Journal of Oral & Facial Pain and Headache, 04/2020

Aims: To evaluate the influence of self-reported physical activity level on painful mechanical somatosensory profile and psychosocial characteristics. Methods: A total of 90 participants, male and female, were divided into three groups based on the frequency, duration, and intensity of physical activity over the last 3 months. The classification followed a modified criterion of the short version of the International Physical Activity Questionnaire (IPAQ). Mechanical quantitative sensory tests were performed in the region of the anterior temporalis muscle and on the thenar area of the dominant hand, and psychosocial aspects were assessed using questionnaires measuring state and trait anxiety, pain catastrophizing, lifestyle, and quality of life. Results: There was no significant main effect of group on any of the somatosensory variables (F < 0.34 and P > .416). As for psychosocial aspects, the low level of physical activity group had the lowest scores on the lifestyle questionnaire (P < .009). Conclusion: Level of physical activity did not significantly influence mechanical somatosensory thresholds or temporal summation in the orofacial region, and worse quality of life was found in participants reporting a low level of physical activity. Keywords: exercise, face pain, physical activity, quality of life, quantitative sensory testing

Aims: To compare two pain models of myalgic TMD, delayed-onset muscle soreness (DOMS) and injections of nerve growth factor (NGF), in terms of pain-related and motor function outcomes, as well as activity-related temporal summation. Methods: Fifty age- and gender-matched healthy participants were recruited and randomized into one of three groups: to a repeated eccentric contraction task to cause DOMS (n = 20), to receive NGF injections into the masseter muscle (n = 20), or to a control group (n = 10). Mechanical sensitivity of masticatory muscles, chewing parameters, jaw function limitation, maximum bite force, and activity-related temporal summation were assessed at baseline and at days 1, 2, and 7 following the intervention. Results: Compared to baseline, both model groups showed increased mechanical sensitivity, jaw function limitation, pain on chewing, and decreased chewing efficiency, lasting longer in the NGF group than in the DOMS group (P < .05). Furthermore, also compared to baseline, the NGF group showed increased pain on maximum bite and decreased pain-free maximum opening (P < .05). No increases in activity-related temporal summation were shown for any of the model groups when compared to baseline or the control group (P > .05). Conclusion: Both models produced similar painrelated outcomes, with the NGF model having a longer effect. Furthermore, the NGF model showed a more substantial effect on motor function, which was not seen for the DOMS model. Finally, neither of the models were able to provoke activity-related temporal summation of pain. Keywords: experimental pain, mechanical sensitivity, myalgia, temporal summation, trigeminal motor physiology

Aims: To develop the Malay DC/TMD through a formal cross-cultural adaptation (CCA) process for use in non–English speaking populations and to determine the reliability and validity of the Malay Graded Chronic Pain Scale (M-GCPS) and Malay Jaw Functional Limitation Scale (M-JFLS). Methods: The English DC/TMD was translated into the Malay language using the forward-backward translation procedures specified in the INfORM guideline. The initial Malay instrument was pre-tested, and any discrepancies were identified and reconciled before producing the final Malay DC/TMD. Psychometric properties of the M-GCPS and M-JFLS were evaluated using a convenience sample of 252 subjects and were assessed using internal consistency and test-retest reliability, as well as face, content, concurrent, and construct validity testing. Internal consistency was assessed using Cronbach’s alpha, while test-retest reliability was examined using intraclass correlation coefficient (ICC). Concurrent and construct validity of both domains were performed using Spearman ρ correlation test. In addition, construct and discriminant validity were appraised using Kruskal-Wallis and Mann-Whitney U tests, respectively. Results: Cronbach’s alpha values for the M-GCPS and M-JFLS were 0.95 and 0.97, respectively. The ICC was 0.98 for the M-GCPS and 0.99 for M-JFLS. The majority of the tested associations for both domains were found to be statistically significant, with good positive correlations. Conclusion: The M-GCPS and M-JFLS were found to be reproducible and valid. The Malay DC/TMD shows potential for use among Malay-speaking adults. Keywords: cross-cultural adaptation, DC/TMD, Malay language, temporomandibular disorders, translation

Aims: To investigate how estrogen level, dietary loading, and aging affect cartilage structure and the expression of major collagens (types I, II, and X) in rat mandibular condylar cartilage (MCC). Methods: A total of 96 outbred Sprague Dawley female rats were randomly divided into two groups by ovariectomy (OVX) at 7 weeks old. One week later, the rats in each group were further divided into three subgroups on the basis of food hardness: hard food (diet board), normal food (pellet), and soft food (powder). The rats were sacrificed at the age of 5 or 14 months. The thickness of the fibrous, proliferative, and chondroblastic layers of the mandibular condylar cartilage were measured after toluidine blue staining. Immunohistochemical analysis was performed to evaluate the expression levels of types I, II, and X collagen. A linear regression model was used to investigate the main factors affecting changes in thickness and collagen expression. Results: The expression levels of types II and X collagen were decreased by ovarian estrogen deficiency and increased by dietary loading. Increased dietary loading was the main factor affecting an increase in thickness of the cartilage layers, while aging was the main factor affecting a decrease in thickness of the fibrous layer. A significant age-related increase was found in the expression of type I collagen. There was some degree of interaction between aging and dietary loading that affected the thickness of the chondroblastic layer and the expression of type X collagen. Conclusion: The physiologic level of estrogen plays a role in MCC development by promoting the expression of types II and X collagen. Dietary loading is essential to increase the expression of types II and X collagen, as well as the thickness of cellular layers, to maintain the integrity of the MCC. Aging seems to reduce the ability of the MCC to withstand occlusal loading. Keywords: aging, collagen, dietary loading, estrogen, fibrocartilage, mandibular condylar cartilage

Aims: To evaluate the association between sleep bruxism (SB) and quality of life (QoL) in the general population. Methods: A systematic review was conducted, and studies were included with no restrictions regarding age, gender, or language. SB and general health–related QoL and/or oral health–related QoL (OHRQoL) measures in the included studies needed to be based on validated tools. The databases searched were Google Scholar, LILACS, OpenGrey, ProQuest, PubMed, Science Direct, Scopus, and Web of Science. Quality of evidence was evaluated using the Joanna Briggs Institute critical appraisal checklists and GRADE (Grading of Recommendations Assessment, Development, and Evaluation) criteria. Results: Fourteen studies met the inclusion criteria. Ten studies were published in English, and four in Portuguese. All studies evaluating the association of SB with health-related QoL showed no statistical significance when overall scores were considered. The overall quality of evidence was considered very low due to high heterogeneity among the studies. SB seemed not to be associated with health-related QoL, but did have a negative impact on some characteristics of OHRQoL. Conclusion: There is insufficient scientific evidence to support or disprove the association between SB and QoL/OHRQoL in the general population. Keywords: bruxism, quality of life, sleep bruxism

Aims: To systematically review the literature to assess whether genetic polymorphisms affect orofacial pain sensitivity in healthy individuals and in patients with chronic orofacial pain disorders. Methods: Electronic searches were conducted to identify observational studies and clinical trials investigating the association between genetic polymorphisms and orofacial pain sensitivity in healthy individuals and/or patients with chronic orofacial pain disorders. Searches were carried out in PubMed, Embase, and Scopus databases using Medical Subject Headings and free terms. Results: Seven studies fulfilled the eligibility criteria: four analyzed healthy subjects, two included chronic orofacial pain patients, and one included samples of healthy subjects and patients with neuropathic pain. The results showed that genes associated with mechanical and thermal pain sensitivity were mostly related to opioid, catecholaminergic, inflammatory, and dopaminergic pathways. Conclusion: Genetic polymorphisms related to opioid, catecholaminergic, inflammatory, and dopaminergic pathways were associated with sensitivity to thermal and pressure stimuli in the orofacial region. Therefore, genetic factors should be taken into account for an accurate interpretation of orofacial pain sensitivity. These results will allow for a better understanding of the etiopathogenesis of chronic pain affecting the orofacial region, and consequently for finding new therapeutic targets. Keywords: chronic pain, genetic polymorphism, orofacial region, pain sensitivity, quantitative sensory testing

Aims: To study the effect and cost-effectiveness of jaw exercise treatment in patients with masticatory myofascial pain. Methods: A total of 97 patients with myofascial pain according to the RDC/TMD were randomized into three groups: (1) jaw exercises; (2) stabilization appliance; or (3) no treatment. After 3 months, the patients were evaluated according to the following instruments: pain intensity according to a visual analog scale (VAS); global improvement according to the Patient Global Impression of Change scale (PGIC); depression and anxiety according to the Hospital Anxiety and Depression Scale (HADS); jaw function according to the Jaw Functional Limitation Scale (JFLS-20); consumption of analgesics; and frequency of tension-type headache. Results: Pain intensity during jaw movement decreased significantly more in the jaw exercise group compared to the no treatment group (P < .001). There was no statistically significant difference between the jaw exercise and stabilization appliance groups in this aspect. The patients in the treatment groups reported greater improvement on the PGIC compared to the no treatment group (P < .001). There was a significant decrease in headache frequency (P = .028), consumption of analgesics (P = .007), and JFLS scores (P = .008) in the jaw exercise group compared to the no treatment group. In the jaw exercise group, patients had fewer appointments and a lower mean treatment time compared to the group that received stabilization appliance treatment. Conclusion: Jaw exercises are effective in reducing pain intensity, headache, and consumption of analgesics in patients with masticatory myofascial pain. Jaw exercises are also cost-effective when compared to treatment with a stabilization appliance. Keywords: dentistry, exercise, facial pain, physical therapy modalities, temporomandibular joint dysfunction syndrome

Recurrent painful ophthalmoplegic neuropathy (RPON) is a very rare disease characterized by recurrent attacks (at least two) of unilateral headache associated with ipsilateral ophthalmoplegia due to paresis of one or more cranial motor nerves, not due to any orbital, parasellar, or posterior fossa lesions. The differential diagnoses for this condition are broad. In addition to disability during an acute attack, this disease could also cause a permanent neurologic deficit. The understanding of RPON pathogenesis has changed over time, leading to a change in the classification of this disorder between editions of the International Classification of Headache Disorders, in which the condition was moved from the chapter on migraine to the chapter on cranial neuralgias and central causes of facial pain. There is no consensus on the pathogenesis of RPON. It is possible that multiple pathogenic mechanisms underlie various clinical forms of the disease. A depiction of pathologic analyses of patients with radiologically confirmed changes in the affected nerves during and outside of attacks would significantly contribute to knowledge of its pathogenesis. Brain imaging should be performed in each patient during an acute RPON attack and at a regular schedule between attacks. Further case reports and case series are required before further conclusions can be made regarding RPON pathogenesis and proposals for treatment options. Keywords: headache, migraine, neuropathy, ophthalmoplegia, painful ophthalmoplegic neuropathy, pathogenesis, RPON

Aims: To assess the prevalence of catastrophizing in patients with temporomandibular disorders (TMD) and the possible associations between catastrophizing and treatment outcome. Methods: This review was registered in the Prospero database (CRD42018114233). Electronic searches were performed in PubMed, Scopus, and PsycINFO from the inception of each database up to October 26, 2018, and were combined with a hand search. Articles focusing on levels of catastrophizing and how catastrophizing affects pain levels and treatment outcomes for patients diagnosed with TMD were included, as well as studies reporting how treatment outcomes were affected by cognitive behavioral treatment as an addition to standard treatment for TMD. Reviews and case reports were excluded. Risk of bias was assessed with the Newcastle-Ottawa scale. Results: The literature search identified 266 articles. After screening of abstracts, the full texts of 59 articles were assessed. Of these, 37 articles, including 4,789 patients with TMD and 6,617 controls, met the inclusion criteria. Higher levels of pain catastrophizing were reported in patients with TMD, with a large effect size (Hedges’ g = 0.86) compared to pain-free controls. Furthermore, associations of higher levels of catastrophizing with higher symptom severity and with poorer treatment outcome were reported together with indications of positive effects from cognitive behavioral therapy. Conclusion: The results suggest an association between catastrophizing and TMD that may affect not only symptom severity but also treatment outcome. Assessing levels of pain catastrophizing might therefore be valuable in the assessment and management of patients with TMD. Keywords: catastrophizing, cognitive behavioral therapy, pain, temporomandibular disorders, treatment outcome

Aims: To investigate inflammatory mediator levels in TMJ synovial fluid (SF) and blood and to investigate clinical TMJ symptoms in relation to general and TMJ symptom duration in patients with rheumatoid arthritis (RA). Methods: Examination of 80 TMJs (68 patients; median age 55 years; 85% women) included the following variables: TMJ pain at rest, maximum mouth opening, and palpation; jaw movement capacity; number of painful movements; crepitus; and degree of anterior open bite. Levels of tumor necrosis factor (TNF), TNF soluble receptor II, interleukin 1β, IL-1 receptor antagonist, IL-1 soluble receptor II, and serotonin in TMJ SF and blood; systemic disease activity; and duration of general and TMJ symptoms were assessed. General symptom duration ≤ 2 years was considered early RA. Results: TMJ symptoms predominantly developed within 5 years following general symptom onset. Logistic regression analysis showed that number of involved joints, general pain, maximum mouth opening, anterior open bite, and TNF plasma levels combined explained 46% of the distinction between early and established RA. Furthermore, TMJ pain at rest and maximum mouth opening, contralateral laterotrusion, painful movements, crepitus, and SF TNF levels combined explained 35% of the distinction. In these analyses, higher general pain and maximum mouth opening, TMJ pain on maximum mouth opening, and crepitus were associated with early RA. Conclusion: This study indicates that TMJ pain and crepitus in RA usually occur within 2 years following general symptom onset. Pain-related dysfunction and structural changes develop with time. TNF in plasma and TMJ SF are associated with this development. This makes early (clinical) recognition of pain and inflammation important, enabling early treatment to minimize later irreversible damage. Keywords: inflammatory mediators, pain, rheumatoid arthritis, synovial fluid, temporomandibular joint