Abstract
Aims
The purpose of this study was to assess the biopsychosocial factors associated with acute temporomandibular joint disorders (TMD) based upon the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD).
Methods
Participants were assessed in community-based dental clinics, and evaluated by trained clinicians on physical and psychosocial measures. A total of 207 subjects were evaluated. Patients’ high-risk versus low-risk status for potentially developing chronic TMD was also determined. Analyses of variance and chi square analyses were applied to these data.
Results
Participants’ characteristic pain intensity differed among RDC/TMD Axis I diagnoses. They also significantly varied in their: self-reported graded chronic pain; depression; somatization, pain inclusive; somatization, pain excluded, and physical well-being. In addition, participants with differing RDC/TMD Axis I diagnoses varied in self-reported pain during their chewing performance. Finally, there were also significant differences in chewing performance between high-risk vs. low-risk (for developing chronic TMD) patients.
Conclusions
Participants with multiple diagnoses reported higher pain, as well as other symptoms, relative to participants without a TMD diagnosis. For chewing performance, participants with mutual diagnoses reported more pain compared to other participants. Finally, the risk-status of patients significantly affected chewing performance.
Keywords: Temporomandibular disorders, temporomandibular muscle and joint disorders, diagnostic criteria, biopsychosocial profiles, clinical utility
Temporomandibular joint disorder, commonly referred to as TMD, is a collection of disorders characterized by orofacial pain, chewing dysfunction, or a combination of the two (1). Common symptoms of facial pain include pain, headache, joint discomfort or dysfunction, earaches, ringing in the ear, dizziness, pain in the upper and lower back, or neck aches (2–5). Patients may also experience clicking, popping, or grating noises when opening or closing the mouth (2–3). Pain may also be accompanied by dental changes, such as tooth wear and excessive overbite (4). Hoffman and colleagues (5) have noted many other associated clinical comorbidities associated with TMD. The severity of TMD symptoms can range from noticeable, but otherwise insignificant problems, to seriously debilitating pain and dysfunction (1). Moreover, TMD ranks as one of the highest commonly occurring musculoskeletal conditions resulting in pain and disability, second only to chronic low back pain. It is the most common cause of facial pain (6). In the U.S. alone, the prevalence of TMD is estimated to be between 5–15% (1). The National Institute of Dental and Craniofacial Research (6) estimated TMD cost an average of $4 billion annually.
Presently, a dual-axis system developed by Dworkin and LeResche is accepted as the best and most widely used classification scheme for TMD (7). It is referred to as the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD), and was developed in order to define the subtypes of TMD and to standardize the diagnosis of them. The RDC/TMD is comprised of two parts: the history questionnaire and self-report measures completed by the patient; and a physical examination, conducted by a trained clinician. The RDC/TMD has two particular strengths: clinical researchers have the capability to accurately diagnose TMD in a standardized format; and the RDC/TMD is a comprehensive conceptualization of the disorders (8). It should also be noted that a new revised RDC/TMD is being considered, based upon the RDC/TMD Validation Project as reviewed previously in this Journal (9).
Axis I of the RDC/TMD assesses the clinical characteristics of TMD, by means of palpation and physical measures of oral and facial tasks (8). Diagnoses are split into three categories: masticatory muscle disorders; disc displacements; or other degenerative joint conditions, such as arthralgia and osteoarthritis. Group I (muscle pain disorder or MPD) includes two subgroups, which are defined based on jaw opening limitations. Disc displacements (DD) constitute Group II of the clinical conditions, and include three subcategories, which are also defined based on the restrictions of the mandible opening. Group III includes degenerative joint diseases (DJD), namely arthralgia, arthritis, and arthrosis. The RDC/TMD diagnoses within the three groups are not mutually exclusive, allowing a patient to be diagnosed with anywhere from zero up to five diagnoses (one muscle diagnosis, one disc displacement, and one diagnosis from Group III for each joint). Axis II provides a reliable, valid assessment of psychosocial factors, including: pain intensity, pain-related disability, depression, and nonspecific physical symptoms [i.e., somatization; (8, 10)]. It blends three reliable clinical questionnaires in order to assess for these psychosocial factors. Finally, a brief jaw disability checklist is incorporated to assess the amount of interference TMD has on patients as it relates to mandibular function, such as talking or chewing. Thus, the RDC/TMD is a system that provides several pieces of reliable information, including demographics, patient characteristics, Axis I diagnoses, and an Axis II profile. With this array of variables, it is not surprising that the treatment of TMDs varies greatly. The most common forms of treatment include biopsychosocial interventions, self-care interventions, physical therapy, pharmacologic therapies, and surgery; albeit, not necessarily in this order (1, 5, 11).
Patients with chronic MPD (Group I on the RDC/TMD) report higher pain levels, as well as more distress, relative to patients with arthritic conditions (12). Kino et al. (13) also found that chronic TMD patients with a diagnosis of MPD reported higher disability scores in activities of daily living compared to other diagnostic categories. The current body of literature, though, has not extensively investigated biopsychosocial factors of RDC/TMD Axis I diagnoses in acute TMD patients. However, Epker, Gatchel, and Ellis (14) were able to accurately predict whether an acute patient was at “high risk” for developing chronic TMD by combining two variables: measurements of self-reported pain and the presence of myofascial pain. A series of studies have further demonstrated the predictive validity of this high risk-low risk dichotomy in acute TMD patients (15–20). Thus, patients with myofascial pain disorder could have a more dysfunctional biopsychosocial profile compared to patients with either disc displacements or degenerative joint disorders.
The purpose of the present study was to examine the common biopsychosocial factors associated with the three major RDC subcategories among an exclusively first-time diagnosed acute TMD population. This is the first study of its type examining this population. While most of the literature on TMD has focused on chronic facial pain, fewer studies have focused specifically on the area of acute jaw pain. Relatedly, a second goal was to further evaluate the construct validity of the “high-risk versus low-risk” model for the development of chronic TMD.
METHOD
Participants
A consecutive cohort of 207 first-time diagnosed acute TMD patients, who met criteria for the study, were recruited and evaluated in community-based dental clinics in the Dallas/Ft. Worth metroplex. These participants completed a pre-intervention biopsychosocial evaluation and were eligible for treatment. They were considered eligible for participation if they were over 18 years old and had acute TMD pain or discomfort for 6 months or less at the time of their entry into the study. Potential participants with a comorbid pain-exacerbating physical condition (such as other musculoskeletal pain conditions or cancer), or a history of jaw pain before the most recent episode, were excluded from the current study. Collaborating dentists and clinical research associates at each clinical site determined patients’ eligibility for this study. High-risk subjects (those at risk for progressing to chronic TMD) were identified at intake using an algorithm developed in previous studies to predict risk score (14, 21). Participants were evaluated between September, 2008 and August, 2010. As can be seen in Table 1, the majority of the sample was female, Caucasian, married, and graduated from college. This demographic composition was representative of the dental clinics in the Dallas-Ft. Worth metropolitan area that treat TMD patients. The study was specifically conducted in community clinics in order to ensure the generalization of results to the general population. Indeed, these demographic characteristics were similar to a large-scale study reported by Hoffman and colleagues (5), thus strengthening the external validity of the results found in the present study.
Table 1.
Demographic Variables for Pre-Intervention Participants
| Variables | (n=207) |
|---|---|
| Age-Mean (SD) | 43.36 (15.73) |
| Range in Years | 18–80 |
| Gender (%) | |
| Male | 46 (22.2) |
| Female | 161 (77.8) |
| Race (%) | |
| Caucasian | 142 (68.6) |
| Latino (a) | 24 (11.6) |
| African American | 25 (12.1) |
| Asian | 6 (2.9) |
| Other | 10 (4.8) |
| Marital Status (%) | |
| Single | 77 (37.2) |
| Married | 100 (48.3) |
| Divorced or separated | 24 (11.6) |
| Widowed | 1 (0.5) |
| Missing data | 5 (2.4) |
| Years of Education (%) | |
| 8–15 Years | 88 (42.5) |
| 16 Years | 80 (38.6) |
| 17+ Years | 39 (18.8) |
| Risk Status (%) | |
| Low-Risk | 95 (45.9) |
| High-Risk | 112 (54.1) |
Procedure
The participants in this study were primarily recruited and referred to the study by collaborating dental practices in the Dallas-Ft. Worth area. After the collaborating dentist or clinical research associate determined a participant’s eligibility, the potential participant was given a packet consisting of a consent form, HIPAA form, patient information form, and payment voucher ($20). Participants were then scheduled for a series of pre-intervention biopsychosocial (BPS) evaluations. The pre-intervention biopsychosocial (BPS) evaluation was preferably completed within one week. The evaluation included both physical measures and psychosocial measures. Trained clinicians administered the RDC/TMD, including the components of the “at-risk” screening algorithm. These evaluators were initially trained on the RDC/TMD administration by an experienced oral surgeon. Inter-rater reliability for correct completion of the TMD Exam form was conducted on non-subject volunteers prior to the beginning of the study. Quality control of evaluators was then maintained by re-evaluating randomly selected cases throughout the project, as well as re-calibrating evaluations. The initial guidelines delineated by Dworkin, LeResche and Derouen (22) were followed. This produced close to 100% reliability. The screening algorithm consisted of: Question 3 from the RDC History Questionnaire; the Characteristic Pain Intensity (CPI); and the evaluation of oral facial pain, as assessed by muscle palpation on Items 1, 8 and 10 of the Oral Facial Examination. The trained clinician also administered the Functional Evaluation of Chewing Performance, another physical measure. The psychosocial measures that were included in this study were as follows: GCPS; CPI; Perceived Stress Scale; Beck Depression Inventory-II; Health Care Utilization, which collects information about types of care received, both related and unrelated to jaw pain; Medication Use Information; SF-36 Health Survey; Symptom Checklist; Headache Questionnaire; Orthodontic History Questionnaire; and Treatment Cost Data. It should also be noted that clinical research associates were all educated at the Masters-level and licensed in their respective disciplines (i.e., Social Work, Counseling).
Measures
RDC/TMD
The RDC/TMD is a system used to define the subtypes of TMD and to standardize the diagnosis of TMD (8). As reviewed earlier, the RDC/TMD is comprised of two axes. Axis I is a physical measure that outlines the clinical characteristics of TMDs, separating them into three categories: myofascial pain disorder (MPD); disc displacements (DD); and degenerative joint conditions (DJD). Axis II assesses psychosocial factors commonly seen in patients with TMD.
Characteristic Pain Inventory (CPI)
The CPI is a self-report measure derived from the RDC/TMD History Questionnaire and appraises current pain, average pain, and worst pain in the jaw. The patient’s score ranges from 0 to 100, with 100 being in the most pain. The mean score of Questions 7 through 9 are taken and then multiplied by 10.
Graded Chronic Pain Scale (GCPS)
The Graded Chronic Pain Scale (GCPS) is a measure derived from Axis II of the RDC/TMD and assesses pain intensity, interferences with usual activities, family and leisure activities, work-related activities, and disability days due to pain. A disability score gives researchers the extent to which TMD pain interferes with daily activities for a participant and the number of activity days that was lost due to pain. This score ranges from 0 to 100. The GCPS uses simple scoring rules to categorize pain severity into four hierarchical groups. Grade I is TMD pain of low intensity with little pain-related impediment. Grade II is high-intensity pain and is associated with low amounts of pain-related interference. Grade III is related to pain-related disability with a high pain intensity. Grade IV is the most debilitating, with severely-limiting pain intensity and a high disability score.
Symptom Check List-90 (SCL-90R)
Two subscales of the Symptom Check List are incorporated into the RDC/TMD to assess for symptoms of Depression and Somatization. The complete version of the SCL-90-R is a 90-item self-report symptom inventory intended to measure psychological well-being and pathology (23). It is considered appropriate for use within health care settings. While the complete version of the Inventory assesses psychological distress across nine separate psychosocial dimensions, only the two mentioned above (depression and somatization) are incorporated into the RDC/TMD.
Medical Outcomes Shortform-36 Health Status Questionnaire (SF-36)
This 36-item self-report inventory assesses mental and physical health-related quality of life (24). It was developed to assess treatment outcomes in health-care settings, and is composed of eight subscales and two composite scales. The two composite scales help to provide an overall snapshot of a patient’s sense of physical (Physical Component Scale; PCS) and mental (Mental Component Scale; MCS) well-being. The SF-36 is especially informative when used in pain management settings because normative data are already available from medical populations, as well as a reported high test-retest reliability coefficient. Cronbach’s alphas have been reported above .80 for internal consistency (24).
Beck Depression Inventory-II (BDI-II)
The BDI-II is a widely-accepted 21-item measure that indicates the occurrence and severity of the physical and emotional symptoms associated with depression in adults and adolescents 13 and older (25). This self-report measure uses a 4 point scale (0 to 3) for each item. The sum of the 21 items is compared to scoring guidelines in order to establish an interpretive range. The suggested scoring guideline is as follows: less than 10, absence of depression; 10–18, mild to moderate depression; 19–29, moderate to severe depression; and over 29, severe depression.
Chewing Performance
The major indices used were the evaluations of median particle size and broadness of the distribution, as well as the participant’s self-rating of pain during the task. Standardized tablets (5 mm thick and 20 mm in diameter) of a new, softer CutterSil® (which is a condensation silicon impression material) are formed using a Plexiglass template. The tablets are cut into quarters, after hardening for at least one hour. Five portions, containing three quarter-tablets each, are packaged for each subject (26). Subjects were asked to chew the tablets at their normal rate of chewing, as a measure of how they usually chew foods (27). Once the chewed samples were obtained from subjects, they were air dried in filter papers over a stainless steel colander. The samples were then separated, using a series of 7 sieves, with mesh sizes 5.6 mm, 4.0 mm, 2.8 mm, 2.0 mm, 0.85 mm, 0.425 mm, and 0.25 mm, stacked on a mechanical stacker and vibrated for two minutes. Once the sample was separated, the contents of each sieve were weighted to the nearest 0.01 gm. Cumulative weight percentages (defined by the amount of the sample that can pass through each successive sieve) were calculated for each chewed sample. From these percentages, the median particle size (MPS) and broadness of particle distribution were estimated using the Rosin-Rammler equation (28). The reproducibility of this procedure has been demonstrated by Oltoff and colleagues (29) to be excellent. Chewing performance measures were collected for both sides of the jaw. Values were used for the side that the participant indicated produced the most discomfort during the tasks, or were averaged for participants who reported equal discomfort on both sides.
Data Analysis Plan
The variables under investigation were examined thoroughly prior to conducting data analyses in order to ensure that the assumptions of the statistical tests were met. First, demographic differences among the TMD diagnostic groups were examined using chi-square tests of independence or analysis of variance (ANOVA) models as appropriate. Differences in chewing performance measures were examined using ANOVA models, with either TMD diagnostic group or Risk Status as the between-subjects factor. Univariate ANOVA models were conducted to examine differences in the psychosocial variables (i.e., CPI, GCPS, depression, quality of life, and somatization) among the TMD diagnostic groups, or between the Risk Status groups. All post-hoc analyses were conducted using Holm Bonferroni corrections to minimize the Type I error rates (30).
RESULTS
Demographics
Group Composition by TMD Diagnosis
From the core sample of 207 participants who completed baseline measurements, 22 (10.6%) did not meet the criteria for an RDC/TMD Axis I diagnosis, 62 (30%) had a diagnosis of MPD only, 32 (15.5%) had a diagnosis of either DD or DJD, and 91 (44%) had diagnosis of MPD in combination with either diagnoses of DD or DJD (see Table 2). Gender was associated with TMD diagnoses; specifically, women were less likely than expected, and men were more likely than expected, to not meet criteria for a TMD diagnosis. Additionally, patients who were classified as having Low Risk status were more likely than expected to not meet criteria for a TMD diagnoses, and less likely than expected to have a diagnoses of MPD in combination with either DD or DJD. Conversely, patients who were classified as High Risk were less likely than expected to not meet TMD diagnostic criteria and were more likely than expected to have a diagnoses of MPD in combination with either DD or DJD. Race/ethnicity was not a significant factor for participants with differing RDC/TMD Axis I Diagnoses.
Table 2.
Demographics of Participants by RDC/TMD Axis I Diagnosis
| Variables | Axis I Diagnostic Category
|
F or χ2 | df | p** | |||
|---|---|---|---|---|---|---|---|
| None (n=22) | MPD (n=62) | DD or DJD (n=32) | Combination of MPD and DD or DJD (n=91) | ||||
| Age-Mean (SD) | 45.50 (14.56) | 43.37 (16.97) | 41.03 (15.27) | 43.65 (15.44) | .376 | 3, 203 | .770 |
| Range in Years | 24–70 | 19–80 | 18–70 | 19–72 | |||
| Gender (%) | 15.11 | 3 | .002** | ||||
| Male | 11 (50.0) | 8 (12.9) | 10 (31.3) | 17 (18.7) | |||
| Female | 11 (50.0) | 54 (87.1) | 22 (68.8) | 74 (81.3) | |||
| Race (%) | 13.64 | 12 | .324 | ||||
| Caucasian | 16 (72.7) | 38 (61.3) | 19 (59.4) | 69 (75.8) | |||
| Latino (a) | 3 (13.6) | 8 (12.9) | 6 (18.8) | 7 (7.7) | |||
| African American | 1 (4.5) | 10 (16.1) | 3 (9.4) | 11 (12.1) | |||
| Asian | 2 (9.1) | 2 (3.2) | 1 (3.1) | 1 (1.1) | |||
| Other | 0 (0.0) | 4 (6.5) | 3 (9.4) | 3 (3.3) | |||
| Marital Status (%) | 20.58 | 12 | .057 | ||||
| Single | 4 (18.2) | 31 (50.0) | 13 (40.6) | 29 (31.9) | |||
| Married | 16 (72.7) | 24 (38.7) | 15 (46.9) | 45 (49.5) | |||
| Divorced or separated | 0 (0.0) | 6 (9.7) | 3 (9.4) | 15 (16.5) | |||
| Widowed | 0 (0.0) | 0 (0.0) | 0 (0.0) | 1 (1.1) | |||
| Missing data | 2 (9.1) | 1 (1.6) | 1 (3.1) | 1 (1.1) | |||
| Years of Education (%) | 4.92 | 6 | .554 | ||||
| 8–15 Years | 8 (36.4) | 26 (42.6) | 13 (40.6) | 45 (49.5) | |||
| 16 Years | 7 (31.8) | 16 (26.2) | 13 (40.6) | 27(29.7) | |||
| 17+ Years | 7 (31.8) | 19 (31.1) | 6 (18.8) | 19 (20.9) | |||
| Risk Status (%) | 23.28 | 3 | .000** | ||||
| Low Risk | 18 (81.8) | 32 (51.6) | 18 (56.2) | 27 (29.7) | |||
| High Risk | 4 (18.2) | 30 (48.4) | 14 (43.8) | 64 (70.3) | |||
Significant at p < 0.05
Physical Measures of RDC/TMD Axis I Diagnoses
As presented in Table 3, ANOVA models were conducted to determine whether the type of RDC/TMD Axis I diagnosis had a significant impact on a participant’s self-reported pain and his or her chewing performance (i.e., ability to breakdown materials by chewing). Diagnoses were separated based on a diagnosis of MPD, and are as follows: no diagnoses, MPD diagnosis only; DD or DJD only; combination of MPD and DD or DJD. Participants with multiple diagnoses, including MPD, reported more pain during the chewing task than did those with no diagnoses, those with only MPD, and those with DD or DJD only. However, no differences were found among the RDC/TMD Axis I Diagnoses for broadness of particle distribution, or median particle size after chewing.
Table 3.
Results of Chewing Performance by RDC/TMD Axis I Diagnoses vs. Groups II and III Diagnoses.
| Chewing Performance Measure | RDC/TMD Axis I Diagnosesa |
F (df), p-value** | ηp2 | |||
|---|---|---|---|---|---|---|
| None M(SD) | MPD M(SD) | DD or DJD M(SD) | Combination of MPD and DD or DJD M(SD) | |||
| Pain Rating | 2.26 (1.49) (n=21) | 3.17 (2.64) (n=55) | 3.15 (2.33) (n=27) | 4.65 (2.22) (n=84) | F (3, 183) = 8.99, p<.001** | 0.128 |
| Median Particle Size | 3.58 (1.01) (n=20) | 3.55 (1.16) (n=53) | 3.80 (1.27) (n=23) | 3.89 (1.17) (n=73) | F (3, 165) = 1.05, p =.37 | 0.019 |
| Broadness | 16.10 (13.98) (n=20) | 16.43 (15.00) (n=53) | 22.74 (15.08) (n=23) | 20.73 (15.60) (n=73) | F (3, 165) = 1.53, p=.21 | 0.027 |
Group Diagnosis is based upon the RDC/TMD criteria
Significant at p < 0.05
Psychosocial Measures of RDC/TMD Axis I Diagnoses
Overall, it was found that participants with a combination of MPD and other disorders (DD or DJD) differed significantly from participants with no diagnoses, MPD only, or DD or DJD only on many psychosocial variables (Table 4). Results of one-way ANOVAs indicated that, on average, participants with a combination of MPD and other diagnoses reported more pain, relative to those without an RDC/TMD Axis I disorder, and those with MPD only. Participants with DD or DJD also reported higher CPI scores than did those without a RDC/TMD diagnosis. In addition to higher CPI scores, participants with MPD combined with another TMD disorder had significantly higher GCPS disability scores, compared to participants without an RDC/TMD Axis I Diagnosis, and participants with DD or DJD. Participants with MPD only did not differ from the other groups.
Table 4.
Psychosocial Measures Examining RDC/TMD Axis I Diagnoses
| Measure | RDC/TMD Axis I Diagnosesa |
F (df), p-value** | ηp2 | |||
|---|---|---|---|---|---|---|
| None | MPD | DD or DJD | Combination of MPD and DD or DJD | |||
| CPI | 37.42 (20.34) (n=22) | 48.44 (20.06) (n=62) | 51.67 (20.32) (n=32) | 57.84 (15.61) (n=91) | F (3, 203) = 8.52, p<.001** | 0.112 |
| GCPS | 13.48 (16.57) (n=22) | 24.03 (24.04) (n=62) | 20.73 (18.72) (n=32) | 33.04 (23.71) (n=91) | F (3, 203) = 6.14, p <.001** | 0.083 |
| Depression, RDC/TMD | 0.40 (0.27) (n=22) | 0.82 (0.68) (n=62) | 0.66 (0.56) (n=32) | 0.94 (0.77) (n=91) | F (3, 203) = 4.26, p=.006** | 0.059 |
| Depression. BDI-II | 4.90 (4.17) (n=21) | 9.16 (7.32) (n=58) | 7.93 (7.21) (n=29) | 11.03 (9.68) (n=88) | F (3,192)= 3.57, p=.015** | 0.053 |
| Somatization, Pain Included | 0.37 (0.22) (n=22) | 0.72 (0.58) (n=62) | 0.45 (0.40) (n=32) | 0.90 (0.71) (n=89) | F (3,201)= 7.67, p<.001** | 0.103 |
| Somatization, Pain Excluded | 0.20 (0.19) (n=22) | 0.50 (0.55) (n=62) | 0.27 (0.41) (n=32) | 0.70 (0.75) (n=90) | F (3,202)= 6.62, p<.001** | 0.090 |
| Somatization, BDI-II | 3.25 (2.49) (n=20) | 6.71 (5.31) (n=58) | 6.00 (4.80) (n=27) | 7.45 (5.72) (n=84) | F (3,185)= 3.62, p=.014** | 0.055 |
| Physical Composite Score, SF-36 | 54.18 (4.39) (n=22) | 48.06 (9.03) (n=53) | 51.85 (7.59) (n=29) | 46.61 (9.19) (n=78) | F (3,178)= 6.10, p=.001** | 0.093 |
Note. Standard deviations appear in parentheses below means
Group Diagnosis is based upon the RDC/TMD criteria
Significant at p < 0.05
Using the questions derived from the SCL-90 portion of the RDC/TMD History Questionnaire, significant differences were found among participants with regard to depression scores (again, see Table 4). Participants with a mutual diagnosis of MPD and either DD or DJD had significantly higher levels of depression compared to participants with no TMD diagnoses, but participants with MPD only or with DD or DJD did not differ from the other groups. This finding was further reinforced when assessing depression scores using the BDI-II. There were also significant differences among participants with differing diagnoses of TMD in terms of nonspecific physical symptoms (taken from the SCL-90 somatization component of the RDC/TMD), excluding or including pain. Post-hoc tests again revealed that those with a combination of diagnoses had more somatic complaints compared to those with either no RDC/TMD Axis I diagnosis, or those with a diagnosis of only DD or DJD. Participants with MPD only did not differ on their amount of somatic complaints, relative to those who also had DD or DJD. This finding was reinforced by the somatic score derived from the BDI-II for which the group with multiple diagnoses reported more somatic complaints than did the group with no RDC/TMD Axis I diagnosis. Furthermore, those with a combination of diagnoses reported poorer quality of life on the physical composite score of the SF-36, as compared to those with no RDC/TMD Axis I diagnosis or those with a diagnosis only of DD or DJD. Participants with MPD only reported poorer quality of life than the group with no diagnosis.
Physical Measures of High- vs. Low-Risk Participants
Differences in chewing performance based on risk status were examined using ANOVA models (Table 5). Analyses revealed that High Risk participants reported more pain while chewing, relative to Low Risk participants. However, High- and Low-Risk participants did not differ on median particle size or broadness of particle distribution.
Table 5.
Results of Chewing Performance by Risk Status
| Chewing Performance Measure | Risk Status
|
F (df), p-value** | ηp2 | |
|---|---|---|---|---|
| Low Risk M(SD) | High Risk M(SD) | |||
| Pain Rating | 2.47 (1.65) (n=72) | 4.57 (2.60) (n=93) | F (1, 163) = 35.59, p<.001** | 0.179 |
| Median Particle Size | 3.72 (1.20) (n=66) | 3.74 (1.17) (n=85) | F (1, 149) = .019, p=.89 | 0.000 |
| Broadness | 19.84 (15.62) (n=66) | 18.19 (14.94) (n=85) | F (1, 149) = .43, p=.51 | 0.003 |
Significant at p < 0.05
Psychosocial Measures of High- vs. Low-Risk Participants
Participants’ psychosocial response to TMD was also evaluated based upon their risk status (Table 6). One-way ANOVAs were conducted on the same psychosocial variables, namely, CPI, GCPS, depression, quality of life, and somatization. Results indicated that High Risk participants reported more pain on the CPI, relative to Low Risk participants. High Risk participants also reported significantly more interference with daily activities due to TMD symptoms compared to Low Risk participants. Significant differences were also found among participants with regard to depression scores, somatic complaints, and physical well-being. High Risk participants had significantly higher levels of depression as compared to Low Risk participants in both the RDC/TMD and BDI-II measures of depression. High Risk participants were also more likely to have complaints of symptoms with and without including pain, relative to those who were Low Risk on both the RDC/TMD and BDI-II measures. Additionally, High Risk participants also reported lower quality of life on the physical composite score of the SF-36.
Table 6.
Psychosocial Measures by Risk Status
| Measure | Risk Status
|
F (df), p-value** | ηp2 | |
|---|---|---|---|---|
| Low Risk | High Risk | |||
| CPI | 36.00 (13.14) (n=95) | 65.39 (11.98) (n=112) | F (1, 205) = 283.02, p<.001** | 0.580 |
| GCPS | 16.60 (17.71) (n=95) | 34.64 (23.75) (n=112) | F (1, 205) = 37.26, p <.001** | 0.154 |
| Depression, RDC/TMD | 0.68 (0.63) (n=95) | 0.90 (0.72) (n=112) | F (1, 205) = 5.45, p=.021** | 0.026 |
| Depression, BDI-II | 8.07 (7.85) (n=90) | 10.46 (8.71) (n=106) | F (1, 194) = 4.03, p=.046** | 0.020 |
| Somatization, Pain Excluded | 0.55 (0.54) (n=95) | 0.87 (0.65) (n=112) | F (1,203)= 14.83, p<.001** | 0.068 |
| Somatization, Pain Included | 0.36 (0.52) (n=95) | 0.66 (0.69) (n=112) | F (1,204)= 12.16, p=.001** | 0.056 |
| Somatization, BDI-II | 5.50 (4.78) (n=86) | 7.47 (5.61) (n=103) | F (1,187)= 6.57, p=.011** | 0.034 |
| Physical Composite Score, SF-36 | 51.74 (7.15) (n=83) | 46.30 (9.33) (n=99) | F (1,180)= 18.93, p<.001** | 0.095 |
Note. Standard deviations appear in parentheses below means
Significant at p < 0.05
DISCUSSION
Results of the present investigation revealed that, among acute TMD participants, those with multiple diagnoses (including MPD) were more likely to report higher pain, as well as more interference with daily activities due to pain, relative to participants who did not have a TMD diagnosis. Participants diagnosed with mutual diagnoses of MPD and DD or DJD also had significantly higher symptoms of depression compared to participants with no diagnosis. Finally, participants with MPD and DD or DJD reported higher somatization, relative to participants with no diagnosis and participants with a diagnosis of only DD or DJD. Such findings suggest that patients with more than one diagnosis, including MPD, may experience greater pain, thereby affecting their depressive symptoms, somatization, and ability to engage in daily activities. Other studies have found similar results with regard to chronic TMD patients (12–13). While having only one diagnosis does not significantly differ from a healthy control, participants with multiple diagnoses, including MPD, were found to experience many more biopsychosocial symptoms. This appears to be related to the fact that the presence of MPD is one major predictor of acute TMD developing into chronic TMD without proper intervention (14).
Thus, the above results clearly demonstrate that multiple biopsychosocial factors differentiated among the TMD diagnostic groups, as well as the low- versus high-risk groups. For the RDC diagnostic groups, there were differences found for self-reported pain during chewing performance, CPI pain and GCPS disability scores, measures of depression (both on the BDI-II and the depression score component of the SCL-90), as well as on measures of somatization (on the somatic component of the BDI-II, the somatization score component of the SCL-90, and the physical component score of the SF-36). In terms of the low- versus high-risk group categorization, there were again significant differences on the aforementioned measures. It should be noted that because the CPI is used in the algorithm to differentiate between low-high risk, it should not be viewed as a valid measure of pain used to further validate this dichotomy. However, there were other independent measures of pain to differentiate the low-versus high-risk groups – pain during chewing performance and the GCPS.
These above findings have significant implications for clinical research using the RDC/TMD. For example, Truelove and colleagues (31) have concluded that this diagnostic system has acceptable validity for detecting myofascial TMD pain. However, the validity for the diagnosis of disc displacements, and some DJD disorders such as arthrosis, was found to be poor. This may explain why MPD was the most consistent diagnostic entity involved in the results found in the present study. In addition, these results further highlight the fact that masticatory muscle pain needs to be more extensively investigated in predicting orofacial pain, as recently suggested by Davis et al (32), as well as Fricton (33). The fact that the present study evaluated only first-time diagnosed acute TMD patients made the resultant findings even more valuable to the scientific clinical research literature.
With regard to chewing performance, participants with a combination of MPD and DD or DJD significantly differed in the amount of reported pain during the test, relative to participants with either no diagnoses, only MPD, or DD or DJD diagnoses at the pre-intervention stage. Measures of median particle size and broadness of particles, though, were not found to be significant. However, for those patients who were classified as “high risk,” there was a significant difference in self-reported pain during chewing performance and RDC/TMD functioning, as compared to “low risk” patients. These “high risk” patients also differed from the “low risk” patients on a number of psychosocial measures evaluated. Combined with earlier studies that have demonstrated the predictive utility of this “high-versus low-risk” model (16, 18, 34–35), these results further document the construct validity of the high-low risk dichotomy for acute TMD patients. Moreover, they correspond closely with the findings by Ohrbach and coworkers (36) that these RDC/TMD Axis II measures not only have good psychometric properties, but also good clinical utility. This clinical utility now appears especially true in the case of acute High Risk TMD patients.
In conclusion, results of this study indicate that HR participants suffer from more self-reported pain, interference with daily activities, depression, and somatization. Additionally, participants who are at a high-risk of developing chronic TMD symptoms experience more pain while chewing, relative to Low Risk participants. Overall, the general findings clearly reinforce the need for a new revised RDC/TMD, as called for by Sessle (9). The MPD category of Axis I was the only consistently predictive measure found in the present study. In addition, the demonstration of biopsychosocial differences (chewing performance and Axis II psychosocial measures) between High Risk versus Low Risk patients further demonstrate the validity of this “at risk” dichotomy algorithm.
Footnotes
This research was supported by Grant 5U01DE010713-14 from the National Institute of Dental and Craniofacial Research.
Contributor Information
Angela Liegey Dougall, The University of Texas at Arlington.
Carmen A. Jimenez, The University of Texas at Arlington.
Robbie A. Haggard, The University of Texas at Arlington.
Anna W. Stowell, The University of Texas at Arlington.
Richard R. Riggs, Richardson, Texas.
Robert J. Gatchel, ABPP, The University of Texas at Arlington.
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