Association of functional state of stomatognathic system with mobility of cervical spine and neck muscle tenderness

Kinematic Relationship Between Temporomandibular and Cervical Spine Joints

INTRODUCTION

The temporomandibular joints (TMJs) and the cervical spine exhibit a complex functional relationship due to their anatomical and biomechanical connections. Understanding how the mobility of these structures is assessed is important for comprehending their potential interplay in musculoskeletal disorders of the head and neck.

AIM

To synthesize and compare the methodologies and findings of studies that simultaneously assessed the mobility of both the TMJs and the cervical spine.

MATERIALS AND METHODS

A comprehensive search of databases was conducted to identify relevant studies. The analysis included 15 studies that objectively analyzed movements of both the TMJs and the cervical spine. The methods used for assessing TMJ and cervical spine mobility were extracted and compared.

RESULTS

The most commonly used methods for assessing TMJ mobility were rulers or calipers for linear measurements, along with the TheraBite or Cranio-Mandibular Scale. The Zebris digital axiograph was the least frequently used. For cervical spine movements, the cervical range of motion or an inclinometer was most often used. In assessing TMJ mobility, maximal mouth opening (MMO) was consistently examined, while other movements were assessed less frequently. In assessing cervical spine mobility, flexion and extension were most often examined, followed by rotation and lateral flexion in some studies, with flexion and extension of the upper cervical spine being the least frequently assessed. Notably, no study examined TMJ mobility in different head positions relative to the body in the frontal plane (i.e., during lateral flexion of the cervical spine). None of the analyzed studies considered age and sex differences. The methodological heterogeneity of the studies made it difficult to draw unambiguous conclusions. The diversity of tools and protocols used made it difficult to compare results among studies.

CONCLUSION

Further research is needed to better understand the kinematic relationship between the TMJs and the cervical spine and to develop standardized assessment protocols. The methodological inconsistencies across existing studies highlight the need for more uniform approaches in future investigations.

Co-contraction behaviour of masticatory and neck muscles during tooth grinding

The objective of this study was to analyse the co-contraction behaviour of jaw and neck muscles during force-controlled experimental grinding in the supine position. Twelve symptom-free subjects were enrolled in the experimental study. Electromyographic (EMG) activity of semispinalis capitis, splenius capitis and levator scapulae muscles was recorded bilaterally with intramuscular fine-wire electrodes, whereas that of sternocleidomastoideus, infrahyoidal, suprahyoidal, masseter and anterior temporalis muscles were registered with surface electrodes. EMG and force measurements were performed during tasks simulating tooth grinding on custom-made intraoral metal splints. The mean EMG activity normalised by maximum voluntary contraction (% MVC) of each of the neck muscles studied during grinding was analysed and compared with previous data from jaw clenching at identical force (100 N) and (supine) position. The occurrence of low-level, long-lasting tonic activation (LLTA) of motor units was also documented. The mean three-dimensional force vector of the grinding forces was 106 ± 74 N. In the frontal plane, the incline to the midsagittal plane ranged between 10° and 15°. In the midsagittal plane, the incline to the frontal plane was negligibly small. Posterior neck muscle activity during grinding ranged between 4.5% and 12% MVC and during clenching with 100 N between 1.8% and 9.9% MVC. Masticatory muscle activity during grinding ranged between 17% and 21% MVC for contralateral masseter and ipsilateral temporalis and between 4% and 6.5% for ipsilateral masseter and contralateral temporalis. LLTA had an average duration of 195 ± 10 seconds. The findings from this study do not support pathophysiological muscle chain theories postulating simple biomechanical coupling of neck and jaw muscles. Co-contractions of neck and masticatory muscles may instead occur as a result of complex neurophysiological interactions.

Headache Children with Temporomandibular Disorders have Several Types of Pain and other Symptoms

The aim was to investigate the association between temporomandibular disorders (TMD) and overall muscle tenderness, depressive symptoms, sleep difficulties, headache frequency and related symptoms in children with primary headache in comparison with controls. Based on an unselected population sample of 1135 Finnish schoolchildren classified according to the type of headache at age 12, altogether 297 children aged 13-14 from different headache groups and healthy controls were randomly selected for an interview and clinical examinations. Children with migraine had more TMD signs than children with nonmigrainous headaches or healthy controls. High TMD total scores were associated with palpation tenderness in other parts of the body and with frequent headache attacks. We conclude that children with overall headache, migraine in particular, and high total TMD scores showed an increased overall tenderness to muscle palpation and multiply manifested hypersensitivity pain.

Co-activation of jaw and neck muscles during submaximum clenching in the supine position

OBJECTIVE

The purpose of this study was to test the hypothesis that jaw clenching induces co-contraction and low-level long-lasting tonic activation (LLTA) of neck muscles in the supine position.

DESIGN

Ten healthy subjects developed various feedback-controlled submaximum bite forces in different bite-force directions in supine position. The electromyographic (EMG) activity of the semispinalis capitis, semispinalis cervicis, multifidi, splenius capitis, levator scapulae, trapezius, sternocleidomastoideus, masseter and infra/supra-hyoidal muscles was recorded. For normalization of EMG data, maximum-effort tasks of the neck muscles were performed.

RESULTS

Co-contractions of the posterior neck muscles varied between 2% and 11% of their maximum voluntary contraction. Different bite forces and bite-force directions resulted in significant (p<.05) activity differences between the co-contraction levels of the neck muscles. In addition, LLTA of specific neck muscles, provoked by the jaw clenching tasks, was observed.

CONCLUSIONS

This study demonstrated for the first time moderate co-contractions of jaw and neck muscles in the supine position under controlled submaximum jaw clenching forces. LLTA of most neck muscles was observed, outlasting clenching episodes and indicating an additional neuromuscular interaction between the two muscle groups.

Professional musicians with craniomandibular dysfunctions treated with oral splints

Craniomandibular dysfunction (CMD) symptoms occur frequently in violin/viola and wind players and can be associated with pain in the neck, shoulders and arm. In the current study, the effect of oral splint treatment of CMD on reducing pain and symptoms especially in these areas was investigated. Thirty (30) musicians undergoing CMD treatment with oral splints participated in this study. They completed a questionnaire that addressed CMD symptoms, localization of pain, and subjective changes in symptoms. Pain in the shoulder and/or upper extremity was the most frequent symptom reported by 83% of subjects, followed by neck pain (80%) and pain in the teeth/TMJ regions (63%). Treatment with oral splints contributed to a significant decrease in neck pain in 91%, teeth/TMJ pain in 83%, and shoulder and upper extremity pain in 76% of the musicians. Eighty percent (80%) of the patients reported improvement of their predominant symptoms. CMD can be a potential cause for pain in the neck, shoulders, and upper extremities of musicians. It is paramount that musicians with musculoskeletal problems be examined for CMD symptoms. Treatment with oral splints seems to be valuable. Further prospective, randomized controlled studies are necessary to confirm efficacy of oral splint treatment in CMD-associated pain and problems in the neck, shoulder, and the upper extremities in musicians.

Cervical spine signs and symptoms: perpetuating rather than predisposing factors for temporomandibular disorders in women

Aim:

The purpose of this study was to assess in a sample of female community cases the relationship between the increase of percentage of cervical signs and symptoms and the severity of temporomandibular disorders (TMD) and vice-versa.

Material and Methods:

One hundred women (aged 18-26 years) clinically diagnosed with TMD signs and symptoms and cervical spine disorders were randomly selected from a sample of college students.

Results:

43% of the volunteers demonstrated the same severity for TMD and cervical spine disorders (CSD). The increase in TMD signs and symptoms was accompanied by increase in CSD severity, except for pain during palpation of posterior temporal muscle, more frequently observed in the severe CSD group. However, increase in pain during cervical extension, sounds during cervical lateral flexion, and tenderness to palpation of upper fibers of trapezius and suboccipital muscles were observed in association with the progression of TMD severity.

Conclusion:

The increase in cervical symptomatology seems to accompany TMD severity; nonetheless, the inverse was not verified. Such results suggest that cervical spine signs and symptoms could be better recognized as perpetuating rather than predisposing factors for TMD.

Pain characteristics of temporomandibular disorder: a pilot study in patients with cervical spine dysfunction

Objective:

The purpose of the present pilot study was to describe pain complaints of TMD patients and cervical spine dysfunction.

Methods:

Fourteen women with myogenous TMD, cervical motion limitation and rotation of at least one of the three first cervical vertebrae evidenced by radiographic examination participated in this study. The multidimensional pain evaluation was accomplished by a Brazilian version of the McGill Pain Questionnaire.

Results:

The results showed that the most painful body site mentioned was cervical spine, followed by scapular region and temporomandibular joint. More than half of the volunteers reported temporal pain pattern as rhythmic, periodic and, or still, intermittent. The majority of the patients classified the pain intensity assessed at the moment of the evaluation as mild to discomforting. Absolute agreement was not observed among volunteers regarding word dimensions used to describe their pain, although a great number of patients chose the descriptor related to tension as the better expression to describe their painful complaint.

Conclusion:

Pain characteristics of TMD patients with cervical spine dysfunction showed cervical spine as a common painful region reported and words related to affective and emotional dimensions of pain perception can be used by these patients to qualify their pain complain.

Asymmetric muscle function in patients with developmental mandibular asymmetry

The aim was to test the hypothesis that developmental mandibular asymmetry is associated with increased asymmetry in muscle activity. Patients with mandibular condylar and/or ramus hyperplasia having unilateral cross-bite were compared with healthy subjects with normal occlusion. Muscle activity was recorded with surface electrodes in the masseter, suprahyoid, sternocleidomastoid muscle (SCM) and upper trapezius areas during jaw opening-closing-clenching, head-neck flexion-extension, and elevation-lowering of shoulders. Root mean square (RMS) and mean power frequency (MPF) values were calculated and analysed using anova and t-tests with P < 0.05 chosen as significance level. The SCM and masseter muscles showed co-activation during jaw and head movements, significantly more asymmetric in the patients than in the healthy subjects. The RMS and MPF values were higher in the patients than in the controls in the SCM and suprahyoid areas on both sides during jaw opening-closing movement. The results indicate that the ability to perform symmetric jaw and neck muscle activities is disturbed in patients with developmental mandibular asymmetry. This is of clinical interest because asymmetric activity may be an etiologic factor in temporomandibular joint and cervical pain. The results support that co-activation occurs between jaw and neck muscles during voluntary jaw opening and indicate that postural antigravity reflex activity occurs in the masseter area during head extension. Further studies, where EMG recordings are made from the DMA patients at early stages are motivated to verify activity sources and test if the asymmetric activity is associated with muscle and joint pain in the jaw and cervical areas.

Temporomandibular disorders, head and orofacial pain: cervical spine considerations

Head and orofacial pain originates from dental, neurologic, musculoskeletal, otolaryngologic, vascular, metaplastic, or infectious disease. It is treated by many health care practitioners, such as dentists, oral surgeons, and physicians. The article focuses on the nonpathologic involvement of the musculoskeletal system as a source of head and orofacial pain. The areas of the musculoskeletal system that are reviewed include the temporomandibular joint and muscles of mastication--collectively referred to as temporomandibular disorders (TMDs) and cervical spine disorders. The first part of the article highlights the role of physical therapy in the treatment of TMDs. The second part discusses cervical spine considerations in the management of TMDs and head and orofacial symptoms. It concludes with and overview of the evaluation and treatment of the cervical spine.

Deranged jaw-neck motor control in whiplash-associated disorders

Recent findings of simultaneous and well coordinated head-neck movements during single as well as rhythmic jaw opening-closing tasks has led to the conclusion that 'functional jaw movements' are the result of activation of jaw as well as neck muscles, leading to simultaneous movements in the temporomandibular, atlanto-occipital and cervical spine joints. It can therefore be assumed that disease or injury to any of these joint systems would disturb natural jaw function. To test this hypothesis, amplitudes, temporal coordination, and spatiotemporal consistency of concomitant mandibular and head-neck movements during single maximal jaw opening-closing tasks were analysed in 25 individuals suffering from whiplash-associated disorders (WAD) using optoelectronic movement recording technique. In addition, the relative durations for which the head position was equal to, leading ahead of, or lagging behind the mandibular position during the entire jaw opening-closing cycle were determined. Compared with healthy individuals, the WAD group showed smaller amplitudes, and changed temporal coordination between mandibular and head-neck movements. No divergence from healthy individuals was found for the spatiotemporal consistency or for the analysis during the entire jaw opening-closing cycle. These findings in the WAD group of a 'faulty', but yet consistent, jaw-neck behavior may reflect a basic importance of linked control of the jaw and neck sensory-motor systems. In conclusion, the present results suggest that neck injury is associated with deranged control of mandibular and head-neck movements during jaw opening-closing tasks, and therefore might compromise natural jaw function.

Changes in weight distribution at the feet due to occlusal supporting zone loss during clenching

To establish the relationship between the condition of the stomatognathic system and body posture, changes in the weight distribution at the feet using the four-quadrant weight scale were investigated when the occlusal supporting zone was lost unilaterally and bilaterally. The results were as follows: 1. Regardless of occlusal conditions, the weight distribution was changed during clenching; 2. The weight distribution was shifted anteriorly during clenching regardless of the condition of the occlusal supporting zone. Additionally, weight distribution shifted more laterally to the opposite side of the lost occlusal supporting zone during clenching with the occlusal supporting zone lost more unilaterally than bilaterally. From the present findings, it is suggested that the body posture may be affected and changed to an unusual position causing neck or shoulder pain, especially when the occlusal supporting zone is lost both unilaterally and bilaterally.

Orientation of craniofacial planes and temporomandibular disorder in young adults with normal occlusion

The aim of this study was to investigate the relationship between orientation of craniofacial planes relative to the true horizontal and temporomandibular disorder (TMD), in normal occlusion. Fourteen university dental students, with full natural dentition and bilateral Angle Class I occlusion, who exhibited signs and symptoms of TMD, were compared with 14 age- and sex-matched healthy controls. Frontal and lateral photographs were taken in natural head position with the subject standing up, clenching a Fox plane and having a facial arch positioned. Photographs were examined by a standardized image analysis. Inter-pupillary axis, Frankfurt, occlusal and Camper planes were evaluated. In frontal view, the Frankfurt plane was right rotated relative to the true horizontal both in TMD subjects (P < 0.01) and controls (P < 0.05), but rotation was larger in TMD subjects (mean difference between groups, 1.1 degrees, 95% confidence interval, 95% CI, 0.2-2.0 degrees ). No significant deviation from the horizontal or difference between groups was observed for the interpupillary axis and occlusal plane. In lateral view, the Frankfurt plane was upward-orientated relative to the true horizontal in TMD group (mean angular deviation 2.8 degrees, 95% CI, 1.0-4.6 degrees ). The occlusal and Camper planes were downward-orientated in both groups (P < 0.0001), but inclination of occlusal plane tended to be smaller in TMD subjects (mean difference between groups, -3.8 degrees, 95% CI, -7.6-0.1 degrees ). Angles between any craniofacial planes did not significantly differ between groups. The findings show that in young adults with normal occlusion, a weak association exists between the orientation of craniofacial planes in natural head position and signs and symptoms of TMD. Furthermore, they suggest that, within this population, TMD might be mainly associated with head posture rather than with craniofacial morphology.

Changes in head position due to occlusal supporting zone loss during clenching

To establish the relationship between the condition of the stomatognathic system and body posture, changes in the head position during clenching were observed and investigated when the occlusal supporting zone was lost unilaterally and bilaterally. The results were as follows: 1. Regardless of the occlusal conditions, the head position was changed by clenching; 2. The occlusal conditions did not affect the changed distance of the head position; 3. The head position was changed forward and down by clenching regardless of the condition of the occlusal supporting zone. The head position changed more laterally to the opposite side of the lost occlusal supporting zone by clenching with the occlusal supporting zone lost unilaterally rather than bilaterally. Based on this study, it is suggested that unilateral loss of the occlusal supporting zone may cause the neck muscles to become inharmonious and thus affect body posture.

Comorbidity of internal derangement of the temporomandibular joint and silent dysfunction of the cervical spine

The aim of this evaluation was to examine correlations between internal derangement of the temporomandibular joint (TMJ) and cervical spine disorder (CSD). A prospective controlled clinical study was carried out. Thirty patients with signs and symptoms of internal derangement but without any subjective neck problems and 30 age- and gender-matched control subjects without signs and symptoms of internal derangement were examined. The investigation of the temporomandibular system was carried out using a 'Craniomandibular Index'. Afterwards an examiner-blinded manual medical investigation of the craniocervical system was performed. This included muscle palpation of the cervical spine and shoulder girdle as well as passive movement tests of the cervical spine, to detect restrictions in the range of movement as well as segmental intervertebral dysfunction. The internal derangement of the TMJ was significantly associated with 'silent' CSD (t-test, P < 0.05). Patients with raised muscle tenderness of the temporomandibular system exhibited significantly more often pain on pressure of the neck muscles than patients without muscle tenderness of the temporomandibular system (t-test, P < 0.05). As a result of the present study, for patients with internal derangement of the TMJ an additional examination of the craniocervical system should be recommended.

Unilateral temporomandibular disorder and asymmetry of occlusal contacts

STATEMENT OF PROBLEM

The relationship between temporomandibular disorders and occlusal tooth contacts is unclear and controversial.

PURPOSE

This study assessed whether unilateral temporomandibular disorders were associated with the absence of bilateral symmetry in the number of occlusal contacts.

MATERIAL AND METHODS

Fifteen university dental students who had complete natural dentition and normal occlusion and exhibited unilateral signs and symptoms of temporomandibular disorders were compared to 15 age- and sex-matched healthy control subjects. All participants met specific inclusion and exclusion criteria. Occlusal contacts were recorded in the intercuspal position with wax registrations. Dental impressions were made and poured in type I stone. Contacts were classified according to location and intensity. Four experienced dentists using an established protocol made all measurements. Assessment of the reliability of the occlusal registration procedure showed a small (<4%) within-subject variability. Statistical analysis was based on the binomial distribution and nonparametric tests (P < .05).

RESULTS

Subjects with unilateral temporomandibular disorders had greater bilateral difference in the number of contacts than controls. The median (95% confidence interval) difference was 3 (2 to 4) and 2 (1 to 2), respectively. In unilateral temporomandibular disorder subjects, the number of occlusal contacts was greater on the side with, rather than without, disorder (median number 20 vs. 16). The median (95% confidence interval) difference between sides with and without unilateral temporomandibular disorders was 3 (2 to 4) for all contacts and 2 (1 to 3) for contacts on the posterior teeth.

CONCLUSION

Within the population of this study, a weak association was found between unilateral temporomandibular disorders and asymmetry in the number of occlusal contacts.

Disturbed jaw behavior in whiplash-associated disorders during rhythmic jaw movements

As shown previously, "functional jaw movements" are the result of coordinated activation of jaw as well as neck muscles, leading to simultaneous movements in the temporomandibular, atlanto-occipital, and cervical spine joints. In this study, the effect of neck trauma on natural jaw function was evaluated in 12 individuals suffering from whiplash-associated disorders (WAD). Spatiotemporal characteristics of mandibular and concomitant head movements were evaluated for three different modes of rhythmic jaw activities: self-paced continuous maximal jaw-opening/-closing movements, paced continuous maximal jaw-opening/-closing movements at 50 cycles/minute, and unilateral chewing. Compared with healthy subjects, the WAD group showed smaller magnitude and altered coordination pattern (a change in temporal relations) of mandibular and head movements. In conclusion, these results show that neck trauma can derange integrated jaw and neck behavior, and underline the functional coupling between the jaw and head-neck motor systems.

Asymptomatic cervical spine dysfunction (CSD) in patients with internal derangement of the temporomandibular joint

Patients with temporomandibular disorders (TMDs) frequently show symptoms related to the cervical spine. It is however unknown whether patients with TMD who have no symptoms in the neck region often have signs of cervical spine dysfunction (CSD) and whether there is a predominant localization of these asymptomatic CSDs. In a prospective and controlled examiner-blinded clinical trial, the prevalence and localization of asymptomatic CSD in patients with TMD was examined. Thirty patients with internal derangement of the temporomandibular joint but without any neck problems were compared with 30 age and gender matched healthy controls. Significantly more asymptomatic dysfunctions of the vertebral joints and increased muscle tenderness were found in the patient group. The difference between patents and nonpatients for vertebral joint dysfunction and muscle tenderness was greatest in the upper cervical spine. These findings support the thesis that a complementary examination of this area should be performed, even when TMD patents do not report any neck problems.

Temporomandibular disorders, occlusion, and neck pain in subjects with facial pain: a case-control study

The etiology of facial pain is multifactorial. Based on the results of a questionnaire included in the study of the 1966 Northern Finland Birth Cohort, performed in 1997-98, we found an association of facial pain with subjective symptoms of temporomandibular disorders (TMD), neck pain and with occlusal factors reported by 5,696 subjects. The aim of the present study was to examine these associations clinically. In the year 2000, a new inquiry was sent to the following subjects living in Oulu: 1. all subjects who had reported facial pain in the former questionnaire (n=162) (case group); and 2. to a randomly selected group of nonpain controls (n=200), group matched for gender. Those who reported willingness to participate were invited to a clinical examination. Finally, the total number of subjects was 104, including 52 (10 men, 42 women) cases and 52 (10 men, 42 women) controls. Anamnestic data were collected, and clinical stomatognathic and musculoskeletal examinations were performed, both the clinicians and the subjects being unaware of the case-control status. Anamnestically, stress was the most often reported provoking factor for facial pain. Facial pain associated significantly with reported TMD symptoms and allergies. Based on clinical findings, most of the cases were classified in the myogenous subgroup of TMD. The risk for facial pain was six-fold in subjects with clinically assessed TMD, defined as moderate (DiII) or severe (DiIII) by Helkimo's clinical dysfunction index, almost six-fold in subjects with protrusion interferences and approximately three-fold in subjects with clinically assessed tenderness of distinct fibromyalgia (FM) points in the neck. According to the adjusted logistic regression analyses, TMD had the strongest influence on facial pain, followed by protrusion interferences, anamnestically reported allergies and "other headaches". The present study shows that as well as being connected with TMD, facial pain is associated with pain and muscle tenderness in the neck area.

Signs and symptoms of temporomandibular disorders in children with different types of headache

Headache is a common symptom among children and teenagers. Both bruxism and muscle and joint tenderness have been found in children with headache. Children with migraine headache report more temporomandibular disorder (TMD) symptoms than do those with tension-type headache. The aim of the present study was to investigate the association of different types of headache with TMD and sex in children. Altogether 297 randomly selected schoolchildren aged 13-14 years participated in a blind study setting. There were no statistically significant differences between the headache groups with regard to TMD signs, although the migraine and migraine-type headache groups had the highest percentage of subjects with more severe TMD signs. Nor were there any statistical differences between sexes or between the headache groups with regard to subjective symptoms of TMD. The present results with children differed from earlier results with adults. First, no association was found between tension headache and TMD, and, second, no sex difference in TMD children was observed at this age.

Prevalence of cervical spinal pain in craniomandibular pain patients

It has often been suggested that patients with a craniomandibular disorder (CMD) more often suffer from a cervical spine disorder (CSD) than persons without a CMD. However, in most studies no controlled, blind design was used, and conclusions were based on differing signs and symptoms. In this study, the recognition of CMD and CSD was based upon the presence of pain. The aim of this study was to determine the prevalence of cervical spinal pain in persons with or without craniomandibular pain, using a controlled, single-blind design. From 250 persons, a standardised oral history was taken, and a physical examination of the masticatory system and the neck was performed. Three classification models were used: one based on symptoms only; a second on signs only; and a third one based on a combination of symptoms and signs. The CMD patients were also subdivided in three subgroups: patients with mainly myogenous pain; mainly arthrogenous pain; and both myogenous and arthrogenous pain. Craniomandibular pain patients more often showed cervical spinal pain than persons without craniomandibular pain, independent of the classification model used. No difference in the prevalence of cervical spinal pain was found between the three subgroups of craniomandibular pain patients.

Psychological distress in chronic craniomandibular and cervical spinal pain patients

Recent studies to chronic pain have shown that the number of painful body areas is related to the level of psychological distress. Therefore, the first aim of this study was to analyse differences in level of psychological distress between craniomandibular pain patients with or without cervical spinal pain. In this analysis, the number of painful body areas below the cervical spine was also taken into account. The second aim was to determine psychological differences between subgroups of craniomandibular pain patients. In this study, 103 out of 250 persons with or without craniomandibular pain were included in the final analyses. Patients who suffered from both craniomandibular and cervical spinal pain showed higher levels of psychological distress, as measured with the Symptom Checklist 90 (SCL-90) than patients with local craniomandibular pain and persons without pain. Further, a positive relationship was found between the number of painful body areas below the cervical spine, as measured on a body drawing, and the SCL-90 scores. No psychological differences were found between myogenous and arthrogenous craniomandibular pain patients. In conclusion, chronic craniomandibular pain patients with a coexistent cervical spinal pain showed more psychological distress compared to patients with only a local craniomandibular pain and asymptomatic persons.

Elevated intramuscular concentration of bradykinin in jaw muscle increases the fusimotor drive to neck muscles in the cat

Patients suffering from temporomandibular dysfunction exhibit clinical findings such as fatigue, painful muscles, and muscles that are tender to palpation, not only in the temporomandibular area, but also in the neck/shoulder region. The mechanisms behind this are not known, although previous studies of similar spreading phenomena have revealed a possible involvement of the fusimotor system. In the present study, we evaluated the activity of this system by recording the activity of muscle spindle afferents from dorsal neck muscles after intramuscular injections of 6 microg to 25 microg bradykinin in the ipsilateral masseter muscle. A total of 23 muscle spindle afferents from the trapezius and splenius muscles was recorded at the C3-C4 level in 7 adult cats anesthetized with alpha-chloralose. Of these 23 afferents, 17 (74%) showed significantly different responses to bradykinin injections compared with control injections (dissolving agent, Tyrode), and the majority of the effects were compatible with an increased static fusimotor drive to the muscle spindle system. Thus, the results demonstrate potent reflex connections from groups III and IV masseter muscle afferents to fusimotor neurones on the C3-C4 level. It is concluded that the fusimotor system might play a significant role in the mechanisms behind the spread of muscle pain and tension from the temporomandibular region to the neck.

Masticatory force and function in patients with hemispheric brain infarction and hemiplegia

Recent functional animal studies have reported that the motor control of masticatory muscle function is bilaterally guided by both hemispheres, which may fundamentally differ from the cortical control of limb muscle function. In this study, we investigated whether unilateral cortical brain infarction induces different impairments in masticatory and upper limb motor performance. Evidence of the importance of both hemispheres in controlling masticatory movements would be greater if the masticatory function were shown to be unimpaired in patients with severe hemiplegia. The masticatory function of 16 patients with severe hemiparesis caused by brain infarction in the region of the middle cerebral artery was studied by means of interview, clinical examination, and bite-force measurements. Finger-thumb grip-force measurements and clinical examination of the upper limbs were also performed for evaluation of the effect of infarction on upper limb motor function. Localization of the infarction was confirmed with computer tomography and magnetic resonance imaging. The Scandinavian Stroke Scale demonstrated that each patient had a major unilateral cortical infarction which had caused a marked handicap with a serious impairment of upper limb function on the contralateral side. The clinical examination revealed no major signs of temporomandibular disorders, and the masticatory muscles, when examined by palpation, contracted symmetrically. None of the patients with unilateral brain infarction showed any differences in bite forces between the healthy and paralyzed sides. These results indicate that, in hemiparetic patients, great differences may exist between the motor performances of the masticatory and upper limb muscles. The present investigation clinically illustrates the importance of both hemispheres in the control of masticatory function and movements.

Concomitant mandibular and head-neck movements during jaw opening-closing in man

To test the hypothesis of a functional relationship between the human mandibular and cranio-cervical motor systems, head-neck movements during voluntary mandibular movements were studied in 10 healthy young adults, using a wireless optoelectronic system for three-dimensional (3D) movement recording. The subjects, unaware of the underlying aim of the study, were instructed to perform maximal jaw opening-closing tasks at fast and slow speed. Movements were quantified as 3D movement amplitudes. A consistent finding in all subjects was parallel and coordinated head-neck movements during both fast and slow jaw opening-closing tasks. Jaw opening was always accompanied by head-neck extension and jaw closing by head-neck flexion. Combined movement and electromyographic recordings showed concomitant neck muscle activity during head-neck movements, indicative of an active repositioning of the head. No differences in 3D movement amplitudes could be seen with respect to speed. The head movement was 50% of the mandibular movement during jaw opening, but significantly smaller (30-40%), during the jaw closing phase. In repeated tests, the 3D movement amplitudes of the concomitant head movements were less variable during slow jaw movement and during the jaw opening phase, than during fast and jaw closing movements, suggesting speed- and phase-related differences in the mechanisms controlling the integrated mandibular and head-neck motor acts. The present results give further support to the concept of a functional trigeminocervical coupling during jaw activities in man.

Cervical signs and symptoms in patients with Meniere's disease: a controlled study

This study compares the frequency of signs and symptoms from the cervical spine in 24 patients diagnosed with Meniere's disease and 24 control subjects from a population sample. From a previous controlled comparative study concerning signs and symptoms of craniomandibular disorders, 24 patients diagnosed with Meniere's disease (10 males and 14 females) and their 24 matched control subjects participated in this investigation on the state of the cervical spine. Symptoms of cervical spine disorders, such as head and neck/shoulder pain, were all significantly more frequent in the patient group than in the control group. Most of the patients (75%) reported a strong association between head neck movements in the atlanto-occipital and atlanto-axial joints and triggered attacks of vertigo. Also, 29% of the patients could influence their tinnitus by mandibular movements. Signs of cervical spine disorders, such as limitations in side-bending and rotation movements, were significantly more frequent in the patient group than in the control group. Tenderness to palpation of the transverse processes of the atlas and the axis, the upper and middle trapezius, and the levator scapulae muscle were also significantly more frequent in the patient group. The study shows a much higher prevalence of signs and symptoms of cervical spine disorders in patients diagnosed with Meniere's disease compared with control subjects from the general population.

Temporomandibular and cervical spine disorders. Self-reported signs and symptoms

STUDY DESIGN

The authors assessed the results of an anamnestic self-administered questionnaire given to 111 patients with temporomandibular disorders and 103 patients with cervical spine disorders.

OBJECTIVES

The present study was performed to investigate whether patients with cervical spine disorders and subgroups of patients with temporomandibular disorders differ regarding specific and accompanying signs and symptoms of temporomandibular disorders and cervical spine disorders.

SUMMARY OF BACKGROUND DATA

Patients with temporomandibular disorders frequently show signs and symptoms related to cervical spine disorders, and, vice versa, patients with cervical spine disorders may show signs and symptoms related to temporomandibular disorders. Many authors have pointed out the existence of neuroanatomical and biomechanical relationships.

METHODS

The questionnaire included questions about pain, symptoms of temporomandibular disorders, accompanying signs and symptoms, psychosocial factors, and general health. Before their clinical examination, all patients were requested by mail to complete the questionnaire.

RESULTS

Patients with cervical spine disorders reported fewer symptoms of temporomandibular disorders than the subgroups of patients with temporomandibular disorders, more general health symptoms than patients with temporomandibular disorders with an arthrogenous or myogenous component, and fewer ear symptoms than patients with temporomandibular disorders. There was no difference between the patient groups regarding other associated signs and symptoms and psychosocial factors as measured with the questionnaire. Logistic regression analyses showed that six variables (jaws, ears, eyes, temporomandibular joint sounds, complaints of the shoulders, and pain in joints other than the temporomandibular joint) correctly classified 91% of the patients as having temporomandibular disorders or cervical spine disorders.

CONCLUSIONS

The results of this study do not support the theoretical concept that cervical spine disorders may give rise to temporomandibular disorders. The authors' results indicate that the anamnestic questionnaire can be used as an aid to distinguish patients with cervical spine disorders from subgroups of patients with temporomandibular disorders.

Maximal contraction force and endurance of human jaw-closing muscles in isometric clenching

Maximal unilateral bite force and endurance times from maximal bite force to the 75% and 50% levels of maximal values were recorded for 13 men and 15 women with bite openings of 10 and 14 mm. Measurements were made both from right and left molar regions and from the incisal region. Bite force values were significantly higher than previously measured in endurance tests by devices with unilateral housings. Men achieved greater bite force than women in the molar region in every trial. The general assumption that women's muscles are superior to those of men in static endurance when both are working at the same percentage of maximal voluntary contraction was not supported by this work for jaw-closing muscles. The endurance times to 75% and 50% levels of maximal bite force were shorter than could be expected from previous reports, and endurance times to the 50% level were even shorter than those reported for muscles of limbs.