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D R Gratton

Publications and source records attributed to D R Gratton.

10 recordsLinked to original sources

The performance of conventional, fixed bridgework, retained by partial coverage crowns.

A retrospective study was carried out on 248 partial coverage retained fixed bridges, in 211 patients. All were inserted at an undergraduate dental clinic and their length of service ranged from 1 to 19 years. In 211 prostheses, on which current information was available a total of 20 (9.5%) bridges had failed. The reasons for failure were loss of retention and, to a lesser extent, caries. Using a LIFE TABLE of survival, it was calculated that the percentage of short span, partial veneer retained prostheses that would survive TEN years was 76.5% +/- 5.99% (standard error). This figure is comparable to that quoted for resin-bonded bridges, and hence would militate against the use of conventional partial coverage fixed retainers on intact teeth. Where abutment teeth are heavily restored, full coverage retainers provide a more predictable, long term result.

Adolescent↗

Working time of synthetic elastomeric impression material.

This study will introduce a new method for measuring the working time of elastomeric impression materials, taking into account the perceived shortcomings of existing systems for evaluating these times. The working times of various commercially available polysulfide, addition reaction silicones and polyethers were determined at room temperature (20 degrees C), following storage in a refrigerator (6 degrees C), and at mouth temperature (35 degrees C). At room temperature, the polysulfides demonstrated the longest working times and the silicones the shortest. Both the polysulfides and the silicones had longer working times following storage at 6 degrees C for 24 hours. However, the polyethers were found to be unusable at this temperature. All the impression materials had shorter working times when placed into the testing apparatus, which had been heated to mouth temperature.

Dental Impression Materials↗