A multiple logistic regression analysis of the risk and relative odds of temporomandibular disorders as a function of common occlusal features

Increasing Vertical Dimension of Occlusion (VDO): Review

The need to increase the Vertical Dimension of Occlusion (VDO) to restore lost dental function or optimise specific dental treatments is a common occurrence in daily dental practice. The common belief that the Vertical Dimension at Rest (VDR) is fixed hinders the development of restorations with a VDO that encroaches on or surpasses the interocclusal rest space (IRS), thereby preventing potential tissue damage to the masticatory apparatus. Recent studies have shown that the mandible rest position falls within a range termed as the "comfort zone". The range of this zone may vary from one person to another and within the same person over time due to factors such as age or health status. In this review, we have concluded that a permanent increase in the VDO, once indicated, is a safe procedure for dentulous patients. However, it is important to minimise the extent of the increase to simplify the prosthodontics treatment process. An inter-incisal increase exceeding 5 mm is seldom needed. Moreover, it is important to consider the functional, aesthetic, and biological elements associated with VDO. The biological and functional environment closely related to the VDO had great adaptive capacities, which have for a historically been underestimated. Patient adaptation has been observed in dentate patients, edentulous patients, and even cases involving implant-supported prostheses. Muscle relaxation and changes in muscle length are likely the primary adaptation mechanisms, rather than the restoration of the original VDO through dentoalveolar maturation. Intervention with a fixed restoration is more predictable and results in a higher and more rapid level of adaptation. Finally, the increase should include the entire arch to prevent relapse of the VDO to its previous value, and changes in VDO should be assessed by utilising temporary diagnostic restorations for a period before implementing definitive prostheses, in order to evaluate the adaptive muscle response.

The association between orthodontic treatment and temporomandibular disorders diagnosis and disease characteristics

BACKGROUND

The association between orthodontic treatment and temporomandibular disorders (TMD) has been contentious in the literature.

OBJECTIVES

To analyse the associations between orthodontic treatment and TMD diagnosis and diseases characteristics.

METHODS

This case-control study included 291 individuals, 192 TMDs and 99 controls. All patients underwent assessment based on a questionnaire and a clinical examination according to Axis I of the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). Differences in orthodontic treatment between TMDs and controls, as well as across different TMD diagnoses within the TMD group were analysed. Patients who underwent orthodontic treatment were compared to those who did not, regarding their trauma history, bruxism, aggressive teeth brushing, level of oral hygiene, pain scores, muscle tenderness scores and subjective sleep quality.

RESULTS

Of the 291 participants, 119 (40.9%) underwent orthodontic treatment and 172 (59.1%) had no orthodontics experience. Orthodontic treatment included: mandibular orthodontic treatment (102 subjects) and maxillary orthodontic treatment (113 subjects) of those 47 used a headgear. Following multivariate analysis among TMDs, orthodontic treatment was associated with a good level of oral hygiene versus poor (Odds ratio [OR]: 5.17 [1.04-25.59]), lower number of tender muscles [OR = 0.84 (0.74-0.96)] and lower (better) Pittsburgh Sleep Quality Index (PSQI) scores (OR = 0.86 [0.76-0.97]). None of the studied parameters maintained a statistically significant association with orthodontic treatment in the multivariate analysis among the entire study population.

CONCLUSIONS

Utilising a holistic approach, this study supports the main hypothesis that orthodontic treatment is not associated with TMD diagnosis and disease characteristics.

Temporomandibular Disorders: Implications in Restorative Dentistry and Orthodontics

Over the past several decades, the science of restorative/reconstructive dentistry and orthodontics has evolved tremendously, following sound principles passed down from robust literature and scientific rationale. These principles have been solid and instrumental in enhancing dentistry, from a single tooth restoration to complex full-mouth rehabilitations. However, it must be noted that some of the principles and philosophies followed over these decades have been questioned based on the advances in science, technology, and evidence-based medicine. The scenario became complex when clinicians were faced with the question of guidance for optimum joint and muscle health as related to restorative dentistry and orthodontics.

Association of congenitally missing teeth with adult temporomandibular disorders in the urban health checkup population

BACKGROUND

Congenitally missing tooth is the most common dental abnormality which leaves spaces in the arch, leads to numerous forms of malocclusion due to the Bolton index discrepancy and is even associated with abnormal craniofacial morphology. Even though the roles of malocclusion and tooth loss in temporomandibular disorders (TMD) development remain controversial, basic researches have found some common molecules are involved in osteoarthritis and dental agenesis. However, the association of congenitally missing teeth with TMD is unknown. We hence investigated the association of congenitally missing teeth with TMD.

METHODS

A cross-sectional analysis of 586 control participants (male: 287, female: 299, 38.33 ± 11.65 years) and 583 participants with non-third molar congenitally missing teeth (male: 238, female: 345, 39.13 ± 11.67 years) who consecutively received routine dental and TMD checkup according to Diagnostic Criteria for Temporomandibular Disorders Axis I in Health Management Center, Xiangya Hospital was performed. Logistic regression analysis was used to study the association of congenitally missing teeth with TMD.

RESULTS

The congenitally missing teeth group included 581 hypodontia and 2 oligodontia participants. The congenitally missing anterior teeth participants, the congenitally missing posterior teeth participants and participants with both congenitally missing anterior and posterior teeth accounted for 88.34%, 8.40% and 3.26% of the congenitally missing teeth group respectively. Congenitally missing teeth group had greater ratios of females and orthodontic history. Participants with congenitally missing teeth had a significantly higher prevalence of overall TMD (67.24%) in comparison to control participants (45.90%). After adjusting age, gender, presence of congenitally missing teeth, number of congenitally missing teeth, number of non-congenitally missing teeth, number of dental quadrants with missing teeth, visible third molar and orthodontic history, the variables of age, gender, presence of congenitally missing teeth and number of dental quadrants with missing teeth were significant for overall TMD. Multivariable logistic regression analysis showed congenitally missing tooth was significantly related with overall TMD [odds ratio (OR):1.689(1.080-2.642), P = 0.022], intra-articular TMD [OR: 1.711(1.103-2.656), P = 0.017] and pain-related TMD [OR: 3.093(1.321-7.239), P = 0.009].

CONCLUSION

Congenitally missing tooth is a risk factor for TMD. When treating the congenitally missing teeth population, TMJ evaluation and multidisciplinary strategies are necessary.

The Role of Maxillofacial Structure and Malocclusion on Condylar Displacement in Maximum Intercuspation and Centric Relation in Patients Seeking Orthodontic Treatment-A Scoping Review

BACKGROUND

Available knowledge about malocclusion and cephalometric variables and their connection with an increased risk of condylar displacement (CD) is scarce. This article aims to present current information on the relationship between centric relation-maximum intercuspal position discrepancies and maxillofacial morphology and malocclusion in patients seeking orthodontic treatment as well as to identify those who require expanded diagnostic evaluation for this disorder.

METHODS

This review analyzed the PubMed, Cochrane Library, Web of Science, and Scopus electronic databases up to February 2022. Keywords and additional manual searches were performed. Literature selection was based the PRISMA-ScR checklist. The JBI Critical Appraisal Tool assessed the methodological quality of included studies.

RESULTS

The databases search provided 2321 studies. A total of 10 studies were included in this review after eligibility criteria and JBI assessment. This review was separated into five parts that evaluated CD correlations depending on the following: maxillofacial structure in different vertical and sagittal skeletal patterns, vertical, horizontal, and transverse malocclusions.

CONCLUSIONS

A hyperdivergent facial skeletal structure is a risk factor for increased CD, particularly in the vertical dimension. The condylar processes are usually displaced in a posteroinferior direction. Further studies are warranted to elucidate the relationship among remaining skeletal and dental malocclusions and the occurrence of CD.

The 50 most-cited articles on temporomandibular disorders: A bibliometric analysis

BACKGROUND

Temporomandibular disorders (TMD) are musculoskeletal conditions involving masticatory muscles and temporomandibular joints. Bibliometric analysis has been introduced as a new method for collecting and analyzing information on scientific articles.

OBJECTIVE

The aim of this study was to identify the 50 most cited articles on TMD, performing a bibliometric analysis of the identified papers to favor research and clinical practice.

METHODS

On December 17, 2021 a systematic research was performed to find all papers on TMD published in the literature. The Incites Journal Citation Reports dataset and Scopus database was used to obtain bibliometric indexes of the authors and metrics data of the journals, including Impact Factor, Eigenfactor Score, and Normalized Eigenfactor. VOSviewer was used to visualize the keyword mapping networking, with the nodes standing for keywords and the edges for keyword relationships.

RESULTS

Out of 24372 papers obtained by the search strategy, the 50 most cited articles on TMD were analyzed. The paper with the highest number of citations (n= 3020) was on TMD research diagnostic criteria. Rate of citations per year collected by the 50 most cited articles on TMD has been increasing over time (from 627 in 2006 to 1483 in 2021). Most of them were cross-sectional studies (n= 20; 40.0%) and narrative reviews (n= 14; 28.0%).

CONCLUSION

This bibliometric study showed an increasing number of citations for articles on TMD, testifying a high interest in the last years. Starting from this analysis, future studies might provide high-quality evidence on TMD management.

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.

Analysis of the Volumetric Asymmetry of the Mandibular Condyles Using CBCT

Objectives

The aim of this study was to analyse volumetric asymmetries between the right and left condyles in relation to age, gender, and dental status.

Materials and methods

A retrospective analysis of 150 cone beam computed tomography (CBCT) scans was conducted. A single investigator performed the volumetric analysis of the CBCT scans using Vesalius 3D software. The volumetric data were analysed in relation to the gender, age, and dental status.

Results

The mean right condylar volume was significantly higher (P < .01) than the left condylar volume. Right and left condylar volumes were significantly higher (P < .01) in male study participants when compared to female study participants. There was no significant difference (P = .47) in the volumetric asymmetry between the male and female study participants. The volumetric asymmetry was significantly higher (P < .01) in the older age groups when compared to the younger age groups. The volumetric asymmetry was significantly higher (P < .01) in the partially and completely edentulous patients when compared to the dentate study participants. The condylar volume on the side having a partially edentulous area was significantly lower than the condylar volume of the contralateral dentate side (P < .001).

Conclusions

The volumetric asymmetry between the right and left condyle significantly increases with age and edentulousness. The result of the study encourages the clinicians to perform volumetric evaluation of the condyles in cases of radiographically evident condylar asymmetries to obtain a more accurate diagnosis.

Age-related variations in position and morphology of the temporomandibular joint in individuals with anterior openbite and crossbite: a multi-cross-sectional comparative study

BACKGROUND

This study aimed to compare the age-related positional and morphological characteristics of the temporomandibular joint (TMJ) between individuals with anterior openbite or crossbite and controls.

METHODS

This multi-cross-sectional comparative study analysed cone-beam computed tomography images of 750 participants, equally divided into the openbite, crossbite, and control groups (OBG, CBG, and CG, respectively). Each group was further divided into five subgroups (8-11 years, 12-15 years, 16-19 years, 20-24 years, and 25-30 years). Measurements of the TMJ included the position of the condyles in their respective fossae and morphology of the condyles and fossae. Data were submitted to statistical analysis. The study adhered to the STROBE Statement checklist for reporting of cross-sectional studies.

RESULTS

Condyles were positioned more posteriorly with increasing age in all groups, and the condylar position was more posterior in the OBG than in the CBG. The articular eminence inclination increased with age in all the groups. There were significant differences in the articular eminence inclination among the three major groups at the age of > 15 years, and the condylar path was flatter in the CBG than in the OBG.

CONCLUSIONS

Age-related morphological and positional characteristics of the TMJ differed considerably among OBG, CBG and CG. Contrary to CBG, OBG was found to have relatively posterior condylar position and steeper condylar path.

Centric relation: a matter of form and substance

The recent review article by Zonnenberg, Türp and Greene ‘Centric relation critically revisited – What are the clinical implications’? opens an important debate by addressing topics of central relevance in Dentistry, namely the relationship between occlusion and the condyle‐to‐glenoid‐fossa position, and the need for diagnostic assessment and therapeutic alteration of the condylar position in orthodontic patients. Zonnenberg, Türp and Greene concluded that the mandibular condyle is correctly situated in most orthodontic patients. Thus, in their view, orthodontists can disregard this aspect during treatment, and rely on the plastic properties of the masticatory supporting structures, while aiming at finishing the cases in a good occlusal relationship.

We think that this approach fails to consider that biological variation of the stomatognathic structures can also be pathological and that, as dental occlusion determines condylar relative position within the glenoid fossa, changes in the occlusion are likely to alter the original condylar‐to‐glenoid‐fossa relation. Hence, we claim that whenever the occlusal relationship must be changed, the clinician should carefully monitor the condyle position and the mandibular function to prevent possible iatrogenic effects.

To advance the discourse on the topic, we invite Zonnenberg, Türp and Greene to clarify their definition of ‘average patient’ and their interpretation of ‘full‐mouth orthodontic and orthognathic treatment’, their understanding of ‘biologically acceptable condylar relationship’, their justification of maximum intercuspation as reference position, the extent to which they think it is safe to rely on the TMJ resilience, and finally their alternative to centric relation in the treatment of patients needing condylar repositioning.

Prevalence of sagittal molar and canine relationships, asymmetries and midline shift in relation to temporomandibular disorders (TMD) in a Finnish adult population

OBJECTIVE

To examine the prevalence of sagittal relationships, asymmetries and midline shift, and their associations with temporomandibular disorders (TMD) in the Northern Finland Birth Cohort 1966 (NFBC1966).

MATERIALS AND METHODS

1845 subjects participated in a clinical examination at the age of 46. Occlusal measurements were performed using 3D models. Symptoms of TMD were screened using validated questions, and signs and diagnoses of TMD were assessed using a modified protocol of the Diagnostic Criteria for TMD (DC/TMD) and questionnaires. Associations between variables of occlusion and TMD were evaluated with χ²-test and Fisher's exact test and using logistic regression analyses, adjusted for self-reported general health, mental health, bruxism, and rheumatoid arthritis.

RESULTS

The most common sagittal relationships were Class I and normal canine relationship. Half-cusp Class II and post-normal canine relationship were more frequent in females, and Class III and pre-normal canine relationship in males. Deviations from normal cuspid or molar relationships showed a weak but statistically significant association with TMD, especially in females. Half-cusp Class II and Class II relationships were more frequent in relation to joint-related TMD signs and diagnoses while missing canines were associated with pain-related TMD diagnoses.

CONCLUSIONS

The present study findings gave some indications that canine relationships are associated with pain-related TMD, whereas Angle II sagittal occlusal relations may associate with joint-related TMD. Occlusal characteristics should therefore be taken into account as one possible associating factor in subjects with TMD.

Orthodontic treatment for posterior crossbites

BACKGROUND

A posterior crossbite occurs when the top back teeth bite inside the bottom back teeth. The prevalence of posterior crossbite is around 4% and 17% of children and adolescents in Europe and America, respectively. Several treatments have been recommended to correct this problem, which is related to such dental issues as tooth attrition, abnormal development of the jaws, joint problems, and imbalanced facial appearance. Treatments involve expanding the upper jaw with an orthodontic appliance, which can be fixed (e.g. quad-helix) or removable (e.g. expansion plate). This is the third update of a Cochrane review first published in 2001.

OBJECTIVES

To assess the effects of different orthodontic treatments for posterior crossbites.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched four bibliographic databases up to 8 April 2021 and used additional search methods to identify published, unpublished and ongoing studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of orthodontic treatment for posterior crossbites in children and adults.

DATA COLLECTION AND ANALYSIS

Two review authors, independently and in duplicate, screened the results of the electronic searches, extracted data, and assessed the risk of bias of the included studies. A third review author participated to resolve disagreements. We used risk ratios (RR) and 95% confidence intervals (CIs) to summarise dichotomous data (event), unless there were zero values in trial arms, in which case we used odds ratios (ORs). We used mean differences (MD) with 95% CIs to summarise continuous data. We performed meta-analyses using fixed-effect models. We used the GRADE approach to assess the certainty of the evidence for the main outcomes.

MAIN RESULTS

We included 31 studies that randomised approximately 1410 participants. Eight studies were at low risk of bias, 15 were at high risk of bias, and eight were unclear. Intervention versus observation For children (age 7 to 11 years), quad-helix was beneficial for posterior crossbite correction compared to observation (OR 50.59, 95% CI 26.77 to 95.60; 3 studies, 149 participants; high-certainty evidence) and resulted in higher final inter-molar distances (MD 4.71 mm, 95% CI 4.31 to 5.10; 3 studies, 146 participants; moderate-certainty evidence). For children, expansion plates were also beneficial for posterior crossbite correction compared to observation (OR 25.26, 95% CI 13.08 to 48.77; 3 studies, 148 participants; high-certainty evidence) and resulted in higher final inter-molar distances (MD 3.30 mm, 95% CI 2.88 to 3.73; 3 studies, 145 participants, 3 studies; moderate-certainty evidence). In addition, expansion plates resulted in higher inter-canine distances (MD 2.59 mm, 95% CI 2.18 to 3.01; 3 studies, 145 participants; moderate-certainty evidence). The use of Hyrax is probably effective for correcting posterior crossbite compared to observation (OR 48.02, 95% CI 21.58 to 106.87; 93 participants, 3 studies; moderate-certainty evidence). Two of the studies focused on adolescents (age 12 to 16 years) and found that Hyrax increased the inter-molar distance compared with observation (MD 5.80, 95% CI 5.15 to 6.45; 2 studies, 72 participants; moderate-certainty evidence). Intervention A versus intervention B When comparing quad-helix with expansion plates in children, quad-helix was more effective for posterior crossbite correction (RR 1.29, 95% CI 1.13 to 1.46; 3 studies, 151 participants; moderate-certainty evidence), final inter-molar distance (MD 1.48 mm, 95% CI 0.91 mm to 2.04 mm; 3 studies, 151 participants; high-certainty evidence), inter-canine distance (0.59 mm higher (95% CI 0.09 mm  to 1.08 mm; 3 studies, 151 participants; low-certainty evidence) and length of treatment (MD -3.15 months, 95% CI -4.04 to -2.25; 3 studies, 148 participants; moderate-certainty evidence). There was no evidence of a difference between Hyrax and Haas for posterior crossbite correction (RR 1.05, 95% CI 0.94 to 1.18; 3 studies, 83 participants; moderate-certainty evidence) or inter-molar distance (MD -0.15 mm, 95% CI -0.86 mm to 0.56 mm; 2 studies of adolescents, 46 participants; moderate-certainty evidence). There was no evidence of a difference between Hyrax and tooth-bone-borne expansion for crossbite correction (RR 1.02, 95% CI 0.92 to 1.12; I² = 0%; 3 studies, 120 participants; low-certainty evidence) or inter-molar distance (MD -0.66 mm, 95% CI -1.36 mm to 0.04 mm; I² = 0%; 2 studies, 65 participants; low-certainty evidence).  There was no evidence of a difference between Hyrax with bone-borne expansion for posterior crossbite correction (RR 1.00, 95% CI 0.94 to 1.07; I² = 0%; 2 studies of adolescents, 81 participants; low-certainty evidence) or inter-molar distance (MD -0.14 mm, 95% CI -0.85 mm to 0.57 mm; I² = 0%; 2 studies, 81 participants; low-certainty evidence).  AUTHORS' CONCLUSIONS: For children in the early mixed dentition stage (age 7 to 11 years old), quad-helix and expansion plates are more beneficial than no treatment for correcting posterior crossbites. Expansion plates also increase the inter-canine distance. Quad-helix is more effective than expansion plates for correcting posterior crossbite and increasing inter-molar distance. Treatment duration is shorter with quad-helix than expansion plates. For adolescents in permanent dentition (age 12 to 16 years old), Hyrax and Haas are similar for posterior crossbite correction and increasing the inter-molar distance. The remaining evidence was insufficient to draw any robust conclusions for the efficacy of posterior crossbite correction.

Evaluation of Dental Status in Relation to Excessive Horizontal and Vertical Overlap in North Indian Population

Introduction:

Tooth wear (attrition) is a multifactorial entity, the pathogenesis of which involves many factors but the role of malocclusion cannot be undermined. Overjet and overbite play an important role in defining occlusion, hence they should also play an important role in causing attrition.

Objectives:

This study aims to evaluate the relationship of dental health status between the vertical and horizontal overlap.

Materials and Methods:

This study was conducted on 600 patients selected randomly from rural population which were divided into three equal groups as per the predefined criteria, namely, horizontal overlap, vertical overlap, and control group. All patients were examined for the tooth attrition.

Results:

In Group 1 – 73 patients out of 200 showed one or more teeth attrition, in Group 2 – 38 patients out of 200 showed one or more teeth attrition, and in the control group, 22 patients out of 200 showed one or more teeth attrition.

Conclusion:

It was concluded that both vertical and horizontal abnormal relationships of teeth play an important role in the etiology of attrition, with abnormal horizontal overlap being the more detrimental as compared to the vertical one.

The impact of occlusal support on temporomandibular disorders: a literature review

Temporomandibular disorders are a multifactorial disease. Occlusal support and the number of teeth in dentition have significant effects on the masticatory system. The current study aims to review the role of occlusal support in association with findings of temporomandibular disorders. Data sources were PubMed, Web of Science and Google Scholar, with 1411 citations published over the period 1992–2019. The selection criteria stipulated that articles must have reported the association between the number of teeth, occlusal unit, occlusal support and temporomandibular disorders. A total of 15 full-text articles was finally accessed for eligibility in the current review. The studies on temporomandibular disorders were collected from various sources, including articles reporting temporomandibular disorder symptoms ( n=1), temporomandibular disorder signs ( n=5), temporomandibular joint osseous changes ( n=1), temporomandibular joint dysfunction using the Helkimo index ( n=2), and temporomandibular disorder classification ( n=6). Of these articles, significant associations were found between: the number of missing teeth and temporomandibular disorders ( n=5); the number of occlusal units and occlusal supports and temporomandibular disorders ( n=3); the position of the lost occlusal units and temporomandibular disorders ( n=1). Loss of the occlusal unit has more impact on temporomandibular disorders than the loss of posterior teeth. The total loss of unilateral occlusal support seems to be an aetiological factor for temporomandibular disorders, and maintenance of balanced posterior occlusal support has a role in the prevention and management of temporomandibular disorders.

Asymmetry of dental or joint anatomy or impaired chewing function contribute to chronic temporomandibular joint disorders

INTRODUCTION

The etiologies of most chronic temporomandibular joint disorders are unknown. However, an association between habitual chewing on a particular side and chronic temporomandibular joint disorders has been reported. The aim of this study was to investigate the differences between sides (affected vs unaffected) of biodynamic factors (including lateral dental guidance determined by dental anatomy) or condylar path angles (determined by temporomandibular joint morphology) and chewing function (physiological alternate chewing vs single habitual chewing side). The study scope was to investigate possible etiological factors to improve the understanding of temporomandibular joint disorders. The null hypothesis was that no difference would be found between sides that are or are not affected by chronic temporomandibular joint disorders in chewing function or in levels of dental or temporomandibular joint remodeling.

METHODS

This cross-sectional, double-blind study involved 24 adults with substantial, chronic, unilateral symptoms diagnosed as temporomandibular joint disorders. Chewing function, temporomandibular joint remodeling (using axiography) and dental anatomy (lateral guidance angles using kinesiography) were assessed.

RESULTS

Habitual chewing on one particular side was observed in 17 of 24 participants; significantly more (n=15) chewed on the affected side than on the unaffected side (P=0.002 in a two-tailed Fisher's exact test; risk estimate=4.5; 95% CI 1.326-15.277). The condylar path (CP) angle was steeper on the affected side than on the unaffected side (mean (standard deviation)=50.52° (9.98°) versus 45.50° (7.98°); P=0.002 in a two-tailed t-test). The lateral guidance (LG) angles were flatter on the affected side in all 24 participants.

CONCLUSION

Our results suggest that habitual chewing on one side may be associated with increasing condylar path, with flattening lateral guidance angles, and also with chronic temporomandibular joint disorder on the habitual chewing side.

Is the Temporomandibular Joints' Reciprocal Clicking Related to the Morphology and Position of the Mandible, as Well as to the Sagittal Position of Lower Incisors?-A Case-Control Study

The number of patients diagnosed with temporomandibular joint (TMJ) internal derangements, who are seeking orthodontic treatment, is increasing. The aim of the study was to assess the relationship between the presence of TMJ reciprocal clicking and the morphology and position of the mandible, and position of lower incisors, examined on the lateral cephalograms. Fifty patients diagnosed with reciprocal clicking in at least one of the TMJs and 55 patients with no symptoms of TMJ dysfunction were included in the study. Cephalometric analysis was used for the assessment of: skeletal class, sagittal and vertical position of the mandible, angle of the mandible, inclination of the mandibular ramus and the mandibular corpus, as well as for the assessment of the position of the mandibular incisors. The statistical significance level was set at p = 0.05. There were no statistically significant differences between the examined groups regarding the sagittal and vertical position of the mandible, as well as regarding the sagittal position of the mandibular incisors. Presence of TMJ reciprocal clicking is not associated with the position and the morphology of the mandible, as well as with the sagittal position of the mandibular incisors. Patients with early stages of TMJ internal derangements do not present any significant changes in Cephalometrics. Patients diagnosed with TMJ internal derangements before orthodontic treatment require an interdisciplinary approach to the treatment, including physiotherapy.

The Association between Occlusal Features and Temporomandibular Disorders in Northern Jordan: A Cross-sectional Study

Objective:

To evaluate the possible correlation between basic occlusal features and the outcomes of the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) Axis I.

Materials and Methods:

A convenient sample of Northern Jordanians was used in the study. Participants were examined in accordance with DC/TMD protocol. Nine occlusal features represented the independent variables; overjet, overbite, midline deviation, pain-free opening, maximum assisted opening, maximum unassisted opening, lateral excursions and protrusion, in addition to the opening pattern (classified as straight, corrected deviation and uncorrected deviation). DC/TMD diagnostic outcomes and their associated features represented the dependent variables, namely, pain-related TMD, Intra-articular Disorders (IAD), Degenerative Joint Disease (DJD), joint sounds (clicking and crepitus), joint locking and headache attributed to TMD. Binary logistic regression, multinomial logistic regression and Chi-square tests were used for statistical analyses.

Results:

A total of 400 participants represented the study population (mean age = 32.3±12.4 years, males=48%, females=52%). 71 subjects (18%) were diagnosed with pain-related TMD, 52 (13%) with IAD, 6 (1.5%) with DJD and 38 (10%) with headache due to TMD. Gender had a significant correlation with pain-related TMD (p= 0.014, OR= 2.16). Maximum pain free opening had a significant inverse relationship with pain related TMD (p= 0.013, OR=0.94), while midline deviation and corrected deviation mouth opening pattern had a significant correlation with IAD (p= 0.04,0.02, OR= 1.30,2.74, respectively). Overbite, midline deviation and pain free opening were significantly associated with unilateral open/close clicking (p= 0.04,0.05,0.03, OR= 0.77, 1.31, 0.94, respectively).

Conclusion:

There is a minimal clinical significance of the correlation between dental occlusion and TMD.

Orthodontic Treatment and Craniocervical Posture in Patients with Temporomandibular Disorders: An Observational Study

Orthodontic treatment acts through the application of forces and/or by stimulating and redirecting the functional forces within the craniofacial complex. Considering the interrelationship between craniomandibular and craniocervical systems, this intervention may alter craniocervical posture. Thus, our aim is to (a) compare craniocervical posture, hyoid bone position, and craniofacial morphology before, after, and also in the contention phase at least one year after the orthodontic treatment, in patients with temporomandibular disorders and (b) to verify whether the presence of condylar displacement, the skeletal class, or the facial biotype interferes with the abovementioned outcomes. To do so an observational, analytical, longitudinal, and retrospective design study was carried out. A non-probabilistic convenience sampling method was applied. The sample consisted of clinical records of patients diagnosed with temporomandibular disorders in order to compare pre-orthodontic treatment with post-orthodontic treatment (n = 42) and contention phase data (n = 26). A cephalometric analysis of several variables was performed. The p-value was set as 0.05. When the pre- and post-orthodontic treatment data were analyzed, there were statistically significant changes in variables concerning craniocervical posture (CV angle, C0-C1, and AA-PNS) and also concerning hyoid bone position (C3-Rgn). When pre- and post-orthodontic treatment and contention phase data were analyzed the variables concerning craniocervical posture (C0-C1, CVT/Ver, NSL/OPT, NSL/CVT, NSL/Ver; OPT/CVT, OPT/Ver) and facial biotype had statistically significant changes. This allowed us to conclude that in the sample studied, there were significant differences regarding hyoid bone position (pre- versus post-orthodontic treatment) and craniocervical posture (pre- versus post-orthodontic versus contention), with the craniocervical posture being prone to return to basal values. The presence of condylar displacement was found to significantly increase the H-H1 distance in the three moments of evaluation. Facial biotype was found to significantly increase the NSL/Ver angle on hypodivergent compared to hyperdivergent in the contention phase.

Temporomandibular Joint Osteoarthrosis: A Review of Clinical Aspects and Management

The symptoms of TMJ Osteoarthrosis/Osteoarthritis(TMJ OA) are characteristic and in most cases specific to the disorder. There is, however, an overlap of symptoms with other TMDs.Treatment of TMJ OA is generally directed towards management of the symptoms as the temporomandibular joint does retain the capacity throughout life to repair and remodel. Non-conservative and invasive treatment is only rarely necessary.It should be remembered that the mandibular condyle retains the capacity to repair and remodel throughout life and patients should be encouraged to bear this in mind. Conservative measures are usually sufficient to treat symptoms and a period of time should be allowed to elapse before undertaking a more aggressive treatment plan, which, in the overwhelming majority of patients, will not be necessary. This disorder should be approached on the terms of 'a quality of life issue' and treatment should be directed towards patient needs.

Is There an Association between Temporomandibular Disorders and Articular Eminence Inclination? A Systematic Review

(1) Background: In order to determine the correlation between the inclination of articular eminence (AEI) and the development of temporomandibular disorders (TMDs), a systematic review was performed. (2) Methods: A systematic literature research was conducted between 1946 and January 2020, based on the following electronic databases: PubMed, Cochrane Library, Embase, Medline, Scope, SciELO, and Lilacs. Observational studies, analytical case-control studies, and cohort studies written in English were identified. The articles were selected and analyzed by two authors independently. The PICO format was used to analyze the studies and the Newcastle-Ottawa Scale (NOS) was used to verify the quality of the evidence. (3) Results: Sixteen articles were included in this review, ten case-control studies and six cohort studies. Eight articles (50%) established a positive relation between AEI and TMDs and eight (50%) did not. The scientific quality was medium-low, mainly influenced by the exposure to the risk of bias and the lack of clinical methods with adequate consistency and sensitivity on the diagnosis of TMDs. (4) Conclusions: It is controversial to establish a causal relationship between the TMDs and the AEI in the field of stomatology, due to limited and inconclusive evidence. However, it is suggested that the AEI defined by some specific methods may be associated with some special pathological stages of TMDs. High-quality prospective studies are required to draw any definitive conclusions.

Novel hypotheses related to Temporomandibular joint derived from Ankylosing spondylitis

Ankylosing spondylitis (AS) is a seronegative arthropathy that affects fibrocartilaginous joints leading to arthritis and eventually ankylosis. Temporomandibular joint (TMJ), a fibrocartilaginous joint is affected to a lesser extent than the other joints, very rarely precipitating TMJ ankylosis. No explanation exists for the same in the present literature. Several hypothesis have been presented to explain this phenomenon of rarity of TMJ ankylosis in AS. The presence of an intraarticular disc acts as a physical barrier to the ankylotic process. However, in cases with AS, that present with TMJ ankylosis, this hypothesis needs several clarifications since the intraarticular disc is a constant phenomenon in TMJ. The cause of TMJ ankylosis in these cases might be explained by two hypotheses. Firstly, Pathological condylar loading in some cases; secondly, an application of the orthopaedic concept of functional enthesis to the TMJ disc and thirdly, an application of the concept of enthesis organ to TMJ. Using these hypotheses, important concepts on the anatomy and evolution of TMJ can be derived with evidence from literature. The intraarticular disc may be considered as an involuted tendon of the lateral pterygoid muscle which not only attaches to the mandibular condyle but also to the temporal bone via a elastic fiber mediated enthesis extending to the malleus through the discomalleolar ligament. The fibrocartilaginous changes that occur on the undersurface of the disc may support the concept of functional enthesis and provide a reverse evidence for the disc being a tendon. The evidence presented from extant monotremes may also throw light on the embryological development of the articular disc. These evidences are more of an anecdote than being focussed. Several scientific experiments, studies and data collection needs to be carried out to validate them. The proof of these hypotheses will be of use in establishing the development and role of the articular disc in TMJ function and TMJ disorders, including AS. The understanding of the role of the articular disc is important since many firstly, TMJ disorders are being treated by discectomy with good results, apparently rendering the disc vestigial and secondly, in the era of tissue engineering where efforts are being made to artificially produce articular disc and its analogues.

Occlusal Features and TMJ Clicking: A 30-Year Evaluation from a Cohort Study

Occlusal features that deviate from normative values have been historically considered risk factors for temporomandibular joint (TMJ) disorders. Nowadays, a putative association between dental occlusion and TMJ disorders remains controversial, with research findings on associations being inconsistent and inconclusive. We hypothesized that putative occlusal features identified during adolescence are associated with TMJ clicking later in life. The Dunedin Multidisciplinary Health and Development Study is a longitudinal birth cohort study investigation of 1,037 children (48.4% female) born in Dunedin, New Zealand, between April 1, 1972, and March 31, 1973, and assessed repeatedly since then. Associations between posterior crossbite, overbite, and overjet at age 15, as well as both self-reported and clinically assessed TMJ clicking sounds at age 45, were studied. Data were analyzed using multivariate logistic regression, after controlling for sex, emotional style, self-reports of tooth clenching and sleep bruxism, and history of orthodontic treatment. Self-reported and examiner-reported TMJ clicking at age 45 affected 18.3% and 23.8% of the study sample, respectively, and were not associated with the presence of a posterior crossbite or abnormal overjet/overbite values during adolescence. Self-reported history of tooth clenching and emotional style were associated with self-reported TMJ clicking later in life. In addition, there is a suggestion that high overbite during adolescence is negatively associated with TMJ clicking later in life. A history of orthodontic treatment was not associated with TMJ clicking. Abnormal occlusal features, such as posterior crossbite and high and low overjet/overbite in adolescence, are not associated with higher prevalence of TMJ clicking later in life. Personality also appears to influence self-reports of TMJ clicking later in life.

Occlusion and Temporomandibular Disorders: A Long-Standing Controversy in Dentistry

The relationship between temporomandibular disorders (TMDs) and occlusion remains controversial. Some authors believe that occlusion is the primary factor in the onset of TMD symptoms, whereas others feel that occlusion has no role in this at all. The majority of reasoning behind causation is based upon anecdotal rather than scientific evidence. Existing evidence in the literature supports the absence of a disease-specific association. This article describes this controversy and provides the reader with findings from contemporary literature.

Evaluation of Disclusion Time in Various Angle's Malocclusions by T-Scan III System

Objective  The main purpose of this article is to evaluate the disclusion time (DT) in the lateral excursions and protrusion among subjects with Angle’s malocclusions using a T-Scan III system.

Materials and Methods  One hundred subjects with malocclusions were divided into Class I, Class II division 1, Class II division 2, and Class III ( n = 25 per group). All groups’ DT of each excursion was evaluated by a T-Scan III system.

Statistical Analysis  One-way analysis of variance, followed by a post hoc test, was used to analyze the numerical data at p < 0.05.

Results  In the respective malocclusions, means ± standard deviations in second(s) of the DT were 2.08 ± 0.65, 2.13 ± 0.74, 2.12 ± 0.72, and 3.19 ± 1.34 during left excursion; 2.15 ± 0.94, 2.58 ± 1.16, 2.37 ± 1.07, and 3.28 ± 1.25 during right excursion; and 1.88 ± 0.99, 2.08 ± 1.11, 2.07 ± 0.68, and 3.01 ± 1.53 during protrusion. When compared to Class I and Class II malocclusions, Class III showed a significantly higher mean DT of each excursion ( p < 0.05).

Conclusion  Class III had the significantly highest mean DT of each excursion and the significantly longest DT in all excursions.

Estimated functional space of centric condyle positions in temporomandibular joints of asymptomatic individuals using MRI

Magnetic resonance imaging (MRI) studies on centric condyle positions lack 3D comparisons of guided and unguided methods, which are used for accomplishing centric relation reference positions. The purpose of this study was to describe the space, in which mandibular condyles are placed in vivo by dental intercuspation, Dawson’s bimanual manipulation, and neuromuscular position. Twenty asymptomatic individuals aged 23 to 37 years underwent separate bite registrations using bimanual manipulation and the unguided neuromuscular technique. Subsequent 3-Tesla MRI scans of both temporomandibular joints yielded 3D data of the most superior condylar points at maximum intercuspation and both centric relation positions. We found concentric condyle positions in maximum intercuspation but considerable variation of condyle position after bimanual manipulation and neuromuscular technique. Their 95% predictive confidence ellipses overlapped substantially and created a space of reference positions. Its smallest volume averaged 2 mm³ for a minimal convex hull (95% confidence interval 1.1–3.2) and 3.5 mm³ for a minimal ellipsoid hull (95% confidence interval 1.8–5.4). Visualized in vivo by MRI, condyle positions at bimanual manipulation and neuromuscular position were not predictable and showed substantial variation in asymptomatic subjects. Clinicians should be aware of the functional space and its effect on dental intercuspation.

Effect of Orthodontic Treatment With Straight-Wire Appliance on the Incidence of Temporomandibular Disorders—A 3-Year Cohort Study

Introduction: A change in occlusion during orthodontic treatment can affect muscles and joints surrounding the jaw, resulting in temporomandibular disorders (TMD). The aim of this study was to determine the effect of orthodontic treatment with straight-wire appliance on the incidence of TMD in young adults.

Materials and Methods: A cohort study was carried out involving 177 adult patients (91 in the treatment group and 86 in the control group). Fonseca’s questionnaire was used for TMD evaluation for all patients at the time of obtaining orthodontic pretreatment records (T0). TMD assessment was repeated after an average of 3 years of initial assessment for both the treatment and control groups (T1).

Results: The number of patients with TMD changed significantly ( P < .001) from T0 to T1 in both groups. The prevalence of TMD increased from 36.3% to 41.8% in the treatment group and decreased from 46.5% to 38.4% in the control group after 3 years. The relative risk of developing TMD after orthodontic treatment was 1.16, whereas the odds of TMD resolution after orthodontic treatment was 0.73, both of which were statistically nonsignificant ( P > .05).

Conclusion: Orthodontic treatment with noncustomized straight-wire appliance has nonsignificant effects on the incidence of TMD in young adults.

Computerized ultrasonic axiographic evaluation of condylar movement in patients with internal derangement of the temporomandibular joint

OBJECTIVES

To evaluate condylar movement during lateral excursion in individuals with internal derangement of the temporomandibular joint (TMJ) using ultrasonic axiography.

MATERIALS AND METHODS

A total of 34 patients with internal derangement of the TMJ and 34 participants in the control group were examined. Mandibular functional movement was recorded by ultrasonic axiography. Three-dimensional condylar movement was measured in the working and balancing condyles.

RESULTS

Significant differences in condylar movement were found between the two groups. In the group with internal derangement of the TMJ, the three-dimensional linear distances of the condylar path in a working condyle were greater than in the control group during lateral excursion. The speed of the balancing condyle in the returning path of lateral excursion was significantly greater in the group with internal derangement than in the control group.

CONCLUSIONS

The results of the present study indicate that internal derangement of TMJ may affect the working and balancing condylar movements during lateral excursion.

The inconclusiveness of research on functional pathologies of the temporomandibular system and body posture: Paths followed, paths ahead: A critical review

Objective: Literature on the functional pathologies of the temporomandibular system (FPTS) in its relationships with body posture is plagued with inconclusiveness. Despite being sometimes altogether disregarded, the issue is most relevant, due to its clinical implications. This paper aims for a deeper understanding of the origins of the inconclusiveness of research on such relationships by means of a critical analysis of the scientific literature on the subject, in order that clinicians may better treat patients with FPTS.Methods: Analysis of over 100 studies, published from 1918 through March 2018 in the PubMed database, using descriptors temporomandibular joint disorders and posture.Results: The analysis of the paths followed by researchers allowed for pinning down several methodological issues that may have led to the prevailing ambiguity on the matter.Conclusion: This review then proposes certain standardization of procedures in future studies, to be conducted by a proposed consortium of researchers.

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.

Effect of Shortened Dental Arch on Temporomandibular Joint Intra-articular Disorders

AIMS

To investigate whether a shortened dental arch (SDA), as identified by reduced posterior occlusal contacts, is a risk factor for the progression of temporomandibular joint (TMJ) intra-articular disorders (ID), as identified using imaging techniques.

METHODS

This multisite, prospective observational study with a mean follow-up period of 7.9 years had a sample of 345 participants with at least 1 temporomandibular disorder (TMD) diagnosis at baseline. SDA was defined as reduced occlusal posterior support due to lack of occlusal intercuspal contacts in the molar region on the left and/or right side. SDA was assessed at baseline and at follow-up with metalized Mylar Tape. The presence or absence of a TMJ ID and the specific TMJ ID diagnoses for baseline and follow-up images were established by a calibrated, blinded radiologist at each of three sites by using bilateral magnetic resonance imaging for soft tissue imaging for disc displacement and by bilateral multidetector computed tomography or cone beam computed tomography for hard tissue imaging for degenerative joint diseases. Wilcoxon rank sum test and linear regression analyses were used to test for an impact of SDA on TMJ ID status.

RESULTS

At baseline, TMJ ID status of either side was not significantly affected by the presence of SDA on the ipsilateral or contralateral side of the jaw (all P > .05). Furthermore, the presence or absence of SDA at baseline was also not a significant predictor for progression of the TMJ ID status between baseline and follow-up (all P > .05).

CONCLUSION

The findings of this study suggest that there is no significant effect of SDA on progression of TMJ ID.

Impact of shortened dental arch on oral health-related quality of life over a period of 10 years - A randomized controlled trial

OBJECTIVES

To compare oral health-related quality of life (OHRQoL) in patients with either molar replacement by partial removable dental prostheses (PRDP) or with restored shortened dental arches (SDA) over a period of 10 years.

METHODS

In this multi-center RCT, a consecutive sample of 215 patients with bilateral molar loss in at least one jaw was initially recruited in 14 prosthodontic departments. Of those patients, 150 could be randomly allocated to the treatment groups (SDA: n = 71; PRDP: n = 79), received the allocated treatment, and were available for follow-up assessments. OHRQoL was assessed using the 49-item version of the Oral Health Impact Profile (OHIP) before treatment (baseline) and at follow-ups after treatment (4-8 weeks and 6, 12, 24, 36, 48, 60, 96, and 120 months). To investigate the course of OHRQoL over time, we longitudinally modelled treatment and time effects using mixed-effects models.

RESULTS

OHRQoL substantially improved from baseline to first follow-up in both groups indicated by a mean decrease in OHIP scores of 20.0 points (95%-CI: 12.5-27.5). When compared to the SDA group, OHRQoL in the PRDP group was not significantly different (-0.6 OHIP points; 95%-CI: -7.1 to 5.9) during the study period when assuming a constant time effect. OHRQoL remained stable over the 10 years with a statistically insignificant time effect (p = 0.848).

CONCLUSIONS

For patients requesting prosthodontic treatment for their lost molars, treatments with SDA or PRDP improve clinically relevantly OHRQoL and maintain it over a period of 10 years with no option being superior to the other.

CLINICAL SIGNIFICANCE

Since there was no significant difference between the two treatment options over the observation period of 10 years, and since results have stayed stable over time, patients can be informed that both treatment concepts are equivalent concerning OHRQoL.

[Mandibular repositioning in adult patients. An alternative to surgery in some patients? A two-year follow-up]

INTRODUCTION

A number of adult patients with skeletal discrepancies refuse surgical intervention.

AIMS

The aim was to assess the reaction to mandibular repositioning in simulating a skeletal correction in such patients.

MATERIALS AND METHODS

32 consecutive patients without any signs of temporo-mandibular dysfunction (TMD) were offered mandibular repositioning, as a non-invasive alternative and it was explained to them that the approach was based on the results described in case reports. Before initiating any treatment initial records, headfilms, study casts and photos were taken (T₀) and the mandible was repositioned to camouflage the skeletal discrepancy by means of an occlusal built-up in Triad^® Gel.

RESULTS

Three months later (T₁) 23 patients had adapted to the new occlusion reflected in absence of functional problems and lack of fracture of the built-up. In these patients the mandibular position was maintained by orthodontics adjusting the occlusion to the built-up position (T₁). The skeletal changes occurring during repositioning were assessed on sagittal and frontal head films while intra-articular changes occurring during a 2-year follow-up period (T₂) were evaluated on images constructed from CBCT images. No significant changes, neither in the direction of a relapse nor in the direction of further normalization of the condylar positioning, were observed during the 2-year observation period.

CONCLUSIONS

Repositioning is a non-invasive intervention and may be considered a valid alternative to surgery in some patients. Morphological variables from the radiographs taken at T₀ and the results of the initial clinical evaluation of dysfunction yielded only vague and insignificant indications regarding the predictability of adaptation to the repositioning.

Association of midline discrepancy with tempromandibular joint disorder. A systematic review

Aim

The aim is to evaluate the association between midline discrepancies and tempromandibular disorders (TMDs).

Methods

Literature search was performed by using various search engines to include human studies in English. TMDs include a wide variety of signs and symptoms such as pain in and around TMJ, jaw muscles, clicking and locking of jaws, pain during mandibular movement and restricted mandibular movements. The etiology is multifactorial, including one or several of the following factors like severe malocclusions (increased overjet, retroclination of incisors, cross bite, CR CO discrepancies etc), stress and psychological factors, structural abnormalities as possible etiology. There are controversies concerning the association between different traits of malocclusion and TMDs. The aim of the present study was to find out any association between signs and symptoms of TMDs with midline discrepancies, which represent an important trait of malocclusion.

Result

Of the seven studies evaluated in this systematic review for investigating the association between midline discrepancy and TMD, six had moderate grade (B) of evidence. Four studies of moderate grade evidence (B) showed a significant association between the presence of midline shift and TMDs, and the remaining studies (two) had non-significant association. Only one study had a strong grade of evidence (A) and interestingly it denies the presence of midline shift to be a causative factor for TMDs. So, it can be concluded that the results are inconclusive regarding the association of midline discrepancies with TMDs. Nonetheless, this requires concrete evidence which necessitates further long term research into this aspect.

Does orthognathic surgery improve myofacial pain in individuals with skeletal class III? One-year follow-up

OBJECTIVE

The objective of the study was to evaluate the effect of orthognathic surgery on temporomandibular disorder (TMD) in patients with skeletal class III malocclusion.

STUDY DESIGN

Forty-seven patients undergoing surgery were evaluated by a trained examiner using Axis I of the Research Diagnostic Criteria/TMD index, consecutively, at 3 different periods: 1 week before operation (T0), 6 months after operation (T1), and 1 year after operation (T2). Bivariate analyses were performed to compare the evaluation periods (P < .05).

RESULTS

The prevalence of TMD in the sampled patients from T0 to T1 decreased from 30 (63.8%) to 22 (46.8%) (P = .021). Even in T2, the prevalence of TMD remained lower than that in T0, at 21 (44.7%) diagnosed patients (P = .049). The reported frequencies of myofascial pain and headache were lower in T1 and T2 than in T0 (P < .001). Decrease in the frequency of joint pain and joint sounds was observed only from T0 to T1 (P = .039 and P = .021, respectively). The mean maximum of mouth opening decreased from T0 to T1 (P < .001) and increased again at T2 (P < .001).

CONCLUSIONS

Orthognathic surgery promoted reduction in the frequencies of myofascial pain and headache reported by patients with skeletal class III malocclusion.

Temporomandibular disorders in growing patients after treatment of class II and III malocclusion with orthopaedic appliances: a systematic review

OBJECTIVE

To determine if the use of orthopaedic appliances in growing patients applied to correct Class II and III malocclusion is related to the development of temporomandibular disorders (TMD).

MATERIAL AND METHODS

A systematic review was conducted between 1960 and July 2017, based on electronic databases: PubMed, Cochrane Library, Embase, Medline, Scopus, EBSCOhost, Scielo, Lilacs and Bireme. Controlled clinical trials (CCTs) and randomized controlled trials (RCTs) were identified. The articles were selected and analyzed by two authors independently. The quality of the evidence was determined according to the guidelines of the Cochrane Risk Bias Assessment Tool and the Cochrane Quality Study Guide.

RESULTS

Seven articles were included, four CCTs and three RCTs. The studies were grouped according to malocclusion treatment in (a) class II appliances (n = 4) and (b) class III appliances (n = 3). The quality of evidence was low due to the high risk of bias, independent of the association reported. All studies concluded that the use of orthopaedic appliances would not contribute to the development of TMD.

CONCLUSIONS

The quality of evidence available is insufficient to establish definitive conclusions, since the studies were very heterogeneous and presented a high risk of bias. However, it is suggested that the use of orthopaedic appliances to correct class II and III malocclusion in growing patients would not be considered as a risk factor for the development of TMD. High-quality RCTs are required to draw any definitive conclusions.

The role of occlusion in temporomandibular disorders (TMD) in the Northern Finland Birth Cohort (NFBC) 1966

OBJECTIVE

To investigate the role of occlusion in temporomandibular disorders (TMDs) in the Northern Finland Birth Cohort 1966 (NFBC 1966).

METHODS

Subjects (n = 1962) participated in clinical medical and dental examinations. The association between TMD signs and diagnoses with occlusal disturbances, i.e. malocclusions and occlusal interferences, was examined. Pearson's chi-square test, as expressed by odds ratios (OR) and 95% confidence intervals (CI) and logistic regression models, were used in the analysis.

RESULTS

A statistically significant association was found between myalgia and lateral scissor bite and also between arthralgia and lateral deviation in the retruded contact position and intercuspal contact position (RCP-ICP) slide. Pain in the masticatory muscles was associated with negative overjet and the amount of RCP-ICP slide.

DISCUSSION

Occlusal factors showed a statistically significant association with TMD. The TMD signs were associated with unstable occlusion, especially the amount and lateral deviation in RCP-ICP slide, as well as negative overjet.

Effect of temporomandibular joint articular disc repositioning on anterior open-bite malocclusion: An orthodontic-surgical approach

An anterior open bite is a challenge to orthodontic treatment; it has a multifactorial etiology and a wide range of intervention options. Temporomandibular joint (TMJ) disorders are a risk factor for the development of malocclusions such as the anterior open bite, especially in patients who have TMJ osteoarthritis with disc displacement. Articular disc repositioning surgery is an available option for treating this pathology, and it contributes to maintaining the condyles in a more stable position. The aim of this article was to report the case of a 20-year-old woman diagnosed with anterior open bite and TMJ osteoarthritis with bilateral disc displacement. The patient received both orthodontic treatment and TMJ disc repositioning surgery. Cone-beam computed tomography was used to create 3-dimensional models of the condyles with regional superposition, and assessment of bone remodeling was performed at different time intervals. Complete orthodontic and surgical treatment time was approximately 12 months. The results provided a stable correction of the patient's anterior open bite with a 2-year follow-up and favorable bone remodeling of the condyles due to functional improvement of the TMJ.

Evaluation of the relationship between the occlusion parameters and symptoms of the temporomandibular joint disorder

Background.

The aetiology of temporomandibular joint disorders (TMD) is multifactorial, whereas occlusal disharmony is one of the predisposing factors. Researchers still discuss the relation between occlusion and TMD.

Objective.

The study aims to investigate the relation between static occlusal parameters and TMD clinical symptoms using T-Scan II analysis system.

Material and methods.

The sample consisted of 44 persons divided into the treatment group of 20 TMD patients and the control group of 24 subjects without TMD. The main task of T-Scan II computerized occlusal analysis system was to record every patient’s occlusion and estimate static occlusal parameters: centre of occlusal force, asymmetry index of maximum occlusal force and occlusion time. These results were compared between groups, data related to patients’ complaints and clinical symptoms. The analysis was carried out using Mann-Whitney U, Kruskal-Wallis and Chi-square tests.

Results.

Averages of the centre of occlusal force in TMD subjects were 6.55 ± 0.99 mm, in the control group – 5.88 ± 0.69 mm; the asymmetry index of maximum occlusal force averages: 15.90 ± 2.71 and 12.93 ± 1.88; occlusion time: 0.281 ± 0.036 s and 0.236 ± 0.022 s, respectively. There were no statistically significant differences between two groups but they were found in the centre of occlusal force and the asymmetry index in the two groups (p < 0.05).

Conclusions.

There exists a relation between complaints of patients with TMD and static occlusion parameters. Values of the centre of the occlusal force distance and the asymmetry index of occlusal force in TMD patients with pain in the temporomandibular joint (TMJ) were significantly higher than in the control group.

Jaw biodynamic data for 24 patients with chronic unilateral temporomandibular disorder

This study assessed 24 adult patients, suffering from severe chronic unilateral pain diagnosed as temporomandibular joint (TMJ) disorder (TMD). The full dentate patients had normal occlusion and had never received an occlusal therapy, i.e., were with natural dental evolution/maturation. The following functional and dynamic factors were assessed: (1) chewing function; (2) TMJ remodeling or the condylar path (CP); and (3) lateral jaw motion or lateral guidance (LG). CPs were assessed using conventional axiography, and LG was assessed by K7 jaw tracking. Seventeen (71%) of the 24 (100%) patients consistently showed a habitual chewing side. The mean (standard deviation [SD]) of the CP angles was 47.90 (9.24) degrees. The mean (SD) of the LG angles was 42.95 (11.78) degrees. Data collection emerged from the conception of a new TMD paradigm where the affected side could be the habitual chewing side, the side with flatter lateral jaw motion or the side with an increased CP angle. These data may lead to improved diagnosis, therapy plans and evolution in TMD patients.

Centric relation-intercuspal position discrepancy and its relationship with temporomandibular disorders. A systematic review

OBJECTIVE

The objective of this study is to assess the relationship between centric relation-intercuspal position discrepancy (CR-ICP discrepancy) and temporomandibular disorders (TMDs), by systematically reviewing the literature.

MATERIALS AND METHODS

A systematic research was performed between 1960 and 2016 based on electronic databases: PubMed, Cochrane Library, Medline, Embase, Scopus, EBSCOhost, BIREME, Lilacs and Scielo, including all languages. Analytical observational clinical studies were identified. Two independent authors selected the articles. PICO format was used to analyze the studies. The Newcastle-Ottawa Scale (NOS) was used to verify the quality of the evidence.

RESULTS

Four hundred and sixty-seven potentially eligible articles were identified. Twenty studies were analyzed, being grouped according to intervention in studies in orthodontic patients (n = 3) and studies in subjects without intervention (n = 17). Quality of evidence was low, with an average score of 3.36 according to Newcastle-Ottawa Scale. In most studies, the presence of CR-ICP discrepancy is associated with the presence of muscle (pain) and joint disorders (noise, disc displacement, pain, crepitus, osteoarthritis and osteoarthrosis). However, the lack of consistency of the results reported reduces the validity of the studies making it impossible to draw any definite conclusions.

CONCLUSIONS

Because of the heterogeneity of the design and methodology and the low quality of the articles reviewed, it is not possible to establish an association between CR-ICP discrepancy and TMD. The consequence of CR-ICP discrepancy on the presence of TMD requires further research, well-defined and validated diagnostic criteria and rigorous scientific methodologies. Longitudinal studies are needed to identify CR-ICP discrepancy as a possible risk factor for the presence of TMD.

Pattern analysis of patients with temporomandibular disorders resulting from unilateral mastication due to chronic periodontitis

Purpose

The purpose of the present study was to perform a pattern analysis in patients with temporomandibular disorder (TMD) resulting from unilateral mastication due to chronic periodontitis.

Methods

Thirty participants with signs or symptoms of TMD who engaged in unilateral mastication due to periodontitis-related discomfort (test group) were selected. Another 30 subjects exhibiting signs or symptoms of TMD resulting from unilateral mastication not due to chronic periodontitis (control group) were also recruited. An interview-based questionnaire was administered, and an examination of the temporomandibular joint (TMJ) with determination of periodontal status was performed.

Results

The duration of unilateral mastication was significantly longer in the control group than in the test group. There was a significant negative correlation between the duration of unilateral mastication and the Community Periodontal Index score. Using the Research Diagnostic Criteria for TMD (RDC/TMD) axis I algorithms, all the subjects were assigned to 3 main groups. The test group exhibited significantly a higher diagnostic distribution of group III (arthralgia, osteoarthritis, or osteoarthrosis), and in both the test and control groups, the number of diagnoses was larger for the non-chewing side. The control group showed a significantly higher diagnostic distribution of group I (myofacial pain), and in both the test and control groups, the number of diagnoses was larger for the chewing side.

Conclusions

The results of the present study indicate that unilateral mastication due to chronic periodontitis could induce not only pain but also structural TMJ changes if adequate treatment is not administered and supported within a short time from the onset of the condition. Therefore, immediate treatment of chronic periodontitis is recommended to prevent not only the primary progress of periodontal disease, but also secondary TMJ-related problems. Furthermore, subjects who have suffered chronic long-term periodontitis without treatment should be urged to undergo a TMJ examination.

Osteoarthrosis of Temporomandibular Joint Related to the Defects of Posterior Dentition: A Retrospective Study

Osteoarthrosis (OA) of temporomandibular joint (TMJ) is a progressive degenerative disease, gradually affecting cartilage, synovial membrane and bone structures. OA of TMJ clinically manifests with joint noises, pain and restricted mouth opening. In late stages, it results in severe damage of TMJ structures and development of ankylosis. Osteoarthrosis is a multifactorial disease; the occurrence is associated with TMJ overloading. The cohort included 619 patients [538 women (87%) and 81 men (13%), with average age 40.6 years (age range 8-89 years)] with TMJ disorder, who were examined in the year 2014 in Department of Dental Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Czech Republic. The aim of this retrospective study was to analyse, if the lack of posterior teeth (supporting teeth zones) is the main etiologic factor of osteoarthrosis of TMJ. Diagnosis of OA was established on the clinical signs and the panoramic X-ray signs. Simultaneously other etiologic factors of OA were assessed. The presence of OA changes on X-ray had 171 patients (i.e. 27.6% of the total number of 619). 17.5% from these patients with OA had defect in posterior dentition. Other aetiological factors (stress, skeletal or vertebrogenous disorders) showed higher incidence of OA changes on X-ray. Defect of posterior dentition is not negligible, but it is not the main aetiological factor for osteoarthrosis of TMJ.