This randomised controlled study investigated the effect of intermittent use of occlusal splints on sleep bruxism compared with that of continuous use by measuring masseter muscle electromyographic activity using a portable electromyographic recording system. Twenty bruxers were randomly allocated to the continuous group and intermittent group. Subjects in the continuous group wore stabilisation splints during sleep for 29 nights continuously, whereas those in the intermittent group wore splints during sleep every other week, that is they used splints on the 1st-7th, 15th-21st and 29th nights. Electromyographic activity of the masseter muscle during sleep was recorded for the following six time points: before (baseline), immediately after, and 1, 2, 3 and 4 weeks after the insertion of a stabilisation splint. The number of nocturnal masseter electromyographic events, duration and the total activity of sleep bruxism were analysed. In the continuous group, nocturnal masseter electromyographic events were significantly reduced immediately and 1 week after the insertion of the stabilisation splint, and duration was reduced immediately after the insertion (P < 0·05, Dunnett's test), but no reduction was observed at 2, 3 and 4 weeks after insertion. In the intermittent group, nocturnal masseter electromyographic events and duration were significantly reduced immediately after and also 4 weeks after insertion of the stabilisation splint (P < 0·05, Dunnett's test). The obtained results of the present exploratory trial indicate that the intermittent use of stabilisation splints may reduce sleep bruxism activity for a longer period compared with that of continuous use.

Although masticatory performance was not decreased in the unilateral group, the degree of mastication predominance was increased. Decreased masticatory performance was observed in the bilateral group, and for foods with normal hardness and soft foods, the degree of mastication predominance was increased. These results suggested that mastication predominance should be considered in the recovery of masticatory performance in patients with missing posterior teeth.

Dentists occasionally experience occlusal dysaesthesia (OD) patients, who complain of bite discomfort without evident occlusal abnormalities. It is suggested that this condition is related to somatosensory abnormalities of the trigeminal system and/or psychological problems such as somatoform disorders. The aim of this study was to investigate the characteristics of OD with a bio-psycho-social approach. Twelve OD patients (10 women, two men; mean age 54.7 years) and twelve healthy volunteers (10 women, two men; mean age 54.8 years) were selected. They were assessed using (i) interdental thickness discrimination ability test using 2-, 5- and 10-mm-thick standard blocks and 12 test blocks that were thinner or thicker than the corresponding standard block and (ii) psychological tests: General Health Questionnaire (GHQ60) and Profile of Mood States (POMS) brief-form. There was no significant difference in the interdental thickness discrimination ability between OD patients and controls (mixed-model anova, P=1.000). Regarding psychological tests, there were no significant differences between OD patients and controls in the total scores for either GHQ60 (P=0.143) or POMS brief-form (P=0.319) (Wilcoxon's test). However, OD patients showed significant differences from controls in several subscales, that is, 'somatic symptoms' (P=0.039) and 'severe depression' (P=0.039) for GHQ60 and 'depression-dejection' (P=0.014) and 'vigour' (P=0.008) for POMS brief-form (Wilcoxon's test). These results suggest there is no difference in interdental thickness discrimination ability between OD patients and normal controls, but OD patients tend to score higher on psychosomatic distress.

We aimed to investigate mastication predominance in healthy dentate individuals and patients with unilateral posterior missing teeth using objective and subjective methods. The sample comprised 50 healthy dentate individuals (healthy dentate group) and 30 patients with unilateral posterior missing teeth (partially edentulous group). Subjects were asked to freely chew three kinds of test foods (peanuts, beef jerky and chewing gum). Electromyographic activity of the bilateral masseter muscles was recorded. The chewing side (right side or left side) was judged by the level of root mean square electromyographic amplitude. Mastication predominance was then objectively assessed using the mastication predominant score and the mastication predominant index. Self-awareness of mastication predominance was evaluated using a modified visual analogue scale. Mastication predominance scores of the healthy dentate and partially edentulous groups for each test food were analysed. There was a significant difference in the distribution of the mastication predominant index between the two groups (P < 0·05). The mastication predominant score was weakly correlated with self-awareness of mastication predominance in the healthy dentate group, whereas strong correlation was observed in the partially edentulous group (P < 0·05). The results suggest that the individuals with missing unilateral posterior teeth exhibited greater mastication predominance and were more aware of mastication predominance than healthy dentate individuals. Our findings suggest that an objective evaluation of mastication predominance is more precise than a subjective method.

The primary objective of rehabilitating occlusion is to improve stomatognathic function in patients experiencing dysfunction in mastication, speech, and swallowing as a consequence of tooth loss. The procedure of occlusal treatment involves improving the morphology and the stomatognathic function. Several practical methods and morphological endpoints have been described in occlusal rehabilitation. We made a selection of these (mandibular position, occlusal plane, occlusal guidance, occlusal contact, face-bow transfer, use of an adjustable articulator and occlusal support) and performed a literature review to verify the existence of compelling scientific evidence for each of these. A literature search was conducted using Medline/PubMed in March 2011. Over 400 abstracts were reviewed, and more than 50 manuscripts selected. An additional hand search was also conducted. Of the many studies investigating stomatognathic function in relation to specific occlusal schemes, most studies were poorly designed and of low quality, thus yielding ambiguous results. Overall, there is no scientific evidence that supports any specific occlusal scheme being superior to others in terms of improving stomatognathic function, nor that sophisticated methods are superior to simpler ones in terms of clinical outcomes. However, it is obvious that the art of occlusal rehabilitation requires accurate, reproducible, easy and quick procedures to reduce unnecessary technical failures and/or the requirement for compensatory adjustments. Therefore, despite the lack of scientific evidence for specific treatments, the acquisition of these general skills by dentists and attaining profound knowledge and skills in postgraduate training will be necessary for specialists in charge of complicated cases.