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Biomedical subjects

C H Gibbs

Publications and source records attributed to C H Gibbs.

At least 37 records · Page 2Linked to original sources
PubMed1984

Investigation of chewing patterns in deep-bite malocclusions before and after orthodontic treatment.

A knowledge of chewing provides a better understanding of normal jaw movement and can help form a basis for assessing the effects of malocclusion on jaw function. This study was conducted to describe the effects of deep-bite malocclusion on masticatory function and to determine what changes may occur with orthodontic correction. Five subjects, each exhibiting deep overbite in the early permanent or adult dentition, were selected for this study. Two subjects had Class II, Division 1 malocclusions, and the other three had Class I malocclusions. By means of the "replicator system" jaw movements during border movements and unilateral chewing were recorded and analyzed by computer plots. The typical chewing pattern of all five subjects was characterized by midsagittal opening, wide lateral closing movements, tooth gliding, and a pause at the intercuspal position and during swallowing. Comparison of these findings with chewing data from normal children in previous studies indicated that the deep-bite malocclusion did not create a major disturbance in chewing. Some differences between the preoperative and postoperative condition were noted, however. Prior to treatment, three subjects showed a nearly vertical chewing cycle which avoided tooth contact at the border path. Following treatment, all subjects showed a greater coincidence between the closing chewing path and the lateral border movement. This indicated more gliding tooth contact after treatment. Following deep-bite correction, the border paths showed a refinement of the intercuspal position (IP) and an increased steepness in lateral tooth guidance near IP. The total vertical component of tooth guidance was reduced by treatment.

Adolescent↗
PubMed1982

The instantaneous hinge axis - its reproducibility and use as an indicator for dysfunction.

This study investigated irregularities in hinge movement in 113 subjects. These irregularities were analyzed by computer with an instantaneous three-dimensional "screw axis method." The variation in hinge movement was measured by the dispersion of the hinge axis instant centers. Dispersion of instant centers was greater for muscle pain patients than for the normal, indicating that instant center data could make a contribution to diagnosis and treatment planning.

Adult↗
PubMed1981

Occlusal forces during chewing and swallowing as measured by sound transmission.

Forces during the phase of occlusal contact during chewing and swallowing are surprisingly high (36.2% and 41%), about 40% of the subject's maximum biting force. Previous studies using transducers in fixed partial dentures measured only a portion of the total force and have given the impression that chewing forces are much less than the data reported in this study. The importance of occlusal stability in the intercuspal position is of utmost clinical significance. Steep anterior guidance does not appear to expose the teeth to extreme lateral forces. The gliding contacts of the teeth while entering and leaving the intercuspal position have been shown to be of short duration and low magnitude when compared with the forces generated in the intercuspal position. During chewing, the peak occlusal force occurred well after the peak EMG activity. EMG activity by itself does not directly correlate with the force generated during chewing. The sound transmission method for measuring interjaw force during chewing, which was developed as part of this project, proved to be practical for research purposes. No intraoral devices are required, and the time relationship to force is accurate to within 15 ms.

Adolescent↗
PubMed1981

Chewing patterns in normal children.

Chewing patterns are precisely plotted in deciduous, mixed and permanent dentitions. These show a progression from a large component in the opening movement with a more medial closing path in the deciduous dentition, to a more vertical overall pattern with the closing path lateral to the opening path in the early permanent dentition.

Adolescent↗
PubMed1981

Direct measurement of loads at the temporomandibular joint in Macaca arctoides.

This paper describes a novel technique of directly measuring loads at the condyle in Macaca arctoides and provides recordings on one animal while measuring loads at the TMJ. This study is the first to actually measure loads directly at the articulating surfaces of the condyle. The data collected in this study confirm Hylander's data that the TMJ is a stress-bearing joint. With this pilot study, observations which can be made are: 1) The loads at the condyle are minimal during posterior chewing of both soft and hard foods (1-3 lb), and 2) during mastication of food the load (3-4 lb) at the condyle is larger than for posterior chewing. It was demonstrated during the calibration of the transducer that as the condyle translates forward over the articulating eminence during opening, a load is produced on it which is as large as the load present during incisal biting. Since recordings were only successfully taken on one animal, the above observations must be confirmed with further experiments.

Animals↗
PubMed1978

An evaluation of mandibular border movements: their character and significance.

1. A comparison of protrusive and lateral condylar border movement pathways of 163 subjects revealed considerable similarity when the frequency of 80% of the pathways was compared with the average pathway. 2. A description of the pathways of posterior cusps during lateral contact gliding movement must consider three simultaneously acting guidance factors: (1) the nonworking condyle pathway, (2) the amount of Bennett movement or the working-side condyle displacement, and (3) the anterior guidance or working-side tooth contacts. 3. A Bennett movement of 2.5 to 3.5 mm caused a dramatic flattening of lateral movement pathways of the molar cusp as seen in the frontal plane. The steepness of neither the anterior guidance nor the nonworking condylar pathway had much influence on the molar cusp pathway in the presence of this excessive Bennett movement. 4. Viewed in the horizontal plane, excessive Bennett movement contributed to the greatest potential for collisions of molar cusps during lateral movements. This phenomenon was more pronounced on the nonworking side. 5. When the Bennett movement was 0.75 mm or less the tracing in the frontal plane showed that the 40-degree anterior guidance became the dominant influence over molar cusp lateral movement pathways.

Adult↗
PubMed1977

A new articulator emphasizing centric occlusion and the anterior determinants.

A new articulator is described which has the advantages of the rigidity of a simple articulator in the upper member and the flexibility of an adjustable articulator in the lower member. A link between the members and the frame along with the posterior controls establishes a full range of functional chewing movements and defines the extreme lateral or border paths. The articulator has condylar element controls which permit releasing and remounting the mandibular cast in a manner that serves the same function as the split-cast technique, but this method is faster and shows the amount of discrepancy. The condylar element control is an improvement over existing devices for comparing interocclusal records in that it not only indicates differences in position but it also provides quick remounting of the casts in a working articulator. Other features of the articulator are: (1) a condylar lock mechanism which is activated by only a half turn, (2) adjustable spring tension, (3) precise long centric and wide centric controls, (4) an incisal pain which can be removed and replaced on the articulator without changing its setting, (5) a Bennett movement carefully selected to avoid the complication of a pantograph type of face-bow, and (6) a new sponge wall type of mounting plate which supports both casts for simultaneous mounting.

Dental Articulators↗
PubMed1976

Study of gliding tooth contacts during mastication.

Tooth gliding occurs frequently both in the opening (55.9%) and closing (60.5%) chewing strokes. The average glide length was 1 mm. Good occlusions could not be distinguished from poor occlusion on the basis of frequency and length of gliding contacts. The greater the component of lateral movement during the closing stroke, the greater the probability that gliding contacts would occur.

Adult↗