Evaluation of the genotoxic effects of formocresol application in vital pulp therapy of primary teeth: a clinical study and meta-analysis.

OBJECTIVES: This in vivo research investigated whether pulp treatments using formocresol for 7 days would cause mutagenic changes in children's lymphocytes. MATERIALS AND METHODS: The mutagenicity was tested in lymphocyte cultures established from the peripheral blood of children living in Brazil. The samples consisted of 2000 cells from teeth undergoing formocresol pulpotomies in which the formocresol pellet was sealed in the primary tooth for 7 days. It was removed on the seventh day, the base was placed, and the tooth was restored. Two venous blood samples (6-8 ml) were collected from each child; the first was prior to pulp therapy, and the second was 7 days later. Two thousand metaphases were analyzed. The level of significance adopted for the statistics was P < 0.05, and a random effects meta-analysis was performed combining this and two previous studies. RESULTS: There was no significant difference found in the metaphase analysis between the blood samples taken before and after the pulpotomy treatment (Wilcoxon signed rank test); however, the meta-analysis showed a significant difference between the combined studies. CONCLUSIONS: This study did not reveal any mutagenic effects, but based on the combined meta-analysis, we recommend the careful use of formocresol. CLINICAL RELEVANCE: This research helps to bring scientific evidence of the safe use of formocresol in deciduous pulpotomy treatments.

A tunnel shape defect on maxillary bone after accidental injection of formocresol instead of anesthetic solution.

Accidental injection or leakages of various chemical disinfectants used during root canal preparation into adjacent tissues have been shown to have deleterious effects on surrounding tissue. Formocresol (FC) is an effective intracanal disinfectant used in endodontic procedures. However, it is known to have harmful effects into adjacent tissues. The aim of this article is to present an unusual case in which a 28-year-old male patient developed gingival and bone necrosis after the accidental injection of FC instead of local anesthetic solution for tooth extraction and to review cases in the literature where complications have occurred due to the use of FC.

Genotoxic effect of formocresol pulp therapy of deciduous teeth.

OBJECTIVE: To investigate whether formocresol, in Buckley's original formulation, used for pulp therapy of deciduous teeth, can have a genotoxic effect. Genotoxicity was tested in lymphocyte cultures from the peripheral blood of children aged 5-10y, in Recife, Pernambuco, Brazil. This was a case-control study. The sample comprised 40 children who had primary teeth with non-vital pulps. Two venous blood samples (6-8ml) were collected from each child, the first prior to pulp therapy (control group) and the second 24h after pulp therapy (experimental group). Lymphocyte cultures were grown in 78% RPMI 1640 medium, 20% fetal bovine serum, 2% phytohemagglutinin. The lymphocytes were assessed for chromosomal aberrations; each sample involved analysis of 100 metaphases. There was a statistically significant difference between the control and treated groups for the isochromatid gap (p<0.001), chromatid break (p<0.009), isochromatid break (p<0.046), other chromosomal alterations (p<0.001), and for total aberrations. In view of these results, caution in the use of formocresol in pediatric dentistry is recommended.

Morphological and biochemical changes during formocresol induced cell death in murine peritoneal macrophages: apoptotic and necrotic features.

The present study was conducted to investigate the role of Formocresol (FC)-induced apoptosis and necrotic cell death in murine peritoneal macrophages (pMø). Macrophages were cultured with 1:100 FC for 2 to 24 h. The viability (trypan blue assay), cell morphology (scanning electronic microscope), and apoptotic and necrotic indexes (light and fluorescent microscopy) were determined at different scheduled times. Simultaneously, the expressions of proteins related to stress, survival, and cell death were measured by western blotting. FC-exposed macrophages exhibited maximal apoptosis from 2 to 6 h, coincident with Bax overexpression (P < 0.001). Additionally, Bcl-x(L) showed maximal expression between 12 and 24 h suggesting its survival effect in pMø. The lowest pMø viability and the increment of the necrotic rate from 4 to 12 h were observed in accordance to Fas and Hsp60 overexpressions. In summary, all the experimental data suggest that two different pathways emerge in pMø exposed to FC, one leading Bax-dependent apoptosis (2-6 h) and the other one favoring necrosis (4-18 h), related to Fas-receptor and Hsp60 stress signal.

In vitro toxicity of MTA compared with other primary teeth pulpotomy agents.

OBJECTIVE: The main goal of this work is to compare the In vitro toxicity of MTA with other primary teeth pulpotomy agents. STUDY DESIGN: The In vitro toxicity of MTA, calcium hydroxide, ferric sulphate solution, diluted formocresol and Buckley's formocresol were tested using MTT and Neutral Red Uptake cell viability assays. The results for MTA were compared to those obtained for the other substances using ANOVA and Tukey statistical tests (p < 0.05). RESULTS: MTA had the lower in vitro toxicity and Buckley's formocresol, the higher, with statically significant difference. CONCLUSION: Among the primary teeth pulpotomy agents tested, MTA showed the lower In vitro toxicity, standing as the most promising substitute to formocresol.

Is formocresol obsolete? A fresh look at the evidence concerning safety issues.

Concern has been expressed about the safety of formocresol use in pediatric dentistry Formaldehyde, a primary component in formocresol, is a hazardous substance and is considered a probable human carcinogen by the International Agency for Research on Cancer, Health Canada, the Agency for Toxic Substances and Disease Registry in the U.S. Department of Health and Human Services, and the U.S. Environmental Protection Agency Humans inhale and ingest formaldehyde daily however, and produce formaldehyde during cellular metabolism. The human body is physiologically equipped to handle formaldehyde through multiple conversion pathways. The resultant single carbon atom released during metabolism is deposited in the "1-carbon pool," which, in turn, is used for the biosynthesis of macromolecules including DNA and RNA. Reevaluation of earlier research that examined potential health risks associated with formaldehyde exposure has shown that this research was based on flawed assumptions, which resulted in erroneous conclusions. The purpose of this review was to examine more recent research about formaldehyde metabolism, phormacokinetics, and corcinogenicity. These results indicated that formaldehyde is probably not a potent human carcinogen under low exposure conditions. Extrapolation of these research results to pediatric dentistry suggests an inconsequential risk associated with formaldehyde use in pediatric pulp therapy/

"New age" pulp therapy: personal thoughts on a hot debate.

This article outlines the counterpoint delivered in the debate "Is Formocresol Obsolete?" It addresses the opinion supporting the need to move away from formaldehyde-containing preparations in the dental care of children. It is suggested that such a move should be made not just because of concerns relating to the possible toxicity of formaldehyde but to reflect a more contemporary, biologic approach to pulp therapy in the primary dentition.

Effect of formaldehyde on rat liver in doses used in pulpotomies.

Many studies have questioned the toxic effects of formocresol, one of which is its systemic distribution. This study focused on determining whether there was risk of acute hepatic lesion after the use of intravenous formaldehyde in doses for multple pulpotomies in rats. Histological and biochemical changes were evaluated. Results showed that very high doses of formaldehyde injected into rats, doses that were much higher than those given for multiple pulp treatments in a single session in Pediatric Dentistry, showed no signs of liver toxicity.

Cytotoxicities and genotoxicities of cements based on calcium silicate and of dental formocresol.

Increasing interest is being paid to the toxicities of dental materials. The purpose of this study was to determine the cytotoxicities and genotoxicities of endodontic compounds to Chinese hamster ovary (CHO-K1) reproductive cells. Cultured CHO-K1 cells were treated with dental formocresol, two types of calcium hydroxide paste, and two types of mineral trioxide aggregate cement for 24h. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay was performed on each culture, and the micronucleus frequency was determined by performing a micronucleus assay. Alkaline comet assay and γ-H2AX immunofluorescence assay were used to detect DNA damage. Out of the five materials tested, only dental formocresol significantly increased DNA damage. The mineral trioxide aggregate cements based on calcium silicate were not found to be potentially genotoxic. The data suggest that dental formocresol should not be recommended for use in vital pulp therapy on young teeth.

Assessment of genotoxicity of 14 chemical agents used in dental practice: ability to induce chromosome aberrations in Syrian hamster embryo cells.

To assess the genotoxicity of 14 chemical agents used as locally applied agents in dental practice, the ability of these agents to elicit chromosome aberrations was examined using Syrian hamster embryo (SHE) cells. Chromosome aberrations in SHE cells were induced by treatment with three of eight chemical agents used as endodontic medicaments, i.e. ethylenediaminetetraacetic acid (EDTA), formocresol (a mixture of formalin and tricresol), and sodium arsenite. The other five chemical agents, i.e. chloramphenicol, p-chlorophenol, p-phenolsulfonic acid, sodium hypochlorite, and tetracycline hydrochloride exhibited a negative response for chromosome aberrations. Assessment of three dyes used for disclosing dental plaque showed chromosome aberrations induced by basic fuchsin but not by acid fuchsin and erythrosine B. Three local anesthetics, lidocaine hydrochloride, prilocaine hydrochloride, and procaine hydrochloride, were negative for chromosome aberrations. Among the ten chemical agents that exhibited a negative response in the assay, p-chlorophenol, sodium hypochlorite, and erythrosine B induced chromosome aberrations in SHE cells when treated in the presence of exogenous metabolic activation. The percentages of cells with polyploidy or endoreduplication were enhanced by formocresol, sodium arsenite, p-chlorophenol, p-phenolsulfonic acid, sodium hypochlorite, erythrosine B, prilocaine hydrochloride, and procaine hydrochloride in the absence or presence of exogenous metabolic activation. Our results indicate that the chemical agents that had a positive response in the present study are potentially genotoxic to mammalian cells.

Persuasive evidence that formocresol use in pediatric dentistry is safe.

Concern has been expressed about the safety of formocresol use in pediatric dentistry. Formaldehyde, a primary component in formocresol, is a hazardous substance and is considered a probable human carcinogen by Health Canada. However, humans inhale and ingest formaldehyde daily and also produce this compound as part of normal cellular metabolism. The human body is physiologically equipped to handle this exposure through multiple pathways for oxidation of formaldehyde to formate and incorporation into biological macromolecules via tetrahydrofolate-dependent one-carbon biosynthetic pathways. Recent re-evaluation of earlier research that examined potential health risks associated with formaldehyde exposure has shown that the research was based on flawed assumptions, which resulted in erroneous conclusions. This review examines more recent research about formaldehyde metabolism, pharmacokinetics and carcinogenicity, the results of which indicate that formaldehyde is probably not a potent human carcinogen under conditions of low exposure. Extrapolation of these research results to pediatric dentistry suggests an inconsequential risk of carcinogenesis associated with formaldehyde use in pediatric pulp therapy. Areas for further investigation are suggested.

In vitro toxicity of propolis in comparison with other primary teeth pulpotomy agents on human fibroblasts.

AIM: The aim of this study was to assess and compare the in vitro toxicity of propolis with other primary teeth pulpotomy medicaments. METHODS: Human periodontal ligament (PDL) cells were subjected to different concentrations of propolis, formocresol, ferric sulfate, and gray mineral trioxide aggregate (MTA) (0.05, 0.5, 5, 50, and 100 µg/mL) for 24 h at 37°C. Cells that were not exposed to the tested materials served as the negative control. In vitro toxicity was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Statistical analysis of the data was accomplished using anova and Tukey statistical tests (P < 0.05). RESULTS: Only propolis and gray MTA had comparable cell viability to the negative control group. Almost all remaining concentrations of tested materials were significantly inferior to the negative control after 24 h of exposure (P < 0.05). CONCLUSION: Propolis and MTA are more biocompatible than formocresol and ferric sulfate since they were both able to preserve PDL fibroblasts for up to 24 h.

In vitro toxicity of formocresol, ferric sulphate, and grey MTA on human periodontal ligament fibroblasts.

AIM: This was to assess and compare the in vitro toxicity of formocresol, ferric sulphate and MTA on cultured human periodontal ligament (PDL) fibroblasts. STUDY DESIGN: PDL cells were obtained from sound first permanent molars and cultured in Dulbecco's modified Eagle's medium. METHODS: PDL cells were subjected to different concentrations of formocresol, ferric sulphate, and grey MTA for 24, 48, and 72 h at 37 °C. Cells that were not exposed to the tested materials served as the negative control. In vitro toxicity was assessed using MTT assay. STATISTICS: Statistical analysis of data was accomplished using ANOVA and Tukey statistical tests (p<0.05). RESULTS: The overall toxicity ranking of the tested materials was as follows: formocresol>ferric sulphate>grey MTA. Only grey MTA had comparable cell viability to the negative control, the other tested materials were significantly inferior at the three exposure periods (p<0.05). CONCLUSION: Regarding the viability of PDL fibroblasts, MTA stands as the most promising substitute to formocresol. However, considering MTA's unavailability and high price in Jordan, ferric sulphate may be the best alternative to formocresol in pulpotomy of primary teeth.

Embryotoxicity and teratogenicity of formocresol on developing chick embryos.

White Leghorn chick embryos were used to investigate the embryotoxicity and teratogenicity of 25 and 50% Buckley's formocresol. Embryos were injected at 48 h and sacrificed on the ninth day of incubation. The percentage of mortality of sham and vehicle controls was 4.8 and 17.7%, respectively, whereas eggs injected with 25 and 50% formocresol displayed a 40 and 100% mortality rate. Gross morphological abnormalities, weights, and crown-rump lengths were determined, demonstrating that Buckley's formocresol is embryotoxic and teratogenic in chick embryos. Gross morphological changes were noted to include cranial hematomas, facial abnormalities, eye and beak deformities as well as alterations in feather germ appearance. Histological changes included alterations in the organization of the eyes, and formation of the beak, palate, vasculature, musculature, cartilage, and bone. Moreover, experimental embryos displayed a retardation of development in that they lagged behind their controls by approximately 24 to 36 h.

Lack of genotoxicity of formocresol, paramonochlorophenol, and calcium hydroxide on mammalian cells by comet assay.

Formocresol, paramonochlorophenol, and calcium hydroxide are widely used in dentistry because of their antibacterial activities in root canal disinfection. However, the results of genotoxicity studies using these materials are inconsistent in literature. The goal of this study was to examine the genotoxic potential of formocresol, paramonochlorophenol, and calcium hydroxide using mouse lymphoma cells and human fibroblasts cells in vitro by the comet assay. Data were assessed by Kruskal-Wallis nonparametric test. The results showed that all compounds tested did not cause DNA damage for the tail moment or tail intensity parameters. These findings suggest that formocresol, paramonochlorophenol, and calcium hydroxide do not promote DNA damage in mammalian cells and that the comet assay is a suitable tool to investigate genotoxicity.

Differential sensitivity of normal human pulp and transformed mouse fibroblasts to cytotoxic challenge.

Six different lines of diploid cells from human pulp and one commonly used transformed-cell line, L929 (a continuous fibroblast line of mouse lung connective tissue origin), were challenged by sera changes, an agar-overlay toxicity test and transfilter-histochemistry-toxicity test. The normal diploid cells showed greater sensitivity than transformed cells in each test. Although a different parameter of cell toxicity was measured in each test, the data indicate greater toxic response in diploid cells by all measurements. These normal diploid human cells are more appropriate cells for toxicity testing materials for human use.

A critical look at glutaraldehyde.

Glutaraldehyde has been proposed as an alternative to formocresol in pulpotomy treatment of primary teeth. Data regarding effects of the two medicaments have been discussed in the literature, but little attention has been given to critical comparisons concerning parameters of toxicity, mutagenicity, and systemic distribution of the two agents. This paper reviews previous data on systemic distribution of glutaraldehyde and formocresol from pulpotomy sites, as well as cytotoxicity and mutagenicity of the agents. Comparisons reveal little difference between the agents on the parameters reviewed. The authors question the rationale for glutaraldehyde as an alternative to formocresol.

The acute nephrotoxicity of systemically administered formaldehyde in rats.

AIM: The purpose of this study was to assess the acute nephrotoxicity of formaldehyde, as it is believed to be the toxic component of formocresol. METHODS: A sample of 24 Sprague-Dawley rats was used in the study and divided into 3 groups of 8 rats each. The following procedures were performed: group A) formaldehyde equivalent dose to 20 pulpotomies, injected into the main vein of each rat's tail; group B) formaldehyde equivalent dose to 100 pulpotomies injected; group C) control group with a saline solution injected. Blood analyses were performed after 24 and 48 hours to assess urea and creatinine levels. Urine samples were taken after 24 hours to analyse for LDH protein levels. Rats were sacrificed after 48 hours and histology samples of renal tissue were studied for any pathological defects. RESULTS: Evaluation of histological samples of kidney tissue did not show any inflammation or other tissue lesions. No significant differences were found, using an ANOVA test procedure, among the variables of LDH protein or creatinine levels after 24 and 48 hours. Significant differences were found between the levels of urea and creatinine after 48 hours between the control group and the other test groups. CONCLUSION: The use of formaldehyde at the usual clinical doses or with an amount equivalent to 100 pulpotomies did not produce renal tissue damage and the blood and urine factors analysed did not show significant changes after 48 hours in the experimental model used.

Formaldehyde in dentistry: a review for the millennium.

This article reviews the history and use of formaldehyde in dentistry. Research from outside the dental field is included, particularly those articles that pertain to mutagenicity and carcinogenicity. The controversies over the use of formocresol continue, despite overwhelming research citing deleterious effects.