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Biomedical subjects

J A Clayton

Publications and source records attributed to J A Clayton.

At least 19 recordsLinked to original sources
PubMed1992

Comparison of the intercondylar distance and the interfacial width as used with the electronic pantograph.

The electronic pantograph (Pantronic) records mandibular movements and computes the articulator settings. The Pantronic pantograph does not determine the intercondylar distance but approximates it from the interfacial width at the condyles. An average distance of 12.5 mm is subtracted from each side to determine the intercondylar distance. This study recorded 45 patients' articulator intercondylar distances that had been set from a mechanical pantograph and they were compared with the Pantronic's approximation. The difference between the interfacial width and the actual intercondylar distance was 15.1 mm on the right side and 14.9 mm on the left side. A numerical value of 15.0 mm was statistically superior to the Pantronic's 12.5 mm in estimating the average distance between the intercondylar distance and the surface of the skin at the condyle. No statistically significant difference was found between the differences of interfacial width and intercondylar distance values for men and women (p greater than 0.05). The mean intercondylar distance was 56.5 mm on the right side and 56.7 mm on the left side. A statistically significant difference was found between the mean intercondylar distances of men and women (p less than 0.05).

Adult↗
PubMed1991

Effects of changes in articulator settings on generated occlusal tracings. Part I: Condylar inclination and progressive side shift settings.

An occlusal scribing device attached to a fully adjustable articulator was used to generate occlusal tracings. The tracings were analyzed to determine the effect changes in progressive side shift and condylar inclination settings had on molar occlusal morphology. The progressive side shift adjustment affected the cusp height and ridge and groove position, primarily in the nonworking excursion. The condylar inclination adjustment affected the cusp heights in the protrusive and nonworking excursion without affecting the working excursion.

Dental Articulators↗
PubMed1991

Effects of changes in articulator settings on generated occlusal tracings. Part II: Immediate side shift, intercondylar distance, and rear and top wall settings.

An occlusal scribing device attached to a fully adjustable articulator was used to generate occlusal tracings. The tracings were analyzed to determine the effect changes in immediate side shift, intercondylar distance, and rear and top wall settings had on molar occlusal morphology. When ranked from greatest to least effect, a 0.2 mm change in the immediate side shift setting had the greatest effect on the occlusion, whereas a 5-degree change in the rear and top wall settings had the least effect.

Centric Relation↗
PubMed1990

A clinical study of joint sounds in subjects with restored occlusions.

It has been implied that temporomandibular joint sounds must be treated to eliminate the sounds before restorative treatments are attempted. This study explored the possibility that joint sounds do not present a problem when other symptoms are absent. A group of 35 subjects with restored occlusions were studied for the presence of temporomandibular joint dysfunction symptoms using clinical examination, questionnaires, and the pantographic reproducibility index. Forty-six percent had some degree of temporomandibular joint dysfunction. Seventeen of 18 subjects (94%) with joint sounds were free of other symptoms. Therefore, the use of joint sounds as a symptom of temporomandibular joint dysfunction is questionable when not accompanied by other clinical symptoms. Subjects who had temporomandibular joint dysfunction symptoms were treated with occlusal splint therapy and occlusal adjustments. The period of time to eliminate the symptoms was 2 to 16 weeks with an average of 7 weeks. This study concludes that the presence of only joint sounds does not seem to be a hindrance to restorative treatments.

Adult↗
PubMed1990

[Occlusion in osseointegrated prosthesis].

Occlusion plays a significant role in the successful restoration of natural teeth and in replacing missing teeth. Over the decades, standards for occlusion have been established. Implants, osseointegrated, have provided a rigid, usable abutment for restorations of occlusion and for the replacement of missing teeth. The natural tooth, due to it's mobility dynamics, presents problems related to occlusion. The osseointegrated, rigid implant, due to it's lack of mobility, presents in many respects problems related to occlusion. Substantial amounts of research has been presented on implants as it relates to success of osseointegration and acceptance by bone, and the acceptance of oral mucosal tissues to penetration of the implant. Failures of implant fixtures and their parts have been experienced. Not much information has been presented on the causes of failures. The question becomes obvious What is the role of the forces of occlusion? The purpose of this article is to present some aspects of occlusion that are important in restoring natural teeth and complete dentures. The problems in applying these aspects to the osseointegrated, rigid implant will be presented. The factors to consider in the control of the forces of occlusion in using implants will be established. It is not possible to cover all the possibilities of occlusion for implantation. However, the factors to consider in making intelligent choices will be presented.

Bite Force↗
PubMed1989

A graphic comparison of mandibular border movements generated by various articulators. Part II: Results.

A method was described in Part I in which mandibular border movements of a subject can be compared with the movements generated by various articulators (fully adjustable Denar SE and semiadjustable Denar Mark II) by using an electronic pantograph, the Pantronic. The mean values of 12 sets of plots from this device were calculated and graphs were generated. For the subject studied, differences were detected by the Pantronic pantograph between human border movements and those generated by each articulator and method of adjusting it. In the horizontal table, the semiadjustable articulator without immediate side shift always showed the potential of greater errors, especially as excursions started. When the semiadjustable instrument was programmed with immediate side shift, its movements were comparable with the fully adjustable articulator. Neither articulator exactly simulated the subjects' movements.

Dental Articulators↗
PubMed1988

Evaluation of a digitizer and computer system designed to analyze articulator-generated occlusal tracings.

Occlusal tracings generated on a Denar fully adjustable articulator were photographed, projected, digitized, and stored in a computer data file. These steps were accomplished with sufficient accuracy for clinical analysis. This study demonstrated that appropriately referenced tracing data can be transferred accurately into a machine-readable form. Studies of pantographic tracings for mandibular movements are facilitated by this convenient and accurate method of handling data.

Dental Articulators↗
PubMed1988

A graphic comparison of mandibular border movements generated by various articulators. Part I: Methodology.

A method was described by which mandibular border movement of a subject can be compared with the movements generated by various articulators. The fully adjustable articulator, Denar SE, and the semiadjustable instrument, Denar Mark II, were used in this study. The movements were recorded by an electronic pantograph, the Pantronic. The mean values of 12 sets of print-out plots from this device were calculated by using Microsoft Excel software. These mean values were then used by CricatGraph software to generate combined graphs. Both software programs were used with an Apple Macintosh Plus personal computer. The clinical significance of the findings will be discussed in Part II of this study.

Dental Articulators↗
PubMed1986

Comparison of mandibular movements recorded by two pantographs.

Denar and Stuart pantographic tracings were obtained at 10 separate appointments with one patient. Twenty pantographic recordings were transferred to the Stuart fully adjustable articulator. One pantograph from each appointment was used to set the articulator. The second pantograph of each appointment was mounted on the articulator without altering the setting adjustments and compared to the first pantograph of the previous 10 sessions. Overlay tracings were generated on the articulator as a permanent record of how accurately the articulator had been set and to compare measurements to the nearest 0.1 mm. Each working and orbiting path tracing was measured at four locations with a total of 960 measurements. Paired and Student t tests determined statistically significant differences. Mean data showed a 0.007 mm difference between Stuart and Denar recordings and was not statistically significant. Of the 12 lines on each set of tracings, the right vertical working path revealed significant data. Of the 48 measuring sites, the right vertical working path and the left vertical orbiting path displayed noteworthy data.

Dental Articulators↗
PubMed1986

An electronic, computerized pantographic reproducibility index for diagnosing temporomandibular joint dysfunction.

One of the signs and symptoms of TMJ dysfunction is incoordinated mandibular movements. The PRI quantitates the incoordinated movements and gives a muscle dysfunction score and the relative severity of TMJ dysfunction. An electronic, computerized pantograph (Pantronic) has been developed that can be used in place of the mechanical pantograph. This study was undertaken to determine if the Pantronic can be programmed to produce PRI scores that are comparable to the M-pantograph PRI scores. Several programs were written for the computer until the Pantronic PRI was comparable to the M-pantograph PRI. The Pantronic PRI was within zero to 5 points of the M-pantograph PRI in all of the 25 patients studied. Because of this close comparison, studies used to validate the M-pantograph PRI also validate the Pantronic PRI. There was, however, a statistically significant difference (.05 level) between the two PRI scores. In spite of this difference the categories of TMJ dysfunction remained the same. The Pantronic PRI can be determined clinically in 20 to 30 minutes. It can be used to determine the presence and, more important, the absence of TMJ dysfunction; the success of occlusal splint therapy, occlusal adjustment, and restorative treatment; the changes in dysfunction over time; the success of other treatment modalities; and the level of dysfunction in TMJ dysfunction research.

Computers↗
PubMed1986

Electronic PRI consistency in diagnosing temporomandibular joint dysfunction.

Pantographic reproducibility was compared using electronic and mechanical pantographs. The scores were calculated electronically or manually by a single scorer. It can be concluded that (1) with 65.4% of dysfunction-free patients, the electronic pantograph is more consistent than the mechanical pantograph within sessions and over time in recording PRI dysfunction, (2) operators with varying experience need not cause P-PRI fluctuations with dysfunction-free patients, and (3) PRI fluctuations can be caused by temporomandibular joint dysfunction.

Dental Equipment↗