An evaluation of the toxicity potential of cavity varnish for use in endodontic surgery

Microleakage of retrograde root fillings: assessment using a novel measurement system

In the past, measurement of microleakage has been based on measurement of dye or radioactive isotope penetration. A method has been developed to allow electronic monitoring of microflow in the same specimen over a period of time. This method was used to compare previously reported retrograde materials with an amalgam/sealer combination. The material that performed best was amalgam/sealer, particularly in the first week. The role of cavity varnish in limiting leakage has been controversial, and the results in the present study do not indicate any significant benefit. The range of leakage measured for specimens in the same group suggests that in vivo the expected leakage could be considerable for the materials tested and that small differences in experimental leakage between groups may not have any practical significance.

Sealing efficacy of a zinc oxide-eugenol cement, a cyanoacrylate, and a cavity varnish used as root canal cements

Forty single-rooted human central incisor teeth were biomechanically instrumented. Thirty teeth were divided into three groups of 10 and obturated with laterally condensed gutta-percha and one of three cementing mediums. These were zinc oxide-eugenol root canal cement, cyanoacrylate, and cavity varnish. The remaining 10 teeth were not obturated and served as a control. All of the teeth were suspended in a 1% methylene blue dye for 1 wk. Following sectioning the apical dye penetration was measured, and the leakage values were subjected to statistical analysis. The results showed that the teeth obturated with zinc oxide-eugenol and cyanoacrylate, in conjunction with gutta-percha, exhibited less leakage than the cavity varnish and control groups. This finding was statistically significant (p less than 0.0001). There was, however, no significant difference detected between the zinc oxide-eugenol and cyanoacrylate groups.

Toxicity of root canal sealers on rat bone cells in primary culture

The cytotoxic effects on cultured rat bone cells of newly-developed root canal sealers and commercially available sealers were compared. Various root canal sealers were applied to cultured bone cells obtained from rat calvaria by the enzyme digestion method. Measurement of [3H]-thymidine incorporation, alkaline phosphatase activity, and calcium release were performed after 24 and 48 h. No significant difference was found in cellular DNA synthesis and alkaline phosphatase activity between cells exposed to New B-1, New B-5 and controls after exposure for 24 and 48 h. Cells in contact with Tubliseal, Diaket and AH-26 demonstrated a significant difference from controls in DNA synthesis and alkaline phosphatase activity. Calcium release at 24 h was significantly different in the cells treated with New B-1 and New B-5 than in controls. No appreciable difference was found, however, between New B-6, Sealapex and controls. At 48 h, cells treated with New B-1, New B-5 and New B-6 showed differed significantly difference from controls, but the cells exposed to Sealapex did not. The newly-developed root canal sealers had lower toxicity in vitro than five types of commercially available root canal sealers.

Apical sealing efficacy of two reverse filling techniques versus cold-burnished Gutta-percha

The apical seal produced by the cold-burnished gutta-percha method and two amalgam reverse filling techniques was investigated in an in vitro study using 36 extracted human single-rooted teeth. Following root canal obturation, 27 teeth were divided into three experimental groups and each group was subjected to one of the three following filling techniques: (a) cold-burnishing of gutta-percha; (b) amalgam reverse filling; and (c) amalgam reverse filling in conjunction with cavity varnish. The remaining nine teeth served as controls (4). The teeth were placed in methylene blue dye for a period of 1 wk, after which they were retrieved, washed, sectioned, and the apical dye penetration measured. The results showed that amalgam with cavity varnish demonstrated less dye penetration than the other experimental groups. The difference was statistically significant (p less than 0.0001).

A dye penetration study of retrofilling materials

The apical sealing ability of amalgam, cold-burnished gutta-percha, amalgam with cavity varnish, and SuperEBA cement was evaluated in extracted human teeth. For each experimental group, the roots of 20 single-rooted teeth were sectioned from their crowns. Canals were cleaned, shaped, and obturated with vertically condensed warmed gutta-percha and Kerr Pulp Canal Sealer. Following apical preparation and placement of test materials, root ends were placed in 1% methylene blue dye for 2 wk, after which the roots were sectioned longitudinally, and linear measurements of dye penetration were recorded. Results demonstrated statistically less linear dye penetration in the test group sealed with amalgam and cavity varnish. Statistical differences were not detected among the other test groups.

The effect of newly developed root canal sealers on rat dental pulp cells in primary culture

Cytotoxicity was compared between new root canal sealers (New A, New B, and New B-2) and conventional root canal sealers (AH26, Diaket, Canals, Tubi-Seal, and Sealapex). Dental pulp cells of rats, obtained through primary cell culture, were used. In the experiments with the freshly prepared sealers, the incorporation of [3H]thymidine into cellular DNA was analyzed. In the experiments with the set sealers, the morphological changes of cells were microscopically examined. In the experiments with the fresh sealers, AH26 and Diaket showed strong inhibitive effects on the DNA synthesis, whereas no such effects were noted with the new sealers and Sealapex. On the other hand, in the experiments with the set sealers, the new sealers and Diaket exerted little influence on the cells. However, other sealers had considerable toxicity. These results suggest that the new sealers were the least toxic in vitro, compared with five conventional sealers.

An evaluation of the biocompatibility of a glass ionomer-silver cement in rat connective tissue

Pellets of a glass ionomer-silver cement and a zinc oxide-eugenol cement were implanted into the soft tissues and bones of 30 rats. Following experimental periods of 14, 30, and 80 days, the animals were killed and tissue sections were prepared. The responses to each of the materials initially and at 30 days consisted of mild inflammation. No severe inflammatory responses were noted in any of the groups. By 80 days, although mild inflammation persisted, the materials appeared to be well tolerated. Bone apposition occurred in the glass ionomer-silver cement group; the zinc oxide-eugenol group produced fibrosis.