Determination of 4-chloroaniline and its derivatives formed in the interaction of sodium hypochlorite and chlorhexidine by using gas chromatography.

INTRODUCTION: The combination of sodium hypochlorite (NaOCl) and chlorhexidine (CHX) results in the formation of a precipitate. In a previous study, we demonstrated the formation of 4-chloroaniline (PCA) in the precipitate by using x-ray photon spectroscopy (XPS) and time of flight secondary ion mass spectrometry (TOF-SIMS). The TOF-SIMS results showed a peak at 127 amu, which is characteristic of 4-chloroaniline. However, this could also be characteristic of other isomers of 4-chloroaniline such as 2-chloroaniline and 3-chloroaniline. AIMS AND METHODS: The aim of this study was to further identify the precipitate by using gas chromatography-mass spectrometry (GC-MS). RESULTS: The results showed an absence of other aniline derivatives in the precipitate. Only PCA was found. CONCLUSIONS: Further investigations of the precipitate should address the bioavailability of PCA leaching out from dentin and its cytotoxicity. Until the precipitate is studied further, it would appear prudent to minimize its formation by avoiding the use of CHX together with NaOCl.

Antibacterial efficacy of MTAD final rinse and two percent chlorhexidine gel medication in teeth with apical periodontitis: a randomized double-blinded clinical trial.

INTRODUCTION: Clinical assessment of the efficacy of novel root canal disinfection protocols is an important focus in endodontic research. This randomized double-blinded study assessed the antibacterial efficacy of a final rinse with BioPure MTAD (MTAD) and intracanal medication with 2% chlorhexidine gel (CHX) in teeth with apical periodontitis. METHODS: Canals in 30 teeth (single-rooted and multi-rooted) were prepared by using 1.3% NaOCl, rinsed with MTAD or saline in random sequence, medicated with CHX for 7 days, irrigated with 1.3% NaOCl, and filled. Bacteriologic root canal samples were obtained by aspiration before (1A) and after (1B) canal preparation, after the final rinse (1C), after CHX was flushed (2A), and after final irrigation (2B). Bacteria were enumerated by epifluorescence-microscopy (EFM) by using 2 staining methods and by colony-forming-unit (CFU) counts after 14 days of incubation. RESULTS: Bacterial counts (EFM) in 1B were greater than 95% decreased from 1A. Low bacterial densities in 1B, 1C, 2A, and 2B did not differ significantly from each other. EFM counts were consistently higher than CFU counts. CONCLUSIONS: The final rinse with MTAD and medication with CHX did not reduce bacterial counts beyond levels achieved by canal preparation with NaOCl.

Using diazotization to characterize the effect of heat or sodium hypochlorite on 2.0% chlorhexidine.

INTRODUCTION: The combination of sodium hypochlorite (NaOCl) and chlorhexidine (CHX) results in the formation of a precipitate. In a previous study, we demonstrated the formation of 4-chloraniline (PCA) in the precipitate in an amount directly related to the concentration of NaOCl used. AIMS AND METHODS: The aim of the present study was to use a diazotization technique to confirm the presence of an aromatic amine (like PCA) in the NaOCl/CHX precipitate and also in the 2.0% CHX at different temperatures (37 degrees C and 45 degrees C). RESULTS: The results corroborated the presence of the aromatic amine in the precipitate and in the CHX at 45 degrees C. CONCLUSIONS: Further investigations of the precipitate should address the bioavailability of PCA leaching out from dentin and its cytotoxicity. Until the precipitate is studied further, it would appear prudent to minimize its formation.

Evaluating the effect of an ozone delivery system on the reversal of dentin hypersensitivity: a randomized, double-blinded clinical trial.

The aim of this study was to evaluate the effect of an ozone delivery system (HealOzone; KaVo, Biberach, Germany) in reducing dentin hypersensitivity. An 8-week, 3-visit, triple-blinded, randomized controlled clinical trial with 2 HealOzone machines (ozone/air) involving 44 subjects was conducted. The pain in response to tactile stimulus or desiccation was assessed by using a 100-mm visual analogue scale. Also, the global subjects' perception of sensitivity was assessed at each visit by using the visual analogue scale. No subjects reported an increase in pain or any adverse effect. All subjects reported a clinically significant reduction of pain at each follow-up relative to baseline; however, the difference between the study groups was not statistically significant. The effect of treatment of hypersensitive teeth with ozone reduces the pain sensation, but this effect cannot be distinguished from the placebo treatment. There was a large placebo effect that narrowed the range over which to detect treatment differences.

Characterization of an ex vivo model for the assessment of root canal disinfection.

Root canal bacteria in teeth with apical periodontitis were enumerated after extraction and incubation. Canals in 36 teeth were sampled after: S1, incubation for 2 hours (group A), 2 days (group B), 4 days (group C), and 6 days (group D); S2, subsequent incubation for 1 week; S3, canal disinfection; and S4, final incubation for 1 week. Bacterial concentrations were determined by culture (colony-forming unit [CFU]) and epifluorescence-microscopy (EFM) and compared by using pairwise and exact-permutation tests (p < 0.05). CFU counts were lower than EFM counts. CFU counts in S1 were higher in Gp(A) than in Gp(C) (p < 0.004) and Gp(D) (p < 0.02). EFM counts in S1 were higher in Gp(A) than in Gp(C) (p < 0.02). Both enumeration methods showed bacterial counts decreasing from S1 to S2 (p < 0.04). EFM was superior to culture in this ex vivo model. The indigenous flora survived incubation for 6 days, but the adverse effect of initial access would preclude testing of disinfection protocols that require two sessions.

Prion disease: the implications for dentistry.

The aim of this article was to provide the dental community with a brief overview of the characteristics, risk of transmission, and the infection-control implications of prions in dentistry. MEDLINE, EMBASE, CINAHL, The Cochrane Library, and relevant databases were searched, and a targeted internet search was conducted up to July 2007. Transmissible spongiform encephalopathies (TSEs) are a group of fatal neurodegenerative diseases that are rapidly progressive and always fatal, with no approved cure, and their definite diagnosis can only be obtained at post mortem autopsy. The causative agent, prion protein, resists conventional sterilization methods especially when infected tissue becomes dried onto glass or metal surfaces. To date, there are no reported definite or suspected cases of disease transmission arising from dental procedures, and there seems to be no correlation between dental treatment and TSEs. Because there is a theoretical but real risk of transmission of prion disease from dental instruments (although it is extremely low, especially in North America), as a general rule, appropriate family and medical history (including the risk for prion diseases) should be obtained from all patients, before all dental procedures. TSE research regarding diagnosis, transmission, treatment, and inactivation of prions and other transmissible amyloidoses are ongoing, and, thus, dental professionals should maintain optimal and up-to-date standards of knowledge, infection control, and decontamination.

Antibacterial efficacy of chlorhexidine gluconate intracanal medication in vivo.

The antibacterial efficacy of intracanal medication with 2% chlorhexidine liquid (CHX) was assessed in teeth with apical periodontitis. Canals in 22 teeth were instrumented at the first session, medicated with CHX, and reaccessed after 7 to 15 days. Bacteriological samples were aspirated at the first and second sessions, before (1A, 2A) and after (1B, 2B) canal instrumentation. Viable bacterial counts were obtained by culture (CFU) and microscopy using vital dyes. Microscopic counts were higher than CFU counts. Consistently high CFU counts in 1A samples (mean, 2 x 10(5) microL(-1) canal volume) decreased significantly (p < 0.0001) in 1B samples, increased significantly (p < 0.04) in 2A samples, and decreased in 2B samples to the level of 1B samples. Proportions of negative cultures followed the pattern of CFU counts. Intracanal medication with CHX did not reduce the bacterial concentration. Bacterial counts expressed per microliter canal volume added information beyond the counts per tooth as expressed in previous studies.

Interaction between sodium hypochlorite and chlorhexidine gluconate.

The combination of sodium hypochlorite (NaOCl) and chlorhexidine (CHX) results in the formation of a precipitate. The aim of this study was to determine the minimum concentration of NaOCl required to form a precipitate with 2.0% CHX. This was accomplished with a serial dilution technique. X-ray photon spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) were used to qualify and quantify the precipitate. A color change and precipitate were induced in 2.0% CHX by 0.023% and 0.19% NaOCl, respectively. Both XPS and TOF-SIMS showed the presence of para-chloroaniline in an amount directly related to the concentration of NaOCl used. Until this precipitate is studied further, its formation should be avoided by removing the NaOCl before placing CHX into the canal.

Salivary sIgA and cortisol: markers for functional dependence in older adults.

Elderly persons with health problems and physical limitations have reduced independence. Since poor functional ability is a known risk factor for disease among older populations, including oral disease, this study was undertaken to assess whether salivary defense factors and the stress hormone cortisol are significant markers for functional dependence. Oral examinations; salivary and microbial analyses; and interviews using the Activities of Daily Living (ADD index, the Mini Nutritional Assessment (MNA) and the Perceived Life Stress Questionnaire (PLSQ) were conducted for 123 dentate subjects. Of the subjects, 80 lived independently in the community or in apartments at the Baycrest Centre for Geriatric Care in Toronto, Canada, and 43 resided in the Baycrest nursing home or the Baycrest Hospital. Whole saliva samples were assayed for total secretory immunoglobulin A (sIgA), sIgA1, sIgA2, total protein and cortisol using ELISA. Dependent residents in the nursing home/hospital scored significantly lower in the nutritional assessment, had higher mean PLSQ scores, increased total protein and cortisol concentrations, and reduced salivary flow rates in comparison to ambulatory residents in the community/apartments. In multivariable logistic regression, factors associated with functional dependence were: being male, perceiving income as inadequate, having low salivary flow rate and drinking less than 5 cups of water per day. These results indicate that salivary flow and cortisol may be useful markers of functional dependence; however, the ability of these markers to predict functional decline cannot be confirmed until longitudinal studies are conducted.