Effect of Occlusal Splint Thickness Used as Therapeutic Measure on Masticatory Muscle Activity and Occlusal Plane Orientation in Patients with Tooth Wear: Randomized Clinical Trial

Abstract

Advanced tooth wear leads to the progressive loss of dental hard tissues, significantly impairing masticatory efficiency, altering occlusion, and reducing bite force. These changes often result in a decreased Occlusal Vertical Dimension (OVD), negatively impacting muscle coordination and the patient’s quality of life. This study evaluated the electromyographic (EMG) and cephalometric impacts of vertical dimension alterations using occlusal splints, comparing the therapeutic efficacy of 3mm and 6 mm thickness on masticatory muscle activity and craniofacial structures. Ten subjects (6 males and 4 females, aged 35 – 55 years )) with occlusal wear and reduced OVD were subjected to in OVD increase of 3 mm and 6mm using occlusal splints. EMG recordings per patient were obtained for the elevator muscles (temporalis and masseter ) before and after two weeks of wearing the splint of both thickness with a one-week washout period, using the BioEMG III amplifier. Additionally, the occlusal plane orientation and skeletal relationships were investigated using cephalometric radiographs. The results indicated, no statistically significant differences (P > 0.05) between the two thicknesses across all studied muscles (RT, LT, RM, and LM) during active clenching, Although 3 mm splint generally exhibited lower mean activity values compared to 6 mm splint, At Rest Position: both thicknesses maintained muscle activity within a very low physiological range (2.4 to 3.7 μV) with no significant differences (P > 0.05). Regarding the Skeletal Relationship (ANB angle), the difference between the 3 mm intervention (2.78° ± 2.44°) and the 6 mm intervention (2.93° ± 3.16°) was negligible (P = 0.917). However, the 6 mm intervention exhibited significantly higher mean values for the occlusal plane angle (13.37° vs. 11.19°) and mandibular inclination angle (30.12° vs. 27.0°), with these differences being statistically significant. Furthermore, while both splint thicknesses effectively influence muscle activity without significant neuromuscular differences between them, increasing the thickness to 6 mm exerts a significant internal structural influence, leading to observable changes in the vertical skeletal profile.