Efficacy of an email-based recording and reminding system for limiting daytime non-functional tooth contact in patients with temporomandibular disorders: A randomized controlled trial.

BACKGROUND: Oral parafunctional activities such as daytime non-functional tooth contact (nFTC) are considered aetiological factors for temporomandibular disorders (TMD). OBJECTIVES: To evaluate the effectiveness of an email-based recording and reminding system for limiting daytime nFTC in patients with TMDs. METHODS: Thirty patients with TMDs (mean age, 30.7 ± 8.7 years) were randomly assigned to three groups according to the intervention for limiting nFTC: cognitive behavioural therapy (CBT) with an email-based recording and reminding system for 20 days (e-CBT group, n = 10), CBT with a sticky note reminder for 20 days (s-CBT group, n = 10) and simple verbal instructions to avoid nFTC that were provided before the experimental period (control group, n = 10). The frequency of nFTC, range of pain-free unassisted mouth opening and pain intensity during painful unassisted maximum mouth opening was evaluated before and after the experimental period. RESULTS: The frequency of nFTC significantly decreased after the intervention in the e-CBT and s-CBT groups. Among the three groups, the decrease in the nFTC frequency was the maximum in the e-CBT group (P < .01). In addition, the range of pain-free unassisted mouth opening showed a significant increase in all three groups, with the maximum improvement in the e-CBT group (analysis of variance, P < .01). CONCLUSIONS: The present findings suggest that our email-based recording and reminding system may have the potential to effectively control daytime nFTC and could be an effective strategy for the management of TMDs.

Relationships between craniofacial morphology and masticatory muscle activity during isometric contraction at different interocclusal distances.

OBJECTIVE: The aim was to investigate relationships amongst interocclusal distances, masticatory muscle electromyographic (EMG) activity during isometric contraction of masticatory muscles, and craniofacial morphology. DESIGN: Twenty-eight women and 12 men (25.3 ± 3.8 years old) participated. After measuring maximal voluntary occlusal bite force (MVOBF) between the right-first premolars, the participants were asked to bite at submaximal levels of 0 (= holding the bite force transducer), 15, 22.5, and 30% MVOBF with the use of visual feedback. The thickness of a bite force transducer was set at 10, 12, 13, 14, 16, 17, 18, 19, 20, 22, and 24 mm (= interocclusal distance: IOD). Nine soft tissue craniofacial factors were assessed through digital photograph: face height, middle face height, lower face height, face width, inter-pupil distance and mandibular plane angle, lower face height / face height ratio, inter-pupil distance / facial width ratio and face width / face height ratio. RESULTS: In the masseter muscle, EMG activity decreased with increased IODs. The participants with higher mandibular plane angle had more negative slope coefficients of IOD-EMG graphs at 0% MVOBF especially in male temporalis and female masseter and temporalis muscles, suggesting that a greater mandibular plane angle is associated with lower EMG activity at longer IOD. CONCLUSIONS: Overall the findings support the notion that craniofacial morphology is associated with differences in neuromuscular activity of the masticatory muscles, and suggest that the neuromuscular effects of oral appliances may be dependent on patients' craniofacial morphology and the thickness of the device. (247/250 words).