Fibrous ceramic aluminum silicate as an alternative to asbestos liners

Priest, George; Horner, Jack A.

doi:10.1016/0022-3913(80)90046-3

Cited by 13 publications

(3 citation statements)

References 27 publications

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“…This enhanced setting expansion has generally been accepted, though some workers, preferring a lower setting expansion, have advocated the use of a dry, waterproofed asbestos liner (Fusayama, 1959a(Fusayama, , 1959bHanari, 1967), or have recommended dispensing altogether with the rigid metallic ring and its liner (Finger and Jorgensen, 1980). Recently, it was suggested that the use of asbestos ring liners could be regarded as a health risk (Priest and Horner, 1980). The currently accepted threshold limit value for asbestos fibers longer than 5 pum, in air, ranges from 0.2 fibers cm-3for crocidolite to 2 fibers cm-3 for chrysotile (American Conference of Government Industrial Hygienists, 1986), and it has been stated that this limit can be considerably exceeded when dental castings are recovered from asbestos-lined casting rings (Yli-Urpo et al, 1982).…”

Section: Introductionmentioning

confidence: 99%

“…Received for publication December 1, 1987 Accepted for publication August 15, 1988August 15, 1366 Recently, it was suggested that the use of asbestos ring liners could be regarded as a health risk (Priest and Horner, 1980). The currently accepted threshold limit value for asbestos fibers longer than 5 pum, in air, ranges from 0.2 fibers cm-3for crocidolite to 2 fibers cm-3 for chrysotile (American Conference of Government Industrial Hygienists, 1986), and it has been stated that this limit can be considerably exceeded when dental castings are recovered from asbestos-lined casting rings (Yli-Urpo et al, 1982).…”

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The Effect of Casting Ring Liners on the Potential Expansion of a Gypsum-bonded Investment

Earnshaw

1988

J Dent Res

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Cellulose paper (used wet) and ceramic paper (used dry) are replacing asbestos paper as cushioning ring liners in dental casting. A study was made of the effects of all three of these materials on the setting and subsequent thermal expansion of a gypsum-bonded cristobalite casting investment (WIP = 0.40). Thennal expansion measurements were made on the same specimens that were produced during the setting expansion tests.Control specimens setting against a smooth dry surface showed a total expansion of 1. 7%. Specimens setting against dry ceramic liners had similar total expansions, in the range 1. 6 to 1. 7o. Specimens setting against either of the wet lining materials showed an increased total expansion (in the range 2.2 to 2.3%), by virtue mainly ofa large increase in setting expansion.In order for reproducible setting expansion results to be obtained with wet liners, it was necessary to control the amount of absorbed water carefully. Dry asbestos and dry cellulose liners gave higher expansions than pre-wetted ones, since they abstracted water from the mix, reducing its effective WIP ratio (giving a thicker mix), and then functioned as wet liners.These results suggest that, at least as far as potential investment expansion is concerned, wet cellulose liners have an effect similar to that of the traditional wet asbestos liners. Dry ceramic liners give a much lower investment expansion, and when these liners are used, an investment with an increased measured expansion could be an advantage.J Dent Res 67 (11):1366(11): -1370(11): , November, 1988 Introduction.In most dental casting techniques, the investment sets, and is then heated, in a heat-resisting alloy casting ring. The need for a soft ring liner, to reduce the restriction to investment expansion, was first suggested by Souder, who recommended asbestos paper for the purpose (Hollrnback and Rhoads, 1960;Hollenback, 1962Hollenback, , 1964. Since dry asbestos readily absorbs water, the ring liner was pre-wetted to prevent its absorbing water from the unset investment mix. The technique of lining the casting ring with wet asbestos was described by Taylor et al. (1930). From then until comparatively recent times, the use of a wet asbestos liner was a standard procedure.It was soon recognized that the wet ring liner produced an increased setting expansion of the investment, by virtue of socalled "hygroscopic expansion". Scheu (1935) reported that an investment mix setting in contact with wet asbestos paper had its setting expansion raised from 0.25 to over 1%.He found that dry asbestos paper also increased the setting expansion, since it was rapidly wetted by absorption of water from the unset investment mix. This enhanced setting expansion has generally been accepted, though some workers, preferring a lower setting expansion, have advocated the use of a dry, waterproofed asbestos liner (Fusayama, 1959a(Fusayama, , 1959bHanari, 1967), or have recommended dispensing altogether with the rigid metallic ring and its liner (Finger and Jorgensen, 1980).Received for p...

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Section: Introductionmentioning

confidence: 99%

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The Effect of Casting Ring Liners on the Potential Expansion of a Gypsum-bonded Investment

Earnshaw

1988

J Dent Res

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“…For many years, the material used to coat these cylinders was asbestos due to its mechanical properties, heat resistance, and incombustibility. Although this product is currently withdrawn from the market due to its carcinogenic properties, its substitute, ceramic paper, has also been reported to be as dangerous as asbestos, because it contains fibres of a size that also produce lung cancer [ 29 , 30 , 31 , 32 ]. In the cylinder, a dry strip of asbestos was glued by carefully adapting it to the internal face of the cylinder, a strip that when peeled off dispersed the particles of this material.…”

Section: Discussionmentioning

confidence: 99%

Prevention of Occupational Hazards Due to Asbestos Exposure in Dentistry. A Proposal from a Panel of Experts

Anaya-Aguilar

Bravo

Magán‐Fernández

et al. 2022

IJERPH

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Asbestos in all its forms is a Group 1 material agent with proven carcinogenic effects in the human being since 1977. Exposure to asbestos can be considered unsafe. The use of asbestos in the field of dentistry had a common use in the manufacture of dental prostheses in the 1960s and 1970s. Taking into account the long induction period of this agent and the plausibility for being a risk factor in dentistry, the objective of this study is to propose a plan for the prevention of occupational risks due to asbestos exposure in dentistry by means of the contribution of a panel of experts. An Expert Panel (EP) approach was used in which a group of nine experts identified and documented the use of asbestos in the dental profession. EP was created and followed the protocol in accordance with the EuropeAid Assessment Guidelines. As a result of this study, EP documented the common use and sources of asbestos in dentistry in prosthetic materials, dental dressings, and in the coating of casting cylinders. EP also created a consensus document on the priority measures for the Plan for the Prevention of Risks from Asbestos in Dentistry, based on previous reports from the European Commission Senior Labour Inspectors’ Committee. The document concluded that obtainment of information, receiving specific training on the subject and performing epidemiological studies, and the proper risk assessments were the priority measures to adopt.

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A thermoanalytical study on non-asbestos ring-lining materials for dental application

Wakasa

Matsui

Yamaki

1990

J Mater Sci: Mater Med

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Fibrous ceramic aluminum silicate as an alternative to asbestos liners

Cited by 13 publications

References 27 publications

The Effect of Casting Ring Liners on the Potential Expansion of a Gypsum-bonded Investment

The Effect of Casting Ring Liners on the Potential Expansion of a Gypsum-bonded Investment

Prevention of Occupational Hazards Due to Asbestos Exposure in Dentistry. A Proposal from a Panel of Experts

A thermoanalytical study on non-asbestos ring-lining materials for dental application

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