Electromyography in diagnosing temporomandibular disorders.

BACKGROUND: Although electromyography (EMG) has been used extensively in dentistry to assess masticatory muscle impairments in several conditions, especially temporomandibular disorders (TMDs), many investigators have questioned its psychometric properties and accuracy in diagnosing TMD. TYPES OF STUDIES REVIEWED: The authors conducted a systematic review to analyze the literature critically and determine the accuracy of EMG in diagnosing TMDs. They conducted an electronic search of MEDLINE, Embase, all Evidence-Based Medicine Reviews, Allied and Complementary Medicine, Ovid HealthSTAR and SciVerse Scopus. The authors selected abstracts that fulfilled the inclusion criteria, retrieved the original articles, verified the inclusion criteria and hand searched the articles' references. They used a methodological tool (Quality Assessment of Diagnostic Accuracy Studies [QUADAS]) to evaluate the quality of the selected articles. RESULTS: The electronic database search resulted in a total of 130 articles. The authors selected eight articles as potentially meeting eligibility for the review. Of these eight articles, only two fulfilled the study inclusion criteria, and the authors analyzed them. Investigators in both studies reported low sensitivity (values ranged from 0.15 to 0.40 in one study and a mean of 0.69 in the second study). In addition, investigators in the two studies reported contradictory levels of specificity (values ranged from 0.95 to 0.98 in one study, and the mean value in the second study was 0.67). The likelihood ratios and predictive values were not helpful in diagnosing TMD by means of EMG. The quality of the two studies was poor on the basis of the QUADAS checklist. CLINICAL IMPLICATIONS: The authors of this systematic review found no evidence to support the use of EMG for the diagnosis of TMD.

Topical nonsteroidal anti-inflammatory medications for treatment of temporomandibular joint degenerative pain: a systematic review.

AIMS: To evaluate the efficacy of topical nonsteroidal anti-inflammatory drugs (NSAID) to relieve temporomandibular joint (TMJ) degenerative joint disease (DJD) pain. METHODS: A search of the literature was made using electronic databases complemented with a manual search. Clinical trials comparing topical NSAID with either placebo or an alternative active treatment to treat TMJ DJD pain were identified. Outcomes evaluated were pain reduction/pain control and/or incidence of side effects. RESULTS: A single study (double-blind randomized placebo-controlled trial) with 20 patients was identified that evaluated the efficacy of a topically prepared NSAID over a 12-week duration, measuring functional pain intensity, voluntary and assisted mouth opening, pain disability index, and a brief pain inventory analysis. This study revealed a pain intensity decrease within treatment groups but no significant difference between treatment groups. CONCLUSION: Presently, there is insufficient evidence to support the use of topically applied NSAID medications to palliate TMJ DJD pain.

Patients with temporomandibular disorders have increased fatigability of the cervical extensor muscles.

OBJECTIVES: To determine whether patients with myogenous and mixed temporomandibular disorders (TMD) have greater fatigability of the cervical extensor muscles while performing a neck extensor muscle endurance test (NEMET) when compared with healthy controls. METHODS: A total of 151 individuals participated in this study. Of these 47 were healthy controls, 57 patients had myogenous TMD, and 47 patients had mixed TMD. All patients performed the NEMET. The patients were instructed to maintain a prone lying position with the neck unsupported as long as possible, stopping at signs of fatigue or any discomfort. Electromyographic activity of the cervical extensor muscles during the NEMET and the holding time were collected for all patients and were compared across groups. A 1-way analysis of variance was used to evaluate the differences in holding time between patients with TMD and healthy controls. A mixed model analysis was used to evaluate the differences in normalized median frequency at different times (fatigue index) for the cervical extensor muscles while performing the NEMET between patients with TMD and controls. RESULTS: There were statistically significant differences (P<0.05) in the slopes of the normalized median frequency between patients with TMD and healthy controls at 10, 30, 40, 50, 60, 70, 80, 90, and 100 seconds of the NEMET. Holding time was significantly reduced in both patients with myogenous TMD and mixed TMD when compared with healthy controls (P<0.05). DISCUSSION: These results highlight the fact that alterations of endurance capacity of the extensor cervical muscles could be implicated in the neck-shoulder disturbances presented in patients with TMD.

Head and cervical posture in patients with temporomandibular disorders.

AIM: To determine whether patients with myogenous or mixed (ie, myogeneous plus arthrogeneous) temporomandibular disorders (TMD) had different head and cervical posture measured through angles commonly used in clinical research settings when compared to healthy individuals. METHODS: One hundred fifty-four persons participated in this study. Of these, 50 subjects were healthy, 55 subjects had myogenous TMD, and 49 subjects had mixed TMD (ie, arthrogenous plus myogenous TMD). A lateral photograph was taken with the head in the self-balanced position. Four angles were measured in the photographs: (1) Eye-Tragus-Horizontal, (2) Tragus-C7-Horizontal, (3) Pogonion-Tragus-C7, and (4) Tragus-C7-Shoulder. Alcimagen software specially designed to measure angles was used in this study. All of the measurements were performed by a single trained rater, a dental specialist in orthodontics, blinded to each subject's group status. RESULTS: The only angle that reached statistical significance among groups was the Eye-Tragus-Horizontal (F = 3.03, P = .040). Pairwise comparisons determined that a mean difference of 3.3 degrees (95% confidence intervals [CI]: 0.15, 6.41) existed when comparing subjects with myogenous TMD and healthy subjects (P = .036). Postural angles were not significantly related to neck disability, jaw disability, or pain intensity. Intrarater and interrater reliability of the measurements were excellent, with intraclass correlation coefficient (ICC) values ranging between 0.996-0.998. CONCLUSION: The only statistically significant difference in craniocervical posture between patients with myogenous TMD and healthy subjects was for the Eye-Tragus-Horizontal angle, indicating a more extended position of the head. However, the difference was very small (3.3 degrees) and was judged not to be clinically significant.

Electromyographic activity of the cervical flexor muscles in patients with temporomandibular disorders while performing the craniocervical flexion test: a cross-sectional study.

BACKGROUND: Most patients with temporomandibular disorders (TMD) have been shown to have cervical spine dysfunction. However, this cervical dysfunction has been evaluated only qualitatively through a general clinical examination of the cervical spine. PURPOSE: The purpose of this study was to determine whether patients with TMD had increased activity of the superficial cervical muscles when performing the craniocervical flexion test (CCFT) compared with a control group of individuals who were healthy. DESIGN: A cross-sectional study was conducted. METHODS: One hundred fifty individuals participated in this study: 47 were healthy, 54 had myogenous TMD, and 49 had mixed TMD. All participants performed the CCFT. Data for electromyographic activity of the sternocleidomastoid (SCM) and anterior scalene (AS) muscles were collected during the CCFT for all participants. A 3-way mixed-design analysis of variance for repeated measures was used to evaluate the differences in EMG activity for selected muscles while performing the CCFT under 5 incremental levels. Effect size values were calculated to evaluate the clinical relevance of the results. RESULTS: Although there were no statistically significant differences in electromyographic activity in the SCM or AS muscles during the CCFT in patients with mixed and myogenous TMD compared with the control group, those with TMD tended to have increased activity of the superficial cervical muscles. LIMITATIONS: The results obtained in this research are applicable for the group of individuals who participated in this study under the protocols used. They could potentially be applied to people with TMD having characteristics similar to those of the participants of this study. CONCLUSION: This information may give clinicians insight into the importance of evaluation and possible treatment of the deep neck flexors in patients with TMD. However, future research should test the effectiveness of this type of program through a randomized controlled trial in people with TMD in order to determine the real value of treating this type of impairment in this population.

Reduced endurance of the cervical flexor muscles in patients with concurrent temporomandibular disorders and neck disability.

Subjects with temporomandibular disorders (TMDs) have been found to have clinical signs and symptoms of cervical dysfunction. Although many studies have investigated the relationship between the cervical spine and TMD, no study has evaluated the endurance capacity of the cervical muscles in patients with TMD. Thus the objective of this study was to determine whether patients with TMD had a reduced endurance of the cervical flexor muscles at any level of muscular contraction when compared with healthy subjects. One hundred and forty-nine participants provided data for this study (49 subjects were healthy, 54 had myogenous TMD, and 46 had mixed TMD). There was a significant difference in holding time at 25% MVC between subjects with mixed TMD when compared to subjects with myogenous TMD and healthy subjects. This implies that subjects with mixed TMD had less endurance capacity at a lower level of contraction (25% MVC) than healthy subjects and subjects with myogenous TMD. No significant associations between neck disability, jaw disability, clinical variables and neck flexor endurance test were found.

Is maximal strength of the cervical flexor muscles reduced in patients with temporomandibular disorders?

OBJECTIVE: To determine whether there was a difference in maximal cervical flexor muscle strength in subjects with temporomandibular disorders (mixed and myogenous) compared with healthy subjects. DESIGN: Cross-sectional study. SETTING: Orthopedics/sports laboratory at the University of Alberta. PARTICIPANTS: Subjects (N=149) of whom 50 were healthy, 54 had myogenous temporomandibular disorders (TMD), and 45 had mixed TMD. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Maximal cervical flexor strength, pain. RESULTS: There was no statistically significant difference in maximal cervical flexor strength among groups (P>.05). Subjects' body weight was significantly associated with strength. No significant association between jaw disability with maximal cervical flexor strength was found. A significant but weak association between neck disability and maximal cervical flexors strength was found. CONCLUSIONS: These results indicated that strength evaluation is one of several assessment factors that need to be addressed when evaluating musculoskeletal painful conditions such as TMD and neck disorders, but strength evaluation cannot be considered as a direct measure of disability. Future studies should explore evaluation of strength in other muscular groups such as cervical extensors, rotators, and lateral flexors, and also under different conditions such as rapid movements, and in patients with more severe jaw disability.

Analgesic action of gabapentin on chronic pain in the masticatory muscles: a randomized controlled trial.

Chronic masticatory myalgia (CMM) can be defined as constant pain in the masticatory muscles for more than 6 months and is influenced by the central nervous system. The antiepileptic agent gabapentin acts centrally and is used for managing different types of chronic pain conditions. The objective of this study was to evaluate the analgesic action of gabapentin on CMM. In this 12-week randomized controlled clinical trial 50 patients were randomly allocated into two study groups: 25 received gabapentin and 25 received placebo. The outcome measures utilized were pain reported on a VAS (VAS-pain), Palpation Index (PI) and impact of CMM on daily functioning reported on a VAS (VAS-function). Thirty-six patients completed the study. Gabapentin showed to be clinically and statistically superior to placebo in reducing pain reported by patients (gabapentin=51.04%; placebo=24.30%; P=0.037), masticatory muscle hyperalgesia (gabapentin=67.03%; placebo=14.37%; P=0.001) and impact of CMM on daily functioning (gabapentin=57.70%; placebo=16.92%; P=0.022). It can be concluded from this study that gabapentin is effective for the management of CMM.

The association between the cervical spine, the stomatognathic system, and craniofacial pain: a critical review.

AIMS: Craniofacial pain is a term that encompasses pain in the head, face, and related structures. Multiple etiologies and factors may be related to craniofacial pain; however, the association between the cervical spine and its related structures and craniofacial pain is still a topic of debate. The objective of this critical review was to present and analyze the evidence of the associations between the cervical spine, stomatognathic system, and craniofacial pain. METHODS: A search of the databases Medline, PubMed, Embase, Web of Sciences, Cochrane Library, Cinahl, and HealthStar was conducted for all publications related to the topic in the English and Spanish languages. Relevant information was also derived from reference lists of the retrieved publications. The key words used in the search were cervical spine, cervical vertebrae, neck pain, neck injuries, neck muscles, craniofacial pain, orofacial pain, facial pain, temporomandibular joint pain, and temporomandibular joint disorders. RESULTS: The search provided information referring to the biomechanical, anatomical, and pathological association between craniofacial pain, the stomatognathic system and the cervical spine. CONCLUSION: The information provided by this review suggests an association between the cervical spine, stomatognathic system, and craniofacial pain, but most of this information is not conclusive and was derived from poor-quality studies (levels 3b, 4, and 5 based on Sackett's classification). Better designed studies are needed in order to clarify the real influence that the cervical spine has in relation to the stomatognathic system and craniofacial pain.

The association between head and cervical posture and temporomandibular disorders: a systematic review.

AIMS: To carry out a systematic review to assess the evidence concerning the association between head and cervical posture and temporomandibular disorders (TMD). METHODS: A search of Medline, Pubmed, Embase, Web of Science, Lilacs, and Cochrane Library databases was conducted in all languages with the help of a health sciences librarian. Key words used in the search were posture, head posture, cervical spine or neck, vertebrae, cervical lordosis, craniomandibular disorders or temporomandibular disorders, temporomandibular disorders, and orofacial pain or facial pain. Abstracts which appeared to fulfill the initial selection criteria were selected by consensus. The original articles were retrieved and evaluated to ensure they met the inclusion criteria. A methodological checklist was used to evaluate the quality of the selected articles and their references were hand-searched for possible missing articles. RESULTS: Twelve studies met all inclusion criteria and were analyzed in detail for their methodology and information quality. Nine articles that analyzed the association between head posture and TMD included patients with mixed TMD diagnosis; 1 article differentiated among muscular, articular, and mixed symptomatology; and 3 articles analyzed information from patients with only articular problems. Finally, 2 studies evaluated the association between head posture and TMD in patients with muscular TMD. Several methodological defects were noted in the 12 studies. CONCLUSION: Since most of the studies included in this systematic review were of poor methodological quality, the findings of the studies should be interpreted with caution. The association between intra-articular and muscular TMD and head and cervical posture is still unclear, and better controlled studies with comprehensive TMD diagnoses, greater sample sizes, and objective posture evaluation are necessary.

Triptans for treatment of acute pediatric migraine: a systematic literature review.

The purpose of this article is to evaluate the effectiveness and safety of triptans for the treatment of acute migraine in children and adolescents. Randomized and open label trials of triptans in acute pediatric patients (ages 6-18 years) were identified by Medline (1966-2002) and PubMed (1991-2002). Additional reports were identified from the reference list of the retrieved studies. To study effectiveness, only randomized controlled trials were included, but open label studies were also included to study adverse effects. Pharmacokinetic studies of triptans in pediatric patients were also searched. Four randomized controlled trials were identified. One study reported oral sumatriptan, another oral rizatriptan, and two studies reported nasal spray sumatriptan. Rizatriptan is well tolerated but not clearly beneficial when used in adolescents. Effectiveness of nasal spray sumatriptan in acute pediatric migraine where other medications had failed was supported. Effectiveness of oral sumatriptan was not established. Adverse effects were minor for oral sumatriptan and rizatriptan and nasal sumatriptan. Pharmacokinetics of sumatriptan in pediatric patients has not been established. In conclusion, nasal spray sumatriptan should be considered in acute pediatric migraine in patients not experiencing adequate relief with other interventions.

Topical review: sleep bruxism and the role of peripheral sensory influences.

Sleep bruxism (SB) is an unusual orofacial movement described as a parafunction in dentistry and as a parasomnia in sleep medicine. Since several peripheral influences could be involved in sleep-wake regulation and the genesis of rhythmic jaw movements, the authors have reviewed the relevant literature to facilitate understanding of mechanisms possibly involved in SB genesis. Various animal and human studies indicate that during either wakefulness or anesthesia, orofacial sensory inputs (e.g., from periodontium, mucosa, and muscle) could influence jaw muscle activity. However, the role of these sensory inputs in jaw motor activity during sleep is unclear. Interestingly, during sleep, the jaw is usually open due to motor suppression; tooth contact most likely occurs in association with sleep arousal. Recent physiologic evidence supports an association between sleep arousal and SB; a sequential change from autonomic (cardiac) and brain cortical activities precede SB-related jaw motor activity. This suggests that the central and/or autonomic nervous systems, rather than peripheral sensory factors, have a dominant role in SB genesis. However, some peripheral sensory factors may exert an influence on SB through their interaction with sleep-wake mechanisms. The intent of this review is to integrate various physiologic concepts in order to better understand the mechanisms underlying the genesis of SB.

The significance of saliva during sleep and the relevance of oromotor movements.

Saliva is an essential component of the oroesophageal milieu and allows for normal speech, taste, mastication, food bolus formation and swallowing. Saliva has important functions in protecting the hard and soft tissues of the oral cavity from acids and pathogenic microbes. A large number of people suffer either subjective or objective alterations in quantity and/or quality of their saliva that may be secondary to disease, medications, medical treatments or emotional events. Sleep-related xerostomia is a sensation of dry mouth associated with a report of either mouth and/or throat discomfort that induces awakenings for water intake. The prevalence of self-reported dry mouth complaint during sleep (associated with awakening and water intake) in a Canadian survey was estimated at 23%. The biological significance of decreased saliva during sleep is unknown and it is unclear how the oral cavity compensates for this period of relative dryness. The amount of saliva produced is greatest during the waking hours of the day and diminishes dramatically during sleep and may represent another process in the human body that displays a circadian rhythmicity. Salivary secretion during wakefulness is, in part, associated with oromotor activity involving the masticatory muscles. Rhythmic masticatory muscle activity and swallowing are non-disruptive events that occur during normal sleep. We hypothesize herein that lubrication from saliva is necessary during sleep to protect tissue integrity and health of oroesophageal structures.