Relationship between bruxism and mandibular bone modifications based on medical imaging: a scoping review.

OBJECTIVES: This scoping review aimed to assess the current state of knowledge regarding the relationship between bruxism and changes in density or volume of mandibular bone, based on medical imaging. METHODS: Literature review was conducted following the PRISMA-ScR protocol. PubMed, Web of Science and Cochrane library databases were searched for peer-reviewed articles by two blinded reviewers. Studies based on the evaluation of mandibular bone density and/or bone volume with imaging examination in adult patients were examined. The selected articles were summarized in PICOS tables and assessed for methodological quality. RESULTS: Nine articles were included, according to the inclusion criteria. They showed that bruxer patients had more bony exostoses of the mandibular angle, smaller condyles, and morphological changes for cancellous and cortical mandibular bone compared to non-bruxer patients. CONCLUSION: Bruxism seems to induce morphological and anatomical changes in the different regions of the mandibular bone (condyles, mandibular angle, mandible body). Given the heterogeneity of the included studies, these results should be interpreted with caution. Further studies are needed to support these results, in particular via the analysis of three-dimensional imaging to overcome the limitations of panoramic radiograph.

Evaluation of mandibular bone density in bruxers: the value of panoramic radiographs.

OBJECTIVES: This study aimed to establish a difference in mandibular bone density between bruxer and non-bruxer patients, based on panoramic radiographs. METHODS: Panoramic radiographs of bruxer and non-bruxer patients were analyzed with ImageJ®. Several radiological determinants were studied on the patients' panoramic radiographs: gray values of cancellous bone and cortical bone, and bony exostoses at the mandibular angle. RESULTS: Thirty-seven bruxers and forty-seven non-bruxers were included in the study. A statistically significant difference (p < 0.05) was noted in the cancellous to cortical bone ratios of bruxers and non-bruxers: the density of cancellous bone was greater in bruxers than in non-bruxers. The number of bony exostoses at the mandibular angle was significantly higher in bruxers (p < 0.05). CONCLUSIONS: This study obtained radiological determinants of bruxism from panoramic radiographs. Further studies are needed to supplement this preliminary approach, especially via the analysis of three-dimensional imaging to overcome the limitations of panoramic radiography.

Impacted second molars, which surgical treatment choosing? / Absence d'évolution des deuxièmes molaires, quel traitement chirurgical proposer ?

Introduction: Delayed evolution of second molars is a rare phenomenon with an estimated prevalence in the mandible of 0 to 2.3%. Many etiologies have been proposed to explain these inclusions, among which the reduction of arch perimeter, distalization of first molar, mesio-angulated position of the second molar. However, the presence and position of the third molar does not seem to be a risk factor for this inclusion. Materials and Methods: Several therapeutics options with surgical management have been proposed in the literature; surgical repositioning, surgical release of the crown more or less associated with orthodontic treatment, and sometimes avulsion of the second molar to allow the third molar development. There is no recommendation on this subject, the literature describing mostly retrospective studies and case reports. Conclusion: This article presents the different therapeutic options in the treatment of second molar inclusions.

Introduction: Les retards d'évolution des deuxièmes molaires sont des phénomènes rares avec une prévalence estimée à la mandibule de 0 à 2,3 %. De nombreuses étiologies ont été proposées pour expliquer ces inclusions, parmi lesquelles la réduction du périmètre d'arcade, la distalisation des premières molaires, la position mésio-angulée de la seconde molaire. En revanche, la présence et la position de la troisième molaire ne semblent pas être un facteur de risque de cette inclusion. Matériels et méthodes: Plusieurs options thérapeutiques associant une prise en charge chirurgicale ont été proposées dans la littérature. Il s'agit du repositionnement chirurgical, du dégagement chirurgical de la couronne plus ou moins associé à un traitement d'orthodontie et parfois de l'avulsion de la deuxième molaire pour laisser évoluer la troisième molaire. Il n'existe pas de recommandation sur ce sujet, la littérature décrivant le plus souvent des études rétrospectives et des cas rapportés. Conclusion: Cet article présente les différentes options thérapeutiques dans le traitement des inclusions des secondes molaires.

Concordances and correlations between chronological, dental and bone ages: A retrospective study in French individuals.

Bone and dental maturations are subject to physiological, environmental and pathological variables and are unique to each individual. Numerous methods for age estimation appeared to answer a new demand explained by the contemporary migratory movements and the increase of the crime rates. The objective of this study was to observe the relationships between skeletal and dental maturation stages to estimate which methods can be applied to a French population. This retrospective study was based on panoramic and cephalometric radiographs belonging to 192 (101 females and 91 males) orthodontic patients aged between 9 and 19 years, inhabitants of the Provence-Alpes-Côte d'Azur region. The Demirjian method based on dental calcification was used to estimate dental age. For the assessment of skeletal maturity and bone age, the Cervical Vertebral Maturation (CVM) method (Baccetti et al.) and its computerized version (Decocq et al.) were used. Spearman's correlation tests were performed to estimate the correlation between dental calcification stages and those of cervical vertebral maturation among the study population. The methods of Lin's concordance correlation coefficient and Bland and Altman were used to analyze the concordance between bone, dental and chronological ages. A moderate but statistically significant correlation was obtained between dental and skeletal developmental stages (R = 0.383-0.618). The tooth showing the highest correlation with vertebral stages was the second molar for both sexes. Earlier vertebral maturation stage affiliation was observed in girls. The results confirmed that bone and dental maturations can be assessed to estimate relevant biological ages for children in orthodontic or forensic contexts.

Evaluation of shear bond strength and adhesive remnant index of metal APC™ Flash-Free adhesive system: A comparative in vitro study with APC™ II and uncoated metal brackets.

OBJECTIVE: 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. MATERIALS AND METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.

Comparative study of excess glue around metallic APC™ Flash-Free adhesive system / Étude comparative des excès de colle autour des attaches métalliques préencollées APC™ Flash-Free

Introduction: 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. Materials and Methods: 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. Results: The mean percentage was significantly different between the three groups (p<0.001; ANOVA). It was significantly smaller for brackets in the APC Flash-Free group (p<0.001), and the difference was not significant between conventional brackets and APC (p=0.224). Discussion: The new technique seems to reduce the amount of excessive adhesive around orthodontic brackets.

Introduction: 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. Matériels et méthodes: 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. Résultats: 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-value<0,001), 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). Discussion: La technique de pointe adoptant un matériau non-tissé a l'air de réussir à réduire l'excès d'adhésif périphérique.

[The orthognathic surgery so called « early ¼]. / La chirurgie orthognathique qualifiée de « précoce ¼.

Some young patients with a significant skeletal shift with a strong morpho-aesthetic and psychological impact may require surgical correction during their growth. A good understanding of facial growth, the different treatment options and the effects of surgery on the post-operative growth pattern will allow the practitioner to use the technique most suited to each of his patients and improve long-term treatment outcomes. So-called « interceptive ¼ surgery may therefore be considered in cases of severe skeletal dysmorphism of secondary or functional origin. It will lead to early normalization with the immediate consequence of breaking the « dysmorpho-dysfunctional ¼ spiral.

[Alveolar bone thickness in A point area : how to avoid periodontal failures in front of upper incisors]. / Épaisseur d'os alvéolaire dans la zone du point A : savoir éviter les échecs parodontaux en regard des incisives maxillaires.

Studies on orthodontic-periodontics relationships are numerous but few have benefited from the contribution of new 3D imaging techniques that emphasize iatrogenic effects that orthodontics may have on the periodontium. Periodontal risk in terms of fenestration, bone dehiscences next maxillary incisors are real during or after orthodontic treatment. The accurate assessment of the initial situation in terms of bone quantity in this dental arch anterior segment is thus very important. Our study aimed to evaluate the reliability of conventional lateral cephalograms to quantify alveolar bone thickness in relation to the maxillary incisors by comparing it with data from CT scans. The second objective was to identify an at risk patient profile by assessing possible correlations between this thickness and dysmorphia components. The results revealed a half of assessment error in the estimation of bone thickness and increased risk in case of hyperdivergence typology, Class III skeletal relationships and dento-alveolar protrusion. Finally, in view of these data, we discussed the clinical procedures to avoid such periodontal failures in this anterior segment of the dental arch.

[Failure in anterior rehabilitation of agenesic maxillary lateral incisors]. / Échec dans la réhabilitation antérieure en cas d'agénésies des incisives latérales maxillaires.

Agenesis of the maxillary lateral incisors poses particular problems for dentists, orthodontists and patients. Treatment of these ageneses is still highly controversial, both functionally and esthetically. The patient's smile and anterior guidance are affected and must be restored. The diagnosis is easy. Few mistakes are possible. However, managing patients with missing maxillary lateral incisors can be a challenge, commonly involving two possible treatment approaches: space opening to replace the missing lateral incisor with a prosthetic unit (denture, bridge or implant) or orthodontic space closure replacing the missing lateral incisor with the maxillary canine camouflaged to mimic the appearance of a lateral incisor. One of these two options will be adopted using multiple means...liable to trigger a multitude of possible errors. Ultimately, optimal results can only be achieved if there is excellent coordination between different practitioners in various specialties. Each clinician will have a specific role to play. Also, the patient and family are at the heart of the decision-making process, by virtue of their consent (treatment duration, financial resources) and their motivation. This multi-factorial, multi-disciplinary decision process means that treatment of the lateral incisor is an ongoing challenge for the clinician striving for the best possible result. Each case is different. No set rules exist. No single factor can be neglected if we are to avoid "failure".

[A perspective on the use of bone anchorage as opposed to other types of anchorage techniques]. / Mise en perspective de l'utilisation des ancrages osseux par rapport aux autres techniques d'ancrage.

INTRODUCTION: To convert our objectives into the desired treatment results, we need to control our mechanics and thus the anchorage used by avoiding any unwanted movements. It now seems unthinkable, at the dawn of the 21st century, to ignore the useful contribution of orthodontic screw-borne anchorage. Nevertheless, we are entitled to raise a number of legitimate questions. Do these forms of anchorage offer an alternative to all types of mechanics? Will they permit us to manage clinical situations which are beyond the scope of a more classical approach? Can they enhance the quality of our treatments? MATERIALS AND METHODS: Each of the authors describes clinical situations using screw-borne anchorage and compares with a conventional approach in order to make a non-exhaustive analysis of the mechanics applied, in their own office, and then highlights the most effective technique. RESULTS: With 15 years experience in the use of miniscrews, orthodontists have now adopted them with their many advantages as an integral item in their therapeutic armamentarium. However, treatment plans must be coherent. Our mechanics must be well thought-out and represent a cogent entity under the control of the practitioner. Creating screw-borne anchorage demands total control over anchorage stability.