Clinical effect of digitalized designed and 3D-printed repositioning splints in the treatment of anterior displacement of temporomandibular joint disc

OBJECTIVE

To compare the treatment effectiveness of digitized and 3D-printed repositioning splints with that of conventional repositioning splints in the treatment of anterior displacement of the temporomandibular joint disc.

METHODS

This retrospective study included 96 patients with disc displacement of the anterior temporomandibular joint. They were treated with either digitally designed and 3D-printed repositioning splints or traditional splints and followed up for at least six months. Changes in signs and symptoms such as pain and mouth opening before and after treatment were recorded to evaluate treatment outcomes.

RESULTS

During the first month of treatment, both the digitally designed and 3D-printed repositioning splint groups (Group B) and the traditional repositioning splint group (Group A) showed significant increases in mouth opening, with increases of 4.93 ± 3.06 mm and 4.07 ± 4.69 mm, respectively, and there was no significant difference between the two groups. Both groups had a significant reduction in visual analog scale (VAS) pain scores, with Group B showing a greater reduction of 1.946 ± 1.113 compared to 1.488 ± 0.978 in Group A (P < 0.05). By the sixth month, Group B's mouth opening further improved to 38.65 ± 3.22 mm (P < 0.05), while Group A's mouth opening did not significantly improve. Regarding pain, Group A's VAS score decreased by 0.463 ± 0.778 after one month, and Group B's score decreased by 0.455 ± 0.715; both groups showed significant reductions, but there was no significant difference between the two groups.

CONCLUSION

Compared with traditional repositioning splints, digitally designed and 3D-printed repositioning splints are more effective at reducing patient pain and improving mouth opening. 3D-printed repositioning splints are an effective treatment method for temporomandibular joint disc displacement and have significant potential for widespread clinical application.

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.

Predictors of arthrocentesis outcome on joint effusion in patients with disk displacement without reduction

OBJECTIVES

The aim of this study was to investigate the preoperative variables in patients with articular disk displacement without reduction that may influence the results of arthrocentesis on joint effusion (JE).

STUDY DESIGN

The records of 203 patients with clinical signs and symptoms of unilateral painful disk displacement without reduction and JE, confirmed by magnetic resonance imaging (MRI), and treated with arthrocentesis were selected. The following preoperative data were recorded: sex; age; joint side; pain duration; pain intensity, measurement with the visual analogue scale; and maximum interincisal distance (MID). All patients underwent a second MRI examination 3 to 4 months postoperatively to assess JE. The sample was then divided into 2 groups: group 1 (n = 160) comprised patients with no signs of JE; and group 2 (n = 43) comprised patients still showing signs of JE. Univariate and multivariate analyses were used to compare the groups.

RESULTS

Among the studied variables, pain duration (P = .0175), pain intensity (P < .0001), and MID (P = .0085) were shown to affect arthrocentesis outcomes. The longer the pain duration (odds ratio [OR] = 0.930), the more intense was the pain (OR = 0.346), and the smaller the MID (OR = 0.562), the less were the chances of arthrocentesis completely eliminating JE.

CONCLUSIONS

Pain duration, pain intensity, and MID can be used as predictors for the effect of arthrocentesis on JE outcomes and considered during treatment planning.

Mechanobehavioral Scores in Women with and without TMJ Disc Displacement

Cartilage fatigue may be a factor in the precocious development of degenerative changes in the temporomandibular joint (TMJ). This cross-sectional study estimated potential for cartilage fatigue via TMJ energy densities (ED) and jaw muscle duty factors (DF), which were combined to calculate mechanobehavioral scores (MBS) in women with (+) and without (-) bilateral TMJ disc displacement (DD). All subjects gave informed consent to participate and were examined using Diagnostic Criteria (DC) for Temporomandibular Disorders (TMD) and magnetic resonance (MR) and computed tomography (CT) images. Forty-seven subjects were categorized into +DD ( n = 29) and -DD ( n = 18) groups. Dynamic stereometry (MR images combined with jaw-tracking data) characterized individual-specific data of TMJ stress-field mechanics to determine ED (ED = W/ Q mJ/mm3, where W = work done, Q = volume of cartilage) during 10 symmetrical jaw-closing cycles with a 20-N mandibular right canine load. Subjects were trained to record masseter and temporalis electromyography over 3 days and 3 nights. Root mean square electromyography/bite-force calibrations determined subject-specific masseter and temporalis muscle activities per 20-N bite-force (T20 N, µV), which defined thresholds. Muscle DF (DF = % duration of muscle activity/total recording time) were determined for a range of thresholds, and MBS (ED2 × DF) were calculated. Intergroup differences in ED, DF, and MBS were assessed via analyses of variance with Bonferroni and Tukey honest significant difference post hoc tests. Average ED for contralateral TMJs was significantly larger ( P = 0.012) by 1.4-fold in +DD compared to -DD subjects. Average DF were significantly larger (all P < 0.01) for +DD compared to -DD subjects by 1.7-, 2.5-, and 1.9-fold for day, night, and overall, respectively. Daytime MBS were significantly larger (all P < 0.04) by up to 8.5-fold in +DD compared to -DD subjects. Significantly larger ED, DF, and MBS were shown in women with compared to women without bilateral TMJ DD.

Evaluation of articular disc loading in the temporomandibular joints after prosthetic and pharmacological treatment in model studies

BACKGROUND

Temporomandibular joint dysfunction is often related to excessive load in the stomatognathic system.

OBJECTIVES

The objective of the model tests, using numeric calculations, was to assess the articular disc loads in the temporomandibular joints after prosthetic and pharmacological treatment of functional disorders of the masticatory organ.

MATERIAL AND METHODS

The study involved 10 patients, aged 21-48 years, of both sexes, randomly selected from a group of 120 patients treated with relaxation occlusal splints (60 patients, group I) and intramuscular injection of botulinum toxin type A (60 patients, group II), suffering from temporomandibular joint dysfunction with the dominant muscle component. In all subjects, a specialized functional examination was carried out. Treatment groups: occlusal splint therapy (group I) and intramuscular injection of botulinum toxin type A (group II). An assessment of the loads of 4 disc zones of the temporomandibular joints was carried out based on the results of clinical studies (phase I of the study), and numeric model tests (phase II). In the representatives of the study groups (5 patients in each group), measurements of occlusal forces and an evaluation of tension of the masseter and temporalis muscle were performed.

RESULTS

The results of the average load values for all evaluated zones of the right and left articular disc differ in a statistically significant way in favor of group II, with the exception of the external mid part of the discs. In the case of the anterior of the right disc, the load was lower in patients belonging to group I than in those obtained in group II.

CONCLUSIONS

Botulinum toxin type A significantly reduces the loads within the temporomandibular joints, generated by masseter muscle hypertonia.

Ipsilateral Molar Clenching Induces Less Pain and Discomfort than Contralateral Molar Clenching in Patients with Unilateral Anterior Disc Displacement of the Temporomandibular Joint

AIMS

To assess the influence of clenching side and location (ie, tooth) on the bite force necessary to induce pain or discomfort in patients with unilateral anterior disc displacement (ADD) of the temporomandibular joint (TMJ).

METHODS

A total of 17 patients with unilateral ADD diagnosed clinically and with magnetic resonance imaging were included. A bite force meter was positioned at each of four experimental positions: the mandibular first premolars and first molars, bilaterally. Subjects were instructed to clench on the bite force meter until they felt pain or discomfort in the orofacial area and to report the location of the pain. Differences in pain location (ADD side versus contralateral side) and in the bite force thresholds for eliciting pain or discomfort were assessed by means of the paired t test and Wilcoxon signed-rank test.

RESULTS

Only 18% of subjects (3 out of 17) reported pain in the TMJ with ADD during clenching at the ipsilateral molar, whereas 65% (11 out of 17) reported joint pain during clenching on the contralateral molar (P = .005). At the molars, the mean ± standard deviation bite force necessary to induce pain was 241.2 ± 135.5 N on the side with ADD and 160.9 ± 78.0 N on the contralateral side. The mean molar bite force necessary to induce pain on the side with ADD was significantly higher than that on the contralateral side (P = .002).

CONCLUSION

Patients with unilateral ADD had fewer reports of TMJ pain and discomfort when they were molar clenching on the ipsilateral side compared to molar clenching on the contralateral side.

Dynamic Intra-articular Space Variation in Clicking TMJs

During mandibular movement, the geometric relationships of the articular surfaces in the temporomandibular joint (TMJ) change, so that the disc undergoes different stress concentrations with respect to time and position. In this study, we compared the intra-articular space variations of 13 clicking and 15 asymptomatic TMJs for jaw opening/closing. Magnetic resonance imaging and jaw tracking were combined to display the motion of the whole condyle within the fossa. In clicking TMJs, the mediolateral spread s of the stress-field trajectories was 2.4 ± 1.0 mm ( smax = 4.9 ± 2.1 mm) with an aspect ratio a/h of 2.5 ± 1.6, both significantly greater than in controls (p < 0.05). The stress-field trajectories of the controls coincided during opening/closing ( s = 0.9 ± 0.2 mm, smax = 1.8 ± 0.8 mm, a/h = 1.6 ± 0.3). Clicking TMJs showed much less coincident stress-field paths and much “flatter” stress-fields than controls during jaw opening/closing.

Biomechanical and biochemical outcomes of porcine temporomandibular joint disc deformation

OBJECTIVE

The structure-function relationship in the healthy temporomandibular joint (TMJ) disc has been well established, however the changes in dysfunctional joints has yet to be systematically evaluated. Due to the poor understanding of the etiology of temporomandibular disorders (TMDs) this study evaluated naturally occurring degenerative remodeling in aged female porcine temporomandibular joint (TMJ) discs in order to gain insight into the progression and effects on possible treatment strategies of TMDs.

DESIGN

Surface and regional biomechanical and biochemical properties of discal tissues were determined in grossly deformed (≥Wilkes Stage 3) and morphologically normal (≤Wilkes Stage 2) TMJ discs.

RESULTS

Compared to normal disc structure the deformed discs lacked a smooth biconcave shape and characteristic ECM organization. Reduction in tensile biomechanical integrity and increased compressive stiffness and cellularity was found in deformed discs. Regionally, the posterior and intermediate zones of the disc were most frequently affected along with the inferior surface.

CONCLUSIONS

The frequency of degeneration observed on the inferior surface of the disc (predominantly posterior), suggests that a disruption in the disc-condyle relationship likely contributes to the progression of joint dysfunction more than the temporodiscal relationship. As such, the inferior joint space may be an important consideration in early clinical diagnosis and treatment of TMDs, as it is overlooked in techniques performed in the upper joint space, including arthroscopy and arthrocentesis. Furthermore, permanent damage to the disc mechanical properties would limit the ability to successfully reposition deformed discs, highlighting the importance of emerging therapies such as tissue engineering.

The Basic Conservative Treatment of Temporomandibular Joint Anterior Disc Displacement Without Reduction--Review

Temporomandibular joint derangement is a common disorder of the stomatognathic system. One type of these disorders is disc displacement without reduction with limited mouth opening, characterized by pain in affected TMJ and a decreased range of mouth opening. The natural course of closed lock is self-limiting. However, if there is no significant improvement after 12 weeks of following natural course of disc displacement without reduction, this is an indication that the therapy should be implemented. The article presents a review of the most commonly applied methods of basic conservative closed lock treatment. The most commonly applied methods of closed lock conservative management are: education and counseling, mandibular manipulation, splint therapy, exercise therapy and pharmacotherapy. The first choice method of treatment should be minimally invasive. The surgical management should be considered after unsuccessful conservative therapy. All presented methods of closed lock treatment seem to be effective in decreasing pain and reestablishing physiological range of motion.

Diagnostic group differences in temporomandibular joint energy densities

OBJECTIVES

Cartilage fatigue, due to mechanical work, may account for precocious development of degenerative joint disease in the temporomandibular joint (TMJ). This study compared energy densities (mJ/mm³) in TMJs of three diagnostic groups.

SETTING AND SAMPLE POPULATION

Sixty-eight subjects (44 women, 24 men) gave informed consent. Diagnostic criteria for temporomandibular disorders (DC/TMD) and imaging were used to group subjects according to presence of jaw muscle or joint pain (+P) and bilateral disk displacement (+DD).

MATERIAL AND METHODS

Subjects (+P+DD, n=16; -P+DD, n=16; and -P-DD, n=36) provided cone-beam computed tomography and magnetic resonance images, and jaw-tracking data. Numerical modeling was used to determine TMJ loads (Fnormal). Dynamic stereometry was used to characterize individual-specific data of stress-field dynamics during 10 symmetrical jaw-closing cycles. These data were used to estimate tractional forces (Ftraction). Energy densities were then calculated as W/Q (W=work done or mechanical energy input=tractional force×distance of stress-field translation, Q=volume of cartilage). anova and Tukey-Kramer post hoc analyses tested for intergroup differences.

RESULTS

Mean±standard error energy density for the +P+DD group was 12.7±1.5 mJ/mm³ and significantly greater (all adjusted p<0.04) when compared to -P+DD (7.4±1.4 mJ/mm³) and -P-DD (5.8±0.9 mJ/mm³) groups. Energy densities in -P+DD and -P-DD groups were not significantly different.

CONCLUSION

Diagnostic group differences in energy densities suggest that mechanical work may be a unique mechanism, which contributes to cartilage fatigue in subjects with pain and disk displacement.

Longitudinal study on TMJ disk status and its effect on mandibular growth

OBJECTIVE

This longitudinal study assessed the potential contribution of temporomandibular joint (TMJ) disk status over mandibular linear and angular changes.

DESIGN

Cohort study.

SETTING

Edmonton, Alberta, Canada.

PARTICIPANTS

Seventy-three adolescent subjects attending TMJ or orthodontic clinics with or without TMJ disk abnormality were followed during a mean 3 years 7 months. From this sample 39 subjects underwent orthodontic treatment.

METHODS

Disk displacement and disk length measurements taken from MRIs were utilized to evaluate the TMJ disk status. Mandibular changes were quantified from cephalometric radiographs by superimposing the mandible around the internal cortex of the posterior wall of the mandibular symphysis. Fishman's skeletal maturation system was used to calculate the percentage of mandibular growth remaining during the follow-up. This expected mandibular growth was factored out through a statistical normalization process applied to the actual difference between the initial and final mandibular measurements. In addition, previous orthodontic treatment was also considered for the analysis. A multiple analysis of variance (MANOVA) was used to evaluate interaction between the independent variables (TMJ disk status and previous orthodontic treatment) over the dependent variables (mandibular ramus, mandibular body, mandibular length and gonial angle measurements).

RESULTS

No significant contribution was found of any of the evaluated variables or its interactions over the mandibular measurements.

CONCLUSIONS

No evidence was found of TMJ disk abnormality as an associated significant factor with mandibular dimensional changes. The findings have to be evaluated with caution because of some limitations identified in this study.

Could different TMJ disc positions observed in MRI cause different sounds? Analysis on a group of subjects with ADD with reduction: a pilot study

AIMS

Magnetic resonance imaging (MRI) is the method of choice for examining soft-tissue pathology of the temporomandibular joint (TMJ). MRI shows a high spatial resolution with accuracy for the identification of internal derangement. Tasaki developed a classification system for disc displacement in the TMJ, identifying eight different types of disc displacements in addition to the superior disc position. This study aims to test the ability of electrosonography (ESG) in discriminating different kinds of disc displacement according to the disc position criteria proposed, comparing the ESG results with those obtained by MRI.

METHODOLOGY

Twenty-seven patients were selected from an initial group of 50 patients with articular disc displacement, selected by means of clinical examinations, according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) and who had both MRI and ESG studies performed. For each patient and for each peak in ESG, both in the opening and closing movements, three different parts of the sound were analyzed. The frequency (Hz) and the mean amplitude (μV) of the sounds were calculated in the three analyzed windows. Afterwards, gathering the data for the Tasaki's classes and dividing opening and closing sounds, the number of peaks was calculated, as well as average and standard deviations for both the Hz and µV.

RESULTS

The peak frequency shows significant differences between different disc positions during the first and second third of the opening phase and during the first third of the closing phase. The peak amplitude shows significant differences between different disc positions during all of the opening and closing phases.

CONCLUSIONS

Although limited by sample size, the present study shows the presence of different sounds with different Hzs and μVs associated with different disc positions that were recorded with ESG.

Clinical treatment of a ruptured temporomandibular joint disc: morphological changes at 5-year follow-up

Osteoarthrosis is a disease that affects the temporomandibular joint (TMJ). This case report chronicles the diagnosis and treatment of a patient for whom this pathological condition was accompanied by a rupture of the articular disc. The patient presented with loud sounds in the left TMJ and an irregular mandibular occlusal plane due to condylar intrusion in the glenoid fossa on the ipsilateral side. A noninvasive treatment was selected. A 4-month follow-up revealed remission of the articular sounds, and tissue regeneration was noted. These improvements remained visible at 5-year follow-up.

Correlation Between Disk Morphology on MRI and Time Curves Using Electronic Axiography

This retrospective series was intended to determine whether morphological disk findings in open and closed mouth magnetic resonance imaging (MRI) may be correlated with the time curves in axiography. In this series, 45 temporomandibular joints of 33 patients were subjected to a retrospective evaluation. Magnetic resonance images obtained with closed and open mouth and joint movements assessed by electronic axiography were analyzed. Disk morphology in MRI was classified as normal, partly flattened, partly thickened, or completely thickened. For the axiographic tracings, time curves of the free movements of the respective joint were developed and evaluated. Data obtained were analyzed for any potential correlation using scatter plots and discriminance analysis. No correlation between these data was found suggesting that the axiographic time curves do not provide for any conclusions with regard to disk morphology. Apart from patient history and a thorough clinical evaluation, recording of jaw movements, but also using MRI continues to be of particular value in the diagnostic assessment of anterior disk displacement.

Treatment of Joint Pain and Joint Noises Associated with a Recent TMJ Internal Derangement: A Comparison of an Anterior Repositioning Splint, a Full-Arch Maxillary Stabilization Splint, and an Untreated Control Group

Pain and joint noises associated with temporomandibular joint (TMJ) internal derangement are often treated by using an intra-oral splint. This study evaluated whether an anterior repositioning splint (AR splint) could be more effective in the treatment of these symptoms than a full-arch maxillary stabilization splint (FAMS splint), because of its capability to re-establish immediately the normal condyle/disk relationship. The authors treated 40 patients (average age 16.8; range 8.0-24.0) with confirmed internal derangement, joint pain, and joint noises in at least one TMJ for at least two months, with AR splint (20 subjects) or FAMS splint (20 subjects); 10 untreated patients comprised the control group. Joint noise, joint pain, and the intensity of pain were assessed using a visual analogic scale (VAS), and the pain was characterized (i.e., constant or chewing/biting pain) and evaluated monthly for eight months. Significantly fewer AR splint patients experienced pain after four months of treatment. A significantly lower intensity of pain was experienced by the AR splint patients after two months of treatment. Significantly fewer AR splint patients experienced chewing/biting pain after eight months of treatment. The frequency of joint noises decreased over time, with no significant differences between the groups. In conclusion, the AR splint seems to be more effective in decreasing pain, but it seems to make no difference in the treatment of joint noises.

Response of Temporomandibular Joint Intermittent Closed Lock to Different Treatment Modalities: A Multicenter Survey

This study investigated the clinical picture and different treatment methods and results at a number of institutions with the aim of establishing an effective method of treatment for intermittent closed lock (intermittent lock) of the temporomandibular joint (TMJ). The subjects were 104 patients (29 males, 65 females) diagnosed with intermittent lock among 1787 temporomandibular disorder patients. The cases were classified into two types based on the time and occasion when the intermittent lock occurred. The sudden onset type developed in 69.2%, and the habitually occurring type in 29.8%. The most common treatment was disk repositioning exercises alone (in 41 cases) followed by stabilization splints during sleeping. The highest efficacy rate (60.0%) was obtained with the combination of disk repositioning exercise and a repositioning splint followed by a rate of 52.6% with stabilization splints and 41.7% with disk repositioning exercise alone.

Effect of mechanical strain on solute diffusion in human TMJ discs: an electrical conductivity study

This study investigated the effect of mechanical strain on solute diffusion in human TMJ discs (mean cadaver age 77.8) using the electrical conductivity method. The electrical conductivity, as well as small ion diffusivity, of male and female TMJ discs was determined under three compressive strains. In the male group, the average disc electrical conductivity (mean ± SD) at 0% strain was 5.14 ± 0.97 mS/cm, decreased to 4.50 ± 0.91 mS/cm (-12.3%) at 10% strain, and 3.93 ± 0.81 mS/cm (-23.5%) at 20% compressive strain. Correspondingly, the average disc relative ion diffusivity at 0% strain was 0.44 ± 0.08, decreased to 0.40 ± 0.08 (-8.9%) at 10% strain, and 0.36 ± 0.08 (-16.7%) at 20% compressive strain. In the female group, the average disc electrical conductivity at 0% strain was 5.84 ± 0.59 mS/cm, decreased to 5.01 ± 0.50 mS/cm (-14.2%) at 10% strain, and 4.33 ± 0.46 mS/cm (-25.8%) at 20% compressive strain. Correspondingly, the average disc relative ion diffusivity at 0% strain was 0.49 ± 0.05, decreased to 0.43 ± 0.04 (-11.3%) at 10% strain, and 0.39 ± 0.04 (-19.9%) at 20% compressive strain. The results indicated that mechanical strain significantly impeded solute diffusion through the disc. This mechanical strain effect was larger in the female than in the male human TMJ disc. This study may provide new insights into TMJ pathophysiology.

A role for apoptosis in temporomandibularjoint disc degeneration. A contemporary review

The temporomandibular joint (TMJ) connects the mandible to the skull. TMJ disorders induce degenerative tissue changes in TMJ disc that are largely the result of maladaption to abnormal joint loading. Histopathological studies have documented an association between TMJ arthropathy and loss of tissue cellularity, via apoptosis-related processes, that result in diminished extracellular matrix generation, organization, and repair. However, the exact molecular mechanisms underpinning the development and progression of such degenerative changes are still unclear. We review the most recent findings regarding the involvement of apoptotic mechanisms in TMJ disc degeneration. Although a number of aspects of TMJ disc degeneration have been thoroughly investigated, data on the involvement of apoptotic mechanisms and their mediators are few and quite recent; indeed most of the research conducted on fibrous cartilage apoptosis has focused on the intervertebral disc.

Reproducibility of 2 methods to locate centric relation in healthy individuals and TMD patients

No conclusive evidence exists for any maxillomandibular relationship as the preferable treatment position. Measurement reliability of 2 different methods to attempt to locate centric relation in control and TMD patients was assessed to determine if both methods lead to the same position. A group of 27 controls and 91 TMD patients were examined using the Research Diagnostic Criteria for TMD (RDC/TMD). Three patient groups were recruited: 27 patients with myofascial pain (MYO), 34 patients with disc displacement without reduction (ID), and 30 patients with osteoarthritis (OA). For each study participant centric relation was located with chinpoint guidance and a technique with a leaf gauge, for the controls once, for all TMD patients before and after stabilization splint treatment. The mixed model procedure revealed no significant differences between the methods, the patient groups and the time interval. However the patient groups at baseline and conclusion of treatment differed significantly from the controls. The percentage of patients (15.9%) having a coincident split-cast result for both methods was significantly smaller (P < 0.001) than the corresponding percentage (85.2%) of controls. After splint treatment, the percentage of coincident split-casts increased from 15.9% to 76.8%. Both methods are reproducible techniques to locate centric relation for control and TMD patients. However, the leaf gauge provides the clinician a different centric relation position in TMD patients than chinpoint guidance does.

Biopsychosocial factors associated with the subcategories of acute temporomandibular joint disorders

AIMS

To assess the biopsychosocial factors associated with acute temporomandibular disorders (TMD) based on the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD).

METHODS

Participants were assessed in community-based dental clinics and evaluated by trained clinicians using physical and psychosocial measures. A total of 207 subjects were evaluated. Patients' high-risk versus low-risk status for potentially developing chronic TMD was also determined. Analyses of variance and chi square analyses were applied to these data.

RESULTS

Participants' characteristic pain intensity differed among RDC/TMD Axis I diagnoses. They also significantly varied in their self-reported graded chronic pain, depression, somatization (pain inclusive), somatization (pain excluded), and physical well-being. In addition, participants with differing RDC/TMD Axis I diagnoses varied in self-reported pain during their chewing performance. Finally, there were also significant differences in chewing performance between high-risk versus low-risk (for developing chronic TMD) patients.

CONCLUSION

Participants with multiple diagnoses reported higher pain, as well as other symptoms, relative to participants without a TMD diagnosis. For chewing performance, participants with mutual diagnoses reported more pain compared to other participants. Finally, the risk-status of patients significantly affected chewing performance.

Temporomandibular joint structural derangement and general joint hypermobility

AIM

To explore the relationship between general joint hypermobility (GJH) and displacement of the temporomandibular joint (TMJ) disc as evident from magnetic resonance imaging (MRI).

METHODS

Fifth finger extension, thumb apposition, elbow extension, knee extension, trunk flexion, and ankle dorsiflexion were measured in 66 young female patients with MRI-evident TMJ internal derangement (ID) and in 30 age-matched female controls. The Beighton score of each subject was measured quantitatively. The possible association between TMJ ID and mobility of a single joint or index of GJH, ie, the Beighton score, were assessed with one-way ANOVA with post-hoc Bonferroni and chi-square test, respectively. Correlations of the mobility of every measured joint were also explored.

RESULTS

Very few of the TMJ ID patients and control subjects were diagnosed with GJH according to the Beighton score. The Beighton score did not differentiate between subjects with and without TMJ ID. Subjects with TMJ ID, especially patients with MRI-evident disc displacement without reduction, seemed to have a stiffer trunk than controls, but this may not be of clinical relevance. The mobilities of paired joints were significantly correlated; however, the mobilities of different anatomical joints seemed to be independent.

CONCLUSION

Based on the Beighton score, GJH does not seem to be a reliable indicator of the presence of TMJ ID.

Effect of chewing upon disc reduction in the temporomandibular joint

AIMS

To test whether an intensive chewing exercise influences the moment of disc reduction in subjects with or without reports of intermittent locking of the jaw.

METHODS

This experimental study included 15 subjects with a reducing anteriorly displaced disc (ADD) and with symptoms of intermittent locking and 15 subjects with a reducing ADD without such symptoms. The moment of disc reduction (MDR), quantified using mandibular movement recordings, was recorded at baseline, and after maximally 60 minutes of chewing. Thereafter, MDR was recorded again after 20 minutes of rest, and if necessary after 72 hours, in order to document return of MDR to baseline values.

RESULTS

In subjects without intermittent locking, the MDR after chewing was not different from baseline (P = .25). However, in the subjects with intermittent locking, the MDR value had increased significantly after chewing (P = .008); two subjects showed a later moment of disc reduction, and four showed a temporary loss of disc reduction.

CONCLUSION

While intensive chewing did not influence disc reduction in subjects without intermittent locking, it caused a delay or even hampered disc reduction in approximately half of the subjects reporting intermittent locking.

Perceived symptoms of psychological distress and salivary cortisol levels in young women with muscular or disk-related temporomandibular disorders

OBJECTIVE

To assess any differences in psychological and endocrine variables between homogeneous core groups of young women with well-defined muscle- or disk-related temporomandibular disorders (TMDs) and matched controls.

MATERIAL AND METHODS

Fifteen women, aged 18-24 years, fulfilling the TMD Research Diagnostic Criteria I a/b (but not II or III) and 15 fulfilling the II a/b and III criteria were consecutively selected from referrals to an orofacial pain/TMD clinic. Thirty consecutive healthy age-matched women attending yearly routine check-ups at a general dental clinic served as controls. All 60 subjects answered a questionnaire, the Profile of Fatigue Related Symptoms (PFRS), and salivary samples on waking were collected for analysis of cortisol levels.

RESULTS

Symptom duration and pain levels were similar irrespective of muscle- or disk-related symptoms. Both diagnostic groups obtained scores that were similar and significantly higher than those of controls in all four scales of the PFRS: fatigue, emotional distress, cognitive difficulties and somatic symptoms. Salivary cortisol levels on waking did not differ between patients and controls.

CONCLUSIONS

Patients with TMDs, irrespective of diagnosis, appeared to be more psychologically distressed than controls evaluated psychometrically, which is in line with earlier findings. A corresponding difference was not reflected in a single measurement of morning salivary cortisol. A more comprehensive evaluation of endocrine variables is probably necessary to reveal whether any differences actually exist in this respect.

[Cell sources for engineered temporomandibular joint disc tissue: present and future]

The purpose of this review is to provide a reference for researchers in investigating the tissue engineering of the temporomandibular joint (TMJ) disc. Currently tissue engineering of the TMJ disc is in its infancy, and cell source is one of the key factors that define the development of the tissue engineering of TMJ disc. In this paper, 6 kinds of cells: the TMJ disc native cells, chondrocytes, dermal fibroblasts, bone marrow-derived mesenchymal stem cells, adipose-derived stem cells, and embryonic stem cells are introduced. In addition, the possibility that these cells can be used as cell sources for TMJ disc tissue engineering is described.

Two-year natural course of anterior disc displacement with reduction

AIMS

To test if the disappearance of clicking associated with anterior disc displacement with reduction (ADDR) is related to a gradual loss of reducing capacity of the disc in the temporomandibular joint.

MATERIALS

Twenty-five ADDR subjects without and 30 ADDR subjects with intermittent locking participated in this 2-year follow-up study. Clinical examinations and mandibular movement recordings were performed at baseline and after 1 and 2 years. If mandibular movement recordings no longer showed signs of an ADDR, magnetic resonance imaging (MRI) of the disc was carried out.

RESULTS

Mandibular movement recordings showed the moment of disc reduction (MDR) to be stable over the observation period in the subjects without intermittent locking (P = .95). In the subjects with intermittent locking, MDR had shifted to a later mouth opening (P = .000). In seven of these subjects, clicking had totally disappeared, usually without symptoms of permanent locking. On the MRI scans of these subjects, the disc displacement was still present, but with no, or only a partial, reduction.

CONCLUSION

Intermittent locking may be indicative of the development of a disc displacement without reduction. This loss is only rarely accompanied by symptoms of permanent locking.

Global body posture evaluation in patients with temporomandibular joint disorder

AIM

To identify the relationship between anterior disc displacement and global posture (plantar arches, lower limbs, shoulder and pelvic girdle, vertebral spine, head and mandibles). Common signs and symptoms of anterior disc displacement were also identified.

INTRODUCTION

Global posture deviations cause body adaptation and realignment, which may interfere with the organization and function of the temporomandibular joint.

METHODS

Global posture evaluation was performed in a group of 10 female patients (20 to 30 years of age) with temporomandibular joint disc displacement and in a control group of 16 healthy female volunteers matched for age, weight and height. Anterior disc displacement signs, symptoms and the presence of parafunctional habits were also identified through interview.

RESULTS

Patients with disc displacement showed a higher incidence of pain in the temporomandibular joint area, but there were no differences in parafunctional habits between the groups. In the disc displacement group, postural deviations were found in the pelvis (posterior rotation), lumbar spine (hyperlordosis), thoracic spine (rectification), head (deviation to the right) and mandibles (deviation to the left with open mouth). There were no differences in the longitudinal plantar arches between the groups.

CONCLUSION

Our results suggest a close relationship between body posture and temporomandibular disorder, though it is not possible to determine whether postural deviations are the cause or the result of the disorder. Hence, postural evaluation could be an important component in the overall approach to providing accurate prevention and treatment in the management of patients with temporomandibular disorder.

Evaluation of TMJ articular eminence morphology and disc patterns in patients with disc displacement in MRI

The aim of this study was to assess the shape of the temporomandibular joint (TMJ) articular eminence and the articular disc configuration and position in patients with disc displacement. TMJ magnetic resonance images (MRI) of 14 patients with bilateral disc displacement without unilateral reduction were analyzed. Articular eminence morphology was characterized as box, sigmoid, flattened, or deformed. Articular disc configuration was divided into biconcave, biplanar, biconvex, hemiconvex or folded, and its position, as "a" (superior), "b" (anterosuperior), "c" (anterior) or "d" (anteroinferior). The images were divided and the sides with disc displacement with reduction (DDWR) and without reduction (DDWOR) were compared. Regarding articular eminence shape, the sigmoid form presented the greatest incidence, followed by the box form, in the DDWR side, although this was not statistically significant. In the DDWOR side, the flattened shape was the most frequent (p = 0.041). As to disc configuration, the biconcave shape was found in 79% of the DDWR cases (p = 0.001) and the folded type predominated in 43% of the DDWOR cases (p = 0.008). As to disc position, in the DDWR side, "b" (anterosuperior position) was the most frequent (p = 0.001), whereas in the DDWOR side, "d" (anteroinferior position) was the most often observed (p = 0.001). The side of the patient with altered disc configuration and smaller shape of TMJ articular eminence seems to be more likely to develop non-reducing disc displacement as compared to the contralateral side.

Effect of a jig on EMG activity in different orofacial pain conditions

PURPOSE

The bite stop (jig) is commonly used in clinical practice. It has been recommended as a simple means to routinely record or provide centric relation closure and, more recently, to reduce migraines and tension-type headaches. However, the reason for the jig effect has yet to be explained. This study tested the hypothesis that it works through a decrease in masticatory muscle activity.

MATERIALS AND METHODS

The effect of a jig placed on the maxillary anterior teeth was investigated by recording the electromyographic (EMG) activity of the superficial masseter and anterior temporal muscles at postural position and when swallowing on the jig. EMG recordings were obtained from 2 groups of pain patients (myofascial and neuropathic) and from 2 groups of pain-free patients (disc derangement and controls) unaware of the role of dental occlusion treatments.

RESULTS

EMG activity in postural position was higher in pain groups than in pain-free groups. The jig strongly but temporarily decreased the postural EMG activity for masseter muscles in all groups except for the neuropathic group and for temporal muscles in the myofascial group. The EMG activity when swallowing with the jig was reduced in control, disc derangement, and myofascial groups; however, EMG "hyperactivity" in the neuropathic pain group seemed to be locked.

CONCLUSIONS

The decrease of postural EMG activity, especially in the myofascial group, was short lasting and cannot be considered as evidence to support the hypothesis of a long-term muscle relaxation jig effect. However, the results may uphold certain short-term clinical approaches.

A method for clinically defining "improvers" in chronic pain studies

AIMS

To test a measurement model based on clinicians' assessments of patient data that allows simple and confident clinical validation of any statistical or numerical technique designed to separate patients improving with treatment from those who are not, particularly for pain that shows large daily variation.

METHODS

Diaries using daily visual analog scales (VAS) of pain intensity were obtained from 39 patients treated for chronic temporomandibular disorders. Three experienced clinicians visually assessed 39 VAS/time graphs. Criteria indicating improvement (general trend, height and apparent frequency of graph spikes) evolved over 3 assessments. The third assessment defined improvers visually. Numeric analyses considered the difference between first and last months of treatment for mean, area under the curve (AUC), and maximum VAS scores. Thresholds of 40%, 50%, or 60% pain reduction defined improvement numerically. Aggregate sensitivity and specificity was compared with visual definition to find the optimal threshold.

RESULTS

Patients were defined visually as improvers, nonimprovers, and borderline cases. Interexaminer reliability for identifying improvers was good (k = 0.79). Mean VAS and AUC were highly correlated (r = 0.999). The optimal threshold of mean and maximum VAS relative to visual definition was 50% pain reduction. Cases defined as improvers by both mean and maximum agreed best with the visual definition (sensitivity 90%, specificity 84%).

CONCLUSION

Visual assessment of VAS demonstrates distinct pain/time patterns that can validate numeric definition of complex pain recovery. No single numeric method can be guaranteed to give a clinically valid outcome.

Influence of unilateral disc displacement on the stress response of the temporomandibular joint discs during opening and mastication

The temporomandibular joint plays a crucial role in human mastication acting as a guide of jaw movements. During these movements, the joint is subjected to loads which cause stresses and deformations in its cartilaginous structures. A perfect balance between the two sides of the joint is essential to maintain the physiological stress level within the tissues. Therefore, it has been suggested that a derangement of the joint is a contributing factor in the development of mandibular asymmetry, especially if problems of the temporomandibular joint start in childhood or adolescence. To analyze the movement of the mandible and the stresses undergone by the discs, two finite element models of the human temporomandibular joint including the masticatory system were developed, one corresponding to a healthy joint and the other with a unilateral anterior disc displacement with their movement controlled by muscle activation. A fibre-reinforced porohyperelastic model was used to simulate the behaviour of the articular discs. The stress distribution was analyzed in both models during free opening and closing, and during the introduction of a resistant force between incisors or molars. It was found that a slight unilateral anterior disc displacement does not lead to mandibular asymmetry but to a slight decrease of the maximum gape. With the introduction of a restriction between incisors, the maximum stresses moved to the anterior band in contrast to what happened if the restriction was imposed between molars where maximum stresses were located more posteriorly. Finally, the presence of a unilateral displacement of the disc involved a strong change in the overall behaviour of the joint including also the healthy side, where the maximum stresses moved to the posterior part.

Comparison of imaging follow-up between joints with arthroscopic surgery (lysis and lavage) and those with nonsurgical treatment

PURPOSE

To assess the influence of arthroscopic surgery on radiographically evident degenerative change of the temporomandibular joint (TMJ). The post-treatment course was compared between the joints that underwent arthroscopic lysis and lavage and those that underwent nonsurgical treatment.

PATIENTS AND METHODS

Twenty-eight patients agreed to imaging follow-up examination of 35 joints. Twenty-four joints of 19 patients underwent only nonsurgical treatment (nonsurgical joints). Eleven joints of 9 patients failed the nonsurgical treatment and consequently underwent arthroscopic lysis and lavage (arthroscopic joints). The joints were assessed at first visit and at least 20 months later (mean, 79 months) for disc displacement, disc position, disc morphology, disc mobility, condylar morphology, morphology of the articular eminence, and horizontal condylar angle and size. Thereafter, interval change was assessed and compared between the groups.

RESULTS

There was no significant difference in the prevalence of the progressive degenerative changes between the groups. In addition, there was no significant difference in the change of size and morphology of the condyle. However, a higher prevalence of improvement of disc mobility in the arthroscopic joints rather than the nonsurgical joints was significant (Goodness of fit test for chi(2), P < .05).

CONCLUSIONS

The results of this study suggest that the post-treatment course of radiographically evident degenerative change was not significantly different between arthroscopy and nonsurgical treatment; however, arthroscopic surgery showed a greater ability to improve disc mobility. In imaging follow-up, arthroscopic lysis and lavage is a minimally invasive treatment modality that is equivalent to nonsurgical treatment.

Temporomandibular joint soft-tissue pathology, I: Disc abnormalities

The internal derangements are the most common noninflammatory abnormalities of the disc, observed even in asymptomatic subjects. Because the temporomandibular joint shows large adaptative and compensatory mechanisms over dysfunctional disc motion, these disorders may be asymptomatic or minimally evident for a long time. A careful clinical evaluation, reinforced by imaging findings, should help differentiate asymptomatic derangements from painful conditions that may require treatment.

Effects of orthognathic surgery for class III malocclusion on signs and symptoms of temporomandibular disorders and on pressure pain thresholds of the jaw muscles

The aim of this longitudinal study was to determine the effects of orthognathic surgery on signs and symptoms of temporomandibular disorders (TMD) and on pressure pain thresholds (PPTs) of the jaw muscles. Fourteen consecutive class III patients undergoing pre-surgical orthodontic treatment were treated by combined Le Fort I osteotomy and bilateral sagittal ramus osteotomy. The clinical examination included the assessment of signs and symptoms of TMD and the assessment of PPTs of the masseter and temporalis muscles. Anamnestic, clinical and algometric data were collected during five sessions over a 1-year period. Seven out of 14 patients presented with disc displacement with reduction at baseline, whereas four patients (two of them were new cases) did so at the end of follow up (p>0.05). None of the patients were diagnosed with myofascial pain of the jaw muscles at the beginning or end of follow up. PPTs of the masseter and temporalis muscles did not change significantly from baseline values throughout the whole study period. The occurrence of signs and symptoms of TMD fluctuates with an unpredictable pattern after orthognathic surgery for class III malocclusions.

Disc derangements of the temporomandibular joint

Disc-related derangement of the temporomandibular joint is common and epidemiological research has found that about 20% of the population may be affected. Although very few of these people have the more prominent symptoms, recent data indicate that the numbers who need treatment is increasing. The two clinical variants of disc derangement, reciprocal clicking and closed lock, have long been recognized, but the association between them and their aetiology and pathogenesis is still unclear. As a consequence, there is still uncertainty on how to treat the conditions, and this is even more evident when surgery is involved. This paper describes new tissue research related to disc derangement. A simplified scheme is presented and implications for surgical treatment are discussed.

Anchored disc phenomenon with a normally positioned disc in the temporomandibular joint: Characteristics and behaviour

We aimed to elucidate the pathogenesis and evaluate the therapeutic behaviour of patients with an anchored disc phenomenon but a normally positioned disc of the temporomandibular joint (TMJ). Fourteen patients with internal derangement including closed lock of one TMJ were examined. All had normally positioned discs. Synovial fluid was collected from the TMJ by arthrocentesis. Their symptoms, and the protein concentration in the synovial fluid, were evaluated. Their median duration of illness was 3 months (range 0.5-12), and the median protein concentration was low (343 microg/ml; range 36-791). Arthrocentesis was successful in nine. Arthroscopic findings in the five unsuccessful cases showed severe intra-articular adhesions of the TMJ. The main intra-articular pathological feature was the presence of adhesions, which might be affected by low protein concentrations in the synovial fluid. These findings may provide a new treatment in patients with normally positioned discs, despite the small number studied.

Treatment of Temporomandibular Disorder in a Viola Player - A Case Report

Viola and violin players seem to be predisposed to TMD. This case report illustrates an example where this occupation caused problems and required treatment. The case was managed with a modified Anterior Repositioning Splint (ARPS) that the patient wore while playing.

CLINICAL RELEVANCE

Temporomandibular disorders (TMD) are common within the population. Certain factors can predispose or make one more susceptible. This case report highlights viola players who are predisposed to TMD.

An accurate simulation model of anteriorly displaced TMJ discs with and without reduction

Internal derangement of the temporomandibular joint (TMJ) is defined as an abnormal positional relationship of the disc relative to the mandibular condyle and the glenoid fossa. Among others, the anterior disc displacement is the most common disorder, however its origin and consequences are still unclear. Several finite element simulations of the TMJ have been developed, but none of them has reported dynamic simulations of the disc as a three-dimensional, fiber-reinforced biphasic material under finite deformations, during the opening movement of a pathologic joint affected of an anterior displacement of the disc with and without reduction, using a realistic geometry of the ligaments in the joint. The aim of the work presented here was to compare the stress distribution in the healthy joint and in two pathologic situations, one joint affected of an anterior disc displacement with reduction (ADDWR) and one without reduction (ADDWOR) during an opening movement of the mouth. It was found that, while in the healthy disc the highest compressive stresses were located in the intermediate zone, in the pathologic joints the maximum compressive stresses were located in the posterior band both in the ADDWOR case and in the ADDWR before the reduction. Moreover, although the final stress distribution in the ADDWR was similar to that in the healthy case, the collateral ligaments supported higher stresses, a fact that could lead to degeneration of these components and subsequently to the total anterior displacement of the disc. Finally, the results suggest that an anterior displacement of the disc would lead to higher compressive and tangential stresses in the posterior band of the disc than in the healthy one, and as a consequence, to possible perforations in that zone of the disc which would modify its geometry if no treatment is applied.

Temporomandibular disorders and headache

Headache is a common symptom, but when severe, it may be extremely disabling. It is assumed that patients who present to dentists with headache often are diagnosed with a temporomandibular disorder (TMD), although many may have migraine. TMD as a collective term may include several clinical entities, including myogenous and arthrogenous components. Because headache and TMD are so common they may be integrated or separate entities. Nevertheless, the temporomandibular joint (TMJ) and associated orofacial structures should be considered as triggering or perpetuating factors for migraine. This article discusses the relationship between the TMJ, muscles, or other orofacial structures and headache.

Orthodontic Effects on Dentofacial Morphology in Women with Bilateral TMJ Disk Displacement

OBJECTIVE

To determine the difference in skeletal response to orthodontic treatment between patients with bilateral disk derangement and normal disk position of the temporomandibular joint (TMJ).

MATERIALS AND METHODS

Subjects consisted of 46 women whose malocclusions were treated only by orthodontics. All patients had TMJ magnetic resonance imaging (TMJ MRI) taken prior to orthodontic treatment. They were classified into three groups according to results of the TMJ MRI: bilateral normal disk position (BN), bilateral disk displacement with reduction (BDDR), and bilateral disk displacement without reduction (BDDNR). Twenty cephalometric variables were evaluated by the Kruskal-Wallis test to identify any differences in morphological changes between the three groups during orthodontic treatment.

RESULTS

This study showed that patients with BDDNR had more severe sagittal and vertical skeletal discrepancies than those with BN and BDDR at the pretreatment stage with discrepancies maintained after treatment. Compared to patients with BN, BDDR patients exhibited significant changes in SNB, N perpendicular to pogonion, SN to mandibular plane angle, total anterior facial height, ramus inclination, and effective mandibular length during treatment. This means that patients with BDDR showed more backward movement and rotation of the mandible than those with BN. In contrast, patients with BDDNR who had the most severe skeletal discrepancies did not show any significant skeletal changes during orthodontic treatment compared to those with BN or BDDR.

CONCLUSION

In patients with bilateral TMJ disk displacement, orthodontic treatment should be undertaken carefully to prevent backward rotation and movement of the mandible.

Intraoperative Awakening of the Patient During Orthognathic Surgery: A Method to Prevent the Condylar Sag

PURPOSE

The intraoperative diagnosis, during orthognathic procedures, of an unfavorable condylar position is highly desirable. A simple technique that can reliably identify a malpositioned condyle intraoperatively has obvious advantages. The manual positioning of the condyle is easier, but it requires the utmost care and an experienced operator. Muscle tone is described as maintaining contact across the temporomandibular joint. The anesthetized and curarized patient has a condylar position posterior to that in the same patient when he is awake, with the same seating force applied. Under general anesthesia, the condyle may be inferior and might not feel stable until it moves posteriorly and has adequate compression of the retrodiscal tissues on the posterior wall. Relapse of the occlusion as a result of changes in the condylar position may occur immediately after the removal of the temporary intermaxillary fixation (IMF). The surgeon needs to understand the mechanism of condylar sag and the specific patterns of malocclusion that it may produce. This will enable him to make a diagnosis and to implement the appropriate corrective measures, providing the opportunity for immediate correction of condylar position, thereby obviating the need for a second operation or orthodontic compromise.

MATERIALS AND METHODS

A study group (group A, 76 patients) and a control group (group B, 73 patients) were randomly formed from the dysgnathic patients scheduled for bimaxillary orthognathic surgery (Le Fort I osteotomy and bilateral sagittal split osteotomy). The free mandibular proximal segment was gently and manually positioned in the glenoid fossa. All the mandibles were fixed with bicortical screws. In group A, immediately after the fixation, IMFs were removed and the occlusions were checked with light digital pressure on the chin, then the patients were rapidly awakened (maintaining the intubation) in a state of conscious analgo-sedation and asked to open and close, and to laterally move the mandible. If clinical examination of the passive and active movements of the mandible was suitable, the anesthesia was reinforced and the operation was concluded.

RESULTS

In 11 of the 76 patients of group A, malocclusion was noted, after the rigid fixation, with the method of digital pressure on the chin; the intraoperative awakening of the patients confirmed the clinical appearance and it provided further clinical signs to identify the offending condyle and to favor appropriate corrections. In 8 of the group A patients, malocclusions were not noted with manipulation of the mandible, but they were pointed out during the intraoperative awakening, and then they were appropriately corrected. In 2 of the group B patients, malocclusion was noted, after the rigid fixation, with the method of digital pressure on the chin, and it was immediately corrected. In 7 of the group B patients, malocclusion was not noted during the operation with the method of digital pressure on the chin, but it was noted at the end of the surgical procedure (12-24 hours after).

CONCLUSION

Muscle tone, muscular activity, and proprioception appear to have important roles in the clinical evidence of a postoperative malocclusion during the intraoperative awakening; they can reliably implement the accuracy of the diagnosis of condylar sag, and they can favor its correction.

Condylar Movements of Temporomandibular Disorder Patients with Intermittent Lock: A Pilot Study

The purpose of this study was to clarify which direction of the condylar path is advantageous for releasing TMJ intermittent lock. The subjects were ten patients with temporomandibular disorders (TMD) and intermittent lock caused by anterior displacement of disks without obvious medial or lateral displacement. The patients could not open their mouths fully in habitual opening but could open fully in an intentional winding opening with reduction of the anteriorly displaced disks (winding opening). The two kinds of movement at the kinematic condylar point were measured in each subject and compared. The length of the condylar path in winding opening was significantly larger than that in habitual opening. The affected side condyle of winding opening traced medio-inferior paths in the early part of the condylar translation in comparison with habitual opening. From the viewpoint of the condylar path, the medio-inferior direction of condylar translation is thought to be advantageous for releasing intermittent lock.

Anterior disc displacement with reduction and symptomatic hypermobility in the human temporomandibular joint: prevalence rates and risk factors in children and teenagers

AIMS

To assess the prevalence rates and risk factors of anterior disc displacement with reduction (ADDR) and symptomatic hypermobility in a large sample of children and teenagers. Prevalence rates were also established in samples of young adults and adults.

METHODS

Children from 7 Dutch primary and secondary schools (n = 1,833) aged 4 to 18 years (mean age +/- SD 10.8 +/- 3.9 years), 220 dental students aged 19 to 30 years (mean age +/- SD 21.9 +/- 3.6 years), and 100 dental school employees more than 30 years old (mean age +/- SD 43.5 +/- 9.8 years) were examined. The presence of ADDR or symptomatic hypermobility was scored using well-defined clinical criteria. For the children only, an additional standardized oral history and clinical examination were performed to assess possible risk factors. Odds ratios (ORs) were calculated with the use of logistic multivariate regression analysis.

RESULTS

The prevalence rate of ADDR in at least 1 of the 2 joints increased during childhood and adolescence and stabilized into adulthood at about 26.6%. In children and teenagers, besides age (OR = 1.06 for boys, OR = 1.23 for girls), risk factors for ADDR were a history of orthodontics (OR = 1.57), an increasing overbite (OR = 1.15), and protrusion (OR = 1.12). In children and teenagers, the prevalence rate of symptomatic hypermobility was higher for girls (13.8%) than for boys (8.2%). Besides gender (OR = 2.07), risk factors for symptomatic hypermobility were race (OR = 2.61 for non-Caucasians), masticatory muscle pain (OR = 1.95), and increasing maximum mouth opening (OR = 1.08).

CONCLUSION

In children and teenagers, ADDR and symptomatic hypermobility have different prevalence rates and risk factors.

Oral health-related quality of life in patients with temporomandibular disorders

AIMS

To characterize the level of impairment of oral health-related quality of life (OHRQoL) in a temporomandibular disorder (TMD) patient population.

METHODS

OHRQoL was measured using the German version of the Oral Health Impact Profile (OHIP-G) in a consecutive sample of 416 patients seeking treatment for their complaints in the masticatory muscles and temporomandibular joints and with at least 1 diagnosis according to the German version of the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). The level of impairment of OHRQoL was characterized by the OHIP summary score mean and its 95% confidence interval. OHRQoL was described for each of the 8 RDC/TMD diagnoses (Axis I) and the RDC/TMD Axis II measures (Graded Chronic Pain Scale [GCPS], jaw disability list, depression, and somatization). These findings were compared with the level of impairment of OHRQoL in the adult general population derived from a national sample (n = 2,026).

RESULTS

Among the RDC/TMD Axis I measures, all diagnoses were correlated with much higher impacts compared to the normal population (means for all diagnoses were 32.8 to 53.7 versus 15.8 in the general population). All diagnoses had a similar level of impact except for disc displacement with reduction (which had a lower impact). There were larger differences in mean OHIP-G scores among subgroups of RDC/TMD Axis II measures than among subgroups of RDC/TMD Axis I characteristics. The strongest association was with GCPS, with mean OHIP scores of 33.3 for grade I, 48.1 for grade II, 71.7 for grade III, and 88.5 for grade IV.

CONCLUSION

OHRQoL was markedly impaired in TMD patients. The level of OHRQoL varied across diagnostic categories but more across Axis II, ie, the psychosocial axis; the variation was reflected especially in their level of graded chronic pain.

Temporomandibular joint surgery for internal derangement

Surgery of the temporomandibular joint (TMJ) plays a small, but important, role in the management of patients who have temporomandibular disorders (TMDs). There is a spectrum of surgical procedures for the treatment of TMD that ranges from simple arthrocentesis and lavage to more complex open joint surgical procedures. It is important to recognize that surgical treatment rarely is performed alone; generally, it is supported by nonsurgical treatment before and after surgery. Each surgical procedure should have strict criteria for which cases are most appropriate. Recognizing that scientifically proven criteria are lacking, this article discusses the suggested criteria for each procedure, ranging from arthrocentesis to complex open joint surgery. The discussion includes indications, brief descriptions of techniques, outcomes, and complications for each procedure.

Dental attrition models predicting temporomandibular joint disease or masticatory muscle pain versus asymptomatic controls

AIMS

To determine whether patients with temporomandibular joint disease or masticatory muscle pain can be usefully differentiated from asymptomatic controls using multifactorial classification tree models of attrition severity and/or rates.

METHODS

Measures of attrition severity and rates in patients diagnosed with disc displacement (n = 52), osteoarthrosis (n = 74), or masticatory muscle pain only (n = 43) were compared against those in asymptomatic controls (n = 132). Cross-validated classification tree models were tested for fit with sensitivity, specificity, accuracy and log likelihood accountability.

RESULTS

The model for identifying asymptomatic controls only required the three measures of attrition severity (anterior, mediotrusive and laterotrusive posterior) to be differentiated from the patients with a 74.2 +/- 3.8% cross-validation accuracy. This compared with cross-validation accuracies of 69.7 +/- 3.7% for differentiating disc displacement using anterior and laterotrusive attrition severity, 68.7 +/- 3.9% for differentiating disc displacement using anterior and laterotrusive attrition rates, 70.9 +/- 3.3% for differentiating osteoarthrosis using anterior attrition severity and rates, 94.6 +/- 2.1% for differentiating myofascial pain using mediotrusive and laterotrusive attrition severity, and 92.0 +/- 2.1% for differentiating myofascial pain using mediotrusive and anterior attrition rates. The myofascial pain models exceeded the > or =75% sensitivity and > or =90% specificity thresholds recommended for diagnostic tests, and the asymptomatic control model approached these thresholds.

CONCLUSION

Multifactorial models using attrition severity and rates may differentiate masticatory muscle pain patients from asymptomatic controls, and have some predictive value for differentiating intracapsular temporomandibular disorder patients as well.

Three-dimensional finite-element model of the human temporomandibular joint disc during prolonged clenching

In the temporomandibular joint (TMJ), overloading induced by prolonged clenching appears to be important in the cascade of events leading to disc displacement. In this study, the effect of disc displacement on joint stresses during prolonged clenching was studied. For this purpose, finite-element models of the TMJ, with and without disc displacement, were used. Muscle forces were used as a loading condition for stress analysis during a time-period of 10 min. The TMJ disc and connective tissue were characterized as a linear viscoelastic material. In the asymptomatic model, large stresses were found in the central and lateral part of the disc through clenching. In the retrodiscal tissue, stress relaxation occurred during the first 2 min of clenching. In the symptomatic model, large stresses were observed in the posterior part of the disc and in the retrodiscal tissue, and the stress level was kept constant through clenching. This indicates that during prolonged clenching the disc functions well in the asymptomatic joint, meanwhile the retrodiscal tissue in the symptomatic joint is subject to excessive stress. As this structure is less suitable for bearing large stresses, tissue damage may occur. In addition, storage of excessive strain energy might lead to breakage of the tissue.

Anterior displacement of the TMJ disk: repositioning of the disk using a Mitek system. A 3D finite element study

In this paper the behaviors of the temporomandibular joint (TMJ) with an anteriorly displaced disk without reduction and with a surgically repositioned one were compared with the response of a healthy disk during jaw opening. The movement of each joint was obtained imposing the same opening path between incisors and assuming that the movement of the condyle is determined by the passive action of the masticatory muscles and the restrictions imposed by the articulating surfaces and the ligaments. A fiber-reinforced porohyperelastic model was used to simulate the behavior of the articular disk. The influence of the friction coefficient in the diseased joint was also analyzed, finding that the final displacement of the complex condyle-disk was smaller as the friction coefficient increased. On the other hand, its displacement in the repositioned joint was different than in the healthy case because the artificial sutures used in the surgery do not fully stabilize the disk posteriorly as the retrodiscal tissue does. The stress response of the disk changed in both pathologic cases: in the displaced joint the highest stresses moved from the intermediate zone (healthy case) to the posterior band, and in the reconstructed one the most loaded zone moved posteriorly at total opening. Besides, local stress concentrations appeared in the neighborhood of the artificial sutures and therefore damage of the disk and releasing of the sutures might be possible postoperatively.

The treatment of painful temporomandibular joint clicking with oral splints

BACKGROUND

The authors compared the efficacy of bilateral balanced and canine guidance (occlusal) splints in the treatment of temporomandibular joint (TMJ) pain in subjects who experienced joint clicking with a nonoccluding splint in a double-blind, controlled randomized clinical trial.

METHODS

The authors randomly assigned 57 people with signs of disk displacement and TMJ pain into three groups according to the type of splint: bilateral balanced, canine guidance and nonoccluding. The authors followed the groups for six months using analysis of a visual analog scale (VAS), palpation of the TMJ and masticatory muscles, mandibular movements and joint sounds. They used repeated analysis of variance and a chi(2) test to test the hypothesis.

RESULTS

The type of guidance used did not influence the pain reduction, yet both occlusal splints were superior to the nonoccluding splint, on the basis of the VAS. Despite similar outcomes in relation to opening, left lateral and protrusive movements, TMJ and muscle pain on palpation, subjects who used the occlusal splints had improved clinical outcomes. The frequency of joint noises decreased over time, with no significant differences among groups. Subjects in the groups using the occlusal splints reported more comfort.

CONCLUSION

The type of lateral guidance did not influence the subjects' improvement. All of the subjects had a general improvement on the VAS, though subjects in the occlusal splint groups had better results that did subjects in the nonoccluding splint group.