Journal of Oral & Facial Pain and Headache, 01/2007

Aims: To develop and validate a model in which to assess a loss of function associated with temporomandibular joint (TMJ) inflammation in awake, freely moving rats. Methods: The dependent variable in the model was the time between food rewards (pellets), or interfeeding interval (IFI). IFI was quantified after rats were trained to "bar-press" for food. To validate use of the IFI as a surrogate for temporomandibular disorder (TMD) pain, we determined the impact of several manipulations, including changes in pellet size, the presence and severity of inflammation of the TMJ, masseter muscle, or skin (induced with complete Freund's adjuvant [CFA]), and the influence of preadministration of the non-steroidal anti-inflammatory drug indomethacin (4 mg/kg). Furthermore, in order to determine whether a change in IFI reflected an increase in the time rats spent eating, rats were videotaped, and the amount of time spent eating, grooming, and exploring was analyzed. Results: Inflammation of the TMJ or masseter muscle resulted in significant dose- and pellet size-dependent increases in the IFI. Inflammation of the skin overlying the TMJ had no effect on IFI. Pre-administration of indomethacin reversed the inflammation-induced shift in the IFI. An inflammation-induced increase in IFI was associated with an increase in feeding time. Conclusions: Our model constitutes a relatively fast and sensitive method with which to assess changes in feeding behavior associated with TMJ inflammation. Only 2 days of training are required to obtain a stable baseline IFI. It is possible to detect changes in IFI as small as 40% with 12 rats per group. Keywords: inflammation, nociception, pain, temporomandibular joint disorders

Aims: To evaluate the sensitivity and reproducibility of a multimodal psychophysical technique for the assessment of both spatial and temporal changes in somatosensory function after an infraorbital nerve block. Methods: Sixteen healthy volunteers with a mean (± SD) age of 22.5 ± 3.4 years participated in 2 identical experimental sessions separated by 2 weeks. The subjects rated the perceived intensity of standardized nonpainful tactile, painful pin-prick, warm, and cold stimuli applied to 25 points in 5 3 5 matrices in the infraorbital region of each side. The reproducibility of single points was tested, and a mean difference of 1.4 ± 0.5 was found. A 0-50-100 numerical rating scale (NRS) with 50 denoting "just barely painful" was used. A modified ice hockey mask with adjustable settings was developed as a template to allow stimulation of the same points in the 2 sessions. Assessment of somatosensory function was carried out before the injection (baseline) and after 30 and 60 minutes on both the anesthetized and contralateral (control) side. In addition, the applicability of the psychophysical techniques was tested in pilot experiments in 2 patients before maxillary osteotomy and 3 months afterward. Results: The overall analysis of mean NRS scores, number of points, and center-of-gravity coordinates for all stimulus modalities showed no significant main effects of session. Post-hoc tests for all stimulus modalities demonstrated significantly lower mean NRS scores and significantly more points (hyposensitivity) at 30 and 60 minutes postinjection compared to baseline values on the injection side (Tukey tests: P < .002). In the 2 maxillary osteotomy patients, the psychophysical techniques could successfully be applied, and bilateral hyposensitivity to all stimulus modalities was demonstrated at the 3-month follow-up. Conclusion: The present findings indicate that the psychophysical method is sufficiently reproducible, with no major differences between sessions in healthy subjects. All stimulus modalities demonstrated adequate sensitivity. Furthermore, measurement of points in 5 3 5 matrices allowed a spatial description of somatosensory sensitivity. This method may be valuable for studies on changes in somatosensory sensitivity following trauma or orthognathic surgery on the maxilla. Keywords: local anesthesia, orthognathic surgery, psychophysics, somatosensory sensitivity, trigeminal physiology

Aims: To test in vitro and in vivo the reliability and accuracy of a new algometer, the pressure algometer for palpation (PAP), for measuring pressure pain thresholds (PPTs) and to compare its features with those of a commercially available pressure algometer. Methods: For in vitro accuracy testing, 6 repeated measurements were made at 8 defined test weights from 0.5 to 5 lb. In vivo validity testing compared the PAP to a standard instrument, the hand-held Somedic algometer, at 16 sites including the masticatory muscles, the temporomandibular joints, and the frontalis (as the control site) in 15 temporomandibular disorder (TMD) cases and 15 controls. Intraexaminer reliability was also assessed for both algometers. Results: In vitro reliability was high, with coefficients of variation of < 5% and a single-measurement standard deviation of 2.1 kPa. Accuracy was also high, with PAP measurements correlating with test weights at r = .99 (P < .001). Repeated measures reliability in vivo was high, with intraclass correlation estimates of 0.73 to 0.96 for the PAP and 0.78 to 0.99 for the Somedic algometer. PPT values correlated moderately between the 2 devices (r ranged from 0.38 to 0.66; P ¡Ü .05) and were consistently higher for the PAP at all sites (P < .001). Differences between controls and TMD cases were also significant for both algometers (P < .006). Conclusion: Both the PAP and the Somedic algometer showed high reliability. Concurrent validity was demonstrated by statistically significant correlations between the devices. Both showed equally high capacity for differentiating TMD cases from controls. The PAP yielded significantly higher PPTs than the Somedic algometer. Keywords: algometry, pressure pain threshold, reliability, temporomandibular disorders, validity

Aim: To determine the interexaminer reliability of dynamic and static pain tests in patients with temporomandibular disorders (TMD). Methods: One hundred fifteen consecutive TMD patients participated in the study. At intake, pain on dynamic and static pain tests was scored on a 4-point ordinal scale by 1 of 5 dentists. Pressure was applied to the mandible during mandibular opening, closing, and protrusive movements (dynamic tests) and while the mandible was kept motionless by the patient in an open, closed, or protrusive position (static tests). After this examination, the dynamic and static pain tests were performed a second time by 1 of 2 physical therapists blinded to the outcome of the first examination. Prior to the study, all examiners took part in a yearly training session, while 3 examiners (2 dentists and 1 physical therapist) were trained on a more regular basis. Results: The interexaminer reliability of dynamic and static pain tests ranged from "poor" to "fair to good" (intraclass correlation coefficient [ICC]: 0.29-0.54) but reached the "excellent" level (ICC: 0.34-0.92) when only the data gathered by the more extensively trained examiners were considered. The reliability was higher when the data were analyzed on the 4-point scale as compared to a dichotomized pain scale. Conclusion: The reliability of dynamic and static pain tests for the temporomandibular region is fair to good when rated on an ordinal pain scale. Thorough training of examiners can improve the reliability considerably. Keywords: dynamic and static pain tests, interexaminer reliability, temporomandibular disorders

Aims: To characterize the level of impairment of oral health-related quality of life (OHRQoL) in a temporomandibular disorder (TMD) patient population. Methods: OHRQoL was measured using the German version of the Oral Health Impact Profile (OHIP-G) in a consecutive sample of 416 patients seeking treatment for their complaints in the masticatory muscles and temporomandibular joints and with at least 1 diagnosis according to the German version of the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). The level of impairment of OHRQoL was characterized by the OHIP summary score mean and its 95% confidence interval. OHRQoL was described for each of the 8 RDC/TMD diagnoses (Axis I) and the RDC/TMD Axis II measures (Graded Chronic Pain Scale [GCPS], jaw disability list, depression, and somatization). These findings were compared with the level of impairment of OHRQoL in the adult general population derived from a national sample (n = 2,026). Results: Among the RDC/TMD Axis I measures, all diagnoses were correlated with much higher impacts compared to the normal population (means for all diagnoses were 32.8 to 53.7 versus 15.8 in the general population). All diagnoses had a similar level of impact except for disc displacement with reduction (which had a lower impact). There were larger differences in mean OHIP-G scores among subgroups of RDC/TMD Axis II measures than among subgroups of RDC/TMD Axis I characteristics. The strongest association was with GCPS, with mean OHIP scores of 33.3 for grade I, 48.1 for grade II, 71.7 for grade III, and 88.5 for grade IV. Conclusion: OHRQoL was markedly impaired in TMD patients. The level of OHRQoL varied across diagnostic categories but more across Axis II, ie, the psychosocial axis; the variation was reflected especially in their level of graded chronic pain. Keywords: depression, Graded Chronic Pain Scale, jaw disability, Oral Health Impact Profile, oral health-related quality of life, Research Diagnostic Criteria for Temporomandibular Disorders, somatization, temporomandibular disorders

Aims: To assess the prevalence rates and risk factors of anterior disc displacement with reduction (ADDR) and symptomatic hypermobility in a large sample of children and teenagers. Prevalence rates were also established in samples of young adults and adults. Methods: Children from 7 Dutch primary and secondary schools (n = 1,833) aged 4 to 18 years (mean age ± SD 10.8 ± 3.9 years), 220 dental students aged 19 to 30 years (mean age ± SD 21.9 ± 3.6 years), and 100 dental school employees more than 30 years old (mean age ± SD 43.5 ± 9.8 years) were examined. The presence of ADDR or symptomatic hypermobility was scored using well-defined clinical criteria. For the children only, an additional standardized oral history and clinical examination were performed to assess possible risk factors. Odds ratios (ORs) were calculated with the use of logistic multivariate regression analysis. Results: The prevalence rate of ADDR in at least 1 of the 2 joints increased during childhood and adolescence and stabilized into adulthood at about 26.6%. In children and teenagers, besides age (OR = 1.06 for boys, OR = 1.23 for girls), risk factors for ADDR were a history of orthodontics (OR = 1.57), an increasing overbite (OR = 1.15), and protrusion (OR = 1.12). In children and teenagers, the prevalence rate of symptomatic hypermobility was higher for girls (13.8%) than for boys (8.2%). Besides gender (OR = 2.07), risk factors for symptomatic hypermobility were race (OR = 2.61 for non-Caucasians), masticatory muscle pain (OR = 1.95), and increasing maximum mouth opening (OR = 1.08). Conclusion: In children and teenagers, ADDR and symptomatic hypermobility have different prevalence rates and risk factors. Keywords: anterior disc displacement, prevalence rate, risk factors, symptomatic hypermobility, temporomandibular joint

Aims: To determine orofacial pain (OFP) characteristics, associated disability, and effect on quality of life in elderly community-dwelling Chinese people. Methods: A cross-sectional survey involving elderly people registered with the Family Medicine Unit of the University of Hong Kong served as the sampling frame. Elderly people with recent OFP symptoms and a comparison control group without OFP participated. Standard questions were asked about OFP conditions in the previous month and the Oral Health Impact Profile (OHIP-14), General Health Questionnaire (GHQ-12), and pain-related disability questions were administered prior to a standard clinical examination. Results: Ninety-five people with OFP and 100 people without OFP participated. The median number of pain symptoms per subject was 2.0. Toothache was the most common symptom (58.9%); shooting pain across the face and muscle tenderness were the least common (6.3%). More than half of the pain participants described moderate to severe OFP. The prevalences of patients with neurological/vascular (NV), musculoligamentous/soft tissue (MST), or dentoalveolar (DA) OFP were 35.8%, 33.7%, and 30.5%, respectively. Chronic OFP was common (80%). The mean OHIP-14 summary score was significantly higher in OFP subjects than controls (P < .001) and significantly higher in the MST and DA subgroups than in the NV subgroup (P < .001). GHQ scores of >= 4, indicating greater psychological distress, were more common in OFP subjects than controls (P < .01). Twenty percent of OFP subjects indicated that their conditions interfered with daily life activities, and in 9.9% it affected ability to work. Conclusion: OFP had a substantial detrimental impact on daily life activities, psychological distress level, and quality of life in Chinese elders. MST and DA conditions had the greatest adverse impact on quality of life. Keywords: disability, elderly Chinese, orofacial pain, psychological distress, quality of life