Journal of Oral & Facial Pain and Headache, 03/2006

Aims: To evaluate the risk of self-reported temporomandibular disorder (TMD) pain among adolescents in relation to previous head and/or neck injury. Methods: 3,101 enrollees (11 to 17 years of age) of a nonprofit integrated health-care system were interviewed by telephone. Two hundred four cases with self-reported TMD pain and 194 controls without self-reported TMD pain frequency-matched to the cases by age and gender completed standardized in-person interviews and physical examinations in which reports of previous head/neck injuries were recorded. Odds ratio (OR) estimates and 95% confidence intervals (CIs) of the relative risks of TMD pain associated with prior head and/or neck injuries were calculated using logistic regression. Results: A greater proportion of subjects reporting TMD pain (36%) than controls (25%) had a history of head and/or neck injuries (OR = 1.8, 95% CI, 1.1-2.8). In a separate analysis, the presence of TMD based upon the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) was assessed in relation to prior head and/or neck injury. Cases reporting TMD pain and meeting the RDC/TMD criteria for myofascial pain and/or arthralgia or arthritis were 2.0 (CI, 1.0-3.8) times more likely to have had a prior head injury than were controls with neither self-reported nor RDC/TMD pain diagnoses. Conclusion: The results suggest a modest association of prior head injuries with both self-reported and clinically diagnosed TMD pain in adolescents. Keywords: adolescent, head injury, neck injury, orofacial pain, temporomandibular disorders

Aims: To evaluate the electromyographic (EMG) activity of masseter and temporalis muscles in relation to impact awareness, gender, impact magnitude, and kinematics of head movement in simulated low-velocity rear-end impacts. Methods: Twenty-nine individuals (17 men and 12 women) were subjected in random order to 3 rear-end impacts: 2 unexpected impacts (chair accelerations of 4.5 m/s2 and 10.1 m/s2) and 1 expected impact (chair acceleration of 10.1 m/s2). The EMG activity of the deep and superficial masseter muscle was recorded bilaterally. EMG activity was also recorded for the left anterior temporalis muscle. Angular acceleration and angular displacement of the head were also recorded. The temporal relationship between onset of the masticatory muscle activity and maximum peak of the kinematics of head movement was determined. Results: The magnitude of normalized masticatory EMG activity ranged from 1.4 to 1.8 times higher (P .05) for fast unexpected impacts compared to slow unexpected impacts in all masticatory muscles. The magnitude of normalized anterior temporalis EMG peak response ranged from 1.8 to 2.5 times higher (P .05) in female subjects than in male subjects for all impacts. No significant differences were identified for impact awareness in the magnitude of normalized EMG activity for any masticatory muscle. No significant differences were identified with respect to timing of masticatory muscle response (P > .05). Conclusion: EMG activity increased with increased impact magnitude. Temporal and amplitude awareness of a simulated impact did not produce a difference in the masticatory muscle response. Gender differences were identified in the anterior temporalis muscle response. The onset of the masticatory muscle response occurred after peak angular acceleration of the head but prior to peak angular displacement of the head. Keywords: electromyography, kinematics of head movement, masseter muscle, temporalis muscle, whiplash

Aims: To study the age- and gender-related prevalence of signs of temporomandibular disorders (TMD) in the Finnish adult population. Methods: A clinical health examination was performed as a part of a Health 2000 Health Examination Survey in 2000 and 2001. A nationally representative sample included 8,028 Finns at least 30 years of age, of whom 79% participated also in an oral health investigation, including examination of the stomatognathic system in order to assess the presence of certain TMD signs: maximum interincisal distance 40 mm, pain in temporomandibular joints or masticatory muscles, and sounds in temporomandibular joints (crepitation, clicking). Results: Thirty-eight percent of the subjects had at least 1 sign of TMD. All the signs studied were more common in women than men. Overall, signs of TMD were also associated with age; the older the subject, the higher the prevalence of the TMD signs. However, when stratified by gender, the association with age was not as clear, and gender differences were observed in the prevalence of the single TMD signs at different ages. Conclusion: Signs of TMD may be more common among the elderly than is usually reported. Keywords: age, gender, prevalence, temporomandibular disorders

Aims: To estimate the prevalence and pattern of self-reported orofacial pain symptoms and treatment-seeking behavior in adult Cantonese-speaking Chinese people in Hong Kong. Methods: A cross-sectional population survey involving a telephone survey technique was used to identify 1,222 randomly selected Cantonese-speaking people aged at least 18 years. Standard questions were asked on the experience of 8 orofacial pain symptoms in the previous month and on treatment-seeking behavior. Results: Orofacial pain symptoms were reported by 41.6% of respondents when tooth sensitivity was included and by 24.2% when it was excluded. There was no gender- or age-related difference in pain prevalence (P > .010). Tooth sensitivity was the most common symptom (27.7%), followed by toothache (12.5%), and shooting pain in the face was the least common (1.1%). Almost half those with symptoms reported the pain as moderate to severe, and a fifth had frequent pain. Only 20.3% with pain symptoms sought professional treatment, and use of self-prescribed medication was very low (12.4%). Conclusion: Orofacial pain symptoms appear to affect more than a quarter of the adult population in Hong Kong, and prevalence estimates were consistent with those in Western countries. A substantial proportion of the pain symptoms were frequent and of moderate to severe intensity, with the potential for significant morbidity. Professional treatment seeking was very low and may be related to specific pain behaviors and effective coping strategies in this ethnic group. Keywords: epidemiology, orofacial, pain, prevalence, treatment seeking

Aims: To use a qualitative research study to analyze the experiences of patients with nonspecific chronic orofacial pain with respect to consultations for their pain condition. Methods: Fourteen patients (11 women and 3 men; age range, 21 to 77 years) were strategically selected through a purposive sampling of the chronic orofacial pain patients referred to the Orofacial Pain Unit at the Faculty of Odontology, Malmö University, Malmö, Sweden. A qualitative research strategy based on phenomenological philosophy was chosen. Thematic in-depth interviews were conducted twice with each patient in order to expose the context of the orofacial pain condition. The interviews were audiotaped and transcribed verbatim. The text material was analyzed to determine the attitude of the patients concerning their experience from the consultations. Results: All selected patients consented to participate. The patients expressed dissatisfaction with the consultations and related many examples of poor communication and understanding. The patients also felt a great need to be taken care of and expressed contradictory statements concerning pain improvement. Conclusion: The results suggest that the communication between the patients and the care providers was unsatisfactory and that the patients were limited in their ability to develop a personal coping strategy. Keywords: attitude, communication, consultation, orofacial pain, qualitative study

Aims: To determine the efficacy of amitriptyline and the optimal dosage for treating a somatoform pain disorder in the orofacial region. Methods: Thirty outpatients with orofacial pain who fulfilled the criteria of pain disorder were recruited for the study. Twenty-three patients had specific precipitating events in their past history, which they considered to be the origin of the pain. Amitriptyline was administered and the dose was gradually increased up to a daily dose of 250 mg. The response to treatment was evaluated using a numeric rating scale and the Clinical Global Impression Scales. Results: Five patients dropped out and 25 patients (83%) completed the trial. Twenty-two patients became pain free or nearly pain free, while 3 patients who also completed the study did not respond at all, even though they took a daily dose of 250 mg amitriptyline. For responders, the mean daily dose of amitriptyline was 77.5 ± 51.5 mg (range, 10 to 200 mg). Four patients (16%) obtained pain relief with a daily dose of less than 50 mg, while 3 patients (12%) needed a daily dose of 150 mg or more for pain relief. Adverse side effects were observed in 19 patients. Conclusion: Amitriptyline was effective in relieving pain associated with a somatoform pain disorder in the orofacial region. The dose of amitriptyline may need to be as high as that used to treat a major depression. Keywords: orofacial pain, pain disorders, amitriptyline, tricyclic antidepressants (TCAs), precipitating event

Aims: To investigate whether exogenously administered 5-hydroxy-tryptamine (5-HT) at high or low concentration influences pain and microcirculation in the human masseter muscle. Methods: In 12 healthy female subjects, 5-HT in 2 concentrations (0.1 µmol/L and 1,000 µmol/L) and isotonic saline were injected into the masseter muscles in a randomized and balanced double-blind manner. The pain intensity after injections was recorded with Borg's rating scale, and intramuscular blood flow was monitored continuously during the experiment with a laser-Doppler technique. Nonparametric statistics were used for analyses. Results: Administration of 5-HT at 1,000 µmol/L induced significantly more pain than saline (Wilcoxon: P .05), while there was no difference between 5-HT at 0.1 µmol/L and saline. The blood flow did not change significantly after injection of 5-HT at either concentration compared to saline. However, changes in pain intensity and blood flow were positively correlated after injection of 5-HT at 1,000 µmol/L (Spearman: P .05). Conclusion: Intramuscular administration of 5-HT at 1,000 µmol/L into the human masseter muscle induced pain, but 5-HT did not have any effect on local blood flow at either concentration. Keywords: ischemia, laser-Doppler flowmetry, masseter muscle, pain, serotonin