Setting and hygroscopic expansion of investments

Jones, D W; Wilson, H.J.

doi:10.1038/sj.bdj.4802518

Cited by 17 publications

(7 citation statements)

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“…Factors that influence the setting expansion of phosphate‐bonded investment material have been the subject of a number of investigations (2–15). In these studies, steel casting rings have been used most frequently to contain the setting material (5, 7, 8, 10–13), though Junner and Stevens (9) used a circumferentially clamped PVC ring and Hutton and Marshal (14) a split brass mould. These are rigid moulds with a potential to constrain setting expansion in the radial direction.…”

Section: Discussionmentioning

confidence: 99%

“…To prevent this and produce ‘free‐expansion’, lower compliance moulds have been employed, viz. paper (3, 6), duplicating gel (5), or rubber dam (9). Jones and Wilson (5) and Taira et al .…”

Section: Discussionmentioning

confidence: 99%

“…paper (3, 6), duplicating gel (5), or rubber dam (9). Jones and Wilson (5) and Taira et al . (4) adopted an alternative approach, allowing the investment mixture to set in a rigid mould for just long enough for it to gain sufficient strength to be self‐supporting.…”

Section: Discussionmentioning

confidence: 99%

“…The presence of a lining in the steel ring increases the axial setting expansion (Table 1) and is a recognized effect (5, 7, 8). Clearly, the lining is an important factor.…”

Section: Discussionmentioning

confidence: 99%

“…Variables that were investigated were those that have been reported to influence the value of setting expansion (2‐‐15).…”

Section: Methodsmentioning

confidence: 99%

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Measurement of the setting expansion of phosphate‐bonded investment materials: Part I – Development of the Casting‐Ring Test

Lloyd

Yearn

Cowper

et al. 2004

J of Oral Rehabilitation

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The setting expansion is an important property for a phosphate-bonded investment material. This research was undertaken to investigate a test that might be suitable for its measurement when used in a Standard. In the 'Casting-Ring Test', the investment sample is contained in a steel ring and expands to displace a precisely positioned pin. Variables with the potential to alter routine reproduction of the value were investigated. The vacuum-mixer model is a production laboratory variable that must not be ignored and for this reason, experiments were repeated using a different vacuum-mixer located at a second test site. Restraint by the rigid ring material increased expansion, while force on the pin reduced it. Expansion was specific to the lining selected. Increased environmental temperature decreased the final value. Expansion was still taking place at a time at which its value might be measured. However, when these factors are set, the reproducibility of values for setting expansion was good at both test sites (coefficient of variation 14%, at most). The results revealed that with the control that is available reliable routine measurement is possible in a Standard test. The inter-laboratory variable, vacuum-mixer model, produced significant differences and it should be the subject of further investigation.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

“…The presence of a lining in the steel ring increases the axial setting expansion (Table 1) and is a recognized effect (5, 7, 8). Clearly, the lining is an important factor.…”

Section: Discussionmentioning

confidence: 99%

“…Variables that were investigated were those that have been reported to influence the value of setting expansion (2‐‐15).…”

Section: Methodsmentioning

confidence: 99%

See 3 more Smart Citations