Search

Heatless Glass® (HG) was applied to the basal surface of dentures as a coating material. To evaluate the influence of this material on the retentive force of the dentures, the adhesive force of pairs of resin specimens (heat curing resin), metal specimens (Co–Cr alloy), and HG metal specimens (Co–Cr alloy coated with HG), using tap water or resting saliva as a medium was measured, and the following results were obtained. (i) The adhesive force of metal specimens coated with HG material was significantly larger (by 2·3–2·6 times) than that of resin materials (P < 0·001), and it was slightly lower (0·8–0·9 times) than that of metal specimens, showing no significant difference (P > 0·10). (ii) The adhesive force of specimens using tap water as a medium was approximately one-half to two-third of that of specimens using resting saliva as a medium. (iii) When resting saliva was used as the medium, the maximum difference in the adhesive force of the specimens among subjects was 1·7 times. (iv) These findings suggested that, from the perspective of adhesive force, HG coating material is suitable for application to the basal surface of dentures. [ABSTRACT FROM AUTHOR]

The purpose of this study, which made use of visual biofeedback, was to determine whether jaw tapping force reproduction is related to the strength of tapping and to investigate how jaw tapping force affects the tapping movement curve. Nine healthy examinees were asked to reproduce jaw tapping force. We found that the ease and method of regulating jaw tapping force differed depending on the target force. We also found that jaw tapping force was regulated by alteration of the jaw opening distance, the duration of the tooth contact phase, the duration of the jaw closing phase, the maximum jaw opening velocity, and the maximum jaw closing velocity. However, the duration of the jaw opening phase and cycle time was not affected by force regulation under our experimental conditions. [ABSTRACT FROM AUTHOR]

Several studies have examined the functional relationship between mandibular movement and head or body posture, but head and body motion during jaw movement have not been extensively investigated. Ten healthy participants performed repetitive jaw tapping movement. Piezoelectric accelerometers were attached on the surfaces of the participant's forehead, mentum, and over the spinous processes of the sixth cervical, twelfth thoracic and third lumbar vertebrae. The direction in which the antero-posterior acceleration signals appeared around the onsets of jaw opening and closing were observed for the period from the 6th to the 25th strokes of the jaw tapping. Around the onset of jaw opening, the forehead and the lumbar vertebra tended to move posteriorly, but the cervical and thoracic vertebrae moved anteriorly with significant frequencies. The directions of the motions of these locations reversed themselves at the beginning of jaw closing; so the motions of the forehead and the lumbar vertebra were opposed again to the ones of the cervical and thoracic vertebrae. The results suggest that the head extend–flex motion often accompanied the jaw open–close movement, and the motions of the neck and trunk existed, which would serve the purpose of promoting the mandible to move smoothly. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate how far tooth impacts were propagated in the body and whether the propagation would be influenced by posture. The impacts were propagated to all recording sites on the head and neck of the 10 examinees tested. In the recordings on the limbs, even at the most distal site, the number of examinees detecting the vibration was seven out of nine examinees. These results showed that the impacts exerted on the tooth were propagated to distal sites of limbs through the bones and soft tissues and implied that the propagated vibration would influence the whole of the body. On the other hand, as the amplitude of propagated vibration was influenced by posture and recording site, the posture during jaw functioning appears to be important. [ABSTRACT FROM AUTHOR]