Cytotoxicity of dental alloys, metals, and ceramics assessed by Millipore filter, agar overlay, and MTT tests

https://doi.org/10.1067/mpr.2000.107227Get rights and content

Abstract

Statement of Problem: Biocompatibility of dental materials is dependent on the release of elements from the materials. In addition, the composition, pretreatment, and handling of the materials influence the element release. Purpose: This study evaluated the cytotoxicity of dental alloys, metals, and ceramics, with specific emphasis on the effects of altering the composition and the pretreatment. Material and Methods: By using cells from a mouse fibroblast cell line and the agar overlay test, Millipore filter test, and MTT test, cytotoxicity of various metals, metal alloys, and ceramics for dental restoration were studied. Effects of altering the composition of a high noble gold alloy and of pretreatment of a ceramic-bonding alloy were also studied. In addition, the release of elements into the cell culture medium by the materials studied was measured using an inductively coupled plasma optical emission spectrophotometer. The results of the MTT test were analyzed statistically using ANOVA and Scheffé test at a significance level of P <.05. Results: Specimens manufactured from materials intended for dental restorations and handled in accordance with the manufacturers’ instructions were ranked from “noncytotoxic” to “mildly cytotoxic” according to the agar overlay and Millipore filter tests. For the MTT test, no significant differences were observed between these materials and controls, with the exception of JS C-gold and unalloyed titanium. The modified materials were ranked from “mildly cytotoxic” to “moderately cytotoxic” in the agar overlay and Millipore filter tests and from “noncytotoxic” to “moderately cytotoxic” in the MTT test. Thus, cytotoxicity was related to the alloy composition and treatment. The release of Cu and Zn seemed to be important for the cytotoxic effect. Conclusion: Alterations in the composition and the pretreatment can greatly influence the cytotoxicity, and the results stress the importance of carefully following the manufacturers’ instructions when handling dental materials. (J Prosthet Dent 2000;84:229-36.)

Section snippets

Material and methods

By using cells from a mouse fibroblast cell line and the agar overlay test, Millipore filter test, and MTT test, the cytotoxicity of various metals, metal alloys, and ceramics used to fabricate dental restorations was studied. The effects of altering the composition of a high noble gold alloy and of pretreatment of a ceramic-bonding alloy were also studied. By means of inductively coupled plasma optical emission spectrophotometry, the release of elements (by the materials studied) into the cell

Results

The results of the Millipore filter, agar overlay, and MTT tests are listed in Table III.All the ceramics studied were rated “noncytotoxic.” The alloys intended for dental restorations were all rated “noncytotoxic” according to the Millipore filter and the agar overlay methods, with the exception of the JS G-gold, where the cytotoxic effect was influenced by the treatment (Table III).

Changes in the composition of the JS-C gold increased the cytotoxicity to levels comparable to that of Degussa

Discussion

There was no evidence of cytotoxicity in the dental ceramics studied, indicating good biocompatibility in vitro. Reports on biocompatibility problems with dental ceramics in vivo have been rare. Breakdown products of dental ceramics have not been reported to have known toxic effects, and several of the ions in dental ceramics are considered nontoxic.17 Bagambisa et al18 reported that dental ceramics, used as the substrate, impaired the overgrowth of an osteoblastic cell line and suggested that

Conclusions

On the basis of the results of this study, the materials intended for dental restorations were ranked noncytotoxic or mildly cytotoxic. The results revealed that alterations in the composition of an alloy can greatly influence its cytotoxicity and stress the importance of carefully following the manufacturers’ instructions when handling dental alloys. To ensure biocompatibility, alteration of the original composition or mixing of alloys in dental laboratories should be avoided. The release of

Supplementary Files

Acknowledgements

The valuable discussion and support from Dr Arne Hensten-Pettersen are gratefully acknowledged.

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Reprint requests to: Dr Göran Sjögren, Department of Dental Materials Science, Umeå University, SE-901 87 Umeå, SWEDEN, Fax: (46)90-775617, E-mail: [email protected]

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