Barrie R.D. Gillings

Jaw movements' in young adult men during chewing

Abstract Jaw movements of a selected group of subjects were studied by clinical observation, examination of wax occlusal records and mounted casts, photoelectric mandibulography, and oscilloscopic tracings. Subjects were found to have substantially consistent and reproducible patterns of jaw movement during empty and functional chewing exercises. However, the individual patterns could not be predicted from analysis of occlusal status. Mean values of (1) the chewing cycle time, (2) the pause at centric occlusion, (3) maximum opening, (4) maximum movement to the right and left of the midline, and (5) maximum jaw point velocity while opening, closing, and moving to the right and left were obtained for 22 subjects chewing a single peanut on the right and the left sides. Great diversity in chewing patterns was observed, but in general, individual subjects exhibited specific and repetitive patterns. All subjects exhibited a pause in centric occlusion at the end of a closing masticatory stroke. A substantially constant jaw point velocity was observed for most of a chewing cycle when the open-close, close-open, left-right, and right-left components of jaw movements were analyzed separately.

Photoelectric mandibulography: A technique for studying jaw movements

Abstract The apparatus described in this article enables the investigator to record and view, in three dimensions, the movement of a point on a subjects lower jaw during normal and abnormal function, or at rest, with a minimum restriction of head or jaw movements. Jaw movement activities of various types trace characteristic patterns on recording paper, and examination of these records enables the investigator to obtain information on duration of jaw movement, degree of jaw point movement in three dimensions, velocity of jaw point movement at any time during the movement, duration of maximum tooth contact, the jaw position at initial tooth contact, and the occurrence of abnormal or atypical jaw movements. It enables he investigator to follow the effects of various treatments on jaw function by recording a subjects jaw point movement as each phase of treatment is completed, and viewing these records in sequence. It is a comparatively inexpensive, effective, and easily operated device for studying the dynamic aspects of jaw function.

Jaw movements in young adult men during speech

S tudies of jaw movement and position during speech in subjects with natural and artificial teeth have been generally limited to single or multiple measurements of static positions because of the technical difficulties associated with the continuous monitoring of jaw position by the use of direct-measurement, photograhic, or radiologic techniques?-’ Few reports describe techniques for the continuous recording of movements of the jaw during chewing, speech, and swallowing.*> ’ A previously reported technique for monitoring jaw movements on a continuous basis was employed in this study. lo, l1 The nature of the jaw movements made during speech in a group of young adult men was investigated (1) to determine the relationship between jaw positions during performance of a standard speech exercise and (2) to relate the findings to the clinical use of speech tests.

A Photoelectric Method for Recording Jaw Movements

Recent techniques for investigating jaw movements using various mechanical ioinl electrical devices attached to the lower jaw in conjunction xith various recording methods have been described. The effectiveness of some techniques has been reduced by mechanical linLage between the jaxx and the recording, devicee, which could hinder normal function. This jaw movement recording deevice detects movement lby positional change of light sources, eliminating directt connection letwx-een jax alnd recording apparatus. The light sources are attached to a mandibuo lar rod, fixed with adhesive to the labial surfaces of the incisors Thin insulated wires,;power the lights, and their movement is sensedl y small lhotoelectric cells attached to an adjustable lightweight head frame, which relates the photocells to the head without dliscomfort or restriction to head movements or muscles. Mandibular movement is thus aCCOml)anicldby movement of the lights in relation to the 1)hotocells.

Laser-dye ablation technique for removal of carious dentin and enamel

A GaAlAs semiconductor diode laser operating at a wavelength of 796 nm has been sued in conjunction with Indocyanine Green (ICG) dye to ablate carious dentin and enamel from extracted human teeth. The laser-dye ablation technique offers selective ablation as it is controlled by the placement of the ICG dye. In contrast with other laser techniques, the risk of collateral thermal damage is substantially reduced. The diode laser is suitable for ordinary fiber delivery and is cheaper and more compact than the higher power CO2; Er:YAG, Nd:YAG and Argon lasers currently being used by researchers. This paper reports the ablation of dental caries in fifty extracted teeth with various laser diode powers and dye concentrations. The mass of material ablated, temperature rise in the pulp and surface temperature were measured. The ablation was found to be efficient with negligible thermal damage to surrounding tissue. At the same time average surface temperatures reached during ablation may be sufficient to sterilize the treated surface. Hardness measurements and scanning electron microscopy of the laser treated cavity surfaces show the new surfaces to be suitable for placement of a dental filling.