From: Pain. 2010 May;149(2):222-8. Epub 2010 Mar 16.

Myofascial pain of the temporomandibular region is a common, but poorly understood chronic disorder. It is unknown whether the condition is a peripheral problem, or a disorder of the central nervous system. To investigate possible central nervous system substrates of myofascial temporomandibular pain, the authors compared the brain morphology of 15 women with myofascial temporomandibular pain to that of 15 age- and gender-matched healthy controls. High-resolution structural brain and brainstem scans were carried out using magnetic resonance imaging (MRI), and data were analyzed using a voxel-based morphometry approach.

The myofascial temporomandibular pain group evidenced decreased or increased gray matter volume compared to controls in several areas of the trigeminothalamocortical pathway, including brainstem trigeminal sensory nuclei, the thalamus, and the primary somatosensory cortex. In addition, myofascial temporomandibular pain individuals showed increased gray matter volume compared to controls in limbic regions such as the posterior putamen, globus pallidus, and anterior insula. Within the myofascial temporomandibular pain group, jaw pain, pain tolerance, and pain duration were differentially associated with brain and brainstem gray matter volume. Self-reported pain severity was associated with increased gray matter in the rostral anterior cingulate cortex and posterior cingulate. Sensitivity to pressure algometry was associated with decreased gray matter in the pons, corresponding to the trigeminal sensory nuclei. Longer pain duration was associated with greater gray matter in the posterior cingulate, hippocampus, midbrain, and cerebellum. The pattern of gray matter abnormality found in myofascial temporomandibular pain individuals suggests the involvement of trigeminal and limbic system dysregulation, as well as potential somatotopic reorganization in the putamen, thalamus, and somatosensory cortex.

From: J Oral Rehabil. 2010 May 27. [Epub ahead of print]

The association between cervical spine disorders (CSD) and temporomandibular disorders (TMD) has been extensively investigated. However, no studies investigating the relationship between the level of jaw disability and neck disability have been published. Therefore, the objective of this study was to determine whether there was a relationship between neck disability measured using the neck disability index and jaw disability measured through the jaw function scale. A sample of 154 subjects who attended the TMD/Orofacial Pain clinic and students and staff at the University of Alberta participated in this study. All subjects were asked to complete the neck disability index, the jaw function scale, the jaw disability checklist (JDC), and the level of chronic disability of temporomandibular disorders (chronic pain grade disability questionnaire used in the RDC/TMD). Spearman rho test was used to analyse the relationship between neck disability and jaw disability. Multiple regression analysis was used to determine the association between the level of chronic disability of temporomandibular disorders and neck disability.

A strong relationship between neck disability and jaw disability was found. A subject with a high level of temporomandibular disorders disability (grade IV) increased by about 19 points on the neck disability index when compared with a person without temporomandibular disorders disability. These results have implications for clinical practice. If patients with temporomandibular disorders have neck disability in addition to jaw disability, treatment needs to focus on both areas because the improvement of one could have an influence on the other.

From: Disabil Rehabil. 2010 May 8. [Epub ahead of print]

The purpose of this study is to estimate the prevalence of jaw symptoms and signs during the first year after a neck sprain in a car collision. Further, to determine their relationships to the localisation and grade of the initial neck symptoms and signs, headache, post-traumatic stress and crash characteristics.

One hundred and forty-six adult subjects and crash characteristics were prospectively investigated in an in-depth study during 1997-2001. Head, neck, and jaw symptoms and signs were recorded within 5 weeks and after 1 year. Acute post-traumatic stress was estimated with the Impact of Event Scale-Revised (IES-R).

Jaw symptoms were initially reported by three men (5%) and three women (4%), and subsequently developed in eight women (10%) during the following year. Jaw signs were noted initially in 53 subjects (37%) and in 28 subjects (24%) after 1 year, without difference between sexes, and more often after low-speed impacts. Headache in females, cranial cervical symptoms, pronounced neck problems, post-traumatic stress and whiplash associated disorders (WAD) grade II-III after rear-end impacts were related to jaw signs during the acute phase. After 1 year, jaw signs were related to residual neck problems, headache and post-traumatic stress.

Jaw symptoms are seldom reported during the acute phase after a whiplash trauma. Women more often than men develop jaw symptoms during the first year. Jaw symptoms and signs may develop also after low-speed impacts, especially after rear-end collisions. Jaw symptoms and signs should be observed after whiplash trauma, especially in those with headache, pronounced neck problems, cranial neck symptoms and post-traumatic stress.

From: Arch Oral Biol. 2010 Apr 20. [Epub ahead of print]

The present study aimed to elucidate possible physiological mechanisms behind impaired endurance during chewing as previously reported in whiplash associated disorders. We tested the hypothesis of a stronger autonomic reaction in whiplash associated disorders than in healthy subjects in response to dynamic loading of the jaw and neck motor system.

Cardiovascular reactivity, muscle fatigue indicies of EMG, and perceptions of fatigue, exhaustion and pain were assessed during standardised chewing. Twenty-one whiplash associated disorders subjects and a gender/age matched control group participated. Baseline recordings were followed by two sessions of alternating unilateral chewing of a bolus of gum with each session followed by a rest period.

More than half of the whiplash associated disorders subjects terminated the test prematurely due to exhaustion and pain. In line with our hypothesis the chewing evoked an increased autonomic response in whiplash associated disorders exhibited as a higher increase in heart rate as compared to controls. Furthermore, we saw consistently higher values of arterial blood pressure for whiplash associated disorders than for controls across all stages of the experiment. Masseter EMG did not indicate muscle fatigue nor were there group differences in amplitude and mean power frequency. Pain in the whiplash associated disorders group increased during the first session and remained increased, whereas no pain was reported for the controls.

More intense response to chewing in whiplash associated disorders might indicate pronounced vulnerability to dynamic loading of the jaw and neck motor system with increased autonomic reactivity to the test. Premature termination and autonomic involvement without EMG signs of muscle fatigue may indicate central mechanisms behind insufficient endurance during chewing.

In a previous study in J Dent Res. 2004 Dec;83(12):946-50, it was noted; Jaw movements are the result of coordinated activation of jaw and neck muscles, leading to simultaneous movements in the temporomandibular, atlanto-occipital, and cervical spine joints. Thus, jaw function involves integrative jaw and neck motor control. Given that natural jaw function requires a healthy state of both mandibular and neck motor systems, injury to any of the joints involved might derange jaw function. In fact, the authors had recently shown an association between neck injury and deranged jaw function, as reflected by reduced amplitude, speed, and disturbed coordination of head and mandibular movements.

They note that it has been reported that almost 25% of tmj pain patients have a history of trauma to the head-neck, mainly whiplash trauma. Compared with tmj pain patients without a history of trauma, patients with posttraumatic tmj pain seem to present with more severe jaw-facial pain and dysfunction, and it has been suggested that the prognosis for recovery from jaw-face pain and dysfunction is lower in this group.

Furthermore, it has been reported that post-traumatic tmj pain patients have more symptoms associated with
affective disorders, e.g., sleep disturbances, respond more poorly in reaction time tests, and overall tire more easily than do non-traumatic tmj pain patients. The fact that many of these symptoms are also associated with closed-head injuries indicates that the etiology of posttraumatic tmj pain differs from that of non-traumatic tmj pain.

The authors results corroborate the suggestion that patients with jaw-face pain and dysfunction and with a history of neck injury are unique and more complex with regard to the spread and severity of pain and dysfunction.

Their finding of a severely reduced endurance during chewing in whiplash associated disorders individuals suggests an association between neck injury and impaired functional capacity of the human jaw motor system. Based on these results, examination of jaw function seems recommendable as part of the routine evaluation of whiplash associated disorders patients, and for this, the endurance test described in this study could be a useful tool. Finally, from data suggesting that jaw function involves simultaneous neuro-muscular activation of movements in the temporomandibular, atlantooccipital, and cervical spine joints, and that neck injury can disturb natural jaw function, the authors propose that a suitable term for the condition involving both neck and jaw disorders could be “Cervico-Cranio Mandibular Disorders” (CCMD).

In Swed Dent J. 2004;28(1):29-36, their study indicated the individuals in the whiplash associated disorders group had also more signs of tmj dysfunction. The maximum mouth opening capacity was 48 mm in the whiplash associated disorders group and 54 mm in the C group. In the whiplash associated disorders group 17% had a mouth opening capacity < 40 mm compared with 2% in the C group. Pain on palpation of the jaw muscles and on lateral palpation of the temporomandibular joints was more common in the WAD group. Pain on mandibular mobility was reported by 30% in the whiplash associated disorderswhiplash associated disorders group and by 3% in the C group.

From: Eur J Pain. 2009 Nov;13(10):1043-7. Epub 2009 Jan 24

Recent research suggests bi-directional interactions between the experience of pain and the process of sleep; pain interferes with the ability to obtain sleep, and disrupted sleep contributes to enhanced pain perception. Our group recently reported, in a controlled experimental study, that sleep fragmentation among healthy adults resulted in subsequent decrements in endogenous pain inhibition. The present report follows up that observation by extending this line of research to a sample of patients experiencing persistent pain. Patients with chronic temporomandibular joint disorder pain were studied using polysomnography and psychophysical evaluation of pain responses. The authors assessed whether individual differences in sleep continuity and/or architecture were related to diffuse noxious inhibitory controls, a measure of central nervous system pain inhibition. Among 53 temporomandibular joint disorder patients, higher sleep efficiency and longer total sleep time were positively associated with better functioning of diffuse noxious inhibitory controls. These results suggest the possibility that disrupted sleep may serve as a risk factor for inadequate pain-inhibitory processing and hint that aggressive efforts to treat sleep disturbance early in the course of a pain condition might be beneficial in reducing the severity or impact of clinical pain.

Related:

Comparison of sleep quality and clinical and psychologic characteristics in patients with temporomandibular disorders

From: J Orofac Pain. 2002;16(3):221-8.

To explore the relationships between sleep quality, perceived pain, and psychologic distress among patients with temporomandibular disorders. A total of 137 consecutive patients who sought care at the University of Kentucky Orofacial Pain Center for the management of temporomandibular disorders participated in this study and completed a battery of standardized, self-report questionnaires at their first clinic visit. The Pittsburgh Sleep Quality Index (PSQI) and the Multidimensional Pain Inventory (MPI) were used to measure patients’ sleep quality and multiple dimensions of pain and suffering, respectively. The Revised Symptom Checklist-90 (SCL-90R) was used to evaluate psychologic symptoms. A median cutoff (PSQI total score: 10) divided the patients into 2 groups, i.e., 67 poor sleepers and 70 good sleepers. There were no statistically significant differences in gender and age distributions between the 2 groups. Poor sleepers reported significantly higher scores than good sleepers on each of the 14 scales of the SCL-90R and on 7 of the 13 scales of the MPI. Stepwise multiple regression analyses demonstrated that poorer sleep quality was predicted by higher pain severity, greater psychologic distress, and less perceived life control. This study supports the frequent comorbidity of reported sleep disturbance, perceived pain severity, and psychologic distress in patients with temporomandibular disorders.

How do sleep disturbance and chronic pain inter-relate? Insights from the longitudinal and cognitive-behavioral clinical trials literature.

From: Sleep Med Rev. 2004 Apr;8(2):119-32

Sleep disturbance is perhaps one of the most prevalent complaints of patients with chronically painful conditions. Experimental studies of healthy subjects and cross-sectional research in clinical populations suggest the possibility that the relationship between sleep disturbance and pain might be reciprocal, such that pain disturbs sleep continuity/quality and poor sleep further exacerbates pain. This suggests that aggressive management of sleep disturbance may be an important treatment objective with possible benefits beyond the improvement in sleep. Little is known, however, about how to effectively treat sleep disturbance associated with pain or whether such treatment might have beneficial effects on reducing pain. A small, but growing literature has applied cognitive-behavioral therapies for either pain management or insomnia to patients with chronic pain. In this article, we review the longitudinal literature on sleep disturbance associated with chronic pain and clinical trial literatures of cognitive-behavior therapy for pain management and insomnia secondary to chronic pain with the aim of evaluating whether the relationship between clinical pain and insomnia is reciprocal. While methodological problems are common, the literature suggests that the relationship is reciprocal and cognitive-behavioral therapies treatments for pain or insomnia hold promise in reducing pain severity and improving sleep quality. Directions for future research include the use of validated measures of sleep, longitudinal studies, and larger randomized clinical trials incorporating appropriate attentional controls and longer periods of follow-up.

Related Article: Duration of sleep contributes to next-day pain report in the general population

From: Clin J Pain. 2010 Feb;26(2):116-20

The aim of this study is to examine the difference in the report of bodily pain experienced by patients who develop temporomandibular disorders and by those who do not develop temporomandibular disorders over a 3-year observation period.

This is a 3-year prospective study of 266 females aged 18 to 34 years initially free of temporomandibular disorders pain. All patients completed the Symptom Report Questionnaire (SRQ) at baseline and yearly intervals, and at the time they developed temporomandibular disorders (if applicable). The SRQ is a self-report instrument evaluating the extent and location of pain experienced in the earlier 6 months. Statistical analysis was carried out using repeated measures ANOVA.

Over the 3-year period, 16 patients developed temporomandibular disorders based on the Research Diagnostic Criteria for temporomandibular disorders. Participants who developed temporomandibular disorders reported more headaches, muscle soreness or pain, joint soreness or pain, back pain, chest pain, abdominal pain, and menstrual pain than Participants who did not develop temporomandibular disorders at both the baseline and final visits. Participants who developed temporomandibular disorders also reported significantly more headache, muscle soreness or pain, and other pains when they were diagnosed with temporomandibular disorders compared with the baseline visit.

The development of temporomandibular disorders was accompanied by increases in headaches, muscle soreness or pain, and other pains that were not observed in the Participants who did not develop temporomandibular disorders. Participants who developed temporomandibular disorders also report higher experience of joint, back, chest, and menstrual pain at baseline.

From: BMC Musculoskelet Disord. 2009 Mar 2;10:28

Temporomandibular disorders are musculoskeletal pain conditions characterised by pain and dysfunction in the jaw-face muscles and/or the temporomandibular joint. Musculoskeletal pain conditions occurring at various locations may share pathophysiological mechanisms. Co-morbidity between temporomandibular disorders, headaches and neck/shoulder pain has been reported in temporomandibular disorders patient samples as well as in samples drawn from the general population. Low back pain, one of the most common pain conditions in humans, has been associated with other pains such as neck pain and headaches, which has been interpreted as a tendency for symptoms to cluster in some individuals. The source of these patterns is not known, but neurobiological sensitization processes, genetically determined vulnerability and psychological factors are commonly given as possible explanations. Results of a 3-year prospective study showed a significantly increased risk of developing a new pain condition with presence of a pain condition at baseline. A more recent prospective study based on patients with non-painful temporomandibular disorders indicated a dose-response relationship between the number of pain sites at baseline (head, back, chest, stomach) and the risk of onset of dysfunctional temporomandibular disorders pain among women. Frequency of headaches was found to have a dose-response relationship with occurrence of musculoskeletal symptoms (e.g. pain in neck, shoulders and low back) in a Norwegian population.

The authors have recently shown that patients with long-term spinal pain (neck, shoulder and/or low back) significantly more often have signs and symptoms of temporomandibular disorders than do matched controls. The associations remained statistically significant also after exclusion of those who reported jaw pain. It is not known whether co-morbidity between temporomandibular disorders and neck pain, shoulder pain and/or low back pain occurs within the whole range of variation in symptom frequency and severity. Most analyses in this field have involved dichotomized samples, not taking variations of symptom severity into consideration. The aim of the present study was to test whether a reciprocal dose-response relation exists between frequency and severity of neck pain, shoulder pain and/or low back pain and temporomandibular disorders. The authors tested the following null hypotheses:

1. Occurrence of frequent temporomandibular disorders symptoms and headaches does not differ significantly between study groups with varying frequency and severity of neck pain, shoulder pain and/or low back pain.

2. Presence of frequent neck pain, shoulder pain and/or low back pain does not differ significantly between study groups with varying frequency and severity of temporomandibular disorders symptoms.

The operational definition of ‘spinal pain’ was pain in the neck, shoulders and/or low back. Symptoms in the jaw-face region, head, neck, shoulder and low back regions were assessed by questionnaire. Presence of symptoms was stated for frequency (never; not now, but previously; once or twice a month; once or twice a week; several times a week; daily), duration (< 1 month; 1 month–1 year; 1–5 years; > 5 years) and intensity. The subjects were also asked to estimate the impact of jaw symptoms, headaches, neck-shoulder pain and low back pain on activities of daily living. Intensity and activities of daily living was assessed using the 11-point Numerical Rating Scale.

Presence and severity of temporomandibular disorders was evaluated for the separate symptoms and according to the Helkimo Anamnestic dysfunction Index. This classification grades the severity of symptoms in the jaw-face region into mild (i.e. temporomandibular joint sounds during opening and closing of the jaw and/or tiredness/stiffness in the jaws) or severe (i.e. pain, temporomandibular joint locking and/or difficulties in opening the mouth wide).

The present study showed a dose-response relation between frequency and severity of spinal pain and temporomandibular disorders. The pattern was evident in both directions, the prevalence of frequent temporomandibular disorders symptoms and headaches increasing with increasing frequency/severity of spinal pain, and the prevalence of frequent pain in the neck, shoulders and/or low back increasing with increasing frequency and severity of temporomandibular disorders symptoms. The test for trends showed significant dose-response associations in both directions. The two tested null hypotheses were therefore rejected.

The authors have previously shown that patients with long-term pain in the neck, shoulders and/or low back have a sevenfold risk of reporting pain and dysfunction in the jaw-face region and a fivefold risk of having clinical signs of temporomandibular disorders, compared with matched controls. This finding was recently supported in a cross-sectional analysis based on almost 30,000 adults in the USA, indicating a strong relationship between reported pain in the neck, shoulders and/or low back and jaw-face pain. The present study shows a stepwise positive correlation between severity of spinal pain and pain and dysfunction in the jaw-face region. This dose-response-like pattern should not be interpreted as a sign of exposure and outcome. However, it strengthens previous results of an association between temporomandibular disorders and spinal pain and may point to common underlying biological or psychological mechanisms. It should be emphasized that the results are derived from a cross-sectional study and do not show causality. Owing to the study design we have no information about the temporal sequence of the examined disorders, an essential element in assessing causality. Studies with a prospective design have indicated that presence of a pain condition increases the risk of contracting temporomadibular disorder pain. In a recent prospective study the risk for onset of facial pain, meeting research diagnostic criteria for temporomadibular disorders, was almost four times higher among adolescents with back pain at baseline, than among those without back pain. Papageorgiou et al. followed a cohort without low back pain at baseline and noted that musculoskeletal pain at other sites predicted future episodes of low back pain. These results are interesting, but so far there is no sufficient evidence to conclude that back pain precedes temporomandibular disorders, or vice versa. Psychological factors are often co-morbid with chronic pain conditions. The temporal sequence of pain and depression is however not clear. In a review addressing this question the majority of studies indicated that depression was a consequence rather than an antecedent of pain. Longitudinal studies on these issues are therefore warranted.

It has been suggested that generalized pain (i.e. fibromyalgia) is at one end of a continuum. Vierck presents temporomandibular pain as an example of a focal pain condition where the nociceptive sensory input may contribute to development of generalized hypersensitivity and related susceptibility to further load. In line with this hypothesis one experimental study reports signs of mechanical allodynia in the hindpaw following nociceptive stimuli applied to the masseter muscle of rats. Other experimental studies have shown that perceived muscle pain intensity and distribution is influenced by the stimulation rate (temporal summation) and the number of stimulated afferents (spatial summation). Temporal summation has been shown in temporomandibular disorders patients, as well as in other chronic pain conditions, suggesting a generalized hyperexcitability of the central nociceptive system. In a large population sample grouped with respect to frequency of reported headaches a dose-response pattern was demonstrated between headache frequency and 1-year prevalence of musculoskeletal symptoms (with locations including neck, shoulders, elbows, wrist/hands, chest/abdomen, upper back, low back, hips, knees, ankles/feet). The contribution of input from the craniofacial nervous system in spreading pain may therefore be of significance and more experimental and clinical studies are needed.

Recent studies have shown that genetic polymorphism, with influence on the metabolism of catecholamines, is highly associated with pain sensitivity and the risk for developing temporomandibular disorders. Central sensitization may be one possible explanation for co-morbidity between pain conditions at different locations, as well as presence of allodynia and hyperalgesia. Reflex connections between nociceptors and the fusimotor-muscle spindle system may also be involved in the pathophysiologic mechanisms related to pain and dysfunction.

The allocation of subjects in the present study to different pain in the neck, shoulders and/or low back groups was based on the participants’ reports of pain frequency in the questionnaire. For example, if a subject reported daily shoulder pain, but infrequent low back pain, the grouping was done according to the frequency of shoulder pain. Subjects who had been referred to a rehabilitation programme and who were on sick leave were considered to have more severe spinal pain than subjects with frequent pain but not on sick leave. Symptom description in self-report questionnaires may be a limitation in a strict dose-response discussion; however, frequency as well as intensity and duration of pain and dysfunction are important variables in health care seeking behaviour. Similarly, in this study, pain severity in the separate neck-shoulder pain and low back pain groups demonstrates stepwise increased mean values of reported pain intensity and impact on activities of daily living. In the sub-sample test with symptoms of temporomandibular disorders as independent variable, we included none of the patients from the rehabilitation center. The severity of the temporomandibular disorders symptoms is reflected by the reported interference of jaw symptoms with daily living. The formation of groups, aiming at discrete severity categories (dose), therefore seems valid also with regard to the mean intensity level and the impact of the symptoms on daily living.

The study shows a reciprocal positive dose-response pattern between frequency and severity of neck-shoulder pain and low back pain and temporomandibular disorders. The results indicate a strong co-morbidity between these two conditions, suggesting that they may share risk factors or that they may influence each other. The authors agree with the recently advocated view of a need for hypothesis-based studies on specific pain -pain co-morbidities, but also on pain-dysfunction co-morbidities. The present results are of significance for physicians and dentists, both of whom are expected to manage patients with pain and dysfunction. Collaboration as well as a costing system for cooperation in the diagnosis and management of the two conditions is warranted. Researchers of pain conditions should include the jaw-face region in their efforts to comprehend the pain patient’s case history.

From: World J Orthod. 2008 Winter;9(4):329-36

To test whether there is a relationship between head and neck posture and dentofacial morphology in patients with temporomandibular joint osteoarthritis or osteoarthrosis. The subjects consisted of 34 Japanese females with temporomandibular joint osteoarthritis or osteoarthrosis (aged 24.7 +/- 6.1 years). Six craniocervical angular measurements were constructed for head posture. Two angular and 6 linear measurements were constructed for the skeletal relationship, while 1 angular and 6 linear measurements were constructed for the dental relationship. Pearson correlation coefficients were calculated between head posture and dentofacial variables.

In the skeletal relationship, increased craniocervical angulations were significantly associated with a more posterior position of the maxilla, a decreased Frankfort to mandibular plane angle, decreased mandibular length, and a decreased lower facial height. In the dental relationship, increased craniocervical angulations were significantly associated with more posterior positions of the anterior teeth to the basal bone and decreased alveolar height of the anterior-posterior teeth. The hypothesis was rejected. These results suggest that an association may exist between head and neck posture and dentofacial morphology in patients with temporomandibular joint osteoarthritis or osteoarthrosis.

From: J Orofac Pain. 2009 Winter;23(1):28-37

To evaluate the relationships between gender, diagnosis, and severity of temporomandibular joint disorders with self-reports of the impact of temporomandibular joint disorders on the quality of life, eighty-three individuals seeking temporomandibular joint disorders treatment at the Dental School of Pontifical Catholic University Minas from May to August 2005 were evaluated by a single examiner who was trained and calibrated for diagnosis according to criteria of Axis I of the Research Diagnostic Criteria for temporomandibular joint disorders. The severity of temporomandibular joint disorders was established by the Temporomandibular Index and the impact on quality of life by the Oral Health Impact Profile. Complete data were available for 78 of the 83 initial patients and evaluated by the Mann-Whitney test and Spearman correlation analysis.

Except for one patient, all individuals showed some impact related to physical pain. Of the seven aspects evaluated on the Oral Health Impact Profile, women presented a greater impact than men only for functional limitations. Patients presenting with diagnoses of muscular disorders (group I) or osteoarthritis (group III) reported a greater impact than those without. The Spearman test demonstrated a significant correlation between impact on quality of life and severity of temporomandibular joint disorders. Orofacial pain had a great impact on the quality of life of individuals with temporomandibular joint disorders, without group difference between genders. The presence of muscular disorders (group I) and osteoarthritis (group III) was related to greater impact on quality of life, which was not observed for diagnoses of disc displacement (group II). A correlation between severity of temporomandibular joint disorders and impact on quality of life was clearly observed.

From: Gerodontology. 2008 Dec;25(4):251-7. Epub 2008 Feb 27

The relationship of bony changes in the condylar surfaces in articular disc displacement without reduction in temporomandibular joint was investigated using diagnostic imaging. The study also evaluated whether the bony changes in the condylar surfaces limit disc and condyle motion, and produce pathological joint sounds.

Thirty seven temporomandibular joints in 28 patients diagnosed with degenerative bony changes in the condylar surfaces radiographically and anterior disc displacement without reduction using magnetic resonance imaging (MRI) were studied. The bony changes were assessed by radiographic examination and classified into two types: pathological bone changes including erosion, osteophyte formation and deformity, and adaptive bone changes including flattening and concavity. MRI was performed on the temporomandibular joint to examine the configuration and position of the discs. Joint sounds in the temporomandibular joint were determined using electrovibratograghy with a joint vibration analysis.

The articular disc motion to the condyle in the pathological bone changes group was smaller than in the adaptive bone changes group irrespective of the configuration of the disc, even though there were no significant differences between the two types of bony changes in the disc position during jaw closing. The joint vibration analysis of the temporomandibular joint showed that joint sounds with a higher frequency were observed in the pathological bone changes group than in the adaptive bone changes group. High energy levels needed to produce the higher frequencies were observed only in the pathological bone changes group.