Incidence of temporomandibular joint clicking in adolescents with and without unilateral posterior cross-bite: a 10-year follow-up study

The temporomandibular joint disc: A complex fable about an elusive butterfly

INTRODUCTION

Discussions related to the diagnosis and management of temporomandibular joint (TMJ) disorders (TMDs) have always been interesting, and at times controversial, since they involve combinations of dental, medical, and surgical etiological theories and management strategies. Amongst the various recommendations that emerged over the years was that any dental and surgical procedures that are primarily focused on mandible repositioning and irreversible changes to dental occlusion should be avoided. This statement has important implications for appraising the validity of physiopathology concepts and treatment proposals centered around the evaluation of TMJ disc position, since they also generally lead to performing irreversible procedures.

METHODS

A review of the pertinent TMJ literature related to the articular disc position and its association with TMD symptoms was carried out by the authors.

RESULTS

For many practitioners, the position of the TMJ disc has been regarded as a primary cause of TMJ pain and dysfunction. For decades, incoordination between the TMJ disc, the condylar head and the articular eminence was indeed considered the main factor for the etiology of intracapsular TMD symptoms and consequently an important target for therapy. However, research has shown that synovitis is the more important variable in dealing with those conditions.

CONCLUSION

In this commentary, the biological rationale to consider synovitis, rather than disc position, as the linchpin for clinical symptoms is presented in detail. Hopefully, this might contribute to putting the elusive butterfly characteristics of this topic finally to rest.

The impact of malocclusion on the prevalence of pain-related temporomandibular disorders in children and adolescents: a systematic review

Background

The connection between occlusion and temporomandibular disorders (TMD) remains a topic of discussion, and current research does not provide a definitive answer. Pain-related TMD are the most common types of TMD. They include myalgia, arthralgia, and headaches attributed to TMD. This systematic review aims to synthesize the current scientific evidence regarding impact of malocclusion on the prevalence of pain-related TMD in individuals under 18 years.

Methods

The study was based on a searching of the PubMed, Scopus, Embase, and Web of Science databases. Selection was limited to studies that explored the link between malocclusion and pain-related TMD in young individuals. The Newcastle-Ottawa Scale (NOS) was used to evaluate the quality of the selected research. The certainty of evidence was assessed using the Grading Recommendations Assessment, Development and Evaluation (GRADE) approach. A visual representation of the screening and inclusion processes was created using a Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) diagram. The information from the research was then summarized in a descriptive format.

Results

Out of 868 potentially relevant articles initially identified, 13 studies were selected based on the inclusion criteria. The majority of these studies were determined to be of moderate quality, according to the NOS assessment. The certainty of evidence was assessed as low, according to the GRADE approach. Most of the studies showed that malocclusion may be associated with TMD-pain signs/symptoms in children and adolescents. The most frequent relationship was found between the prevalence of pain-related TMD and posterior crossbite, Class II malocclusion, Class III malocclusion, and anterior open bite.

Conclusion

Certain types of malocclusion may have an impact on the prevalence of some TMD-pain signs and symptoms in young individuals. However, given the limited reliability of existing research and the inconsistencies observed across studies, additional well-structured, long-term investigations are necessary.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42024570950.

Prevalence of psychosocial findings and their correlation with TMD symptoms in an adult population sample

BACKGROUND AND AIM

Some studies suggested an association between Temporomandibular Disorders (TMD) and psychosocial status, but most of them are focused on samples of patients looking for treatment or present limits of sample representativeness. The aim of the present study was to evaluate the psychosocial status in a large sample of adult population, further than to assess its association to TMD symptoms, oral behaviours, and self-reported facial trauma.

RESULTS

the study sample included 4299 subjects older than 18 years randomly recruited from general population in public spaces during their daily life (1700 Males, 2599 Females mean ± SD age = 40.4 ± 18.1). Psychosocial status and pain-related disability were assessed by means of Patient Health Questionnaire 4 (PHQ-4) and Graded Chronic Pain Scale (GCPS). TMD symptoms were assessed by RDC/TMD and validated screening tools for TMD pain. Oral Behaviours Checklist was used to investigate on oral behaviours. Logistic regression model was used to evaluate the association of the psychosocial status, TMD symptoms, trauma, and oral behaviours. The association was tested using both univariate and multivariate models. The PHQ4 evaluation showed a severe impairment in 4.6% of our sample, moderate in 18.8% and mild in 32.5%. We found a Characteristic Pain Intensity (CPI) level and Interference Score greater that 30 respectively in 36.2% and 22.2% of the study sample. The GCPS status revealed a high disability with severe limitation in 2.5% of the sample, high disability with moderate limitation in 7.0%, low disability high pain intensity in 7.4% and low disability low pain intensity in 37.8%. Anxiety and depression's levels were significantly associated with gender, TMD pain, coexistence of TMD Pain and sound, and oral behaviours. GCPS status was significantly associated with age, TMD Pain, coexistence of TMD pain and sound, trauma, and oral behaviours.

CONCLUSIONS

In the general population, psychosocial impairment is associated to TMD pain, female gender, and report of oral behaviours. Hence, in adults with TMD accompanied by pain, psychosocial status should also be evaluated.

Positional, morphologic, and volumetric differences in TMJ in unilateral posterior crossbites and controls: A retrospective CBCT study

OBJECTIVES

The objective of this study was to evaluate if there are any morphologic, positional, and volumetric differences in the temporomandibular joint (TMJ) of patients with unilateral posterior crossbite (UPC) compared to controls. Another objective was to analyse the discrepancy in the TMJ between the crossbite versus non-crossbite side in UPC versus right and left sides in controls. Additionally, this study aimed to evaluate the differences in the bone density at the masseteric insertion site at the angle of mandible in the UPC group and control group.

MATERIAL AND METHODS

One hundred and thirty-two CBCTs were analysed with 66 patients in UPC group and 66 patients in control group (non-crossbite). Temporomandibular joint spaces - Anterior joint space (AJS), Superior joint space (SJS), Posterior joint space (PJS), Medial joint space (MJS), Middle joint space (MiJS), and Lateral joint space (LJS) were measured. Additionally, bone density at angle of mandible and volume of mandibular condyle were evaluated. The measurements were compared between the groups as well as between the crossbite and non-crossbite sides within the UPC group and between right and left sides within the control group. Furthermore, the associations between UPC and changes in TMJ regarding joint space availability, bone density, condylar head volume, and the effects of sex and age were evaluated using regression analysis.

RESULTS

It was observed that UPC group showed a greater condylar volume, than the control group. Additionally, a larger mean discrepancy was observed between the crossbite side and non-crossbite side within the UPC group concerning condylar volume than controls. Concerning age, condylar volume was observed to be larger in adults than children. Adults showed significantly greater bone density and condylar volume than adolescents. Concerning sex, it was observed that males showed a larger SJS (right), MiJS, LJS, and bone density at the mandibular angle than females.

CONCLUSION

There is a difference in the TMJ parameters particularly condylar volume in patients with UPC compared to controls.

The dynamic progression of temporomandibular joint osteoarthritis-like lesions elicited by mandibular shift in a rat model

BACKGROUND

Temporomandibular joint osteoarthritis (TMJ-OA) presents significant challenges due to its complex etiology, often insidious onset, high incidence, and progressive structural deterioration. While research has explored genetic and molecular factors, treatment outcomes remain suboptimal, emphasizing the need for a deeper understanding of disease progression.

OBJECTIVE

This study employs a specific mandibular shift rat model to explore the dynamic progression of TMJ-OA-like lesions and evaluate the potential for self-repair at different stages, aiming to inform early diagnosis and preventative strategies.

METHODS

Seventy-two female Sprague-Dawley rats were randomized into three groups: a control group (n=24; average weight: 157.23±1.63 g) receiving sham surgery. an experimental group (n=24; average weight: 157.78±1.88 g) subjected to mandibular shift induction, and a removal group (n=24; average weight: 158.11±2.20 g) experiencing mandibular shift for one, two, or four weeks followed by a one-month recovery period (designated as 1w Removal, 2w Removal and 4w Removal, respectively). Histomorphological and molecular analyses were conducted at designated time points.

RESULTS

Rats in the 1-week removal group exhibited substantial recovery in condylar morphology, cartilage thickness, extracellular matrix composition, and expression of OA-related genes. Conversely, the 4-week removal group mirrored the experimental group, indicating limited self-repair capacity at later stages. The 2-week removal group presented with variable outcomes, with some animals showing signs of recovery and others resembling the experimental group, indicating a potential transitional phase in the disease process.

CONCLUSION

Recovery from early-stage TMJ-OA involves eliminating provoking factors such as occlusal interference or reducing joint loading. However, advanced stages exhibit diminished self-repair capabilities, necessitating additional therapeutic interventions. These findings emphasize the importance of early diagnosis and intervention in TMJ-OA management.

Relationship between natural or iatrogenic malocclusions and temporomandibular disorders: A case control study

OBJECTIVE

To investigate the link between malocclusions and temporomandibular disorders (TMD) with a focus on iatrogenic malocclusion. Other etiologies of TMD (oral parafunctions) were also assessed.

METHODS

The prevalence of malocclusions was correlated in two groups: patients with TMD (case group) and patients without TMD (control group). Malocclusions involving dental care were specified. Parafunctions in the case group were assessed.

RESULTS

A statistically significant association between TMD and overbite >4 mm, interferences in laterotrusion, and absence of Angle Class I was shown. A potential deleterious effect of iatrogenic malocclusions was highlighted.

CONCLUSION

The multifactorial etiology of TMD was confirmed because an association between TMD and three malocclusions was found, and all case patients had parafunction(s). Current recommendations advising first a reversible treatment, TMD care should start with a behavioral re-education to remove parafunctions. However, it is essential to avoid creating iatrogenic malocclusion during dental care.

Investigating the effect of obsessive-compulsive disorder on clinical symptoms of temporomandibular joint disorders

OBJECTIVES

Temporomandibular disorders (TMD) are a group of clinical conditions involving muscles of mastication, temporomandibular joint (TMJ), and related structures or both. TMD is characterized by facial pain in TMJ and muscles of mastication, limitation or deviation of jaw movement, and TMJ sounds during jaw movement and function. The highest risk of TMD prevalence is between 18 and 24 years, and a relationship is between chronic TMD and psychological disorders such as stress and depression. The knowledge of the function of this joint and those with TMD symptoms when visiting the dentist will help to provide an ideal treatment plan for the patient. Therefore, if the therapist is familiar with the various etiological factors of this disorder, he will provide better treatment, especially if the simultaneous effect of psychological factors such as stress and obsessive-compulsive disorder (OCD) along with occlusal factors such as posterior cross-bite, overjet, and overbite is measured, it can be a valuable guide for clinicians.

METHODS AND MATERIALS

In this study, 385 patients were examined by DASS42 and Maudsley's test and classified into normal, with stress, and stress plus OCD groups. TMJ was examined for each of them by the TMD-RDC test. The presence or absence of TMD was noted in their file.

RESULTS

The prevalence of TMD was 20.7% in the normal group, 30.70% in the stress group, and 44.68% in the stress and OCD group. After analyzing the data by SPSS 24 and performing analysis of variance and Duncan tests, no significant difference was found between the probability of TMD in normal and stressed groups, but the stress and OCD group has a higher chance of TMD.

CONCLUSION

Although the co-occurrence of stress and OCD is associated with the prevalence of TMD, it cannot be considered a cause of TMD.

Orthodontics and Temporomandibular Disorders: An Overview

The relationship between orthodontics and temporomandibular disorders (TMDs) constitutes a subject of paramount significance in dental and craniofacial health. This abstract embarks upon an in-depth examination of the intricate connection between orthodontic practices and TMD, primarily focusing on evaluating the impact of orthodontic treatment modalities on the health and functionality of the temporomandibular joint (TMJ). This exploration elucidates the multifaceted interplay between orthodontic interventions and TMD by traversing a landscape of scholarly research and empirical investigations. The review draws from a broad spectrum of studies to analyze the potential influence of orthodontic treatments, which encompass occlusal adjustments and alterations in jaw positioning, on the development and management of TMD symptoms. The inquiry delves into the diverse range of TMD conditions, considering the implications of orthodontic techniques on occlusal stability, condylar alignment, and overall TMJ function. Through a comprehensive synthesis of the available body of knowledge, this abstract aspires to equip dental practitioners, orthodontists, and researchers with a nuanced understanding of the complex dynamics that govern the relationship between orthodontics and TMD. This knowledge, in turn, offers a foundation for informed clinical decision-making and the formulation of effective treatment strategies for patients presenting with TMD symptoms. By shedding light on the intricate interactions between orthodontic procedures and TMJ health, this abstract contributes to the advancement of clinical practices, promoting improved patient outcomes and well-being in the context of both orthodontics and TMDs.

Malocclusion complexity as an associated factor for temporomandibular disorders. A case-control study

OBJECTIVE

To evaluate the association between temporomandibular disorders (TMD) and malocclusion complexity using the Index of Complexity Outcome and Need (ICON) levels.

METHODS

A prospective, cross-sectional, case and control study was done. Cases and controls were matched in a one-to-one relationship (179 subjects each). The Research Diagnostic Criteria was used to evaluate the presence of TMD, and the ICON was used to quantify malocclusion complexity. A binary logistic regression (p < 0.05) was used to identify associations between variables.

RESULTS

TMD presence was associated with gender and malocclusion complexity (p < 0.05). The largest proportion of controls were in the lowest three levels of ICON complexity, while most cases were in the three highest levels (p < 0.001). Higher malocclusion complexity indicated a greater TMD risk.

CONCLUSION

The results indicate that TMD is associated with malocclusion complexity. As malocclusion complexity increases, so do the odds of presenting with TMD.

Malocclusion Complexity in Patients with Disc Displacement Disorders: A Case-Control Study

This study aimed to determine the possible association between disc displacement (DD) disorders and malocclusion complexity. This cross-sectional study was carried out using a case-control design. The Research Diagnosis Criteria for Temporomandibular Disorders were used to identify cases and controls. The Index of Complexity, Outcome, and Need (ICON) was used to quantify malocclusion complexity as easy, mild, moderate, difficult, or very difficult. A total of 310 subjects were included: 130 cases and 180 controls. A binary logistic regression (p < 0.05) was used to identify associations. The odds ratio (OR) was also calculated. DD was associated with sex, age, and malocclusion complexity (p < 0.05). The malocclusion complexity comparison showed that 89.3% of the controls fell within the easy-moderate levels of the ICON, whereas 85.4% of the cases were in the moderate-very difficult levels (p ≤ 0.001). Difficult and very difficult malocclusions had high ORs (9.801 and 9.689, respectively) compared to the easy cases. In conclusion, patients with malocclusion complexity levels classified as difficult or very difficult have greater odds of presenting DD.

Neural Basis of Etiopathogenesis and Treatment of Cervicogenic Orofacial Pain

(1) Background and Objectives: The aim of this narrative review was to analyze the neuroanatomical and neurophysiological basis of cervicogenic pain in cervico-cranial pain syndromes, focusing particularly on cervico-orofacial syndromes as a background for the proper diagnosis and non-surgical treatment. Relevant literature on the topic from past 120 years has been surveyed. (2) Material and Methods: We surveyed all original papers, reviews, or short communications published in the English, Spanish, Czech or Slovak languages from 1900 to 2020 in major journals. (3) Results: The cervicogenic headache originates from the spinal trigeminal nucleus where axons from the C₁–C₃ cervical spinal nerves and three branches of the trigeminal nerve converge (trigeminocervical convergence) at the interneurons that mediate cranio-cervical nociceptive interactions. The role of the temporomandibular joint in the broad clinical picture is also important. Despite abundant available experimental and clinical data, cervicogenic orofacial pain may be challenging to diagnose and treat. Crucial non-surgical therapeutic approach is the orthopedic manual therapy focused on correction of body posture, proper alignment of cervical vertebra and restoration of normal function of temporomandibular joint and occlusion. In addition, two novel concepts for the functional synthesis of cervico-cranial interactions are the tricentric concept of mouth sensorimotor control and the concept of a cervicogenic origin of bruxism. (4) Conclusions: Understanding the basis of neuroanatomical and neurophysiological neuromuscular relations enables an effective therapeutic approach based principally on orthopedic manual and dental occlusal treatment.

Prevalence of temporomandibular disorders and its association with malocclusion in children: A transversal study

This study investigated the prevalence of temporomandibular disorders (TMDs) in a sample of children and adolescents and evaluated the correlation with occlusal variables. TMD signs and symptoms were recorded in 411 subjects (age range 7-15 years), divided into two groups: 214 subjects treated in Chieti (Italy) CG group and 197 in Murcia (Spain) MG group. Once the Angle dental class was identified, it was recorded if there were signs and symptoms of temporomandibular disorders (TMDs) and occlusal interferences. The percentages of signs and symptoms were compared to determine the differences among the groups for TMDs, bruxism, joint sounds, deviation during the opening, reduced opening/lateral/protrusive movements, malocclusions, and myofascial pain. There is no statistically significant difference between the two groups (χ² = 1.057, p > 0.05). Subjects with Angle Class I (37.37%), deep bite (43.43%), and increased overjet (41.41%) showed a higher prevalence of TMD symptoms.

Effects of functional mandibular lateral shift on craniofacial growth and development in growing rats

BACKGROUND

Unilateral posterior crossbite, one of the most frequent malocclusions, is often associated with functional lateral shift of the mandible. Although the effects of functional lateral shift on the mandible and temporomandibular joint have been examined in various animal experiments, cranial and maxillary changes have received less attention.

OBJECTIVE

This study investigated the effects of functional lateral shift on the craniofacial complex in growing rats.

METHODS

Eighty 5-week-old male Sprague-Dawley rats were randomly. divided into an experimental group (n=40), which received an oblique guide appliance that shifted the mandible to the left during closure, and a control group (n=40). The rats were scanned by cone-beam computed tomography at 3 days and 1, 2, 4, and 8 weeks. The dimensions of the mandibular bone, condyle, maxilla and cranium were measured.

RESULTS

The mandibles of rats in the experimental group were smaller than those of the rats in the control group and were asymmetrical. The condyles of the rats in the experimental group were thinner than those of the control rats. The condylar length on the ipsilateral side was shorter and wider than that on the contralateral side from 4 to 8 weeks. No significant differences in cranial length or height were observed between the experimental and control groups. The height of the upper first molar and alveolar bone on the contralateral side was significantly smaller than that on the ipsilateral side and in the controls from 4 to 8 weeks.

CONCLUSION

Functional shift in the mandible produces morphological asymmetries in the mandible and maxillary region and may cause bilateral condylar degenerative changes.

Evaluation of the three-dimensional (3D) position of cervical vertebrae in individuals with unilateral posterior crossbite

OBJECTIVE

To evaluate the three-dimensional (3D) position of the cervical vertebrae of growing subjects with unilateral posterior crossbite (UPC).

MATERIALS AND METHODS

In this cross-sectional study, cone beam computed tomography (CBCT) scans of 1455 patients were screened, and ultimately 58 scans (26 patients with UPC and 32 controls with normal occlusion) were included after imposing inclusion/exclusion criteria. Roll, yaw, and deviation of the geometric center of C1, C2, and C3 vertebrae were measured and compared between groups. A correlation between these parameters and different variables on mandibular positioning was also carried out.

RESULTS

A statistically significant difference (p < 0.05) was observed between groups for the deviation of pogonium (Pog), mandibular plane roll, and C3 roll, and patients with UPC showed higher cant or deviation. A significant correlation was reported for the roll of C2 and C3 with the deviation of Pog, a roll of the occlusal plane, and roll of the mandibular plane (p < 0.05). The greater the deviation of the Pog to one side, the greater the roll of the vertebrae with this same side up. The same tendency was observed between the roll of the occlusal plane or the mandibular plane with the roll of these cervical vertebrae.

CONCLUSIONS

There is a positive correlation between transverse occlusal changes and positional deviations of the cervical vertebrae, especially C2 and C3.

CLINICAL RELEVANCE

The study results do not allow us to infer the clinical/functional consequences of these deviations, as well as if malocclusion's treatment would result in an improvement of intervertebral relationships.

Cone beam computed tomographic evaluation of the changes in condylar position in growing patients with unilateral posterior crossbite undergoing rapid maxillary expansion followed by fixed orthodontic therapy

PURPOSE

This study aimed at assessing changes in condylar position (CP) in growing patients with unilateral posterior crossbite (UPC) undergoing rapid maxillary expansion (RME) followed by fixed orthodontic treatment (FOT) (experimental-group); and growing patients without posterior crossbite (PC) treated with FOT alone (control-group).

METHODS

Cone beam computed tomography (CBCT) images were obtained before treatment (T0), 6 months after RME (T1) and after FOT (T2) for the experimental-group (n = 19); and at T0 and T2 for the control-group (n = 22). Condylar position-related measurements including the anterior joint space (AJS), superior joint space (SJS), posterior joint space (PJS), lateral position of condyle (LC) and condylar angle (CA) were measured. Non-parametric tests were used.

RESULTS

On the crossbite side, significant increases were found in LC (P = 0.039) and CA (P = 0.007), and on the non-crossbite side significant increases were observed in SJS (P = 0.027) and LC (P = 0.001) between T0, T1 and T2 in patients with UPC. On the right and left sides in the control-group, significant increases were identified in LC (P < 0.001 and P = 0.012, respectively) between T0 and T2.

CONCLUSIONS

In growing patients with UPC, RME followed by FOT is associated with significant changes in CP-related measurements.

Prevalence of temporomandibular disorder pain, jaw noises and oral behaviours in an adult Italian population sample

To evaluate the prevalence of temporomandibular disorder pain (TMD-pain), temporomandibular joint (TMJ) noises, oral behaviours in an Italian adult population sample, their possible association with gender, oral behaviours, self-reported facial trauma and orthodontic treatment. Subjects older than 18 years were recruited from general population in public spaces during their daily life. A specific questionnaire was developed to collect data on TMD-pain, TMJ noises, oral behaviours, orthodontic treatment and facial trauma. A total of 4299 subjects were included in the study. The most common symptom in the sample was TMJ clicking (30.7%), followed by TMD-pain (16.3%) and TMJ crepitus (10.3%). Oral behaviours were reported in 29% of the sample; 43.6% of the sample reported a previous or ongoing orthodontic treatment. TMD-pain and TMJ clicking were significantly associated to gender, oral behaviours and a positive history of previous facial trauma. Crepitus was significantly associated to oral behaviours, facial trauma and higher age. Ongoing orthodontic treatment was significantly associated to TMD-pain and TMJ sounds. In a general Italian adult population sample, TMD-pain is associated to female gender and is less prevalent than TMJ clicking. TMDs are associated to trauma and oral behaviours.

Association between posterior crossbite and/or deep bite and temporomandibular disorders among Palestinian adolescents: A sex comparison

Objective: To assess the prevalence of temporomandibular disorders (TMDs) and posterior crossbite and/or deep bite and any possible association between them. Methods: One thousand-nineteen adolescents responded to a questionnaire regarding oral habits and TMD symptoms. Afterwards, they were diagnosed according to the Axis I of the DC/TMD and underwent a dental examination. The chi-square test was used for statistical analysis. Results: A significant association  was found between posterior crossbite and some TMD diagnosis, but no association was found between deep bite and TMD, nor between occlusal diagnosis and bruxism. TMDs were more prevalent in girls. There was a significant sex difference (more among females) in the prevalence of painful TMDs. Conclusion: Posterior crossbite in the adolescent population analyzed may be related to TMDs, in contrary to deep-bite. The presence of posterior crossbite may have different impact on TMD findings between the sexes.

Evaluation of masticatory muscle activity in patients with unilateral posterior crossbite before and after rapid maxillary expansion

Objectives

The relationship between unilateral posterior crossbite (UPCB) and the possible asymmetric activation of the jaw muscles in children is still under debate. This study aimed at evaluating the jaw muscle activity of children with UPCB before and after rapid maxillary expansion (RME) by means of surface electromyography and a standardized sampling protocol.

Subjects and methods

Twenty-nine children with UPCB (UPCB-group, mean age 9.6 ± 1.6 years) and 40 UPCB-free controls (Control-group, 10.5 ± 1.1) were recruited. The activity of the left and right anterior temporalis (AT) and superficial masseter muscles (MM) was recorded during maximum voluntary clenching and a chewing task (T0). In the UPCB-group, data were collected, also, after the correction of the UPCB with RME (T1) and 6 months later (T2), without any further treatment. Electromyographic indices comparing the activity of paired muscle were computed via software to estimate the extent of asymmetric AT and MM activity. Paired and unpaired t-test or Wilcoxon-signed rank and Mann-Whitney U test, ANOVA or Friedman test and chi-squared test were used in the statistical analysis.

Results

Both groups presented with asymmetric activity of the muscles, which did not differ between groups (T0, all P > 0.05). The treatment determined a decrease in muscular activity (T1, P = 0.040), and a more asymmetric pattern of muscle activation during chewing (T1, P = 0.040), which returned similar to baseline values at T2 (all P > 0.05).

Conclusions

UPCB does not contribute to an asymmetric activation of AT and MM during functional tasks. The treatment of UPCB by RME did not determine a more symmetric activity of the assessed muscles.

Rapid maxillary expansion in the treatment of the functional posterior crossbite: joint noise and electromyographic activity analysis

Abstract Introduction The rapid maxillary expansion (RME) reduces the risk of developing structural and functional disorders in the stomatognathic system. Objective To examine the effects of the RME as a treatment for the posterior crossbite, related with the electromyographic activity of the masticatory muscles and the TMJ noises in a population of children. Material and method 13 girls and 7 boys, regardless of the type of malocclusion, with a mean age of 9 years old (± 3), were treated with RME. The electrovibratography analyzed the TMJ noise, and the electromyography analyzed the masticatory muscles before treatment (T0) and after three months of a short-term follow-up (T1). The comparisons of the affected and unaffected sides by the crossbite were performed using Mann-Whitney’s test, and to compare data before and after treatment the Wilcoxon’s test was used (level of significance: 5%). Result No significant differences were found in the parameters of joint noise in comparison to the sides affected and unaffected by the crossbite, in both T0 and T1 (p>0.05); only the side without the crossbite observed decrease in the peak amplitude of the joint noises after treatment. In the static electromyographic analysis, inter-side differences were observed before and after treatment, since the deliberate unilateral chewing showed greater asymmetry activity in T0 for both sides, which has been corrected after treatment, improving the functional chewing. Conclusion The proposed treatment did not lead to the occurrence of joint noises and improved the functional pattern of electromyographic activity during chewing at the end of treatment.

Current Evidence About Relationships Among Prosthodontic Planning and Temporomandibular Disorders and/or Bruxism

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION

Prosthodontic planning in patients with temporomandibular disorders and/or bruxism: A systematic review. Manfredini D, Poggio CE. J Prosthet Dent. 2017;117(5):606-13.

SOURCE OF FUNDING

Information not available.

TYPE OF STUDY/DESIGN

Review.

Part II: Temporomandibular Joint (TMJ)-Regeneration, Degeneration, and Adaptation

PURPOSE OF REVIEW

Elucidate temporomandibular joint (TMJ) development and pathophysiology relative to regeneration, degeneration, and adaption.

RECENT FINDINGS

The pharyngeal arch produces a highly conserved stomatognathic system that supports airway and masticatory function. An induced subperiosteal layer of fibrocartilage cushions TMJ functional and parafunctional loads. If the fibrocartilage disc is present, a fractured mandibular condyle (MC) regenerates near the eminence of the fossa via a blastema emanating from the medial periosteal surface of the ramus. TMJ degenerative joint disease (DJD) is a relatively painless osteoarthrosis, resulting in extensive sclerosis, disc destruction, and lytic lesions. Facial form and symmetry may be affected, but the residual bone is vital because distraction continues to lengthen the MC with anabolic bone modeling. Extensive TMJ adaptive, healing, and regenerative potential maintains optimal, life support functions over a lifetime. Unique aspects of TMJ development, function, and pathophysiology may be useful for innovative management of other joints.

Temporomandibular Disorders among Dutch Adolescents: Prevalence and Biological, Psychological, and Social Risk Indicators

Aims

To assess the prevalence rates of pain-related temporomandibular disorders (TMDs) and temporomandibular joint (TMJ) sounds in a large group of Dutch adolescents, aged between 12 and 18 years and to determine if the same biological, psychological, and social risk indicators are related to both TMD pain and TMJ sounds.

Methods

In this cross-sectional questionnaire survey, 4,235 questionnaires were analyzed, with an about equal gender distribution.

Results

The overall prevalence of pain-related TMDs was 21.6% (26.1% for girls and 17.6% for boys) and that of TMJ sounds was 15.5% (19.3% for girls and 11.7% for boys). Logistic regression analyses revealed that the following variables appeared to be the strongest predictors of TMD pain: female gender, increasing age, sleep bruxism, biting on lips and/or cheeks, stress, and feeling sad. Regarding self-reported TMJ sounds, the multiple regression model revealed that female gender, increasing age, awake bruxism, and biting on lips and/or cheeks were the strongest predictors.

Conclusions

TMDs are a common finding among Dutch adolescents. Except for the psychological factors that appeared to be associated with TMD pain only, pain-related TMDs and TMJ sounds shared similar biological risk indicators.