Osamu Komiyama

Obstructive sleep apnea (OSA) may contribute to poor sleep quality. This study assessed subjective sleep quality, the Respiratory Event Index (REI), reaction times, and the therapeutic effects of a custom-made mandibular advancement device (MAD) in male Japanese elite rugby athletes. The Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), and level III sleep test (REI and minimum oxygen saturation [SpO_{2 min}]) were used to evaluate sleep quality. MAD therapy was used daily for 3 weeks. A telephone-based reaction time test of kinetic vision (the ability to identify moving objects) was recorded within 15 min of waking and over 5 days of pre- and post-MAD therapy. Differences in variables were evaluated using paired t-tests. Of the 42 players (mean age, 26.3 ± 3.7 years; mean body mass index, 28.7 ± 3.2 kg/m²) included in this study, 29 (69.0%) had poor sleep quality (PSQI > 5.5), and 27 were diagnosed with OSA (64.3%) (mild = 16/moderate = 9/severe = 2). Six were treated with MAD therapy, which significantly improved the REI (p < 0.01), SpO_{2 min} (p < 0.001), ESS score (p < 0.001), reaction times (p < 0.01), and sleep quality. A significant reduction in reaction times suggests that OSA treatment can improve kinetic vision. Future studies should systematically evaluate the impact of sleep-disordered breathing on kinetic vision in athletes.

The examination of jaw movement during exercise is essential for an improved understanding of jaw function. Currently, there is no unified view of the mechanism by which the mandible is fixed during physical exercise. We hypothesized that during strong skeletal muscle force exertion in dynamic exercises, the mandible is displaced to a position other than the maximal intercuspal position and that mouth-opening and mouth-closing muscles simultaneously contract to fix the displaced mandible. Therefore, we simultaneously recorded mandibular jaw movements and masticatory muscle activities during dynamic trunk muscle force exertion (deadlift exercise) in 24 healthy adult males (age, 27.3 ± 2.58 years). The deadlift was divided into three steps: Ready (reference), Pull, and Down. During Pull, the mandibular incisal point moved significantly posteriorly (−0.24 mm, p = 0.023) and inferiorly (−0.55 mm, p = 0.019) from the maximal intercuspal position. Additionally, temporal, masseter, and digastric muscles were activated simultaneously and significantly during Pull (18.63 ± 17.13%, 21.21 ± 18.73%, 21.82 ± 19.97% of the maximum voluntary contraction, respectively), with maintained activities during Down (p < 0.001). Thus, during dynamic trunk muscle force exertion, the mandibular incisal point moved to a posteroinferior position without tooth-touch (an open-mouth position). Simultaneously, the activities of the mouth-opening digastric muscles and the mouth-closing temporal and masseter muscles led to mandibular fixation, which is a type of mandible fixing called bracing.

Oral appliances (OA), a common treatment modality for obstructive sleep apnea (OSA), are not suitable for patients with nasal obstruction. Rhinomanometry, the gold standard technique to assess nasal airway resistance, is not readily available in sleep dentistry clinics. We demonstrate the use of a portable lightweight peak nasal inspiratory flow (PNIF) rate meter to objectively assess nasal airflow and utilized the Nasal Obstruction Symptom Evaluation (NOSE) scale to subjectively assess nasal obstruction in 97 patients with OSA and 105 healthy controls. We examined the correlations between the following variables between the groups: demographics, body mass index, PNIF, NOSE scale scores, apnea–hypopnea index (AHI), minimum SpO₂ (SpO₂min), Mallampati classification, and Epworth Sleepiness Scale (ESS) scores. Patients with OSA had significantly lower PNIF values and higher NOSE scores than controls. In the patient group, PNIF was not significantly correlated with AHI, SpO₂min, Mallampati classification, or NOSE or ESS scores. Lower PNIF values and higher NOSE scores suggested impaired nasal airflow in the OSA group. As daytime PNIF measurement bears no relationship to AHI, this cannot be used alone in predicting the suitability of treatment for OSA with OA but can be used as an adjunct for making clinical decisions.

The aim of this study was to evaluate the relationship between pain intensities and psychosocial characteristics in middle-aged and older patients with temporomandibular disorders (TMDs) and burning mouth syndrome (BMS). Subjects were selected according to the Research Diagnostic Criteria for TMD (n = 705) and International Association for the Study of Pain criteria for BMS (n = 175). Patients were then divided into two age groups: 45-64 years (middle-aged, Group A) and 65-84 years (older, Group B). Pain intensity and depression and somatization scores were evaluated in both groups. In BMS patients, present and worst pain intensities were significantly higher in Group B than in Group A {4.6 [95% confidence interval (CI) = 4.0-5.2] vs. 3.5 [95% CI = 3.1-3.9] and 5.9 [95% CI = 5.2-6.4] vs. 5.0 [95% CI = 4.5-5.6], respectively; P < 0.05}, with no difference observed in TMD patients. The depression and somatization scores were significantly higher in Group A than in Group B among BMS patients [0.57 (95% CI = 0.45-0.69) vs. 0.46 (95% CI = 0.34-0.59) and 0.537 (95% CI = 0.45-0.63) vs. 0.45 (95% CI = 0.34-0.55); P < 0.05], with no difference observed in TMD patients. The results of the present study indicate that pain intensities and psychosocial characteristics in BMS appear to differ between middle-aged and older patients. (J Oral Sci 57, 355-360, 2015)

Summary: The aims of this study were to examine the change of occlusal contact area following the increment of clenching intensity using silicone materials and electromyography (EMG) in normal subjects and to compare direct intra‐oral examination with indirect examination using dental casts mounted by means of two impression methods. Participants were 7 men and 5 women with no more than one missing tooth per quadrant and no pain in the head and neck region. During the task, intercuspal position was maintained with minimal force, 20% maximum voluntary contraction (MVC) and 40% MVC using electromyography visual feedback. Three types of occlusal contact examinations were performed with the aid of blue silicone material in randomised order: (i) intra‐oral direct occlusal contact examination (DE), (ii) indirect occlusal contact examination with dental casts using conventional impression method (IEC) and (iii) using occlusal impression method (IEO). Total occlusal contact area during DE and IEO significantly increased from baseline to 20% MVC and from baseline to 40% MVC, but not during IEC. Total occlusal contact area during DE in all tooth clenching conditions was significantly larger compared to IEO and IEC (P < 0·05). At 40% MVC, total occlusal contact area during IEO was significantly larger than during IEC (P < 0·05). These findings suggest that indirect occlusal contact examinations may not accurately reflect the intra‐oral occlusal condition. If the intra‐oral condition is reproduced using dental casts, these findings also suggest the occlusal impression method was more accurate compared to the conventional method (240 words).

Summary: This study examined the influence of narrative instructions on the occlusal contact area, occlusal contact point and masticatory muscle activities in normal subjects. Twelve healthy men and 12 healthy women with no more than one missing tooth per quadrant participated. Surface EMG was recorded from the masseter and temporal muscle. As a control measurement, intercuspal position was maintained to produce a habitual clenching record (NCR) while the occlusal contact area and occlusal contact point was recorded by means of silicone material. Subsequently, the occlusal contact area was recorded with the narrative instruction for minimum clenching record (MCR), light clenching record (LCR) and strong clenching record (HCR). While the EMG activity (%MVC) increased modestly from MCR to LCR (from 9·3 ± 2·0% to 11·5 ± 1·5%), the occlusal contact area increased rapidly (from 17·2 ± 11·3 mm² to 26·8 ± 15·6 mm²) (P < 0·05). Both EMG activity and occlusal contact area increased gradually from LCR to NCR (to 17·7 ± 2·0% and to 31·4 ± 14·2 mm², respectively). Finally, EMG activity still increased from NCR to HCR (to 44·5 ± 3·7%) (P < 0·05), but the occlusal contact area remained stable (to 36·8 ± 16·6 mm²). Occlusal contact points at left posterior, right posterior, anterior and total area were not significantly different between each task. This study showed that narrative instructions while recording the bite can result in largely stable occlusal contact area. An adequate narrative instruction may therefore contribute to taking a stable occlusal recording in natural dentition.

Summary: This study explored the influence of the thickness of silicone registration material on evaluation of the occlusal contact area and number of occlusal contact points, during increasing tooth clenching conditions in normal subjects. Twenty‐four subjects with no more than one missing tooth per quadrant participated. Surface electro‐myography was recorded from the masseter muscle. As a baseline measurement, intercuspal position was maintained with minimal force, and occlusal contact was recorded using blue silicone material. Occlusal contact was also recorded at 20% maximum voluntary contraction (MVC) and 40% MVC using visual feedback. The occlusal contact area and number of occlusal contact points were analysed using five levels of thickness of silicone registration material: Level 1 (0–149 μm); Level 2 (0–89 μm); Level 3 (0–49 μm); Level 4 (0–29 μm); and Level 5 (0–4 μm). The anterior part and the left and right posterior regions of the dental arch were analysed separately. At all detection levels, the occlusal contact area significantly increased from baseline to 20% MVC and to 40% MVC in the molar area (P < 0·05). In the anterior part, the occlusal contact area significantly increased from baseline to 20% MVC and to 40% MVC only when using Level 5. The number of occlusal contact points significantly increased from baseline to 20% MVC and to 40% MVC only when using Level 5 in the molar area (P < 0·05). It suggested that occlusal contacts may be different at low tooth clenching intensity with potential effects on the teeth or periodontal tissues.

This study was conducted to assess the psychological characteristics of, and determine the effectiveness of group cognitive-behavioral (CB) treatment for, patients with burning mouth syndrome (BMS). The baseline characteristics of 24 female patients (age 69.7 ± 5.9 years) and an identical number of healthy female control subjects (age 69.2 ± 5.5 years) were compared. The patient group had significantly higher anxiety scores (P < 0.05) at baseline. A brief group CB intervention was delivered in a small-group format. Two sessions were planned 6 months apart. A numeric rating scale (NRS) was used to assess pain intensity. Anxiety was evaluated using a state and trait anxiety inventories. Present pain intensity decreased after both the first and second sessions. The session effect was significant (P = 0.02), but no repeat effect was found (P = 0.19). The state anxiety inventory score also decreased after the second session. The session effect was significant (P < 0.01), as was the repeat effect (P < 0.01). The trait anxiety inventory score decreased after the second session, and the session effect was significant (P = 0.013), but the repeat effect was not (P = 0.93). The results suggest that a brief group CB intervention reduces pain intensity and anxiety in patients with BMS. (J Oral Sci 55, 17-22, 2013)