Physiological effects of anterior repositioning splint on temporomandibular joint disc displacement: a quantitative analysis

Abstract

Anterior repositioning splints (ARS) are used primarily for the management of temporomandibular joint (TMJ) anterior disc displacement with reduction (ADDwR). However, the exact physiological effects of ARS are still unclear. This study investigated the short and long-term effects of ARS on disc and condyle angles/positions by metric analysis. Twenty-two subjects diagnosed with ADDwR were recruited. Maxillary full-coverage ARS were fabricated, and MRI of TMJs was obtained before splint treatment, immediate post-insertion and 6 months after splint treatment. Disc-condyle relationship was determined by disc-condyle angle measurement. Disc and condyle positions were described as X-Y coordinates with the summit of glenoid fossa as the origin of the coordinates. Thirty-two TMJs were classified as ADDwR and 12 were normal. Upon ARS insertion, all TMJs with ADDwR got normal disc-condyle relationships. The condyles moved significantly forward and downward, while the discs moved significantly backward and upward. MRI at 6 months after treatment (without ARS insertion) indicated that only 40·6% (13/32) of the joints were maintained in the normal disc-condyle relationship. The majority of condyles returned to their pre-treatment positions, while the discs generally moved anteriorly again. The use of ARS resulted in forward and downward condyle movement, and a concurrent backward movement of the disc resulting in ideal spatial disc-condyle relationship. The stability of this relationship, however, could not be maintained in the majority of TMJs upon ARS removal. Findings explain the good short-term clinical outcomes with ARS and their relatively lower efficacy in the long term.

Condylar repair and regeneration in adolescents/young adults with early‐stage degenerative temporomandibular joint disease: A randomised controlled study

“…While physiologic loading of the TMJs could prevent fibrocartilage breakdown and provide stimulus for fibrocartilaginous cell proliferation, biomechanical overloading may ruin joint lubrication and increase intra‐articular pressure, resulting in temporary hypoxia and consequent degradation of TMJ structure . In our recent quantitative study, ARS moves the condyle significantly forward‐downward by 2 to 3 mm and may cause biomechanical unloading of the TMJ facilitating regenerative condylar bone remodelling …”

“…Signed informed consent for study participation was obtained at the initial visit. A simple randomization technique was used to generate a chance allocation sequence using a computerised random number generator (SPSS software version 21.0) by a blinded assistant, and patients were subsequently randomly allocated into two groups: (a) conservative treatment with ARS therapy, designated the splint group, and (b) conservative treatment without ARS therapy, designated the control group. Conservative treatment included patient self‐care instructions, moist heat treatment and/or oral non‐steroidal anti‐inflammatory drugs (NSAIDs) (Meloxicam, 7.5 mg, once a day) for pain management.…”

“…The presence of an audible TMJ click during mandibular manipulation was a clinical indication of successful TMJ closed‐lock reduction, which was confirmed with MRI . Anterior repositioning splints were subsequently fabricated on the upper arch with the mandible guided into a protrusive position (in an edge‐to‐edge relation), which made the majority (96.7%‐100%) of the reduced discs in a normal disc‐condyle relationship . Patients were instructed to wear their splints 24 hours a day for 3 months.…”

“…Patients were instructed to wear their splints 24 hours a day for 3 months. After the initial 3 months, patients were weaned off daytime wear and instructed to wear splints only during the night while sleeping . The patients with acute DDw/oR in the control group were only treated by arthrocentesis.…”

“…Liu and co‐workers evaluated the osseous changes accompanying anterior repositioning splint (ARS) therapy in 36 patients retrospectively and found that ARS facilitated regenerative remodelling of the condyle . The use of ARS appears to result in downward‐forward condyle movement and a concurrent backward movement of the disc leading to more ideal spatial disc‐condyle relationship …”