Rheumatoid Arthritis and Osteoarthritis in Adult Women: A Functional Approach to the Stomatognathic System.

Rheumatoid arthritis and osteoarthritis both affect the articular cartilage, and are characterized by signs and symptoms that can affect the functions of the human body. This cross-sectional observational study evaluated electromyographic activity in the masseter and temporalis muscles, molar bite force, and mandibular mobility in adult women with rheumatoid arthritis or osteoarthritis. A total of 42 women were distributed into 3 groups: rheumatoid arthritis group (ARG, n=14); osteoarthritis group (OAG, n=14); and a healthy control group (CG, n=14). Electromyography was used to evaluate mandibular tasks at rest, right and left laterality, protrusion, and dental clenching during maximum voluntary contraction, with and without parafilm, and a dynamometer was used to analyse the right and left molar bite forces. A digital caliper was used to measure the range of mandibular movement for maximum mouth opening, right and left laterality, and protrusion. Statistical analyses were performed, including analysis of variance and Tukey's test (P<0.05). Electromyography showed no significant differences between the groups when evaluating the masticatory muscles during the mandibular tasks. Significant difference was observed between the ARG and CG, however, in the maximum right (P=0.007) and left (P=0.02) molar bite forces. Significant difference was observed in the maximum mouth opening of the ARG and OAG groups compared with that of the CG (P=0.009), suggesting that adult women with rheumatoid arthritis or osteoarthritis experience functional alterations in the stomatognathic system, particularly in molar bite force and maximum mouth opening.

Mandibular movement monitor provides faster, yet accurate diagnosis for obstructive sleep apnoea: A randomised controlled study.

Many patients with obstructive sleep apnoea (OSA) remain undiagnosed and thus untreated, and in part this relates to delay in diagnosis. Novel diagnostic strategies may improve access to diagnosis. In a multicentre, randomised study, we evaluated time to treatment decision in patients referred for suspected OSA, comparing a mandibular movement (MM) monitor to respiratory polygraphy, the most commonly used OSA detection method in the UK. Adults with high pre-test probability OSA were recruited from both northern Scotland and London. 40 participants (70 % male, mean±SD age 46.8 ± 12.9 years, BMI 36.9 ± 7.5 kg/m2, ESS 14.9 ± 4.1) wore a MM monitor and respiratory polygraphy simultaneously overnight and were randomised (1:1) to receive their treatment decision based on results from either device. Compared to respiratory polygraphy, MM monitor reduced time to treatment decision by 6 days (median(IQR): 13.5 (7.0-21.5) vs. 19.5 (13.7-35.5) days, P = 0.017) and saved an estimated 29 min of staff time per patient.

Is there a relationship between the presence of external root resorption in second molars adjacent to impacted mandibular third molars with awake bruxism and masticatory muscle activity?

OBJECTIVES: This study aimed to assess whether awake bruxism and masticatory muscle activity could be related to external root resorption (ERR) in second molars adjacent to impacted mandibular third molars. MATERIALS AND METHODS: Sixty patients, with requests for a cone-beam, computed tomography, were divided into two groups: ERR (patients with ERR in the second molar, n = 30), and control group (n = 30). Awake bruxism was assessed through the Oral Behaviors Checklist (OBC) and an ecological momentary assessment (EMA). Surface electromyography (EMG) was used to assess the masseter and anterior temporal muscle function. Normality and homogeneity of variances were demonstrated. Descriptive analysis was performed, using the T-test and Chi-square test to compare the characteristics of the groups. A multiple regression model was performed. RESULTS: The ERR group presented more non-functional oral activities related to awake bruxism than the control group, according to OBC (p = 0.027) and EMA (p = 0.035). In addition, the ERR group had higher EMG activity than the control group in rest and isotonic protocols (p < 0.05). CONCLUSIONS: Awake bruxism and greater masticatory muscle activity seem to be related to the presence of ERR in second molars adjacent to impacted mandibular third molars. CLINICAL RELEVANCE: The results of the present study can reinforce the theory that triggering ERR in the second molars adjacent to impacted mandibular third molars may be related to mechanical forces coming from the masticatory function.

Effects of athletic tape on orofacial pain and jaw movements after 24 hours of use: a randomized clinical trial. / Efeitos da bandagem elástica na dor orofacial e nos movimentos mandibulares após 24 horas de uso: ensaio clínico randomizado.

PURPOSE: To analyze the sensation of pain and the range of mandibular movements of adult individuals with temporomandibular disorder, before and after the application of the athletic tape. METHOD: This is a double-blind randomized clinical trial, in which 22 adults with temporomandibular disorder participated, randomly allocated into two groups, with group A comprising 10 women and one man (mean age 28.2±8.3 years) and group B comprising nine women and two men (mean age 26.2±3.9 years). Group A was submitted to the application of the athletic tape on the masseter with 40% stretch and the group B to the application of the athletic tape on the masseter without stretching. All participants underwent the application of the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Pain threshold assessment was performed using an algometer to apply pressure to measurement points. The measurement of mandibular movements was performed using a caliper. The athletic tape was glued using the I technique, with a fixed point over the insertion and a movable point over the origin of the masseter muscle. Participants remained with the athletic tape for 24 hours and were re-evaluated. RESULTS: There was pain relief in the group A in the temporomandibular joint on the right and at the origin of the masseter on the left. The group B showed a reduction in pain in the left anterior temporal region. No differences were found in mandibular movements after intervention, as well as no difference was found in the comparison by groups. CONCLUSION: The use of the athletic tape over the masseter muscle, with stretching, for 24 hours produced relief from the sensation of pain, on the origin of the right masseter and in the right temporomandibular joint, and, without stretching, in the left anterior temporal muscle. There was no difference in the range of mandibular movements.

OBJETIVO: Analisar a sensação de dor e amplitude dos movimentos mandibulares de indivíduos adultos com disfunção temporomandibular, antes e após aplicação da bandagem elástica por 24 horas. MÉTODO: Trata-se de um ensaio clínico randomizado duplo-cego, do qual participaram 22 sujeitos adultos com disfunção temporomandibular, alocados aleatoriamente em dois grupos, sendo grupo A composto por 10 mulheres e um homem (média de idade de 28,2±8,3 anos) e grupo B por nove mulheres e dois homens (média de idade de 26,2±3,9 anos). Todos os participantes foram submetidos à aplicação do Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Foi realizada a avaliação do limiar da dor, com uso de um algômetro, para aplicação da pressão no masseter e temporal e medição dos movimentos mandibulares, com paquímetro. O grupo A foi submetido à aplicação da bandagem sobre o músculo masseter com estiramento de 40% e o grupo B sem estiramento. A colagem da bandagem foi realizada, com corte em "I", com ponto fixo sobre a inserção e ponto móvel sobre a origem do músculo masseter. Os participantes permaneceram com a bandagem por 24 horas e foram reavaliados. RESULTADOS: Houve alívio da dor no grupo A na articulação temporomandibular à direita e na origem do masseter à esquerda. O grupo B apresentou redução da dor em região de temporal anterior à esquerda. Não foram encontradas diferenças nos movimentos mandibulares após intervenção, bem como não houve diferença na comparação entre os grupos. CONCLUSÃO: O uso da bandagem sobre o masseter, por 24 horas, com estiramento, produziu alívio da dor na origem do masseter direito e na região da articulação temporomandibular direita e, sem estiramento, no temporal anterior esquerdo. Não houve diferença na amplitude de movimentos mandibulares.

Analysis of mandibular jaw movements to assess ventilatory support management of children with obstructive sleep apnea syndrome treated with positive airway pressure therapies.

BACKGROUND: The polysomnography (PSG) is the gold-standard for obstructive sleep apnea (OSA) syndrome diagnosis and assessment under positive airway pressure (PAP) therapies in children. Recently, an innovative digital medicine solution, including a mandibular jaw movement (MJM) sensor coupled with automated analysis, has been validated as an alternative to PSG for pediatric application. OBJECTIVE: This study aimed to assess the reliability of MJM automated analysis for the assessment of residual apnea/hypopnea events during sleep in children with OSA treated with noninvasive ventilation (NIV) or continuous PAP (CPAP). METHODS: In this open-label prospective non-randomized multicentric trial, we included children aged from 5 to 18 years with a diagnosis of severe OSA. The children underwent in-laboratory PSG with simultaneous MJM monitoring and at-home recording with MJM monitoring 3 months later. Agreement between PSG and MJM analysis in measuring the residual apnea-hypopnea index (AHI) was evaluated by the Bland-Altman method. The treatment effect on residual AHI was estimated for both PSG and MJM analysis. RESULTS: Fifteen (60% males) children were included with a median age of 12 years [interquartile range 8-15]. Two (17%) were ventilated with NIV and 13 (83%) with CPAP. There was a good agreement between MJM-AHI and PSG-AHI with a median bias of -0.25 (95% CI: -3.40 to +2.04) events/h. The reduction in AHI under treatment was consistently significant across the three measurement methods: in-laboratory PSG and MJM recordings in the laboratory and at home. CONCLUSION: Automated analysis of MJM is a highly reliable alternative method to assess residual events in a small population treated with PAP therapies.

Prediction of jaw opening function after mandibular reconstruction using subject-specific musculoskeletal modelling.

BACKGROUND: Mandibular reconstruction patients often suffer abnormalities in the mandibular kinematics. In silico simulations, such as musculoskeletal modelling, can be used to predict post-operative mandibular kinematics. It is important to validate the mandibular musculoskeletal model and analyse the factors influencing its accuracy. OBJECTIVES: To investigate the jaw opening-closing movements after mandibular reconstruction, as predicted by the subject-specific musculoskeletal model, and the factors influencing its accuracy. METHODS: Ten mandibular reconstruction patients were enrolled in this study. Cone-beam computed tomography images, mandibular movements, and surface electromyogram signals were recorded preoperatively. A subject-specific mandibular musculoskeletal model was established to predict surgical outcomes using patient-averaged muscle parameter changes as model inputs. Jaw bone geometry was replaced by surgical planning results, and the muscle insertion sites were registered based on the non-rigid iterative closest point method. The predicted jaw kinematic data were validated based on 6-month post-operative measurements. Correlations between the prediction accuracy and patient characteristics (age, pathology and surgical scope) were further analysed. RESULTS: The root mean square error (RMSE) for lower incisor displacement was 31.4%, and the error for peak magnitude of jaw opening was 4.9 mm. Age, post-operative infection and radiotherapy influenced the prediction accuracy. The amount of masseter detachment showed little correlation with jaw opening. CONCLUSION: The mandibular musculoskeletal model successfully predicted short-range jaw opening functions after mandibular reconstruction. It provides a novel surgical planning method to predict the risk of developing trismus.

Natural History of Mandibular Function in Spinal Muscular Atrophy Types 2 and 3.

Background: Hereditary proximal spinal muscular atrophy (SMA) is characterized by abnormal alpha motor neuron function in brainstem and spinal cord. Bulbar dysfunction, including limited mouth opening, is present in the majority of patients with SMA but it is unknown if and how these problems change during disease course. Objective: In this prospective, observational, longitudinal natural history study we aimed to study bulbar dysfunction in patients with SMA types 2 and 3. Methods: We included 44 patients with SMA types 2 and 3 (mean age was 33.6 (95% CI 28.4;38.9) and re-examined them after on average 4 years. None were treated with SMN-modulating treatments before or during the course of this study. Longitudinal assessments included a questionnaire on mandibular and bulbar function, the Mandibular Function Impairment Questionnaire (MFIQ), and a clinical examination of masticatory performance, maximum voluntary bite force, and mandibular movements including the active maximal mouth opening. Results: We found significant higher MFIQ scores and a significant decrease of all mandibular movements in patients with SMA type 2 (p < 0.001), but not in SMA type 3. Masticatory performance and maximum voluntary bite force did not change significantly. Mean reduction of active maximal mouth opening at follow-up was 3.5 mm in SMA type 2 (95% CI: 2.3; 4.7, p < 0.001). SMA type 2 was an independent predictor for a more severe reduction of the mouth opening (ß= -2.0 mm (95% CI: -3.8; -0.1, p = 0.043)). Conclusions: Bulbar functions such as mandibular mobility and active maximum mouth opening decrease significantly over the course of four years in patients with SMA type 2.

Functional treatment of bilateral posterior crossbite improves mandibular kinematics during chewing.

OBJECTIVES: To evaluate the effects of treatment of bilateral posterior crossbite (BPXB) on mandibular kinematics by the percentage of reverse chewing cycles (RCCs) during soft and hard bolus chewing before and after the correction of the malocclusion with function-generating bite (FGB). MATERIALS AND METHODS: This prospective study included 71 subjects: 19 patients with occlusally symmetric BPXB (M = 9; F = 10; mean age 9.3 ± 2.2[yr.mo]), 32 patients with occlusally asymmetric BPXB (19 with more teeth in crossbite on the right side (right prevalent side), M = 7; F = 12; mean age 8.2 ± 1.6 [yr.mo] and 13 on the left side, M = 7; F = 6; mean age 9.6 ± 1.9 [yr.mo]) and 20 controls without malocclusion (M = 8; F = 12; mean age 10.2 ± 1.7 [yr.mo]). Masticatory patterns were recorded before (T0) and after (T1) the correction of the malocclusion with FGB, with the K7-I® kinesiograph using standardized soft and hard boluses. RESULTS: BPXB was corrected in all included patients. At T0, the percentage of RCCs in BPXB was significantly increased compared to controls (P < .0001); symmetric BPXB showed no difference in RCCs between the sides, whereas asymmetric BPXB showed significantly more RCCs on the side with more teeth in crossbite (prevalent side). After treatment with FGB (T1), the percentage of RCCs was significantly reduced in both symmetric BPXB patients (soft bolus, P = .003; hard bolus, P < .001) and asymmetric BPXB patients (prevalent side: soft and hard bolus, P < .00001; non-prevalent side: soft bolus, P = .01 and hard bolus, P = .0002). CONCLUSION: Functional correction of BPXB with FGB significantly improved mandibular kinematics during chewing.

Pathophysiological mechanisms of oromandibular dystonia.

Oromandibular dystonia (OMD) is a rare form of focal idiopathic dystonia. OMD was clinically identified at the beginning of the 20th century, and the main clinical features have been progressively described over the years. However, OMD has several peculiarities that still remain unexplained, including the high rate of oral trauma, which is often related to the onset of motor symptoms. The purpose of this paper was to formulate a hypothesis regarding the pathophysiology of OMD, starting from the neuroanatomical basis of the masticatory and facial systems and highlighting the features that differentiate this condition from other forms of focal idiopathic dystonia. We provide a brief review of the clinical and etiological features of OMD as well as neurophysiological and neuroimaging findings obtained from studies in patients with OMD. We discuss possible pathophysiological mechanisms underlying OMD and suggest that abnormalities in sensory input processing may play a prominent role in OMD pathophysiology, possibly triggering a cascade of events that results in sensorimotor cortex network dysfunction. Finally, we identify open questions that future studies should address, including the effect of abnormal sensory input processing and oral trauma on the peculiar neurophysiological abnormalities observed in OMD.

An Overview of Anterior Repositioning Splint Therapy for Disc Displacement-related Temporomandibular Disorders.

Anterior repositioning splint (ARS) therapy is considered one of the most effective therapies for treating disc displacement-related temporomandibular disorders (TMDs), which account for a large proportion of TMD cases. Owing to the wide application of this therapy, the exact mechanism of remission has increasingly drawn attention. Given that practitioners have different views on ARS therapy, its indications are broadened, and operating methods diverged. This review attempts to provide an overview of ARS therapy and helps practitioners establish indications and suitable operating methods. Representative views in the past 10 years were summarised, and conclusions were drawn as follows: The mechanism of ARS therapy is mainly attributed to internal derangement correction, improvement of stress distribution and recently reported joint remodeling. It has an evident effect in the short term, and the most prevalent operating methods are protruding the mandible to the edge-to-edge position and wearing the ARS for 24 hours daily for 3-6 months. However, long-term stability is not optimal, and thus indications should be selected carefully. Notably, most of the clinical studies in this field are case analyses with low-quality evidence. Well-designed RCTs are required to further validate relevant theories.

Congenital Isolated Bilateral Soft Tissue Syngnathia In A 4-Day Old Baby Boy.

Congenital maxillomandibular syngnathia is characterized by fusion of jaws. Depending on the severity, it has a wide range of clinical presentations. It can be complete /incomplete and may be unilateral or bilateral. Primary concern in such patients is maintenance of airway and feeding difficulties. Therefore, early recognition and management is important to reduce nutritional, feeding, airway difficulties and growth-related problems in such new-borns. This case report presents a case of syngnathia in a 4-day infant with bilateral fusion of maxilla and mandible, leaving a small anterior portion. Early intervention was planned and the fusion was released to facilitate feeding. Good mouth opening was seen on 1week follow-up.

Preliminary clinical experience of robot-assisted surgery in treatment with genioplasty.

Genioplasty is the main way to treat diseases such as chin asymmetry, dysplasia and overdevelopment, which involve the three-dimensional direction abnormalities of the chin. Since this kind of surgery mainly uses intraoral incisions, the narrow surgical field of intraoral incisions and the surrounding important neurovascular tissues make it easy for complications, to occur during the osteotomy process, which results in greater surgical risks. The first craniofacial-plastic surgical robot (CPSR-I) system is developed to complete the precise positioning and improve the surgeon's force perception ability. The Kalman filtering method is adopted to reduce the interference of sensor signal noise. An adaptive fuzzy control system, which has strong robustness and adaptability to the environment, is designed to improve the stability of robot-assisted surgical operations. To solve the problem of the depth perception, we propose an automatic bone drilling control strategy that combines position and force conditions to ensure that the robot can automatically stop when the bone is penetrated. On the basis of model surgery and animal experiments, preliminary experiments were carried out clinically. Based on the early results of 6 patients, the robot-assisted approach appears to be a safe and effective strategy for genioplasty.

Correção da má oclusão de classe II com propulsor mandibular: revisão de literatura / Correction of class II malocclusion with mandibular trusters: literature review

Introdução: a má oclusão de classe II consiste no desequilíbrio da relação entre as arcadas, podendo ser causada por deficiência mandibular, protrusão maxilar, ou ambas, sendo caracterizada pelo molar inferior distalmente posicionado em relação ao molar superior. Objetivo: este estudo tem o objetivo de apresentar uma revisão de literatura sobre a eficiência dos propulsores mandibulares fixos disponíveis no mercado odontológico no tratamento da má oclusão de classe II. Métodos: a pesquisa foi realizada nas bases de dados Google Acadêmico, SciELO e PubMed, para filtragem dos artigos selecionados. Para revisão de literatura, foram utilizados 17 artigos. Entre os protocolos de tratamento de classe II, esses aparelhos se destacam por serem fixos, por esse motivo, não dependem da colaboração direta do paciente. Com o passar dos anos, os propulsores mandibulares fixos foram cada vez mais aprimorados, oferecendo mais simplicidade na sua instalação e maior conforto ao paciente. Considerações finais: concluiu-se que os aparelhos funcionais propulsores mandibulares fixos são uma ótima escolha para o tratamento compensatório na má oclusão de classe II, sendo eficazes na correção da relação dentária e dependendo de menor cooperação do paciente.(AU)

Introduction: class II malocclusion consists of an imbalance in the relationship between the arches, which can be caused by mandibular deficiency, maxillary protrusion, or both, and is characterized by the mandibular molar distally positioned in relation to the maxillary molar. Objective: this study aims to present a literature review on the efficiency of fixed mandibular thrusters available in the dental market in the treatment of Class II malocclusion. Methods: the research was carried out in the Google Scholar, SciELO and PubMed databases to filter the selected articles. For literature review, 17 articles were used. Among Class II treatment protocols, these devices stand out for being fixed, for this reason, they do not depend on the direct collaboration of the patient. Over the years, fixed mandibular thrusters have been increasingly improved, offering more simplicity in their installation and greater comfort to the patient. Final considerations: it was concluded that the fixed mandibular thrusters functional devices are a great choice for compensatory treatment in Class II malocclusion, being effective in correcting the dental relationship and depending on less patient cooperation.(AU)

Functional analysis of POLD1 p.ser605del variant: the aging phenotype of MDPL syndrome is associated with an impaired DNA repair capacity.

Mandibular hypoplasia, Deafness and Progeroid features with concomitant Lipodystrophy define a rare systemic disorder, named MDPL Syndrome, due to almost always a de novo variant in POLD1 gene, encoding the DNA polymerase δ. We report a MDPL female heterozygote for the recurrent p.Ser605del variant. In order to deepen the functional role of the in frame deletion affecting the polymerase catalytic site of the protein, cellular phenotype has been characterised. MDPL fibroblasts exhibit in vitro nuclear envelope anomalies, accumulation of prelamin A and presence of micronuclei. A decline of cell growth, cellular senescence and a blockage of proliferation in G0/G1 phase complete the aged cellular picture. The evaluation of the genomic instability reveals a delayed recovery from DNA induced-damage. Moreover, the rate of telomere shortening was greater in pathological cells, suggesting the telomere dysfunction as an emerging key feature in MDPL. Our results suggest an alteration in DNA replication/repair function of POLD1 as a primary pathogenetic cause of MDPL. The understanding of the mechanisms linking these cellular characteristics to the accelerated aging and to the wide spectrum of affected tissues and clinical symptoms in the MDPL patients may provide opportunities to develop therapeutic treatments for progeroid syndromes.

Mandibular biomechanical behavior of rats submitted to chronic intermittent or continuous hypoxia and periodontitis.

BACKGROUND: The aim of this study was to investigate the effects of exposure to continuous (CH) and intermittent (IH) hypoxia on biomechanical properties of the mandible and periodontal tissue of animals submitted to experimental periodontitis (EP) when applying loads in a hypoxic environment. METHODS: Adult female Wistar rats were exposed during 90 days to IH or CH (simulated high altitude of 4200 m above sea level). Fourteen days prior to the euthanasia, EP was induced to half of the animals of each group. RESULTS: Only in the rats with EP, IH decreased the maximum capacity of the mandible to withstand load and the limit of elastic load. Indicators of intrinsic properties of the bone material were significantly reduced by both types of hypoxia in rats with EP. Hypoxia enhanced the alveolar bone loss induced by EP in the buccal side of the mandible, without showing additional effects in lingual or interradicular bone. Hypoxia increased prostaglandin E2 content in gingival tissue of healthy animals and further elevated the E2 levels increased by EP. CONCLUSIONS: When periodontitis is present, hypoxic stress induces a decrease in mineral properties that ultimately affects the ability of the mandible to resist load, mainly during intermittent exposure to hypoxia. These effects on bone may be related to the higher levels of prostaglandin E2 reached in the surrounding gingival tissue. The findings of this study may stimulate strategies to prevent unwanted effects of hypoxia on periodontal tissues.

A novel mobile application to determine mandibular and tongue laterality discrimination in women with chronic temporomandibular disorder

BACKGROUND: Chronic pain from temporomandibular disorders (TMDs) is caused by a somatosensory disturbance due to sustained activation of central nervous system nociceptive pathways, which can induce changes in neuroplasticity in the thalamus, basal ganglia and limbic system, as well as disturbances in the somatosensory, prefrontal and orbitofrontal cortex and cognitive impairment. The main objective of this study was to determine the discrimination capacity of mandibular and tongue laterality between women with chronic TMDs and asymptomatic women. MATERIAL AND METHODS: This descriptive-comparative study examined 2 groups with a total of 30 women. All participants were between the ages of 23 and 66 years and were assigned to the chronic TMD group or the asymptomatic group according to the inclusion criteria. We employed a mobile application developed specifically for this study to measure the accuracy and reaction time (RT) of mandibular and tongue laterality discrimination. RESULTS: The chronic TMD group had a lower success rate in laterality discrimination (mean mandibular accuracy of 40% and mean tongue accuracy of 67%) than the asymptomatic group (mean mandibular accuracy of 61% and mean tongue accuracy of 90%). These results showed statistically significant differences between the groups for mandibular laterality discrimination (d, 1.14; p < 0.01) and tongue laterality discrimination (d, 0.79; p = 0.03). The asymptomatic group had faster RTs than the chronic TMD group. The data revealed statistically significant differences for the right mandibular RT (d, 0.89; p=0.02) and right tongue RT (d, 0.83; p = 0.03). However, there were no significant differences for left mandibular and left tongue RT. CONCLUSIONS: We found that the women with chronic TMDs had a lower success rate and slower RTs in the discrimination of mandibular laterality when compared with the asymptomatic women

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Biomechanical study on the changes of stress in temporomandibular joints after the orthognathic surgery in patients with mandibular prognathism: a 3D finite element study.

PURPOSE: This study aimed to analyze the changes of the stress distributions in TMJs for the pre- and postoperative patients with mandibular prognathism under unilateral occlusions, a frequent occlusion in mastication. METHODS: Pre- and six-mouth postoperative cone-beam computed tomography images of thirteen patients diagnosed with mandibular prognathism were scanned and used to construct complete maxillofacial models, assigned as the Pre and Post group, respectively. Another ten asymptomatic individuals were defined as the Control group. The inhomogeneous properties were assigned to the models. The muscle forces and boundary conditions corresponding to left and right unilateral occlusions were applied on the models. The analysis of variation (ANOVA) was chosen for the comparison among the groups. RESULTS: The results showed that the Pre group had abnormal stress distributions ang higher stress level in TMJs, compared with those of the Post and Control groups. Moreover, from clinical cases, symptoms of temporomandibular disorders (TMDs) always followed with increased stresses. CONCLUSION: Generally, orthognathic surgeries could improve the stress distribution in TMJs of the patients with mandibular prognathism under the unilateral occlusions. However, the postoperative complications, especially symptoms of TMD, were closely related to changes of stress for patients with mandibular prognathism after orthognathic surgeries. Individual virtual surgery and finite element analysis should be conducted to prevent complications in TMJ.

Morbidity of marginal mandibular nerve post vascularized submental lymph node flap transplantation.

BACKGROUND: This study investigated the morbidity of the marginal mandibular nerve (MMN) post vascularized submental lymph node (VSLN) harvest. METHODS: The VSLN with sacrifying or preserving the medial platysma was retrospectively classified as group I or II. Midline deviation and horizontal tilt were subjectively evaluated. Horizontal, vertical, and "area distribution" of the lower lip excursions of the surgical site were objectively compared with the nonsurgical site. RESULTS: Seventeen patients in group I and 12 patients in group II were included. At a median follow-up of 48.6 ± 16.8 months in group I and 14.8 ± 7.5 months in group II, no MMN palsy was found in both groups. Median midline deviation and horizontal tilt were 4.53 ± 0.52 and 5 ± 0 in group I and 4.67 ± 0.65 and 5 ± 0 in group II, respectively (P = .419 and 1.000). Median horizontal, vertical and area of distribution of lower lip excursions were 97.5 ± 12.3%, 98.8 ± 14.4% and 87.2 ± 14.7% in group I, and 99.3 ± 15.1%, 95.8 ± 8.2% and 84.2 ± 14.2% in group II, respectively (P = .679, .948 and .711). CONCLUSION: The VSLN flap was a safe procedure with minimal MMN morbidity.