Journal of Oral & Facial Pain and Headache, 04/2006

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 stomato-gnathic 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 stomato-gnathic system and craniofacial pain. Keywords: cervical spine, craniofacial pain, neck, neck pain, temporomandibular disorders

Aims: To evaluate the effect of comorbid depression and pain on an early biopsychosocial intervention for acute temporomandibular disorder (TMD) patients. Methods: Depressed (either current or lifetime; n = 32) or nondepressed (n = 31) acute TMD patients received a biopsychosocial intervention, and were evaluated at preintervention and again 12 months postintervention by Characteristic Pain Intensity, the Beck Depression Inventory, and a masticatory function test. Results: Findings revealed that both depressed and nondepressed patients reported comparable pain decreases at 12 months postintervention. Moreover, there were no significant differences between patient groups in masticatory function. Conclusion: With appropriate early biopsychosocial intervention, acute TMD patients, regardless of the presence or absence of vulnerability to depression symptomatology, can be effectively treated. Keywords: biopsychosocial, depression, intervention, masticatory function, pain, temporomandibular disorders

Aims: To assess the effects of oral pain on oral health-related quality of life during pregnancy and document measures taken by pregnant women seeking relief for oral pain. Their experience of other types of pain were also investigated. Methods: A sample of pregnant women who were admitted to a public hospital to give birth were invited to participate in this cross-sectional study. Those who agreed were asked if they had experienced any pain due to problems with their mouth, teeth, or dentures during the 6 months prior to the interviews. Interviewees who answered affirmatively were questioned about the effects of this pain on their normal activities with the Oral Impacts on Daily Performances (OIDP) tool. Results: The study population consisted of 504 subjects (83% of the eligible individuals). A high prevalence of untreated dental caries was found. The prevalences of oral pain, headaches, back pain, and pelvic pain were 39.1%, 61.5%, 59.3%, and 60.9%, respectively. Of those reporting pain, 168 (33.3%) reported having had difficulty doing at least one of the activities included in the OIDP due to oral pain. The most frequently mentioned effects were difficulty in maintaining emotional balance (23.6%), difficulty eating (22.8%), and difficulty cleaning teeth (20%). The mean and median OIDP scores were 13.9% and 8.0%, respectively. Conclusion: Oral pain during pregnancy was an important problem for this group of women and had a negative effect on their quality of life. Keywords: oral health, pain, pregnancy, quality of life, toothache

Aims: To assess the consistency of intentional behavioral performance as an index of whether individuals understood the meanings of the behavioral terms of the Oral Behaviors Checklist, which is a self-report scale for identifying and quantifying the frequency of jaw overuse behaviors. Methods: Surface electromyography was used to measure bilaterally the activity of the masseter, temporalis, and suprahyoid muscles (for assessment of oral behaviors) and the biceps muscles (reference task of biceps curl) in 27 temporomandibular disorder (TMD) cases and 27 controls. Subjects were asked to perform (1) biceps curls to lift 5 weights, with explanation, and (2) 10 oral behaviors (eg, "clench," "yawn") without explanation. Results: Biceps-curl performance resulted in assignments of excellent or very good for linearity-reliability based on inspection and correlation. Test-retest reliability of the 10 performed oral behaviors generally ranged from 0.6 to 0.98 for all 3 muscle groups, and many tasks had reliability coefficients comparable to those for the biceps curl. Across tasks, elevator muscle reliability of cases was 0.87, compared to 0.75 for controls; group values for opening muscles were similar. Conclusion: Individual subjects performed each task at a high level of consistency. Performance was not appreciably altered by being a TMD case versus a control and was not significantly different from the performance level of a reference task, indicating that each individual understood well the meaning of each oral behavior-related word. Keywords: electromyography, oral behaviors, parafunction, reliability, temporomandibular disorders

Aims: To assess the occurrence and the modality of spontaneous orofacial behaviors of awake healthy subjects without pain who were unaware of bruxism during wakefulness. Methods: Sixteen asymptomatic subjects read silently for 30 minutes while polygraphic recordings, including electromyographic (EMG) activity from masticatory and leg muscles, chest respiratory movements, and the movements and sounds of larynx, were made with simultaneous audio-video monitoring. Orofacial behaviors were scored based on the polygraphic and audio-video records. The activity and duration of masseter EMG bursts were calculated for the types of orofacial behaviors. Results: The number of orofacial behaviors varied between subjects; swallowing was most frequently observed. Approximately half of the orofacial behaviors occurred closely with body movements. Of all masseter EMG bursts detected, 55% were associated with functional orofacial behaviors, while 45% were regarded as nonfunctional. More than 80% of these masseter bursts lasted for less than 2 seconds, with an activity less than 20% of maximal voluntary clenching. These values did not differ between the types of associated orofacial behaviors. Conclusion: Although the occurrence of spontaneous orofacial motor activity is variable, asymptomatic subjects can exhibit substantial masseter bursts during wakefulness that are not associated with functional orofacial behaviors. The use of physiological and audio-video records permits spontaneous orofacial behaviors to be specifically identified, thereby allowing nonfunctional masseter EMG activity to be differentiated from functional masseter EMG activity. Keywords: bruxism, electromyography, polygraphic recording, spontaneous orofacial behaviors, wakefulness

Aims: To investigate whether local administration of nerve growth factor (NGF) decreases the mechanical threshold (MT) of putative nociceptive masseter afferent fibers as part of its mechanism of mechanical sensitization. Methods: Electrophysiologic recordings were made from masseter afferents and a randomized, blinded approach was used to test the effects of intramuscular injection of NGF (2.5 or 25 µg/mL) into the rat masseter muscle on the MT of masseter afferents (n = 65) and plasma protein extravasation. Results: The plasma protein extravasation data and electrophysiological recordings indicated that rat NGF injection was not inflammatory and did not evoke afferent discharge or induce mechanical sensitization (as reflected in a decreased MT) in masseter afferents in either male or female rats. To investigate whether the lack of effect of NGF injection might be due to differences between human and rat NGF, additional experiments with human NGF injection (25 µg/mL) were undertaken. Intramuscular injection of human NGF into the rat masseter muscle also failed to evoke afferent discharges; however, it did decrease the MT of masseter afferent fibers. Conclusion: The finding that neither rat nor human NGF excited putative nociceptive masseter afferent fibers is consistent with a previous report that intramuscular NGF injections are not acutely painful in human subjects. The ability of human NGF injection into the rat masseter muscle to induce afferent mechanical sensitization suggests that this experimental approach may be useful for the study of peripheral mechanisms of myofascial pain and tenderness associated with temporomandibular disorders. Keywords: afferent fibers, masseter muscle, muscle pain, nerve growth fibers, temporomandibular disorders