This study compared the short-term efficacy of two treatments (local anesthetics (A) and local anesthetics and lavage (AL)) in patients with permanently displaced discs and temporomandibular disorder (TMD) pain. 45 patients participated in the single-blind randomized controlled trial. All patients had received: a Research Diagnostic Criteria/TMD diagnosis of disc displacement without reduction; and magnetic resonance imaging confirmation of non-reducing disc displacement. Participants were randomized to treatment with A or AL and were assessed at baseline and at 1 and 3 month follow-ups. The primary outcome measure defining success was reduction in pain intensity of at least 30% during jaw movement. At the 3 month follow-up, the success rate was 76% for A and 55% for AL. Both groups reported similar pain relief with no significant difference between the groups. Similar trends were observed for outcome measures in the physical functioning, emotional functioning, and global improvement domains with no significant difference between the groups. Use of lavage to supplement extra-articular local anesthetic treatment of painful jaw movements at non-reducing discs does not appear to improve TMD pain and mouth opening capacity in the short term.
Disc displacement with reduction (DDwR) of the temporomandibular joint (TMJ) is common and found in approximately 30% of the population and in 40–53% of patients with clinical temporomandibular disorders (TMD). Disc displacement without reduction (DDwoR) has been reported in 2–4% of patients with clinical TMD. The majority of patients with disc displacements have no symptoms, but some patients may experience pain and reduced mouth opening when the disc does not reduce to a normal position on opening. Pain and jaw limitation often have an impact on daily function, psychosocial well-being, and quality of life in TMD patients.
Several interventions have been suggested for the treatment of DDwoR. Lavage of the TMJ with or without steroid injections, has been reported to be effective in reducing pain and to improve jaw mobility in patients with DDwoR. Lavage has been recommended for patients with this condition, because the intervention is minimally invasive and has a low rate of side effects and positive treatment outcome. Systematic reviews and a recent randomized controlled trial (RCT) comparing the treatment outcome of lavage with arthroscopic procedures, discectomies, and conservative modalities found that the treatment procedures yielded similar results. A plausible reason for not finding any difference between the various procedures is the difficulty in comparing studies due to limitations in diagnosis, number of participants, study design, and outcome measures.
Several leading scientific journals have made a united effort to set up guidelines for RCTs in the Consolidated Standards of Reporting Trials (CONSORT) statement. The 25 item CONSORT checklist can help avoid pitfalls. To permit meaningful comparisons between intervention studies on chronic pain conditions, the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) suggests that core outcome measures should evaluate six domains : pain; physical functioning; emotional functioning; participant rating of global improvement and satisfaction with treatment; symptoms and adverse events; and participant disposition.
There is, however, no consistent evidence that either supports or refutes the use of arthrocentesis and lavage in TMJ disorders. The present single-blind RCT aimed to compare the efficacy of two treatments (local anesthetics (A) and local anesthetics and lavage (AL)) using a primary outcome measure of at least 30% reduction of pain during jaw movement in patients with DDwoR and TMD pain. The first hypothesis was that patients treated with anesthesia in combination with lavage would experience a greater reduction in TMD pain than patients treated with anesthesia alone. The second hypothesis was that patients in the AL group would report greater improvement in the physical functioning, emotional functioning, and global improvement with treatment outcome domains than patients in group A.
Materials and methods
55 patients fulfilled the inclusion criteria, and of these, 10 were excluded due to one or more of the exclusion criteria. 45 patients (41 women and 4 men, mean ± SD age, 34.9 ± 14.2 years) participated. All patients were recruited between June 2003 and November 2007 ( Fig. 1 ). Sample selection was discontinued at 45 patients because of the long patient selection time.
Inclusion criteria were: age ≥ 18 years; increased TMD pain on chewing or during maximal mouth opening; TMD pain of at least 3 on a 0–10 numeric rating scale (NRS), where the endpoints were 0 = no pain and 10 = worst pain imaginable; pain duration of at least 3 months; a primary TMJ pain complaint diagnosed as arthralgia and disc displacement without reduction according to the Research Diagnostic Criteria (RDC)/TMD ; and magnetic resonance imaging (MRI) confirmation of a non-reducing disc displacement. Patients with a secondary diagnosis of myofascial pain were included since the RDC/TMD allows multiple diagnoses.
Exclusion criteria were: diagnosed systemic muscular or joint disease (e.g. fibromyalgia, rheumatoid arthritis); a whiplash-associated disorder; difficulties with the Swedish language; dental causes for the pain; tumors of the TMJ; disturbed coagulation ability; pacemaker or other contraindications for MRI; and pregnancy. The Regional Ethics Review Board at Lund University approved the study (Daybook no. [Dnr] LU 109-03), and all patients signed an informed consent form. Patients received no monetary compensation.
All patients completed a questionnaire before undergoing a clinical and radiographic examination. Investigators were available to explain any questions and to check the questionnaires for completeness and legibility. The clinical physical assessment comprised an RDC/TMD examination of the masticatory apparatus by an experienced orofacial pain specialist (ECE) calibrated in RDC/TMD examination methods. The radiographic examination comprised: panoramic radiographs to exclude dental causes for the pain; and MRI to verify the clinical diagnosis of DDwoR in one or both TMJs. One examiner, blinded to patient treatment, evaluated the patients at baseline and 1 and 3 months after intervention.
Each included patient was randomized to one of two treatment options: group A received local anesthetics; and group AL received local anesthetics and lavage. Assignment to treatment option occurred in the following way: five large ‘block’ envelopes, each containing 10 opaque, sealed ‘treatment’ envelopes, were assembled. Five of the treatment envelopes in each block envelope indicated treatment option A and five treatment option AL. A new block envelope was not opened until all 10 treatment envelopes in the current block envelope had been assigned to patients.
Randomization assignment was made using a table of random sampling numbers. An examiner who was not involved in the participants’ treatment set up the randomization procedure.
DDwoR was diagnosed if the RDC/TMD indicated DDwoR and MRI confirmed DDwoR.
MRI was performed bilaterally in all patients. A Siemens Magnetom Vision MRI machine was used between 2003 and June 2004 and a Siemens Magnetom Sonata Vision between July 2004 and December 2007 (Siemens, Erlangen, Germany). Both were 1.5 T machines. With both, MR images were taken with a bilateral TMJ surface coil. Images were taken in the closed and open mouth positions. In the closed mouth position, patients closed their mouth with their teeth in contact; sagittal and coronal images of the TMJ were taken. In the open mouth position, patients opened their mouths as much as possible without experiencing unbearable pain and the clinician placed a stepped plastic bite-block between the upper and lower incisors; sagittal images of the TMJ were taken. Sagittal sections were orientated perpendicular to the long axis of the condyle, and coronal sections were taken parallel to the long axis. Proton density and T2-weighted images were acquired using a double-echo turbo spin-echo sequence. Each sequence yielded 8–10 sections.
Two experienced oral radiologists interpreted the MR images blinded, with no knowledge of the patients’ clinical diagnoses. Observer calibration and subsequent image assessment occurred as follows. The observers interpreted the first 10 complete MRI examinations together. Each observer then interpreted the remaining 35 examinations separately. Observer assessments of these 35 examinations were compared, and if they differed, findings were re-evaluated and discussed until a consensus was reached. Anterior DDwoR was diagnosed if: in the intercuspal position, the posterior band of the disc was located clearly anterior to the 12:00 position, at least in the 11:30 position; and on opening, the posterior band remained clearly anterior to the 12:00 position.
Average pain intensity with the jaw at rest and during movement of the jaw was rated on a 0–100 visual analogue scale (VAS) with end definitions of 0 = no pain and 100 = intolerable pain. Pain intensity was recorded in a pain dairy once a day for 7 days. An average mean was calculated for the week at baseline and at the follow-ups.
The characteristic pain index (CPI) describes the mean value of the present, the worst, and the average TMD-related pain during the last 6 months rated on a 0–10 NRS.
The primary outcome measure of the study was pain relief during jaw movement of at least 30% on the VAS.
The short-form jaw functional limitation scale (SF-JFLS) includes eight items: chew tough food, chew chicken, eat soft food, open wide enough to drink from a cup, swallow, yawn, talk, and smile. The patients rate the limitation on a 0–10-point scale where 0 corresponds to no limitation and 10 to maximal limitation. The average score for the eight items determines the global jaw function limitation of the JFLS scale.
The number of patients consuming any analgesics (e.g. non-steroidal anti-inflammatory drugs, paracetamol or opioids) for TMD pain was registered during 1 week before baseline and during 1 week before each follow-up.
The graded chronic pain scale (GCPS) is a self-report instrument that uses seven questions concerning pain intensity, interference in daily activities, and disability days to yield a 0–IV score. Grade 0 is defined as no TMD pain, grade I as TMD pain of low intensity, and grade II as high intensity pain. Grades III and IV reflect moderate to significant pain-related psychosocial disability regardless of pain level. The GCPS was found to be a reliable and valid instrument.
Depression was assessed using the 20 SCL-90R items that contribute to distress.
Nonspecific physical symptoms are measured by 12 items in the SCL-90R. A mean score was determined based on the items in the instrument.
Global improvement with treatment was assessed on a 0–6-point scale (completely well, much better, somewhat better, unchanged, somewhat worse, and much worse).
Treatment beliefs (credibility) were assessed on a VAS (0–100) with the endpoints ‘not at all’ and ‘very effective’. Patients registered their belief in treatment effect after the intervention.
The clinical examination comprised assessing the vertical range of motion of the mandible: unassisted opening without pain, maximum unassisted opening, and maximum assisted opening. These were measured in mm according to the RDC/TMD protocol.
One surgeon (LES) with 5 years of surgical experience performed all treatment procedures. This surgeon did not evaluate treatment outcome. The duration of each treatment was similar.
Premedication and anesthesia regimes were the same in both groups. 1 h before the injections, patients received 1000 mg paracetamol per os. Directly preceding surgery, patients were anesthetized. The TMJ region was scrubbed with 70% alcohol and covered with a sterile drape; 2.5 ml Xylocain-adrenalin (ASTRA Zeneca) 20 mg/ml was then injected for auriculotemporalis block.
In group A, saline was flushed into a cup that was hidden from the patient before the drape was removed to simulate lavage. In the AL group, a cannula was placed in the posterior part of the upper joint compartment. A second, wider cannula was inserted in the same compartment. Drainage was tested by carefully injecting a small amount of saline. The joint was flushed with 50 ml saline. Excess saline was evacuated by aspiration after the procedure. After surgery, all patients in both groups were advised to take paracetamol 1000 mg × 3 daily as needed.
Rescue treatment was given when necessary. Patients who reported increased pain and a desire to receive additional treatment at follow-up were withdrawn from the study and given individually adapted treatment. Patient data up to the time of withdrawal was used in the statistical analyses.
An independent samples t test was used to compare mean values of mouth opening capacity without pain, mouth opening capacity with assistance, and jaw functional limitation between the two patient groups. The χ 2 -test and Fisher’s exact test were used to compare the distribution of categorical variables between the two patient groups for the variables TMD pain reduction, GCPS, and analgesic consumption. For ordinal variables such as pain intensity at rest and during jaw movements, CPI, JFLS, depression, and somatization the Mann–Whitney U -test was used. The Wilcoxon signed ranks test was used for within-group comparisons of ordinal variables and the sign test for within-group comparisons of categorical variables. All inferential statistical tests were two-tailed with a significance level of P ≤ 5%. Statistical analyses were done with the Statistical Package for the Social Sciences (SPSS, ver. 13.0 for Windows; SPSS Inc., Chicago, IL, USA).
Intention-to-treat (ITT) was analyzed for the outcome measures pain relief of at least 30% and 50% on the VAS.
Logistic regression with the likelihood ratio test was used when analyzing if the baseline difference between the groups in JFLS influenced treatment outcome at both follow-ups.
Sample size calculation was determined in a pilot study that compared arthrocentesis with no treatment. A mean ± SD difference of 3.3 ± 3.6 in pain intensity between the groups was found. A group size of 13 patients in each group would yield slightly more than 80% power, with a two-tailed test at the 5% level. The number of patients recruited was higher than the sample size originally planned to compensate for probable drop-outs ( Fig. 1 ).
23 women and 2 men were randomized to group A and 18 women and 2 men to group AL. Figure 1 illustrates the study design. Between the 1 and 3 month follow-ups, 8 patients dropped out: 2 in group A and 6 in group AL. These 8 patients underwent rescue treatment for TMD pain.
The mean age in group A was 35.6 ± 15.6 years and in group AL 34.1 ± 12.6 years. No significant between-group differences in gender or age were found. 39 patients had visited a physician, a dentist or other professional for their orofacial pain problem before entering the study. 6 patients received no treatment for their TMD pain, 2 in group A and 4 in group AL. Median duration of TMD pain was 12 months in group A (range 3–300) and 36 in group AL (range 4–360). Differences between the groups were non-significant.
ITT analysis of the primary outcome measure TMD pain reduction ≥ 30% during movement of the jaw was reported by 14 of 25 (56%) patients in group A and 8 of 20 (40%) patients in group AL at the 1 month follow-up ( P = 0.286). Corresponding numbers at the 3 month follow-up were 19 of 25 (76%) and 11 of 20 (55%). Between-group differences were non-significant ( P = 0.138). ITT analysis of pain reduction ≥ 50% at the 1 month follow-up was reported by 10 of 25 (40%) patients in group A and 5 of 20 (25%) patients in group AL ( P = 0.289). Corresponding numbers at the 3 month follow-up were 16 of 25 (64%) and 10 of 20 (50%). Between-group differences were non-significant ( P = 0.345).
Between-group differences in pain intensity at rest and during mandibular movement were non-significant at baseline and at the follow-ups ( Fig. 2 A and B ). Within group A, a significant decrease in pain intensity at rest was found at 3 months ( P = 0.01). A significant decrease of pain during mandibular movements was found in group A at both follow-ups ( P = 0.018 and P = 0.000, respectively).
Average CPI was 6.6 (±1.7) for all patients with no difference between the groups at baseline ( Table 1 ). Over time, CPI decreased and the differences between groups was non-significant. Within group A, but not group AL, significant differences were found for CPI at both follow-ups compared with baseline.
|Group A||Group AL||P -value|
|JFLS (mean ± SD)|
|Baseline||3.0 ± 1.7||( n = 25)||4.1 ± 1.8||( n = 19)||0.039|
|1 month||2.2 ± 1.5||( n = 25)||3.1 ± 2.3||( n = 20)||0.134|
|3 months||1.2 ± 1.0||( n = 23)||2.3 ± 1.6||( n = 13)||0.041|
|CPI (mean ± SD)|
|Baseline||6.4 ± 1.6||( n = 24)||6.9 ± 1.9||(n = 19)||0.202|
|1 month||5.5 ± 2.1||( n = 25)||6.7 ± 2.1||( n = 20)||0.063|
|3 months||4.4 ± 1.8||( n = 23)||5.8 ± 2.0||( n = 14)||0.058|
|Analgesic consumption (patients)|
|Baseline||11||( n = 25)||12||( n = 19)||0.208|
|1 month||8||( n = 25)||6||( n = 20)||0.885|
|3 months||4||( n = 23)||2||( n = 14)||1.000|
|Baseline||( n = 23)||( n = 19)||0.789|
|1 month||( n = 24)||( n = 20)||0.451|
|3 months||( n = 23)||( n = 13)||0.021|