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D J Setchell

Publications and source records attributed to D J Setchell.

29 records · Page 2Linked to original sources
PubMed1984

An assessment of the jet-test method for solubility measurement of dental cements.

The use of the jet-test method for laboratory measurements of dental cement solubilities was explored. Two cements, a glass-ionomer and a silicate, were used as models. Lactic acid concentrations in the range 0.1-0.005 M, ionic strength, the effect of column height, the effect of continuous and intermittent flow, and the effect of temperature were investigated. Several modifications to the jet-test equipment were made as a result of these studies. All the above-mentioned variables were shown to be critical in obtaining reproducibility, and a failure to control them will most probably give invalid results. The mode of wear (which is linear with time in most cases) is shown to include a significant element of erosive wear as well as one based on chemical attack.

Dental Cements↗
PubMed1983

An investigation of the reproducibility of face-bow transfers.

An investigation was conducted to determine the reproducibility of the position of a maxillary cast in two widely-used semi-adjustable articulators when a face-bow transfer was repeated ten times for the same individual. The results obtained with the Dentatus AEB, Whipmix Quickmount and Almore transfer bows were compared. The variations in cast position rarely exceeded +/- 1.0 mm in any of three planes of space and although the results suggested a ranking in accuracy of the three instruments, all were considered clinically acceptable. On the basis of the results observed, face-bow transfer appears to be a reliable clinical procedure and accuracy in the determination of reference locations is unlikely to be negated by subsequent transfer errors, provided that appropriate care is employed.

Adolescent↗
PubMedDate not supplied

In vitro measurement of cuspal strain and displacement in composite restored teeth.

OBJECTIVES: This study was carried out to measure changes in cuspal strain and displacement occurring during placement and polymerization of bonded composite restorations in extracted human teeth in vitro. METHODS: Strains were measured using electrical resistance strain gauges bonded to the buccal and lingual cusps of each specimen and cuspal displacement was recorded with a linear variable differential transformer. Mesio-occluso-distal cavities of two types were prepared in lower molar teeth. Following enamel acid etching and application of a dentine adhesion promoter, specimens were restored incrementally with a light curing posterior composite material. RESULTS: It was shown that the shrinkage of a composite material during polymerization generated stresses which resulted in tensile strains on the tooth surface. Strains of up to 882 microns/m were recorded and a maximum cusp displacement of 14 microns was also measured. These strains were reduced but not eliminated by preparation and restoration a mesio-distal slot running the full length and depth of the restoration. Statistical analysis revealed significantly higher strains and displacement produced on the buccal cusps of teeth that had a reduced cusp width (P < 0.001). CONCLUSIONS: The in vitro restoration of posterior teeth with a bonded composite material generates polymerization stresses which can be recorded as tensile strains and displacements on the tooth surface. Strains measured during composite placement were greater when the remaining cusp width was less. A stress relief procedure resulted in a decrease in cuspal strain and displacement of approximately 30-40%.

Acid Etching, Dental↗
PubMedDate not supplied

Treatment of the worn dentition. 1.

This is the first of two articles concerning the practical techniques involved in reconstruction of the worn dentition. The authors describe some of the procedures available and assess the appropriateness of 'conformative' versus 'reorganized' approaches to the occlusion. They continue by describing some practical aspects of reconstructive work. Part 2 will look at other practical techniques.

Crowns↗