Journal of Oral & Facial Pain and Headache, 02/2019

Aims: To evaluate the effect of nonstrenuous aerobic exercise on chronic masticatory myalgia (CMM) patients and healthy controls (HC) by means of mechanical temporal summation (TS) and response to mechanical stimulation (RMS) performed on the dominant forearm. Methods: A total of 30 patients diagnosed with CMM and 30 pain-free HCs were first evaluated for maximum number of steps (MNS) on a stepper machine for 1 minute. Additionally, they completed the Generalized Anxiety Disorder (GAD-7), Graded Chronic Pain Scale (GCPS), and Jaw Functional Limitation Scale (JFL) questionnaires. On the second visit, RMS, mechanical TS, exercise-induced hypoalgesia (EIH), blood pressure, pulse pressure, and heart rate were assessed prior to and immediately, 5, 15, and 30 minutes following 5 minutes of stepper exercise at 50% MNS. Results: Compared to HCs, CMM patients demonstrated increased mechanical TS and less efficient EIH. Mechanical TS scores were reduced in both groups; however, the HC reduction was more robust and persistent. CMM patients demonstrated a delayed reduction in RMS following exercise in contrast to an immediate reduction in HCs. GAD-7, GCPS, and JFL scores for CMM patients were higher than for HCs and were associated with baseline pain intensity but not with EIH or TS. Conclusion: These findings suggest that, compared to HC, CMM patients' pain modulation is both suppressed and has a different effect duration and timing pattern. Further research should explore the mechanisms and clinical relevance of the delayed hypoalgesia and the inhibitory effect on TS induced by nonstrenuous aerobic exercise in CMM patients. Keywords: exercise, masticatory myalgia, myofascial pain, pain modulation, temporomandibular disorders

Aims: To deepen knowledge of the impact of iatrogenic trigeminal nerve injury on dental patients. Methods: One-to-one semi-structured interviews and workshops were conducted with 12 patients who had incurred a nerve injury from dental treatment. Nerve injury was diagnosed by oral surgeons via a series of neurosensory tests. Interpretive phenomenologic analysis was used to analyze the narratives from the interviews. Results: Key themes are presented and discussed. These include the personal impact for the patient (which includes a change in self-perception), the impact on relationships, the impact on oral health care, and adjustment to the injury over time. Patients also discussed a change in how they perceived their dentist and other health care professionals and highlighted factors they would like to change within the dental care system. Conclusion: Recommendations are made for clinical practice and future research. Keywords: informed consent, mental health, oral health, qualitative, trigeminal nerve injury

Aims: To examine the analgesic effect, safety, and tolerability of intraoral administration of onabotulinum toxin A (BoNT/A) in patients suffering from intractable continuous dentoalveolar neuropathic pain. Methods: Eight patients (six women and two men) of ages ranging from 21 to 73 years (mean [standard deviation] 52.4 [16.1] years) suffering from continuous dentoalveolar pain for a mean duration of 5.8 (4.4) years received a submucosal injection of 10 to 25 units of BoNT/A into the vestibular mucosa surrounding the painful site. Pain intensity levels were recorded using a verbal rating scale (VRS). Safety and tolerability of BoNT/A were measured based on patient self-report, including any adverse effects reported by the patient at the injection site. Results: Five of eight patients reported positive pain reduction. In this group, mean pain intensity on a 0-10 VAS was 4.8 (2.2) at baseline and 2.6 (2.1) at postinjection. The analgesic effect was maximal between 7 and 14 days postinjection and lasted for 1 to 8 weeks before subsequently returning to the pre-injection levels. No adverse effects were reported at the injection sites. One patient noted transient partial hemifacial paralysis. Conclusion: These results suggest the potential therapeutic benefit of BoNT/A in the management of continuous dentoalveolar neuropathic pain. Further investigations conducted via well-controlled studies in the area of orofacial pain are warranted. Keywords: chronic pain, continuous neuropathic pain, dentoalveolar neuropathic pain, onabotulinum toxin A, orofacial pain

Aims: To evaluate the efficacy of sucrose in the prevention of migraine attacks. Methods: Two randomized double-blinded pilot trials were conducted, one in college students and one in adults. Migraineurs were randomized into two groups that each received an oral liquid: for students, sucrose 5 g/day (s-group; n = 12) or glucose 2.5 g/day (g-group; n = 10) for 3 months; and for adults, sucrose 5 g/day (s-group; n = 10) or fructose 2.5 g/day (f-group; n = 9) for 6 months. The primary endpoint was the frequency of migraine attacks per month, and the secondary endpoints were mean duration and severity of migraine per attack. Continuous measurements were described as mean ± standard deviation (SD). The overall significance of the effects between different groups was tested using repeated measures analysis of variance (RANOVA), and the efficacy was evaluated using an intent-to-treat analysis. Results: Migraine frequency in the students declined significantly in the g-group (mean reduction ± SD: 0.65 ± 0.71; P .01), but not in the s-group (0.33 ± 2.02; P = .58). RANOVA results suggested that the secondary endpoints significantly declined over time (all P .01) with no differences between the groups. In the adult trial, mixed-effects model analysis showed that both the primary and secondary endpoints significantly declined over time with no significant differences between the groups. Conclusion: Long-term consumption of a 5-g dose of sucrose for adult migraineurs or a 2.5-g dose of glucose for college student migraineurs may be as effective as preventive treatments. Keywords: migraine, prevention, sucrose

Aims: To determine whether patients with painful myofascial temporomandibular disorders (TMD) demonstrate facilitated temporal summation (TS) responses to painful heat stimuli applied to the painful trigeminal and extratrigeminal regions and whether there is a side difference in the trigeminal region for myofascial TMD pain patients compared to healthy controls. Methods: Twenty female Chinese myofascial TMD pain patients and 20 age-matched female volunteers participated in this case-control study. Thermal detection thresholds, thermal pain thresholds, and TS of 20 repetitive noxious thermal stimuli were measured on the skin above the masseter muscle on both sides and the thenar eminence of the less painful side/dominant hand. Numeric rating scale (NRS) scores of pain were provided after the 1st, 5th, 10th, 15th, and 20th stimuli, and TS was calculated as the highest NRS score minus the first NRS score in each test. Results: Evidence of TS was found in the trigeminal and extratrigeminal regions for both groups, but with facilitated TS responses in myofascial TMD pain patients (P .001). Within the myofascial TMD group and control group, there were no side-to-side differences (P > .289). Interestingly, the repetition of the TS test was associated with facilitated responses in myofascial TMD pain patients (P .001). Conclusion: The current findings suggest TS of painful heat stimulation is facilitated in myofascial TMD pain patients with no side difference in the trigeminal region. Keywords: hyperalgesia, myofascial pain, temporal summation, temporomandibular disorders, thermal detection

Aims: To evaluate the effectiveness of local anesthetic trigger point injections in adults with myofascial pain syndrome (MPS) in the head, neck, and shoulder regions compared to dry needling, placebo, and other interventions. Methods: Randomized controlled trials using local anesthetic injections in adults diagnosed with MPS were included. The Cochrane Library, MEDLINE via PubMed, Web of Science, and EMBASE libraries were searched. The primary outcome was pain measured with a 0 to 10 visual analog scale (VAS). Secondary outcomes included pain threshold, range of cervical motion, depression scale, and pressure pain intensity (PPI) score. Risk of bias was analyzed based on Cochrane's handbook. Results: The initial search strategy yielded 324 unduplicated references up to April 1, 2018. A total of 15 RCTs were included, with 884 adult patients diagnosed with MPS. Meta-analysis showed a significant improvement in VAS pain scale of 1.585 units at 1 to 4 weeks in the local anesthetic group compared to the dry needling group (95% confidence interval -2.926 to -.245; P = .020). However, when only including double-blinded studies, the effect was not statistically significant (P = .331). There was also a significant improvement in pain of 0.767 units with local anesthetic at 2 to 8 weeks compared to placebo (95% confidence interval -1.324 to -0.210; P = .007). No statistically significant differences were found in other secondary outcomes between local anesthetic and all other interventions. Conclusion: Though local anesthetics provided a significant improvement in pain compared to dry needling, evidence was of low quality, and sensitivity analyses including only double-blinded studies provided no statistically significant difference. Additional studies are needed to confirm these results. Keywords: dry needling, local anesthetic, meta-analysis, myofascial pain, myofascial trigger points, systematic review, visual analog scale

Aims: To assess the correlation between tooth wear and sleep-time masseter muscle activity (sMMA) in a group of healthy young adults who underwent home electromyographic/electrocardiographic (EMG/ECG) recordings with a portable device. Methods: A total of 41 healthy volunteers (23 women, 18 men; mean age 28.8 years, range 25 to 40) with good natural dentition underwent a 2-night in-home evaluation with a portable device that allowed a simultaneous sleep-time recording of EMG signals from both masseter muscles and heart rate. The number of sleep bruxism (SB) episodes per sleep hour (SB index), the number of phasic, tonic, and mixed sMMA events per hour, and the total number of sMMA events per night were calculated. All individuals also underwent an assessment of tooth wear on digital casts with the adoption of a six-degree rating scale. Correlations between sMMA variables and tooth wear were assessed using Pearson test. The null hypothesis was that correlation between the two conditions would not be significant. Results: On average, the SB index was 4.5 ± 2.6, while the total number of sleep-time masseter contractions was 97.2 ± 55.2. Of those contractions, almost 60% were phasic. Average tooth wear was 1.5 ± 0.7, with the canines and mandibular incisors showing the highest wear scores. For all pairwise analyses, correlation values were not significant (P values .11 to .69), with r values ranging from 0.064 to 0.253. Conclusion: The null hypothesis of an absence of correlation between tooth wear and sMMA could not be rejected, implying that tooth wear cannot be used as an indicator of ongoing SB or sMMA. Future studies taking into account the multifaceted nature of tooth wear and the complex natural course of sleep phenomena are encouraged to investigate the issue further, at the individual level. Keywords: electromyography, masticatory muscles activity, sleep bruxism, tooth wear

Aims: To investigate the relationships between three pain parameters (duration, intensity, and frequency), the number of pain sites and comorbidities, and the risk of having coexisting pain and/or comorbidities in patients with temporomandibular disorder (TMD) pain. Methods: The sample consisted of 198 outpatients attending the Dental Hospital of Chulalongkorn University. TMD pain was determined using the Diagnostic Criteria for TMD. Pain lasting 3 months or longer was defined as chronic pain. Pain intensity was reflected using a 0- to 10-point numeric rating scale, and pain frequency was assessed with the percentage of pain days over a 2-week period. The number of pain sites was evaluated using the Widespread Pain Index. The presence of comorbidities was assessed with a validated diagnostic questionnaire. The associations were analyzed using Spearman rho test, multiple linear regression, and logistic regression, with a significance level of P ≤ .05. Age and gender were analyzed as confounders. Results: The number of pain sites was related to pain duration, pain intensity, and age. The number of comorbidities was associated with pain duration. Neither pain frequency nor gender were related to the number of pain sites or comorbidities. When the pain duration reached 1 month, patients had a 1.045-times higher probability of pain beyond the orofacial area (odds ratio [OR] = 1.045; 95% confidence interval [CI] = 1.024 to 1.066; P = .001) and a 1.028-times higher probability of comorbidities (OR = 1.028; 95% CI = 1.005 to 1.05; P = .008). For an increase of 1 score on the numeric rating scale, patients had a 1.206-times higher probability of pain presence beyond the orofacial area (OR = 1.206; 95% CI = 1.068 to 1.344; P = .026). Conclusion: High pain intensity and long pain duration increase the probability of having coexisting pain and comorbidities in TMD pain patients. Keywords: comorbidities, pain parameters, questionnaires, regression analysis, TMD pain

Aims: To assess jaw pain shortly after whiplash trauma in relation to neck pain, physical symptoms, depression, and jaw pain-related disability. Methods: A total of 181 cases (106 women and 75 men, mean ages 33.7 and 36.8 years, respectively) were examined within 1 month after a whiplash trauma and compared to 117 controls (68 women and 49 men, 34.2 and 30.9 years, respectively). Participants rated current jaw and neck pain intensity on a numeric rating scale and rated nonspecific physical symptoms and depression symptoms on subscales of the Symptom Checklist-90-Revised. The nonspecific physical symptoms were further analyzed with and without pain items. Disability related to jaw pain and neck pain was also assessed. Differences between groups were calculated using Mann- Whitney U test, and correlations were measured using Spearman correlation. Results: Compared to controls, cases reported higher current jaw and neck pain intensity (P .0001), together with higher scores for physical nonpain and pain symptoms, depression, and jaw pain-related disability (P .0001 for all). For cases, there were moderate correlations between nonspecific physical symptoms and jaw pain and neck pain, as well as between jaw pain-related disability and jaw pain and neck pain (r = 0.43 to 0.77, P .0001 for all). Low correlations were observed between depression and jaw pain and neck pain (r = 0.34 to 0.39, both P .0001). Conclusion: Shortly after a whiplash trauma, pain in the jaw and neck regions is associated with the severity of psychosocial factors. Thus, psychosocial factors may play a role in the development of pain in the jaw region after whiplash trauma. Keywords: jaw, pain, psychosocial factors, temporomandibular disorders, whiplash injury

Aims: To test whether standardized palpation around the lateral pole of the condyle can influence mechanical sensitivity and unpleasantness and evoke referred sensations/pain in healthy individuals. Methods: Palpometers (0.5, 1.0, and 2.0 kg) with spherical extensions were applied around the lateral pole of the condyle in relaxed and protruded positions of the mandible for 2, 5, and 10 seconds in 30 healthy participants. Mechanical sensitivity, unpleasantness, and referred sensations/pain were assessed using a 0 to 100 numeric rating scale (NRS) for each palpation. The NRS scores were compared using analysis of variance and McNemar test. Results: Participants reported significantly higher mechanical sensitivity and unpleasantness scores for the 2.0-kg stimulus compared to the 0.5- and 1.0-kg stimuli for 2, 5, and 10 seconds (mean NRS > 50; P .001). Application of a 1.0-kg stimulus was significantly different from the 0.5- and 2.0-kg stimuli applied for 5 seconds (mean NRS 50; P .001). One-third of participants reported referred sensations/pain. Conclusion: Application of a 2.0-kg stimulus around the lateral pole of the condyle is painful and unpleasant regardless of time of palpation. Application of a 1.0-kg stimulus for 5 seconds was found to be nonpainful and not unpleasant in healthy participants. Thus, this study supports the Diagnostic Criteria for TMD recommendation for standardized examination of the TMJ and indicates that referred sensation/pain is a common finding in healthy individuals. Keywords: DC/TMD, lateral pole of the condyle, mechanical sensitivity, palpation, referred sensation/pain

Aims: To investigate whether acute dental pain due to pulpal or periapical inflammation is associated with increased expression of cortisol and inflammatory markers and mediators in the saliva, as well as changes in salivary flow rate. Methods: Patients experiencing pain (n = 42) were recruited when seeking emergency dental treatment. A 0 to 10 numeric rating scale (NRS) was used as a measure of the severity of pain, and the number of days with pain sensation was also recorded. Unstimulated saliva was collected for 3 minutes (salivary flow measured in mL/minute) and stored at -80°C. Saliva was analyzed for the biomarkers cortisol, C-reactive protein (CRP), and cytokines interleukin-1β (IL-1β) and interleukin-6. In addition, the participants completed a simple questionnaire about stress-inducing factors such as insomnia, dental anxiety, or home/workplace stress. Patients received a dental examination and diagnosis (eg, symptomatic pulpitis/apical periodontitis or acute apical abscess), which was confirmed during dental treatment. The control group (n = 39) consisted of participants without any pain and no known medical or dental problems. Results: Patients experiencing acute pain due to pulpal or periapical inflammation had a mean NRS score of 7.0 ± 2.59. The mean duration of pain was 6.5 ± 7.9 days. There was no significant difference in pain level between male and female subjects, tooth type affected, or diagnosis. Higher levels of cortisol, IL-1β, and IL-6 and increased salivary flow were detected in patients with pain when compared to controls (P .05). CRP was higher in patients with acute pain compared to control participants without pain, but this difference was not statistically significant. Stress at home or the workplace was reported by 79% of patients experiencing pain and by 28% of control participants. Conclusion: Acute dental pain due to pulpal or periapical inflammation was associated with an increase in salivary cortisol, IL-1β, and IL-6 levels and in salivary flow rate. Stress arising from home or the workplace may aggravate a symptomfree pulpal or periapical inflammation to an acute phase. Inflammation in the pulp and periapical region can have effects in regions remote from the disease site. Keywords: cortisol, CRP, dental pulp. endodontic, IL-1β, IL-6, salivary flow rate