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Biomedical subjects

C H Gibbs

Publications and source records attributed to C H Gibbs.

At least 19 recordsLinked to original sources
PubMed1991

Analysis of repeated-measure multicycle unilateral mastication in children.

This study examined systematic and random errors associated with repeated-measure, multiple-cycle unilateral mastication in children during single recording sessions with the Replicator system. Twenty-six recording sessions with 17 children (10 boys, 7 girls) were examined. Nine of these children had a functional-shift unilateral crossbite malocclusion and were recorded before and after crossbite correction. Repeated recordings (trials) of mandibular movement during each session were made of right-side chewing of similar-sized pieces of cheese. The following variables were computed for each chewing cycle (stroke): time closed, maximum closure velocity, maximum opening velocity, chewing rate, vertical opening, and lateral deviation. From the multiple cycles of each trial, two pattern descriptors--the average and standard deviation--were determined for each variable. In addition, the mean and variance of these pattern descriptors were determined from the multiple trials of each recording session and were the dependent variables in a stepwise multiple regression analysis, with treatment status, sex, age, dentition stage, crossbite presence, and right side status the independent variables. The results disclosed bias in repeated measures of human chewing in response to adaptation to the recording session; this was evident in the average response but not in the variability of the measures. Sex and functional status of the subjects were associated with the mean and variance of measures describing the chewing pattern.

Adolescent↗
PubMed1990

Biting strength and chewing forces in complete denture wearers.

Most studies concur that denture wearers have only about one fifth to one fourth the bite strength and masticatory force of natural dentition subjects. There appears to be a wide range of acceptable chewing forces, as evidenced by the wide variation in bite strength of natural dentition subjects. However, bite strength and masticatory forces in denture wearers fall below the natural dentition range and therefore it is concluded that denture wearers are handicapped in bite force. The occlusal form of the posterior denture teeth did not significantly influence masticatory force.

Analysis of Variance↗
PubMed1990

Temporomandibular joint forces measured at the condyle of Macaca arctoides.

Forces were measured at the articular surface of the temporomandibular joint (TMJ) condyle in two stump-tail monkeys (Macaca arctoides) during chewing, incisal biting, and drinking and also during aggressive behaviors. Force was measured with a thin piezoelectric foil transducer, which was cemented over the anterior and superior surfaces of the condyle. Wires from the upper and lower surfaces of the foil were insulated between two layers of Teflon tape and run subcutaneously to a telemetry unit, which was implanted in the upper back. Force applied across the foil by the condyle was detected by the telemetry unit and transmitted to an FM radio receiver outside the animal. The FM signals were received and demodulated, and a signal proportional to the force applied between the condyle and the TMJ fossa was displayed on a chart recorder. Data were collected over an 8-day period. The animals were not constrained. The TMJ was found to be load bearing. The greatest force of 39.0 lb (17.7 kg) was measured during feisty vocal aggression. Forces ranged as high as 34.5 lb (15.7 kg) during chewing and 28.5 lb (13.0 kg) during incisal biting. Forces were greater on the working (food) side than on the nonworking (balancing) side by average ratios of 1.4 to 2.6. A large unilateral interference at the most distal molar greatly disturbed chewing. It reduced TMJ forces by 50% or more, and the monkey refused to chew on the side opposite the interference.

Aggression↗
PubMed1989

A preliminary study of the effects of tooth guidance on working-side condylar movement.

Clinical observations have indicated that lateral working-side tooth contacts can produce a posterior shift of the working-side condyle, resulting in pain in the temporomandibular joint. This study examined the influence of lateral retrusive and lateral protrusive tooth guidance on the movements of working condyles of the lateral pole. Four patients with lateral retrusive natural tooth contacts and four patients with lateral protrusive natural tooth contacts were studied. Movement of the lateral pole of the working condyle was recorded under the following conditions: (1) natural teeth in contact, (2) wearing of a mandibular acrylic resin splint that created lateral protrusive or lateral retrusive tooth guidance, and (3) a central bearing screw and bearing plate separating the teeth. The results indicated that the condition of the patient's temporomandibular joints was a crucial factor in consistency of condylar tracings. Condylar tracings from patients with temporomandibular joint condyle-disk lacking coordination were inconsistent and unreproducible. Consistent, reproducible tracings for patients without condyle-disk disorders indicated that lateral retrusive guidance can cause a more posterior pathway of the lateral pole of the working condyle than lateral protrusive guidance. Future studies are necessary to establish the relationship between lateral tooth guidance and temporomandibular disorders.

Adult↗
PubMed1988

Description and clinical evaluation of a new computerized periodontal probe--the Florida probe.

A new periodontal probing system has been developed which incorporates the advantages of constant probing force, precise electronic measurement to 0.1 mm and computer storage of the data. The system includes a probe handpiece, displacement transducer with digital readout, foot switch, computer interface and personal computer. A unique movable arm design enables the probe handpiece to maintain smooth operation and makes it easy to clean and sterilize. Electronic recording of the data (actuated by pressing a foot switch) eliminates errors which occur when probe tip markings are read visually and the data are called to an assistant. Computer storage and analysis of the data facilitates detecting changes in pocket depth and attachment level by rapidly comparing data recorded at different visits. The system was evaluated in 3 experiments using a 0.4 mm diameter tip and a 25 g probing force. The standard deviation of repeated pocket depth measurement was less (0.58 mm versus 0.82 mm) than that of a common probe. With paired readings referenced to an occlusal stent, the standard deviation of repeated attachment level measurements was 0.28 mm. A loss of attachment level was detected to a certainty of 99% with less than a 1 mm change. This is a significant improvement over common probes, which require a 2-3 mm change for equivalent positive identification of change in attachment level.

Computers↗
PubMed1988

Correlation between electronic and visual readings of pocket depths with a newly developed constant force probe.

The purpose of this study was to compare probing measurements obtained using a newly developed constant force electronic probe, which eliminates errors of visual reading and variable force, to those obtained using a standard periodontal probe. The probe was connected to a digital readout through a linear variable differential transformer; the digital readout was connected to a printer and a foot switch. When the probe was in position and the foot switch depressed, the pocket depth was printed to the nearest 0.1 mm. 12 subjects with minimal to early periodontitis were selected for the study. The pocket depths of each patient were recorded electronically utilizing a constant force of 25 g, and conventionally using the same instrument in a "locked" position and visual reading. Probings were performed on each subject by 3 different examiners, on 3 separate occasions 2-3 days apart. The results showed a high correlation between manual and electronic probing. The average correlations for the 3 investigators between examinations were consistently higher for the electronic probings. In comparing the 3 examiners to each other, consistently higher correlations were found for the electronic pocket readings. Correlations for single-rooted teeth were lower for all 3 examiners. The pocket depth measurements recorded when using the manual probe with visual readings were consistently deeper than those obtained using the electronic probe with computer readings. It was concluded that the reproducibility of measurements obtained with the electronic probe was significantly superior to that obtained with a manual probe.

Adult↗
PubMed1988

Attachment level measurements with a constant force electronic probe.

The purpose of the present investigation was to evaluate the reproducibility of probing attachment level measurements using a newly developed constant force electronic probe. The probing force was preset at 25 g (probe diameter 0.4 mm) and was connected to a computer through a variable differential transformer. The measurements were performed on 10 patients with minimal signs of periodontal disease, using individually made acrylic stents. When the probe was in place and a foot switch depressed, the measurement was stored on the computer to the nearest 0.1 mm. The measurements were performed by one periodontist and one hygienist during one visit, and were then repeated by the same periodontist and another hygienist during a second visit. The results showed high correlations between the periodontist and the hygienist during one visit, between the two visits for the periodontist, and between the two hygienists at two different visits. The subject threshold for attachment loss was calculated according to Haffajee and co-workers, and was found to average 0.84 mm for the measurements performed by the periodontist and the hygienist during the same visit. For the periodontist during two separate visits and for the two different hygienists, the average threshold was 0.99 and 1.02 mm, respectively. Duplicate measurements were also performed by one periodontist at one visit on 10 patients with advanced periodontal disease. The average subject threshold for these patients was 0.60 mm. It may be concluded that with the constant force electronic probe, loss of attachment can be detected earlier than when conventional instruments are used.

Dental Hygienists↗
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↗