Dentin barrier test with transfected bovine pulp-derived cells.

Growth kinetics of SV40 large T-antigen-transfected bovine pulp-derived cells on dentin were investigated. These cells were used in a dentin barrier test device, and the system was evaluated by testing a set of dental filling materials. Cells (120 cells/mm2) were seeded on dentin slices and incubated for up to 21 days. Cell proliferation was recorded using MTT assay. For cytotoxicity tests 3500 cells/mm2 were seeded on dentin discs, which were then incorporated into the dentin barrier test device. After 72 h preincubation test materials were applied. After a 24 h exposure with or without perfusion of the pulpal part of the test device, cell survival was evaluated using MTT assay. The cells revealed similar growth kinetics on dentin slices and on tissue culture plates. In cytotoxicity tests the cells were more sensitive toward the test materials than previously used three-dimensional cultures of human foreskin fibroblasts and as anticipated from clinical experience. Further improvement is expected by using three-dimensional cultures of pulp-derived cells.

Cytotoxicity of dental glass ionomers evaluated using dimethylthiazol diphenyltetrazolium and neutral red tests.

The purpose of this study was to assess the cytotoxicity of some commonly used glass ionomers. Three chemically cured glass ionomers (Fuji II, Lining cement, and Ketac Silver) and one light-cured (Fuji II LC) were tested. Extracts of mixed non-polymerized materials and polymerized specimens were prepared in accordance with ISO standard 10993-12. The polymerized specimens were cured and placed either directly in the medium (freshly cured), left for 24 h (aged), or aged plus ground before being placed in the medium. The cytotoxicity of extracts was evaluated on mouse fibroblasts (L, 929), using dimethylthiazol diphenyltetrazolium (MTT) and neutral red (NR) assays. Further, the concentrations of aluminum, arsenic and lead were analyzed in aqueous extracts from freshly cured and aged samples, and the fluoride levels analyzed in aqueous extracts from freshly cured samples. All extracts except that of non-polymerized Ketac Silver were rated as severely cytotoxic in both assays. Extracts of polymerized material were significantly more cytotoxic than extracts of non-polymerized material. All freshly cured glass ionomers released aluminum and fluoride concentrations far above what is considered cytotoxic (aluminum >0.2 ppm and fluoride >20 ppm). Extracts from freshly cured Lining Cement contained the highest concentrations of aluminum and fluoride (215 ppm and 112 ppm). Extracts from freshly cured Ketac Silver had the lowest concentrations of aluminum and fluoride but the highest of lead (100 ppm). It can be concluded that all extracts from non-cured, freshly cured, and aged glass ionomers contained cytotoxic levels of substances. Curing did not reduce the toxicity significantly.

Reaction of bony tissue to implanted silver glass ionomer and a reinforced zinc oxide-eugenol cement.

OBJECTIVE: To evaluate the tissue responses to implants of Ketac Silver and Super EBA cement in the guinea pig mandible. STUDY DESIGN: Sixteen guinea pigs were used for 2 experimental periods of 4 and 12 weeks. Both materials were placed in Teflon applicators and implanted into surgically prepared sites in the mandible. A histologic examination for reaction to the material occurred after the animals were killed and processed. RESULTS: After 4 weeks, minimal inflammatory reactions were observed in Ketac Silver implants, whereas the Super EBA implants showed minimal to moderate inflammation. Localized foreign body reaction was present in areas of fragmented small particles of Ketac Silver. At 12-weeks observation, no inflammatory reactions were present around either material. Direct bone contact was observed in 1 Ketac Silver implant. CONCLUSIONS: Ketac Silver and Super EBA cement elicited mild reactions under the conditions of this model. From a biologic point of view, these 2 materials may offer equal utility in endodontic surgery.

Cytotoxicity of endodontic materials.

An in vitro cell culture model of human gingival fibroblasts and L-929 cells was used to measure the cytotoxicity of currently used root canal sealers Endomet, CRCS, and AH26 and root-end filling materials Amalgam, Gallium GF2, Ketac Silver, mineral trioxide aggregate (MTA), and Super-EBA. Cytotoxic effects were assessed using the MTT assay for mitochondrial enzyme activity and the CV assay for cell numbers. Using inserts culture and L-929 fibroblasts. All-Bond-2 was also evaluated. The statistical analysis of results showed that CRCS was the least cytotoxic sealer followed by Endomet and AH26. Among root-end filling materials, MTA was not cytotoxic; Gallium GF2 displayed little cytotoxicity; and Ketac Silver, Super-EBA, and Amalgam showed higher levels of cytotoxicity. All Bond-2 also displayed a high degree of cytotoxicity. CRCS was the best root canal sealer and MTA the best root-end filling material. The outcome was favorable also for Gallium GF2 as a retrofilling material.

Cytotoxicity of Ketac Silver cement.

The aim of this experiment was to investigate the effect of a glass ionomer cement with silver particles (Ketac Silver) on pulp tissue. Class V cavities were prepared in 60 healthy teeth scheduled for extraction for orthodontic reasons. A base of Dycal was placed in each cavity. Thirty teeth were filled with Ketac Silver and 30 with ZOE. Ten teeth of each group were extracted 15, 30, and 60 days later. At 15 days, the pulps in the Ketac group showed vacuolization and disruption of the odontoblastic layer, edema, vasodilation, chronic inflammatory infiltrate (CII), and necrosis. At 30 days, a necrotic odontoblastic layer, severe CII, and extensive areas of necrosis were seen. At 60 days, pulp tissue was almost completely necrotic. The ZOE control group showed a slight CII at 15 days. Our results suggest that under these experimental conditions, this cement is highly toxic and induces irreversible pulpal damage.

A commercially available cell culture device modified for dentin barrier tests.

The suitability of a dentin barrier test based on a commercially available cell culture chamber was evaluated by testing the cytotoxicity of dental cements. The two chambers of the culture device as produced are separated by a membrane. This was replaced by a bovine dentin disk (500 micrometers thick). Mouse fibroblasts were grown on the "pulpal" side of the dentin for 24 h; test materials were then placed into the "cavity" side of the upper chamber. The number of viable cells was determined after 24 h. After exposure to zinc phosphate cement at a powder/liquid ratio of 2:1, approximately 100% of cells survived. A ratio of 1:1 yielded 81% survival. Only 24% and 28% of the cells survived after exposure to Ketac Fil and Ketac Silver, respectively. The light-curing glass ionomer cement (vitrebond) and zinc oxide-eugenol killed all cells. These results agree with those obtained from a previous study, wherein the dentin barrier test device was constructed in our laboratory.