Clinic of Masticatory Disorders and Dental Biomaterials, Center for Dental Medicine, University of Zurich, Plattenstrasse 11, Zurich, CH-8032, Switzerland.
Clin Oral Investig. 2024 Oct 10;28(11):584. doi: 10.1007/s00784-024-05980-0.
Occlusal splints are the main therapeutic choice in the treatment of temporomandibular disorders (TMD). However, their precise working mechanism is unclear. This study aimed to compare the biomechanical effect of three commercially available splint designs (full covering splint, anterior bite splint and posterior bite splint) during biting in a sample of healthy subjects.
Magnetic resonance imaging (MRI) was combined with jaw tracking to measure the minimal intraarticular distance (MID) of 20 human temporomandibular joints (TMJ) whilst simultaneously recording the electromyogram (EMG) of the masticatory muscles. The changes caused by clenching with a bite force of 100 N without splint (baseline) and on each splint were calculated. Repeated measures ANOVA was performed on the means of the MID variations and EMG amplitudes.
Clenching on the anterior bite splint resulted in two times less activation of the anterior temporalis muscle than baseline (p = 0.003), full covering (p = 0.011) and posterior bite splint (p = 0.011). MID was reduced by clenching in all conditions, but the reduction was almost three times larger with the anterior bite splint compared to no splint (p = 0.011). The full covering splint and the posterior bite splint did not differ significantly in EMG activation of both masseter and temporalis muscles and MID variation.
This study showed that splint designs have a different impact on the MID and EMG activation while clenching. The anterior bite splint had a greater impact on the reduction of the muscle activation, whereas clenching on the anterior bite splint led to bigger reduction of MID and thus had the greatest influence on alteration in the condylar position.
The design of the splint can affect MID and muscle activation and is a variable to consider in the treatment of patients with TMD according to their symptoms.
咬合板是治疗颞下颌关节紊乱（TMD）的主要治疗选择。然而，其确切的工作机制尚不清楚。本研究旨在比较三种市售夹板设计（全覆盖夹板、前牙夹板和后牙夹板）在健康受试者咬合时的生物力学效应。
磁共振成像（MRI）与下颌跟踪相结合，测量 20 个人颞下颌关节（TMJ）的最小关节内距离（MID），同时记录咀嚼肌的肌电图（EMG）。计算无夹板（基线）和每种夹板下 100N 咬合力下咬紧时引起的变化。对 MID 变化和 EMG 幅度的平均值进行重复测量方差分析。
在前牙夹板上咬牙时，前颞肌的激活程度比基线时减少了两倍（p=0.003），比全覆盖夹板（p=0.011）和后牙夹板（p=0.011）都减少了。在所有情况下，咬紧都会导致 MID 减小，但在前牙夹板上咬紧时，MID 的减小幅度几乎是无夹板时的三倍（p=0.011）。全覆盖夹板和后牙夹板在双侧咬肌和颞肌的 EMG 激活和 MID 变化方面没有显著差异。
本研究表明，夹板设计在咬牙时对 MID 和 EMG 激活有不同的影响。前牙夹板对肌肉激活的减少影响更大，而在前牙夹板上咬牙会导致 MID 更大程度的减小，从而对髁突位置的改变产生最大影响。
夹板的设计会影响 MID 和肌肉激活，这是根据患者的症状治疗 TMD 时需要考虑的一个变量。
