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Biomedical subjects

T F Watson

Publications and source records attributed to T F Watson.

79 records · Page 5Linked to original sources
PubMed1976

Field accumulation of aflatoxin in cottonseed as influenced by irrigation termination dates and pink bollworm infestation.

Aflatoxin accumulation in Deltapine 16 cottonseed, grown in Yuma, Ariz., in a 3-year study, was significantly influenced by the timing of irrigation terminations and by level of pink bollworm infestations. In 1971 and 1972, termination of irrigations by early August resulted in significantly less aflatoxin than in plots where two additional irrigations were applied. Significantly less aflatoxin also was found in the 1971 and 1973 plots where low levels of pink bollworm infestations were maintained.

Aflatoxins↗
PubMedDate not supplied

The attachment of mineralised tissues to coverslips for observing dynamic events by confocal microscopy.

In confocal scanning optical fluorescence microscopy, using high-aperture oil immersion lenses, the best images are obtained for focus planes immediately under the coverslip, or under a continuation of the coverslip with a medium with the same, high refractive index. Therefore placing the coverslip with a layer of oil underneath it is an advantage if the sample will allow it. If experimental manipulations that can displace the coverslip are involved,--for example, attempts to make dynamic observation of fluid flow--the coverslip is best cemented to the sample with a high-index material. This report describes the use of adhesive systems developed for restorative dentistry to achieve a durable attachment of dental tissues to microscope coverslips. The technique described in this paper has been used for monitoring real-time fluid movement in dentine. The samples were examined with a high-frame-rate confocal microscope (a tandem scanning microscope). The adhesive technology also could be utilised in the microscopic preparation of other porous translucent materials.

Dentin↗
PubMedDate not supplied

Applications of high-speed confocal imaging techniques in operative dentistry.

All confocal scanning optical microscopes are suitable for making high-resolution images of many structures in teeth under near normal conditions. If the microscope can operate at high speed, then the number of applications widens considerably. The high-frame speed of the tandem scanning reflected light microscope (TSM) enables real-time examination of teeth in vivo, especially when the microscope is configured with a stabilising objective, featuring internal focusing elements. Experimental procedures examined microscopically on extracted teeth can include the cutting of the hard tissues, observation of fluid flow in dentine, the application of adhesives, and the fracturing of adhesive interfaces under load. Undertaking experiments where time is an important function has improved our knowledge of many of the materials/substrate interactions involved in dental operative procedures. Storing images on media other than video tape can be expensive, but reductions in the cost of computer memory is making digitisation and storage of images in real-time more widely available.

Dental Materials↗
PubMedDate not supplied

In vitro evaluation of five alternative methods of carious dentine excavation.

This in-vitro, split-tooth study aimed to evaluate the efficiency (time taken) and effectiveness (quantity of dentine removed) of four techniques of carious dentine excavation (bur, air-abrasion, sono-abrasion and Carisolv gel) compared to conventional hand excavation. Eighty freshly extracted human molars were assigned to four experimental groups (n = 20), sectioned longitudinally through occlusal lesions and pre-excavation colour photomicrographs obtained. Using the natural autofluorescence of carious dentine (detected using confocal laser scanning microscopy) as an objective and reproducible guide, carious dentine removal was assessed in each half of the split tooth sample, comparing hand excavation to the test method. The time taken to reach a cavity floor that was hard to a dental probe was noted and final colour photomicrographs were taken. From the results, it was concluded that bur excavation was quickest but overprepared cavities relative to the autofluorescent signature, whereas Carisolv excavation was slowest but removed adequate quantities of tissue. Sono-abrasion tended to underprepare whereas air-abrasion was more comparable to hand excavation in both the time and amounts of dentine removed. Conventional hand excavation appeared to offer the best combination of efficiency and effectiveness for carious dentine excavation within the parameters used in this study.

Air Abrasion, Dental↗
PubMedDate not supplied

Dentine caries: take it or leave it?

In modern dentistry the primary aim when excavating carious dentine is to eradicate only the highly infected, irreversibly demineralized and denatured biomass in order to allow effective restoration of the cavity, restoration of the surface anatomy of the tooth and to prevent disease progression. However, the boundary between this superficial zone of dentine requiring excavation and the deeper, affected but repairable tissue is not always obvious either in the clinic or in the research laboratory. The inherent subjectivity in detecting this excavation boundary can result in clinically significant differences in the quality and quantity of dentine removed by different operators and makes the in vitro comparison of newer excavation techniques more difficult. This article discusses the rationale behind carious dentine excavation and the criteria available to the dentist, both clinical and laboratory, to help identify the dentine requiring removal.

Bacteria↗
PubMedDate not supplied

Resin-modified glass-ionomer materials. Part 2: clinical aspects.

The resin-modified (light-cured) glass-ionomer cements are a relatively recent introduction to restorative dentistry, especially in their restorative form. In Part 1 of this review, the physical and biological properties of these materials were discussed. In this second paper their clinical applications and handling will be addressed.

Composite Resins↗