The efficacy of a specific stabilization splint

BACKGROUND

The use of a Tanner type stabilization splint, fabricated on a leaf gauge articulation for the treatment of patients with disc displacement without reduction, is lacking in the literature.

OBJECTIVES

The purpose of the study is to collect non-controlled, therapy-related observations; in other words, to demonstrate the efficacy of this appliance for the treatment of patients with disc displacement without reduction.

METHODS

The study enrolled 55 patients, 5 men, and 50 women, with the clinical diagnosis disc displacement without reduction, 42 with and 13 without limited mouth opening. All patients received a splint in the musculoskeletally stable centric relation (CR) position. Mouth opening, clinical performance, and the timeframe of splint treatment were assessed.

RESULTS

For 37 patients with a disc displacement without reduction with limited opening, the largest increase in mouth opening (9.5 +/- 5.6 mm) occurred in the first week (7.9 +/- 2.5 days). No occlusal adjustment of the splint was needed during the treatment sequence. For three patients, treatment took up to 3 months (8.1%), for 13 patients, between 3 and 6 months (35.1%), and for 17 patients, within a year (45.9%), making a total of 89.1% successfully treated patients. Out of 50 patients, 29 had a total resolution of signs and symptoms, whereas 21 patients still suffered from solitary temporomandibular disorder (TMD) signs.

CONCLUSION

A Tanner type stabilization splint, fabricated in the musculoskeletally stable CR position, appears to be an effective and efficient means for the treatment of patients with disc displacement without reduction. Its efficacy makes it eligible to be tested in a randomized controlled trial.

CLINICAL IMPLICATIONS

The efficacy of this specific splint, fabricated in the musculoskeletally stable CR position, makes it a promising tool to treat TMD patients with disc displacement without reduction.

The incidence of centric slides in healthy individuals and TMD patients

Controversy exists as to whether centric slide is an etiological factor for temporomandibular disorders. In this cross-sectional study the magnitude of centric slides, obtained with 2 different articulations and one with a millimetre ruler was compared. The study enrolled a group of 27 healthy individuals and 83 TMD patients, the latter divided in 3 groups of 26, 28 and 29 subjects with the RDC/TMD diagnoses of myofascial pain, osteoarthritis and disc displacement without reduction, respectively. Measurement reliability of a chinpoint guided articulation was compared with a musculoskeletally stable articulation, obtained using a leaf gauge. Next, centric slide was measured, if any, intraorally with a millimetre ruler and in both articulations measuring the difference between centric relation and the maximal intercuspal position. A mandibular full-arch Tanner type stabilisation splint was fabricated for each of the TMD patients. After splint treatment, new casts were obtained and mounted using both methods to locate centric relation. The magnitude of centric slide intraorally and in both articulations was reassessed. For the analysis of the variables a mixed-model procedure was applied (alpha = 0.05). At baseline and upon conclusion of splint treatment all groups exhibited centric slides with large standard deviations (ranging from 1.03 +/- 0.83 to 1.97 +/- 1.3 millimetre). In the mixed-model procedure a significant difference in magnitude existed between the millimetre ruler and both the chinpoint guidance as well as the leaf gauge articulation (P < 0.001). No correlation between centric slide and TMD could be demonstrated.

Reproducibility of 2 methods to locate centric relation in healthy individuals and TMD patients

No conclusive evidence exists for any maxillomandibular relationship as the preferable treatment position. Measurement reliability of 2 different methods to attempt to locate centric relation in control and TMD patients was assessed to determine if both methods lead to the same position. A group of 27 controls and 91 TMD patients were examined using the Research Diagnostic Criteria for TMD (RDC/TMD). Three patient groups were recruited: 27 patients with myofascial pain (MYO), 34 patients with disc displacement without reduction (ID), and 30 patients with osteoarthritis (OA). For each study participant centric relation was located with chinpoint guidance and a technique with a leaf gauge, for the controls once, for all TMD patients before and after stabilization splint treatment. The mixed model procedure revealed no significant differences between the methods, the patient groups and the time interval. However the patient groups at baseline and conclusion of treatment differed significantly from the controls. The percentage of patients (15.9%) having a coincident split-cast result for both methods was significantly smaller (P < 0.001) than the corresponding percentage (85.2%) of controls. After splint treatment, the percentage of coincident split-casts increased from 15.9% to 76.8%. Both methods are reproducible techniques to locate centric relation for control and TMD patients. However, the leaf gauge provides the clinician a different centric relation position in TMD patients than chinpoint guidance does.

Variability of centric relation position in TMD patients

Reproducibility of the centric relation position for patients with temporomandibular disorders (TMD) is not documented in the current literature. It was the objective of this study to assess clinical variability of the centric relation position for TMD patients with a muscle-determined technique by means of an anterior deprogramming device, the leaf gauge. A sample of 60 patients with signs of TMD was selected, 8 men (Mean age 28,6, SD 5,2) and 52 women (Mean age 30,5, SD 10,1). All patients were examined with the Research Diagnostic Criteria, including pain on movement and/or function, mouth opening, joint sounds and palpation of masticatory muscles. All 60 patients were allocated to one of the following diagnostic subgroups: myofascial pain, disk displacement with reduction, disk displacement without reduction, osteoarthritis, trauma. Twelve control subjects were taken from a previous study. Three sequential centric relation records were taken; the first one was used to mount a set of casts to an articulator. Criteria of precision were formulated beforehand: 2 out of 3 centric relation records had to be identical in a split-cast procedure. Variables XL and XR represented mandibular displacement in the sagittal plane, variables YL and YR in the transversal plane, and ZL and ZR in the vertical plane, on the left and right condylar level respectively. Variables XMIN, YMIN and ZMIN represented the minimal sagittal, transversal and vertical displacement left or right respectively. Likewise, variables XMAX, YMAX and ZMAX represented the maximal sagittal, transversal and vertical displacement left or right. XDIFF, YDIFF and ZDIFF represented the difference between the minimal and maximal values of X, Y and Z. The diagnostic subgroup trauma was excluded, because there was only one patient. The null-hypothesis of no between-group differences in within-subject and total variability was tested with an analysis of variance (ANOVA). The level of significance was set at 0.05. To minimize type I errors caused by multiple testing Scheffe's test was used to maintain an overall significance of 0.05. No significant difference between patients and control subjects could be found for variables XL, XR, YL, YR, ZR and ZL. Variables XMIN, YMIN, ZMIN, XMAX, YMAX, ZMAX, XDIFF, YDIFF and ZDIFF showed no significant differences. Scheffe's testing for the variables XL, XR, YL, YR, ZL and ZR, as well as the variables XMIN, YMIN, ZMIN, XMAX, YMAX, ZMAX, XDIFF YDIFF and ZDIFF showed no significant differences. The results of this study suggest no variability in centric relation position between TMD-patients and control subjects by means of the leaf gauge.

Reliability of a measuring-procedure to locate a muscle-determined centric relation position

Although reproducibility of centric relation position, determined with an anterior deprogramming device, a leaf gauge, is widely accepted among clinicians, data confirming statistical evidence are lacking in the current literature. The objective of this study was to prove clinical reliability of a measuring-procedure to locate the centric relation position, determined with the leaf gauge. A sample of 15 subjects (6 men, 9 women, age 22 to 46), assessed with the Research Diagnostic Criteria to rule out any TMD-signs, was selected. Three observers each took three sequential interocclusal records with the leaf gauge, to mount a set of casts into the centric relation position in an articulator. Out of 15 subjects, 12 (5 men, 7 women) fitted criteria of precision--three out of three interocclusal records for each of the three observers--in a split-cast procedure. The applied statistical method is an analysis of variance model (ANOVA) with two factors for 3 observers and 12 subjects. The variance components estimation procedure is MIVQUE (0). The a was set at 0.05. No significant difference between observers for the measured variables sagittally (XL, XR), transversally (YL, YR), and vertically (ZL, ZR) could be found. MIVQUE variance components estimates for observers is < 0, varies for subjects from 0.04 to 0.20 and varies for error from 0.12 to 0.25 mm. Reliability of a measuring-procedure to locate a muscle-determined centric relation position could be established satisfactory.