Journal of Oral & Facial Pain and Headache, 03/2003

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 (eg, 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. Keywords: bruxism, micro-arousal, orofacial sensory system, occlusion, rhythmic masticatory muscle activity, sleep, trigeminal reflexes

Aims: To test the hypothesis that there would be no differences in perceived pain intensity and spread and referral of pain evoked by injection of a similar amount of hypertonic saline into 6 different jaw-muscle sites in healthy female subjects. Methods: A total of 15 healthy women participated in 3 experimental sessions separated by 1 week. In a randomized sequence, the deep layers of the masseter, superficial layers of the masseter, anterior temporalis, lateral pterygoid, medial pterygoid, and anterior digastric muscles were injected with 5.8% hypertonic saline (0.2 mL). The subjects rated the perceived intensity of pain on an electronic 0- to 10-cm visual analog scale (VAS). The distribution of pain was drawn by the subjects on anatomical maps of the face, and a Danish version of the McGill Pain Questionnaire (MPQ) was filled out. Results: All injections were associated with moderate to strong pain intensity (mean peak value: 5.6 to 6.4 cm) with no significant differences between muscle sites (analysis of variance [ANOVA]: P = .520). Pain rating indices derived from the MPQ did not suggest significant differences between muscle sites (ANOVA: P = .898). However, the area of perceived pain differed significantly between muscle sites (ANOVA: P = .038) with the greatest area following the injection into the anterior temporalis muscle (Tukey: P .05). On direct inspection, the pain maps appeared quite similar, but a new analysis technique based on a center-of-gravity method revealed significantly different coordinates and length of vectors (ANOVA: P .001) with longer vectors associated with the pain areas in the anterior temporalis muscle compared with the other muscle sites (Tukey: P .05). All muscles were frequently associated with referral of pain to intraoral structures (40% to 87%), but only pain in the anterior digastric muscle was referred to the tip of the tongue (53%). Conclusion: The data suggest no major differences in pain sensitivity between the examined jaw-muscle sites, but pain in the anterior temporalis muscle spreads to a larger area independent of pain intensity. There are subtle but detectable differences in the location and referral of pain patterns between jaw muscles. This will be helpful in the differential diagnosis of myofascial temporomandibular disorder pain. Keywords: jaw-muscle physiology, pain assessment, referred pain, temporomandibular disorder

Aims: Despite many reports about complementary and alternative medicine (CAM) use in the general population, little information exists about specific CAM therapies used for particular health conditions. This study examines the use of CAM therapies among patients with temporomandibular disorders (TMD). Methods: We surveyed 192 patients with documented TMD as part of a larger project on the effectiveness of various CAM modalities for TMD patients. The survey asked about use of and attitudes toward specific CAM therapies for treating TMD and other patient-identified health conditions. The survey also measured physical health, health behavior, and psychosocial functioning. Results: Nearly two thirds of the respondents (62.5%; n = 120) reported using CAM therapies for TMD or a related condition. Of all the therapies reported, massage was rated as the most frequent and among the most satisfactory and helpful. In general, respondents who used CAM for their TMD reported being most satisfied with the "hands on" CAM therapies (massage, acupuncture, and chiropractic care). The vast majority of respondents reported using CAM approaches for TMD simultaneously with conventional care (95.6%; 66 of 69). Those using CAM for TMD tended to be older, had a history of multiple medical problems, and reported more positive psychologic functioning. Respondents who most often reported CAM treatment as "very helpful" for their TMD were likely to be healthier (ie, reporting higher levels of exercise and fewer sleep disturbances). Conclusion: Given the frequent use of CAM treatments by our respondents, allopathic providers should inquire about the adjunctive use of CAM among their TMD patients. Keywords: complementary and alternative medicine, temporomandibular disorders treatment

Aims: To compare the efficacy and safety of diclofenac-K (12.5 mg) vs paracetamol (500 mg) and placebo given in a flexible dosage regimen to treat pain resulting from extraction of impacted third molar teeth. Methods: This was a 2-day, double-blind, double- dummy, randomized, parallel-group, placebo-controlled study of diclofenac-K (12.5 mg) tablets vs paracetamol (500 mg) tablets and placebo in patients with moderate or severe pain within 8 hours of extraction of impacted third molars. Results: After the first 2-tablet dose, patients took on average 2.5 additional tablets of diclofenac-K or 2.4 tablets of paracetamol, almost all as 1- tablet doses. Most placebo patients discontinued by taking rescue medication (ibuprofen 200 mg) on the first day. Pain relief after the initial dose of diclofenac-K (2 x 12.5 mg) was superior to placebo (P .01 for all efficacy outcomes) and comparable to paracetamol (2 x 500 mg). About 30% of patients in each active treatment group took rescue medication during the study, compared to 78% on placebo. About 70% in each active treatment group considered the overall pain relief to be "some," "a lot," or "complete" compared to only 15% on placebo. The incidence of adverse events in each active treatment group was low and comparable between the treatments. Conclusion: An initial double-dose of diclofenac-K (2 x 12.5 mg) or paracetamol (2 x 500 mg) adequately relieved the most intense postoperative pain, and the flexible multiple dose regimen (1 or 2 tablets) maintained adequate pain relief thereafter. Most patients needed only 1-tablet doses following the initial 2-tablet dose. Keywords: diclofenac, paracetamol, dental pain, flexible dosage regimen, analgesia

Aims: To investigate the levels of the capsaicin or vanilloid receptor- 1 (VR1) and the ATP-gated purinoceptor P2X3 in painful and nonpainful human tooth pulps. Methods: Immunohistochemistry with specific antibodies and image analysis was used to quantify VR1- and P2X3-positive nerve fibers in painful (n = 13) and nonpainful (n = 33) human tooth pulps, and VR1 immunoreactivity was compared with immunoreactivity for the structural neuronal marker peripherin. Results: Strong VR1-like immunoreactivity was documented for the first time in dental pulp neurons. Weaker P2X3-like immunoreactivity was also detected in fewer nerve fibers. The ratio of VR1 to peripherin immunoreactivity was not significantly different between nonpainful and painful tissues (mean ± SE % area of VR1 to peripherin; nonpainful 53.4 ± 4.7%, n = 33; pulpitis 35.1 ± 7.1%, n = 13; P = .07). Conclusion: The presence of VR1 and P2X3 in fibers of human tooth pulp suggest that they may play a role in perception of dental pain, but further studies, including quantitation of their ligands, are necessary to elucidate any role they may play in pathophysiologic states. Keywords: human tooth pulp, P2X3, vanilloid receptor

Aims: To test the effect of glucosamine hydrochloride (glucosamine- HCl) on the proteoglycan (PG) concentration of the articular disc of non-arthritic temporomandibular joints (TMJs) in rabbits. Methods: Twenty-four of 48 New Zealand white 10- to 12-week-old male rabbits (2.2 kg average) were injected with the irritant chymopapain in the knee joint. Both groups of 24 rabbits were divided into 3 groups of 8 animals. The rabbits were fed a control diet or a diet supplemented with glucosamine-HCl incorporated at a level to provide 20 mg/kg (approximating the recommended dose 500 mg/tid/70 kg man) or 100 mg/kg, for 8 weeks. Sulfated glycosaminoglycans (GAGs) were assayed in protease K digests of the TMJ articular disc by dimethylmethylene blue method to quantify PG concentration. The groups were compared with 2-way analysis of variance. Results: Glucosamine-HCl did not cause a significant change in the PG concentration of the TMJ articular disc (P > .8). There was also no detectable effect of chymopapain injection to the knee joint on the TMJ (P > .07) and no interaction between glucosamine-HCl treatment and chymopapain injection (P > .3). Conclusion: Glucosamine-HCl has no effect on PG concentration of the articular disc of non-arthritic TMJ in rabbits. Keywords: glucosamine-HCl, glycosaminoglycans, proteoglycan, rabbit, temporomandibular joint

Temporomandibular disorders can usually be diagnosed on the basis of a thorough history and a comprehensive examination of the patient. Additional diagnostic tests, such as imaging of the temporomandibular joint (TMJ) area, are mandatory and must be flawless in case of atypical findings. The aim of this report is to illustrate pitfalls in clinical reasoning and in imaging procedures in the diagnosis of temporomandibular pain and dysfunction. A case report of a patient with osteocartilaginous exostosis of the mandibular condyle, which was erroneously diagnosed and treated as an internal derangement of the TMJ for half a year, is presented. Keywords: osteocartilaginous exostosis, temporomandibular pain, temporomandibular dysfunction

Facial pain can, on rare occasions, be the presenting symptom of lung cancer. This report describes a patient with non-metastatic lung cancer, which was associated with attacks of debilitating facial pain, presenting as cluster headache. Moreover, 32 reported cases of lung cancer-related facial pain (including the present one) are reviewed, and their clinical features are summarized. The facial pain is almost always unilateral, and is most commonly localized to the ear, the jaws, and the temporal region. The pain is frequently described as severe and aching, and may be continuous or intermittent. Aggravation and expansion of the pain, digital clubbing, increased erythrocyte sedimentation rate, and hypertrophic osteopathy, may contribute to the diagnosis. Referred pain, due to invasion or compression of the vagus nerve, as well as paraneoplastic syndrome secondary to the production of circulating humoral factors by the malignant tumor cells, is implicated in the pathophysiology of facial pain associated with non-metastatic lung cancer. Radiotherapy and tumor resection with vagotomy are very effective in aborting the facial pain. Thus, lung cancer should be included in the differential diagnosis of facial pain that is atypical and/or refractory to treatment. Keywords: cluster headache, facial pain, lung cancer, referred pain, vagus nerve