Impact of occlusal proprioception on static postural balance.

Conflicting results on the effects of occlusal proprioceptive information on standing sway have been reported in the literature, partly due to the heterogeneity of the occlusal criterion studied and the experimental protocol used. In this study, occlusal functions, different mandibular positions and visual conditions were used to investigate the involvement of occlusal proprioception information in static postural balance. Postural adjustments of 26 healthy young adults, divided into Class I malocclusion and Class I normocclusion groups, were studied in upright position, in five mandibular positions (1 free, 2 centric and 2 eccentric), with and without vision. Due to different reported test durations, postural parameters were examined for the first and last halves of the 51.2 s acquisition time. A permutation ANOVA with 4 factors was used: group, mandibular position, vision, time window. Mean length of CoP displacement was shorter with vision (ES = 0.30) and more affected by vision loss in the free than in the intercuspal mandibular position (ES = 0.76 vs. 0.39), which has more tooth contacts. The malocclusion group was more affected by vision loss (ES = 0.64). Unexpectedly, with vision, the mean length was smaller in one eccentric occlusion side compared to the other (ES = 0.51), but independent of the left or right side, and more affected by vision loss (ES = 1.04 vs. ES = 0.71). The first-time window of the acquisition time, i.e. 25.6 s, was sufficient to demonstrate the impact of dental occlusion, except for the sway area. Comparison of the two visual conditions was informative. With vision, the weight of occlusal proprioception was not strictly related to occlusal characteristics (number of teeth in contact; centered or eccentric mandibular position), and it was asymmetrical. Without vision, the lack of difference between groups and mandibular positions suggested a sensory reweighting, probably to limit postural disturbance.

Complicated Relationships between Anterior and Condylar Guidance and Their Clinical Implications-Comparison by Cone Beam Computed Tomography and Electronic Axiography-An Observational Cohort Cross-Sectional Study.

A complex prosthodontic treatment is believed to be more successful when the condylar path is replicated using the articulator. However, there is an ongoing major disagreement between the researchers as the exact relationship between the posterior and anterior determinants has not been clear. The purpose of this study was to investigate whether the protrusive movement of the mandible does correlate with the temporomandibular joint (TMJ) anatomy or with incised features. Subjects (15 males and 15 females) were qualified for this study based on an initial interview including the following criteria: age 21-23 (+/-1), no history of trauma, orthodontic treatment, or temporomandibular disorders (TMD). For each patient, the angle of the condylar path, incisal guidance angle (IGA), interincisal angle, as well as overbite and overjet were measured on cone beam computed tomography (CBCT). This was followed by the examination with the Modjaw® electronic axiograph recording and calculating the functional sagittal condylar guidance angle (SCGA) for the right and left TMJ during the protrusion. The results show that the mean functional axiographic measurement of SCGA in protrusion significantly correlates with the TMJ anatomy presented on CBCT. Moreover, a significant correlation was found between the values of SCGA in the functional and anatomical measurements in all its variants. It turned out that, statistically, the AB measurement was the most accurate. Finally, results showed that incisal relationships of permanent teeth such as overbite, overjet, incisal guidance angle and interincisal angle do not correlate with TMJ anatomy, and therefore, regarding an analyzed study group, do not affect the TMJ formation in young adults.

Balkwill's angle, occlusal plane, mandibular shape, and curve of Spee.

OBJECTIVE: This study proposes a cephalometric method to determine an individual radius of the curve of Spee in cases of occlusal prosthetic rehabilitation. METHODS: A retrospective study was conducted on 469 lateral cephalograms. Statistical analysis was performed. Correlations were computed using simple regression, Z tests, paired t-tests, and one-way repeated measures ANOVA. RESULTS: Regression calculations supported a link between the radius of the curve of Spee and occlusal plane inclination, Balkwill's angle, mandibular parameters (MP), with MP = corpus - ramus + Bonwill height. Based on MP, data that are accessible even in the absence of teeth, a regression formula can be proposed to provide an individualized estimation of the radius of the Spee curve (RCS): RCS = 0.624 * MP + 26.583. CONCLUSION: This study proposes an individualized estimation of the RCS from only skeletal mandibular parameters: the length of the ramus, length of the corpus, and the Bonwill height.

Management of idiopathic sleep bruxism in children and adolescents: A systematic review of the literature.

AIM: Primary sleep bruxism (SB) affects between 6 and 30% of children and adolescents. Its frequency increases with age, reaching a peak at 10-14 years of age, after which it drops until adulthood. The treatment of SB has not been extensively documented, resulting in a lack of reference points and legitimate concerns for dentists in their everyday practice. The aim of this literature review was to summarize the available evidence on the management of SB in children and adolescents and the efficacy of the different approaches. METHOD: A systematic literature search was conducted according to PRISMA guidelines from January 2006 to December 2020 using the PubMed, The Cochrane Library, Science Direct, and Google Scholar databases. All types of SB treatment were accepted. Eight studies were selected for their protocol quality, according to the PICOS tool. RESULTS: Several treatment methods were assessed from the eight clinical studies selected, such as occlusal splint, palatal expansion, and pharmacological treatment. Assessment of the treatment methods was difficult because only eight studies were selected, and both the treatment methods and the study protocols used were different. The therapeutic strategies found in the literature were based on the general condition of the case. Treatment approaches were distinguished into treatments for isolated SB and those for SB associated with ventilatory disorders. CONCLUSION: The current study shows the need to define diagnostic criteria adapted to SB in children in order to improve epidemiological surveys and subsequently clinical practice. To overcome the difficulties related to SB diagnostic criteria, a multidisciplinary approach, involving pediatricians, otorhinolaryngologists, and dental practitioners, is essential for a better management and follow-up of young patients. A case-by-case approach, taking into account the specificities of each young patient, seems the most appropriate management today.

Occlusal devices in France: An assessment of professional practice.

STATEMENT OF PROBLEM: Whether recommendations for the use of occlusal devices are made uniformly in terms of indications, designs, and wearing time is unclear. Different recommendations may lead to different clinical outcomes. PURPOSE: The purpose of this survey was to assess the professional practice of dental surgeons in France regarding the use of occlusal devices. MATERIAL AND METHODS: A 26-question cross-sectional survey was sent to a panel of French dentists via the County Councils of the Dental Order. The questionnaire concerned the amount of occlusion-related treatment, the use of an anterior deprogramming device, stabilization splint, and anterior repositioning appliance, and the patient follow-up as well as the drawbacks of using an occlusal device as a therapeutic solution. The statistical tests used in the study were the chi-square test and the Yate correction for continuity. RESULTS: A total of 771 responses were received. Invasive options were still reported as being used as a first-line treatment for temporomandibular disorder, although a statistical difference was found between experienced and recently graduated practitioners, with recent graduates preferring noninvasive options as first-line treatment. Also, the results showed that anterior deprogramming devices were not used or that their application, particularly the length of treatment, was unfamiliar to practitioners. The anterior repositioning appliance seems to be used, but only a few practitioners integrate it into their practice. In general, about one-third of dentists appear to have a good knowledge of occlusion-related treatments, in particular, the use of occlusal devices. CONCLUSIONS: The results indicated that only 20% to 30% of practitioners have good knowledge of contemporary occlusion-related practice. There is a need for the standardization of practice and improved education for practitioners in the use of occlusal devices.

[What is a malocclusion?] / Qu'est-ce qu'une malocclusion ?

Since 1907, the international community has used Angle's classification to assess the mesio-distal relationships of the dental arches. It is the basis of the diagnosis of malocclusion in the sagittal dimension and indicates or not an orthodontic correction treatment. This work was aimed to inventory the classification methods of malocclusions used today. Indices of treatment need were also presented because they are based on one or more occlusal anomalies to indicate treatment. The classifications were criticized and the contribution of a functional analysis based on the use of the trilogy setting, centering and guiding was detailed. The type of anomalies (skeletal and dental) must be completed by the analysis of the occlusal anomaly of setting (centering or guiding) and of the category of occlusion (functional occlusion, functional malocclusion or pathogenic malocclusion), ie its possible pathogenic impact on orofacial structures. A consensus on the classification of occlusal anomalies is necessary in order to better identify the anomalies and their global repercussions, and to better define the needs for orthodontic treatment.

Disc displacement without reduction: a retrospective study of a clinical diagnostic sign.

OBJECTIVE: The purpose of this retrospective study is to evaluate a clinical diagnostic sign for disc displacement without reduction (DDWR), the absence of additional condylar translation during opening compared with protrusion. METHOD: Thirty-eight electronic axiographic and magnetic resonance imaging (MRI) examinations of the TMJ were analyzed in order to compare the opening/protrusion ratio of condylar translation between non-painful DDWR and non-DDWR. RESULT: According to the Mann-Whitney U test, the opening/protrusion ratio in non-painful DDWR differs significantly from non-DDWR (p < 0.0001). DISCUSSION: Among non-painful DDWR, there is no additional condylar translation during opening in comparison with protrusion, and this is probably also the case for DDWR without limited opening, which is a subtype that has not been validated by the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Comparative condylar palpation can analyze this sign, and therefore, further comparative investigations between MRI and clinical examination are needed to validate the corresponding clinical test.

[Focus on the occlusal failure]. / Regards sur l'insuccès occlusal.

The success is evidenced by the longevity of aesthetic and functional therapeutic result. The occlusal «postorthodontic¼ failure could result in dental instability, functional discomfort, dental or musculo-articular complaint. Analysis of the occlusion research potential occlusal pathogenic dysfunction listed in stabilizing (shimming), centering and guiding anomalies. The large capacity of tolerance of the masticatory system makes it difficult to define the border between physiology and pathology but it is necessary to have benchmarks that can be summarized as follows: - shimming: occlusal contact of mesio-lingual cusp of the first maxillary molars (in Class I, II or III) and occlusal contacts between the canines antagonists; - centering: no transversal deflected occlusion between maximal Intercuspation (ICP) and occlusion in Centric Relation (RCP); - guiding: absence of posterior interference, absence of anterior interference (locking).

[Maxillo-facial surgery in skeletal Class II: repercussions on the temporo-mandibular joints]. / La chirurgie des cas de classe II et ses répercussions sur les articulations temporo-mandibulaires.

These interventions usually aimed at the correction of the skeletal discrepancy by mandibular retrognatism with an advancement of the distal portion of the mandible after mandibular osteotomy. The position of the condyle is determined during the osteosynthesis with miniplates. Condyles are set back in relation with the supine position of the patient and the weakness of his (her) curarized muscle. All studies show that surgery of mandibular advancement causes a lateral, torque and backward movement of the condyles, all harmful to the condyles. Factors that predispose to condylar resorption are "the patient": a woman, young (between 15 and 40), high mandibular angle, with a history of temporo-mandibular disorders and surgical overload applied to the condyles. What are the possible solutions to avoid failures? Patient preparation before surgery and surgery simulation with an articulator, condylar position control during surgery, working with surgeons to achieve a condylar portion stabilization system (with the CAD), quickly set up a mobilization of the mandible by physiotherapy.

Optimal placement of the two anterior implants for the mandibular All-on-4 concept.

The novelty of the All-on-4 concept for a mandibular implant-supported fixed dental prosthesis is the inclination of the posterior implants. Typically, the anterior implants are placed lingually relative to the canine/incisor teeth and perpendicular relative to the occlusal plane. According to the laws of elementary biomechanics, the long axis of the implant unit should be aligned to the axis of the occlusal loading forces during clenching in the maximal intercuspal position. When several implants are connected by a prosthesis, the mean axis of the overall occlusal loading must be taken into account. The objective of this report was to propose a different position for anterior implants by tilting them labially to counterbalance the distal inclination of the posterior implants.