The wave analysis of swallowing sounds has been receiving attention because the recording process is easy and non-invasive. However, up until now, an expert has been needed to visually examine the entire recorded wave to distinguish swallowing from other sounds. The purpose of this study was to establish a methodology to automatically distinguish the sound of swallowing from sound data recorded during a meal in the presence of everyday ambient sound. Seven healthy participants (mean age: 26·7 ± 1·3 years) participated in this study. A laryngeal microphone and a condenser microphone attached to the nostril were used for simultaneous recording. Recoding took place while participants were taking a meal and talking with a conversational partner. Participants were instructed to step on a foot pedal trigger switch when they swallowed, representing self-enumeration of swallowing, and also to achieve six additional noise-making tasks during the meal in a randomised manner. The automated analysis system correctly detected 342 out of the 352 self-enumerated swallowing events (sensitivity: 97·2%) and 479 out of the 503 semblable wave periods of swallowing (specificity: 95·2%). In this study, the automated detection system for swallowing sounds using a nostril microphone was able to detect the swallowing event with high sensitivity and specificity even under the conditions of daily life, thus showing potential utility in the diagnosis or screening of dysphagic patients in future studies.

Summary Previous work suggests a relationship between sustained low‐level tooth clenching and the aetiology of myogenous temporomandibular disorder (TMD) pain. This study aimed to establish a reliable system with which to evaluate low‐level electromyographic (EMG) activity related to low‐level tooth clenching while discriminating speech activity, which is one of the most common facial muscle activities to be discriminated from low‐level clenching. This device should facilitate the clinical evaluation of awake muscle activity in TMD patients. Eight female and eight male subjects (38·9 ± 11·3 years) participated in the study to evaluate the validity of estimation of speech duration. Actual speech duration was defined by one examiner by pointing out the timing of beginning and end point of each speech on wave‐editing software. Speech duration, as detected by a voice sensor system, which was activated by a voice loudness of 54·71 ± 5·00 dB, was significantly correlated with the above actual speech duration (P < 0·01, R2 = 0·9935). An actual recording with the system was carried out in one TMD patient and one healthy volunteer and revealed that the duration of diurnal EMG activity higher than 5% MVC was 1649·16 s and 95·99 s, respectively. As the voice sensor system adopted in this study could define the exact onset and offset of each segment of speech, EMG activity during speech could be precisely discriminated. The results of this study demonstrate that the EMG system with voice sensor system would be an effective tool for the evaluation of low‐level masticatory muscle activity.

Patients with unilateral ADD had fewer reports of TMJ pain and discomfort when they were molar clenching on the ipsilateral side compared to molar clenching on the contralateral side.

Background and Objective: The relationship between periodontal sensation and Myofascial Pain (MP) is not yet fully clarified. The aim of this study was to test the null hypothesis that there is no difference in the periodontal sensation threshold between subjects with MP and subjects with no Temporomandibular Disorders (TMD). Methods: Participants have clinically assessed in accordance with the Research Diagnostic Criteria for Temporomandibular Disorders version 1.0 guidelines and assigned to the MP group (mean age 54.8 ± 14.8 years; 1 male and 11 females) or the control group (mean age: 63.9 ± 13.2 years; 1 male and 15 females). The Passive Periodontal Sensation Threshold (PPST) was evaluated using impulsive mechanical stimulation on the occlusal surface parallel to the tooth axis of the maxillary first molar, if present. The difference in the mean PPST between the MP group and the control group was evaluated using the Student t-test after checking for homoscedasticity. Results: The mean PPST value was 1050.1 ± 480.3 mN in the MP group and 712.3 ± 288.5 mN in the control group. A significant difference was observed between these mean PPST values (p = 0.045). Conclusion: There was a significant difference in PPST between the MP group and the control group. Although the etiology of the change of PPST is still unknown, the higher PPST value observed in MP patients suggests that future study on occlusal dysesthesia or occlusal sensation-related pathosis is warranted.

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