Chronic pain in the orofacial region is common worldwide. Pain seems to affect the jaw motor control. Hence, temporomandibular disorders (TMD) are often accompanied by pain upon chewing, restricted mouth opening and impaired maximal bite forces. However, little is known on the effects of pain, in particular the effects of chronic jaw muscle pain on precision biting. The aim of the study was to investigate the effect of chronic and acute jaw muscle pain on oral motor control during precision biting in humans. Eighteen patients with chronic masseter muscle pain and 18 healthy participants completed the experiment. All participants were examined according to the Diagnostic Criteria for TMD. Experimental acute pain was induced by bilateral, simultaneous sterile hypertonic saline infusions into the healthy masseter muscles. A standardized hold and split biting task was used to assess the precision biting. The data was analyzed with non-parametric statistical tests. The results showed no significant differences in the hold forces, split forces, durations of split or peak split rates within or between the pain and pain-free conditions. The mean split rate increased significantly compared to baseline values both in the chronic patients and the pain-free condition. However, this increase was not evident in the experimental acute pain condition. Further, there were no significant differences in the mean split rates between the conditions. The data suggest that jaw muscle pain does not seem to alter precision biting in humans, however, the possibility that a nociceptive modulation of spindle afferent activity might have occurred but compensated for cannot be ruled out.

Background and purpose This case of a 42 year old woman with lower extremity Complex Regional Pain Syndrome (CRPS) after a twisting injury of the ankle, effectively treated with the addition of mirror therapy to a rehabilitation programme, prompted a literature review of both CRPS and mirror therapy. Mirror therapy is a newer adjunct to other forms of pain control and functional restoration for treatment of CRPS as well as other difficult clinical problems. This was a required group project as part of a university based course in chronic pain for healthcare workers. Materials and methods The PubMed database up to September 26,2012 was reviewed using four search word groups: "CRPS mirror therapy", "mirror CRPS", "reflex sympathetic dystrophy OR Complex Regional Pain Syndrome AND mirror" and "reflex sympathetic dystrophy OR Complex Regional Pain Syndrome AND mirror + RCT". Nine studies from PubMed met the criteria that this working group had chosen for inclusion in the analysis of mirror therapy as treatment. These references were supplemented by others on CRPS in order to generate an adequate review of both the syndrome CRPS and mirror therapy itself. Some references were specific for mirror therapy in the treatment of CRPS but others described mirror therapy for the treatment of phantom limb pain, brachial plexus avulsion pain, for physical rehabilitation of stroke related paresis and for rehabilitation after hand surgery. Results Criteria for the diagnosis of CRPS including the International Association for the Study of Pain criteria and the Budapest criteria are reviewed with an emphasis on the specificity and sensitivity of the various criteria for clinical and research purposes. The signs and symptoms of CRPS are a part of the criteria review. The main treatment strategy for CRPS is physical rehabilitation for return of function and mirror therapy is one of many possible strategies to aid in this goal. The patient in this case report had failed many of the adjunctive therapies and rehabilitation had been unsuccessful until the addition of mirror therapy. She then could progress with physical rehabilitation and return to a more normal life. Mirror therapy techniques are briefly described as part of a discussion of its success with relationship to signs and symptoms as well as to the duration of CRPS (and other syndromes). Some discussion of the theories of the central effects of both CRPS and phantom limb pain and how these are affected by mirror therapy is included. An analysis of the 9 most relevant articles plus a critique of each is present in table form for review. Conclusions There appears to be a clear indication for the use of mirror therapy to be included in the multidisciplinary treatment of CRPS types 1 and 2 with a positive effect on both pain and motor function. There is also evidence that mirror therapy can be helpful in other painful conditions such as post stroke pain and phantom limb pain. Implications CRPS is often overlooked as an explanation for obscure pain problems. Prompt diagnosis is es...

Background: Several studies have reported an association between temporomandibular disorder pain (TMD-P) and emotional disorders in children and adolescents. However, no studies have reported if self-reported TMD-P in Saudi Arabia is associated with psychosocial symptoms. Therefore, the current study aimed to evaluate the association between self-reported TMD-P with depression, anxiety and somatic problems in children and adolescents in Saudi Arabia. The hypothesis was that there is an association between self-reported TMD-P and psychological symptoms among children and adolescents.Materials and Methods: The included participants were randomly selected boys and girls aged between 10 and 18 years, with a mean (SD) age of 14.0 (2.3) years. Out of 633 children and adolescents that were invited to participate, 509 voluntarily agreed to participate, and 466 completed all questionnaires. The questionnaires included items retrieved from the Youth Self Report (YSR) and Axis II of the Research Diagnostic Criteria for TMD (RDC/TMD) besides demographic data, medical history, and presence of oral parafunctions. To assess the presence of self-reported TMD-Pain, each participant was verbally asked two validated questions regarding the presence of TMD-P and dysfunction (2Q-TMD).Results: Self-reported TMD-P in children and adolescents was significantly associated with anxiety, depression, somatic symptoms, and social problems (P < 0.0001). Further, the frequencies of anxiety, depression, and somatic disorders were more evident among children and adolescents who suffered from TMD-P (P < 0.0001). The odds of reporting TMD-P in children and adolescents was 1.4 times for border line and clinical diagnosis scores for anxiety and withdrawal depression domains, and 2.6 times for the somatic symptoms' domains. However, in the multiple regression model after controlling for possible confounders, only somatic symptoms and social scores were significant. Moreover, self-reported TMD-P was twice as prevalent among girls compared to boys.Conclusion: This study reports a significant association between psychosocial burden and presence of self-reported TMD-Pain, with a stronger impact on girls than boys. There were significantly higher number of participants with self-reported TMD-P reporting a poor oral and general health. In addition, self-reported TMD-P was higher among those with borderline and clinically diagnosed anxiety/depression scores. Based on this finding, the current study supports that an early approach and recognition of children and adolescents with anxiety, depression, somatic symptoms, and TMD problems. This could result in a lesser burden for these children and adolescents both in regard to pain and psychosocial implications with increased quality of life.

Background: The study was aiming to optimize excessive gum chewing as an experimental model to induce jaw muscle pain and fatigue similar to those in painful TMDs with durations that would allow immediate investigations of jaw-motor function. Further, if any sex differences would be detected in the expression of pain. Methods: This randomized, double blinded study included 31 healthy participants of both sexes. A standardized chewing protocol of either 40-or 60-min of chewing was used with a wash-out period of 1 week. Subjective fatigue, pain characteristics and functional measures were assessed. For statistical analyses, Wilcoxon Signed Rank test, Mann-Whitney Rank Sum test and Friedman's ANOVA with Tukey post-hoc test were used. Results: High subjective fatigue scores that lasted up to 20 min after the end of the trial were significantly induced both in the 40-and 60-min chewing trials (P < 0.001*). Significant but mild pain was induced only in the 60-min trial (P = 0.004*) and only in men (P = 0.04*). Also, the induced pain area was significantly bigger in the 60-min trial (P = 0.009*). However, this increase in pain and pain area did not last to the first 10-min follow-up. There were no significant differences neither between the 40-and 60-min chewing trials, except regarding the pain area (P = 0.008*), nor between the sexes. Conclusion: Taken together, excessive chewing in its current form does not seem to be a proper pain experimental model. The model needs further adjustments in order to mimic TMD-pain especially in women and to prolong the pain duration.

Abstract Background: The study was aiming to optimize excessive gum chewing as an experimental model to induce jaw muscle pain and fatigue similar to those in painful TMDs with durations that would allow immediate investigations of jaw-motor function. Further, if any sex differences would be detected in the expression of pain. Methods: This randomized, double blinded study included 31 healthy participants of both sexes. A standardized chewing protocol of either 40- or 60-minutes of chewing was used with a wash-out period of one week. Subjective fatigue, pain characteristics and functional measures were assessed. For statistical analyses, Wilcoxon Signed Rank test, Mann–Whitney Rank Sum test and Friedman’s ANOVA with Tukey post-hoc test were used. Results: High subjective fatigue scores that lasted up to 20 minutes after the end of the trial were significantly induced both in the 40- and 60-minute chewing trials (P<0.001*). Significant but mild pain was induced only in the 60-minute trial (P=0.004*) and only in men (P=0.04*). Also, the induced pain area was significantly bigger in the 60-minute trial (P=0.009*). However, this increase in pain and pain area did not last to the first 10-minute follow-up. There were no significant differences neither between the 40- and 60-minute chewing trials, except regarding the pain area (P=0.008*), nor between the sexes. Conclusion: Taken together, excessive chewing in its current form does not seem to be a proper pain experimental model. The model needs further adjustments in order to mimic TMD-pain especially in women and to prolong the pain duration.