding form of the pentamorphic arch forms, and superimposition between the initial arch and the final arch. The largest difference between the superimposed arches in each region was measured.This study showed that intercanine distance (P = 0.236), the distance between the first premolars (P = 0.074), and the distance between the first molars (P = 0.616) did not significantly change after orthodontic treatment. In contrast, the distance between the second molars (P = 0.028) and the arch depth (P 0.001) increased significantly after orthodontic treatment. The mean of the largest difference in the absolute value of all the superimpositions is significantly different from the theoretical value 0 (P 0.001), but clinically, this difference is significant only in certain premolars and molars regions.This study has shown that the pentamorphic arch forms maintained the arch shape in the sagittal and transverse directions, except for an expansion of the distance between the mandibular second molars.

Introduction The anteroposterior position of the maxillary incisors has been studied since the beginning of cephalometric research. Most reports of ideal position have been based on measurements made on subjects with Class I occlusion without consideration of other facial variables. However, the ideal position is reflected in the soft tissues by the position of the lips. The purpose of this study was to consider the position of the maxillary incisor relative to other factors, including the thickness of the upper lip, and to evaluate its most aesthetic position using profile photographs. Methods The subjects in this study were 130 patients with Class I occlusion; their sex, age, thickness of the upper lip, and angular position of the maxillary incisor were recorded. From these 130 patients, 70 profile photographs that met the inclusion criteria were chosen for further evaluation. A survey was conducted among 60 lay people, 60 dentists, and 60 orthodontists. They were asked to classify the sets of photographs, from the most esthetic position of the upper lip to the least esthetic. Results For patients with thin lips, raters tended to prefer a more protruded position of the incisor than normal or between 8.0 mm and 11.5 mm in front of the Na-B bone and 4 mm in front of the Na-A bone. For patients with thick lips, the position of the incisor did not affect the perception of the profile. Conclusions A correct skeletal scheme or Class I occlusion does not necessarily result in ideal facial harmony. Therefore, it will be necessary to consider all the factors that come into play, especially the lips, which are a key element in facial esthetics.

A bonding material can be acceptable in orthodontics when Shear Bond Strength (SBS) is higher than 5.9Mpa. The aim of our study was to compare the bonding of a metal orthodontic bracket "in vitro" under different types of healthy enamel surface preparations and with two bonding products: the composite and the Resin Modified Glass Ionomer Cement (RMGIC).Premolars preserved in 1% thymol water were bonded on their vestibular and palatal/lingual surfaces with different techniques of bonding and surface preparation: Group 1: Etching+Bonding+Composite, Group 2: Etching+Fuji Ortho LC, Group 3: V-prep+Fuji Ortho LC, Group 4: V-prep+Fuji Ortho LC+Thermocycling. The SBS was measured in Newton on the universal testing machine and the sample was observed under an optical microscope with 10-fold magnification to note the adhesive remnant index score (ARI), before and after thermocycling.120 premolars were used in this study. RMGIC bonding was significantly increased when the surface was prepared at V-prep (P0.001). In these conditions, RMGIC bonding on the buccal surface was similar to that of the composite and superior on the palatal/lingual surface (P=1). After 2 years of aging using a thermocycling machine for simulation, RMGIC bonding significantly decreased (P0.001). The ARI score was significantly lower for the RMGIC group than the composite group (P0.001).RMGIC bonding with V-prep preparation is recommended for palatal/lingual surfaces and for hard-to-dry surfaces. For vestibular surfaces, studies are still needed to recommend bonding with RMGIC instead of composite.

The purpose of this study was to compare the friction of two types of polycrystalline ceramic brackets before and after aging.A total of 60 second-upper right premolar brackets were divided into two groups: Clarity™ Advanced (3M Unitek, Monrovia, CA) and Clarity™ (3M Unitek). All brackets had a nominal 0.022-in slot size and a McLaughlin Bennett Travesi (MBT) prescription. Each bracket was submitted to a friction test, using the YL01 UTM universal testing machine (YLE GMBH, Germany) before and after thermocycling. All tests were carried out in the presence of artificial saliva, using .019×.025-in. rectangular stainless steel (SS) archwires (3M Unitek). Bracket slot surfaces were observed under an optical microscope (Olympus CX41, Tokyo, Japan) before and after aging.Before aging, the Clarity Advanced group showed significantly lower friction than the Clarity group (P=0.011). After aging, the friction of the Clarity Advanced bracket decreased significantly (P0.001), whereas the friction of the Clarity bracket increased significantly (P0.001). The microscopic qualitative evaluation showed that the slot surfaces of all aged Clarity brackets revealed important pit corrosion when compared with the original brackets.The new Clarity Advanced ceramic bracket shows good physical friction properties due to the various modifications added by the manufacturers.

The aim of this study was to evaluate the impact of the vertical position of the maxillary lateral incisors borders on the perception of smile esthetics of a woman and a man, with respect to the resulting changes of the gingival margin, in order to determine the most esthetics position of the lateral incisors. Pictures of two smiles of different sexes were edited using Adobe Photoshop (Version CS5; Adobe Systems, San Jose, Calif). The vertical position of the lateral incisors was modified, while keeping the same crown length and height/width ratio, thus respecting the resulting changes of the gingival levels. 210 evaluators (70 dentists, 70 orthodontists and 70 laypersons) aged between 18 and 60 years old were asked to grade the pictures with a scale from 0 to 10, with zero as the most unattractive and 10 as the most attractive. 180 evaluators responded to the survey. Orthodontists are the most sensitive to changes in the level of the maxillary lateral incisors. The most attractive vertical relationship between the lateral and the central incisors was the 1.0 mm step. The laypersons were not able to find any statistical difference between the lateral incisors levels for both sexes. Particularly, this group gave a significantly higher score to the 0 mm step in comparison with the scores given by the orthodontists and dentists to the same picture. The perception of smile esthetics was identical between men and women. Flat smiles with central and lateral incisors borders at the same level are more appreciated by laypeople, and more accepted for men. Resume L’objectif de cette etude etait d’evaluer l’impact de la position verticale des bords libres des incisives laterales maxillaires sur la perception esthetique du sourire d’une femme et celui d’un homme, en respectant les changements resultant sur le niveau gingival. Le but est donc de determiner la position la plus esthetique des incisives laterales par rapport aux centrales. Les photos de deux sourires de differents sexes ont subi des changements en utilisant le programme Adobe Photoshop (Version CSS ; Adobe Systems, San Jose, Calif). La position verticale des incisives laterales a ete modifiee tout en gardant la meme hauteur coronaire et le meme rapport hauteur/ largeur, alors en respectant les changements resultant du niveau gingival. 210 evaluateurs (70 dentistes, 70 orthodontistes et 70 profanes) âges entre 18 et 60 ans ont attribue aux photos modifiees un score entre 0 et 10, zero pour le sourire le moins beau, et 10 au sourire le plus beau). 180 evaluateurs ont repondu a l’enquete. Les orthodontistes sont les plus sensibles aux changements du niveau des bords des incisives laterales. Selon cette etude, le plus esthetique est d’avoir des laterales maxillaires a 1 mm par rapport aux centrales, en respectant les changements du niveau gingival. Les profanes ont ete incapables de trouver une difference significative entre les differents niveaux des bords libres des incisives laterales dans les 2 sexes. Plus particulierement, ce groupe a attribue une note significativement plus elevee aux incisives laterales se trouvant a 0 mm par rapport aux centrales, en comparant aux notes donnees par les dentistes et par les orthodontistes. La perception de l’esthetique du sourire est identique chez les evaluateurs des 2 sexes. Les sourires plats avec des centrales et des laterales au meme niveau sont plus apprecies par les profanes, et plus acceptes pour le sourire d’un homme.

This study is aimed at evaluating the Oral Health Related Quality of Life (OHRQoL) in adolescents aged 11-14 years-old during orthodontic therapy and 18 months after the start of treatment and the possible role of psychological parameters. Sixty patients were recruited, and data were collected using self-administrated questionnaires and intraoral clinical examinations. The questionnaires included sociodemographic characteristics (age, gender), the Lebanese version of the Child Perception Questionnaire between 11 and 14 years CPQ11-14 to assess the OHRQoL, the Discrepancy Aesthetic Index (DAI) for malocclusion, and the Child Health Questionnaire « CHQ-CF87 » to appraise Self-Esteem (SE) and Psychological Well-Being (PWB). The mean scores of CPQ11-14 and its four subdomains were significantly better for participants with high SE /PWB compared to those with low SE / PWB at baseline. These same scores improved significantly during orthodontic treatment (p < 0.001). However, DAI was significantly better in patients with low self-esteem and psychological well-being. Our findings showed improvement in oral health perception and psychologic parameters during orthodontic treatment. Investigators should consider the need to control the psychological parameters of patients when assessing orthodontic treatment need and improvement in OHRQoL during orthodontic treatment.

Resume Introduction L’objectif de cette etude est de trouver une correlation entre le pontage de la selle turcique et la presence de canine incluse en position palatine a l’aide des teleradiographies de profil et du CBCT. Materiel et methode On a selectionne les teleradiographies de profil et les CBCT de 60 sujets repondant a des criteres specifiques. Ces radiographies ont ete analysees pour etudier la relation entre le pontage de la selle turcique et plusieurs facteurs. La presence ou l’absence d’un pontage partiel ou complet etait deduite en mesurant les dimensions de la selle turcique et en utilisant un systeme de score precis. Resultats et conclusion Notre etude n’a pas montre d’association statistiquement significative entre le pontage de la selle turcique tel que diagnostique selon la teleradiographie de profil et le CBCT avec les facteurs suivants : âge, sexe, typologie faciale, classe squelettique et presence de canine incluse. Nous avons trouve qu’il y a une difference significative pour la classification de la selle turcique entre ces deux methodes radiographiques.

Summary Introduction The purpose of this study was to find a correlation between sella turcica bridging and the presence of a palatal impacted canine, using lateral cephalograms and CBCT. Material and method We selected the lateral cephalograms and CBCTs of 60 patients meeting specific criteria. The radiographs were analysed to study the relationship between sella turca bridging and several factors. The presence or absence of a partial or total bridging was deducted by measuring the dimensions of the sella turcica and by using an accurate scoring system. Results and conclusion Our study did not show any statistically significant association between sella turcica bridging as diagnosed on the lateral cephalogram and the CBCT images and the following factors: age, gender, facial type, skeletal class and the presence of an impacted canine. We found a significant difference for the classification of the sella turcica between these two radiographic methods.

Resume Introduction L’objectif de cette etude a ete de comparer, in vitro, la resistance d’adhesion au cisaillement du ciment de verre ionomere renforce a la resine (CVIRR) colle sur une surface amelaire preparee, soit par microsablage avec des particules d’oxyde aluminium de 50 μm, soit par deproteinisation avec du NaOCl 5,25 %, soit une combinaison des deux. Materiel et methodes Cent cinquante molaires humaines ont ete nettoyees et randomisees en cinq groupes. Dans le groupe 1, les dents ont ete mordancees en utilisant de l’acide phosphorique 37 % et collees avec du Transbond XT. Dans le groupe 2, les dents ont ete mordancees en utilisant de l’acide phosphorique 37 % et collees avec du Fuji Ortho LC. Dans le groupe 3, les dents ont ete deproteinisees avec du NaOCl 5,25 % pendant une minute puis mordancees avec de l’acide phosphorique 37 % et collees avec du Fuji Ortho LC. Dans le groupe 4, l’email a ete microsable avec des particules d’oxyde d’aluminium a 50 μm pendant 5 secondes avant d’etre mordance et colle avec du Fuji Ortho LC. Dans le groupe 5, les dents ont ete microsablees avec des particules d’oxyde d’aluminium a 50 μm pendant 5 secondes et deproteinisees avec du NaOCl 5,25 % pendant une minute avant d’etre mordancees avec de l’acide phosphorique 37 % et collees avec du Fuji Ortho LC. La resistance au cisaillement a ete testee a l’aide d’une machine d’essai universelle avec une vitesse de traverse de 1,0 mm/min. L’indice d’adhesif restant (IAR) a egalement ete calcule pour chaque groupe. Resultats Les taux moyens de resistance d’adhesion au cisaillement etaient les suivants : groupe 1 : 11,33 ± 2,60 MPa, groupe 2 : 8,14 ± 2,09, groupe 3 : 9,57 ± 3,25 MPa, groupe 4 : 9,49 ± 1,99 MPa et groupe 5 : 9,76 ± 2,29 MPa ( p = 0,0001). Conclusion Les resultats montrent que le pretraitement de l’email par microsablage, par NaOCl ou par les deux, peut augmenter la resistance au cisaillement de facon significative par rapport au seul CVIRR avec mordancage a l’acide.

Introduction : Cette étude a pour objectif d'évaluer la reproductibilité de la position d'équilibre naturel en fonction du temps sur des photographies de profil. Matériels et Méthodes : L'échantillon est de 96 étudiants de la faculté de médecine dentaire de l'université Saint-Joseph de Beyrouth, âgés de 20 à 30 ans. Deux photographies de profil ont été prises pour chaque sujet dans sa position d'équilibre naturel, à intervalle d'une semaine. L'angle formé par la tangente à la columelle du nez passant par le point sous-nasal et la vraie verticale a été mesuré. Résultats : Il n'y a pas eu de différence significative entre T0 et T1 (E = 1,065°). Discussion : D'autres études confirment cette reproductibilité avec le temps. La position d'équilibre naturel peut donc être adoptée comme orientation au niveau des photographies de profil en orthodontie.

Summary Objective The objectives of this prospective clinical study are to quantify the variation of pressure exerted by the upper lip on the upper teeth during the alignment phase and to evaluate its capacity to adapt to changes in dental position. Materials and methods Thirty young subjects in skeletal Class I relationship requiring non-extraction orthodontic treatment were included in this study. The pressure exerted by the upper lip on the upper central incisors and right canine were measured during rest and swallowing positions using a pressure transducer before bracket placement (T0), after bracket placement (T1), three months (T2) and six months later (T3). Maxillary intercanine width (CC), upper arch length (U) and crowding (C) were measured on stone models at T1, T2 and T3 to determine the existence of a correlation between the variation of lip pressure and these variables. Results The lip pressure significantly increased after bracket placement and remained relatively stable during the six-month period. The labial pressure on the incisors was the only variable to significantly decrease at T3, though remaining significantly higher than the starting pressure. A positive correlation was found between the variation of the inter-canine distance and the labial pressure on the canine at rest whereas a negative correlation exists between the crowding and the labial pressure on the incisors at rest. Conclusion This study showed that increasing inter-canine width disrupts the muscle equilibrium and therefore is prone to relapse, whereas the upper lip can better adapt to the protrusion of upper incisors.

Summary Introduction The mouth plays an important role in the overall aesthetic appearance of the face. The aims of this study were to determine the optimal antero-posterior (AP) lip position relative to various rotations of the nasal tip and assess the impact of the nasolabial angle on facial aesthetics. Material and methods Three-dimensional facial volumes, in motion, of one Caucasian male and one Caucasian female with a Class I malocclusion and an orthognathic profile were modified to alter the nasal tip rotation (3 rotations) and the AP lips position (6 positions). 72 generated models were created in two and three-dimensions. Generated models were rated online by 60 dentists, 60 orthodontists and 60 laypeople, using a Visual Analogue Scale. Scores were analysed according to lip position, rater's profession and gender. Results General agreement was found between all groups on the most and least preferred lip positions. No differences between male and female raters were found. All raters were more influenced by the 3-dimensional rotating facial volume than by 2-dimensional angles. Similar angular values for the nasolabial angles were found in the most and least preferred profiles, showing that the most influential factor in facial aesthetics was the lip position, and stressing the need to evaluate each component of the nasolabial angle independently. Conclusion The lip position was the determinant factor in facial aesthetics with little influence of the nose tip rotation. Three-dimensional evaluation of the nose and lip were needed to establish a soft tissue-based treatment plan.

Introduction : L’objectif de cette étude est d’identifier le profil le plus attirant parmi sept photographies distribuées à trois groupes : orthodontistes, dentistes et profanes. Matériels et méthodes : Deux photographies de profil d’un garçon et d’une fille en classe I squelettique ont été modifiées de six façons différentes dans le sens antéro-postérieur au niveau du maxillaire et/ou de la mandibule à l’aide du logiciel Dolphin Imaging System®. Les participants, au nombre de 120, ont classé les photographies de chaque sexe du plus au moins attirant. Résultats : Le profil droit féminin et masculin ont été les mieux classés. Cependant, la protrusion des lèvres chez la femme et la rétromaxillie chez l’homme sont tolérées. Discussion : Nos résultats expriment l’opinion moyenne d’une société caucasienne, cela ne veut pas dire que n’importe quel profil droit est perçu comme beau ou attirant, d’où l’importance d’un plan de traitement individualisé prenant en considération l’esthétique faciale de chaque patient.

The purpose of this study is to evaluate the reproducibility of natural head position with time on profile photographs.Our sample is composed of 96 students (20-30 years old) at the department of dentistry of Saint Joseph University in Beirut. Two profile photographs were taken in natural head position about a week apart.No significant differences were found between T0 and T1 (E = 1.065°).Many studies confirmed this reproducibility with time. Natural head position can be adopted as an orientation for profile photographs in orthodontics.

La préparation orthodontique est la clé du succès d’une chirurgie orthognathique. Ainsi la détection et la correction des compensations dentaires favorisent la correction des décalages et déficits squelettiques. Les objectifs orthodontiques pré-chirurgicaux sont importants à définir dès le début du traitement et ne doivent pas toujours inclure le nivellement complet des arcades, la fermeture complète des espaces, ou l’intercuspidation idéale. La préparation orthodontique dicte les mouvements squelettiques qui sont possibles au moment de la chirurgie. Différents types de malocclusions présentent des compensations dentaires caractéristiques qui peuvent être identifiées et décrites. La planification appropriée, l’individualisation et la communication entre le chirurgien et l’orthodontiste sont critiques afin d’éviter certains pièges dans la préparation orthodontique.

Summary Introduction The purpose of this study was to compare, in vitro, the shear bond strength of resin-modified glass ionomer (RMGI) bonded to an enamel surface prepared by either sandblasting with 50 μm of aluminium oxide particles, deproteinization with 5.25% NaOCl, or by combining both techniques. Material and methods One hundred and fifty human premolars were cleaned and randomly divided into five groups. In group 1, the teeth were etched using 37% phosphoric acid and bonded with Transbond XT. In group 2, the teeth were etched using 37% phosphoric acid and bonded with Fuji Ortho LC. In group 3, the teeth were deproteinized with 5.25% NaOCl for one minute then etched with 37% phosphoric acid and bonded with Fuji Ortho LC. In group 4, the enamel was sandblasted with 50 μm of aluminium oxide particles for 5 seconds prior to etching and bonding with Fuji Ortho LC. In group 5, the teeth were both sandblasted with 50 μm of aluminium oxide particles for 5 seconds and deproteinized with 5.25% NaOCl for one minute prior to etching using 37% phosphoric acid and bonding with Fuji Ortho LC. The shear bond strength was tested using a universal testing machine with a crosshead speed of 1.0 mm/min. The adhesive remnant index (ARI) index was also determined for each group. Results The mean shear bond strengths were as follows: group 1: 11.33 ± 2.60 MPa, group 2: 8.14 ± 2.09, group 3: 9.57 ± 3.25 MPa, group 4: 9.49 ± 1.99 MPa and group 5: 9.76 ± 2.29 MPa (P = 0.0001). Conclusion The results show that pre-treating the enamel with either sandblasting, NaOCl, or both, could give a significantly higher shear bond strength than using RMGI with acid etch alone.

An adequate orthodontic preparation is a key to success of every orthognatic surgery. Therefore, the detection and the correction of the existing dentoalveolar compensation tend to favor the correction of the skeletal defects. The pre-surgical orthodontic goals have to be defined at the beginning of the treatment, thus, not always achieving a complete leveling of the arches, nor a final space closure and ideal intercuspation. The orthodontic preparation aims to guide the surgical skeletal displacements. Many dentoalveolar compensations can be identified as specific to different types of malocclusion. Accordingly, an adequate individualized planning and a good coordination between both orthodontist and surgeon, are of a major importance, in order to avoid unexpected traps during orthodontic pre-surgical preparation.