Home Orthodontics A novel combination of treatments for acute anterior disc displacement without reduction of temporomandibular joint

A novel combination of treatments for acute anterior disc displacement without reduction of temporomandibular joint

by adminjay


Study design

To achieve the research objective, the investigators conducted a cross-sectional retrospective study. The study protocol was approved by the Institutional Ethics Committee of the First Affiliated Hospital of Xinjiang Medical University (approval number: K202108-25) and followed the principles outlined in the Announcement of Helsinki. Informed consent was provided by all subjects and their legal guardian(s).

Patients selection

The Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) list important diagnostic points for TMJ ADD as follows: TMJ clicking or noise during mouth movements, varying degrees of mouth opening limitation, jaw deflection while opening, pain localized in the TMJ area both at rest and during activity20.

The following inclusion criteria were used: (1) diagnosis of ADDwoR confirmed by magnetic resonance imaging (MRI); (2) with a duration of mouth opening restriction ≤ 2 months; (3) patient and/ or the patient’s legal representative are aware of and consent to the treatment. Subject exclusion criteria were as following: (1) prior maxillofacial trauma or inflammation history; (2) prior TMJ treatment history; (3) presence of any systemic joint disease; (4) missing follow-up and incomplete clinical data.

A total of 37 patients were collected from the TMJ Specialist Clinic at the First Affiliated Hospital of Xinjiang Medical University from January 2022 to December 2023. All patients agreed to participate in the investigation. The 37 subjects had an average age of 26.14 ± 9.63 years, ranging from 12 to 51 years, with 29 females and 8 males. There were nineteen cases on the left side, seventeen cases on the right side, and one case on bilateral sides. The study flowchart based on the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) statement21 is shown in Fig. 1.

Fig. 1
figure 1

The flow diagram describing the subjects’ enrollment as well as the working plan. Abbreviations: ADDwoR anterior disc displacement without reduction, ANOVA analysis of variance, MMO maximum mouth opening, MRI magnetic resonance imaging, VAS visual analogue scale.

Treatment procedures

First, we performed arthrocentesis along with HA injection, in accordance with the findings of Li et al.22. After administering local anesthesia of 2% lidocaine hydrochloride injection (ZhaoHui Pharmaceutical, Shanghai, China) and preparing the affected TMJ sterilely, we injected 2 mL of physiological saline into the upper joint cavity. This was done under pressure using a single-needle technique, with the saline being pumped in and out several times. Once the procedure is completed, proceed to inject 1mL (10 mg) of HA (Seikagaku, Tokyo, Japan) into the joint space.

Second, MM is performed to manage the condition of jaw “locking”23. With their thumb on the mandibular molar of the affected side, the clinician gently pulled the mandible downward on the contralateral side. The clinician placed their other hand on the same side of temporal region to stabilize the patient’s head during the MM procedure. Two criteria indicate successful MM: the affected TMJ produces an audible click, and the maximum mouth opening (MMO) is more than 40 mm immediately5,23.

Third, we followed Clark’s guidelines24 to prepare the TBA. The mandible was positioned in an edge-to-edge relationship, and the vertical dimension was augmented by 4–5 mm. The vestibular arch and the screw for lateral expansion in the midline of the maxillary component were omitted from the TBA design. The angle between the upper and lower components of the appliance was precisely calibrated to 70°. The TBA was required to wear the device continuously for one week (24 h per day). The patient followed a liquid or semi-liquid diet and gargled to ensure oral hygiene this week. After the first week, the patients were instructed to wear their TBA only while sleeping at night for the next six months.

Clinical efficacy evaluation

MMO refers to the distance between the upper and lower central incisors. This measurement excludes any overbite and is taken when patients are seated and open their mouths as wide as they can25. The intensity of TMJ pain during MMO was assessed using the visual analogue scale (VAS) score. The VAS is a tool that enables participants to express their pain intensity by choosing a point on a line marked from 0 to 10 25. MMO and VAS pain score were recorded separately at four time points: before treatment, and one week, three months, and six months after treatment.

MRI examination

As described in our previous work26, MRI was performed using a 1.5 T scanner (MAGNETOM Aera; Siemens Healthineers, Erlangen, Germany) with TMJ surface coils. T2-weighted images were obtained in the oblique sagittal plane for both closed and open mouth positions, with a repetition tine of 2 500 ms and an echo time of 60 ms. The slice thickness was set to 2 mm, and the inter-slice spacing was set to 0.2 mm.

MRI is performed before the treatment and six months after treatment to observe the position of the joint disc on the affected side. The disc position is categorized into three distinct conditions for clarity: (1) normal disc-condyle relationship; (2) ADDwR; (3) ADDwoR.

Disc and condyle position measurement

The methodology for accurately measuring the positions of the condyle and disc in joint is thoroughly outlined in Drace & Enzmann27. As shown in Fig. 2, a line (line 1) was defined as a tangent drawn from the lowest part of the articular eminence (point T) to the highest part of the porus acusticus externus (point P). The X-axis, parallel to line 1, was drawn through the highest part of the articular fossa (point G). While the Y-axis was drawn perpendicular to the X-axis from point G, which was designated as the origin of coordinates. The X–Y coordinates of condyle position (points C) and disc position (points D) were recorded respectively.

Fig. 2
figure 2

The procedures for measuring the anatomical positions of the disc and condyle in the joint. Point T: the articular eminence; Point P: the porus acusticus externus; Point G: the articular fossa; Point C: the condyle position; Points D: the disc position.

Statistical analysis

All statistical analyses were performed using SAS software version 9.4 (North Carolina State University, Raleigh, NC, USA). The Shapiro–Wilk test was used to verify the normality of all data. The MMO and VAS values of patients at four different time points were compared utilizing analysis of variance (ANOVA), followed by a least significant difference post hoc analysis performed for normal data with homoscedasticity1. Due to the normal distribution of data with heteroscedasticity, a Dunnett T3 analysis was employed for post-hoc multiple comparisons. A paired t-test was conducted to compare the position of the affected condyle/disc before and after six months of treatment. The differences were statistically significant when P < 0.05.



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