Edward D. Fillery

Streptococcus mutans and Lactobacillus Detection in the Assessment of Dental Root Surface Caries Risk

Forty-five subjects contributing 150 root surfaces with gingival recession were sampled seven times over a 32-month period. We calculated isolation frequencies of lactobacilli on selective Rogosa SL agar and S. mutans in a sensitive enrichment broth and on mitis salivarius agar. Both S. mutans and lactobacilli were isolated more frequently from surfaces which became carious than from those remaining caries-free. Isolation frequencies were also higher for caries-free surfaces in caries-active subjects than for caries-free surfaces in caries-inactive subjects. The presence or absence of S. mutans and lactobacilli in samples taken at baseline could discriminate between subjects who were to be root-caries-active and those who were to remain root-caries-inactive during the subsequent observation period. Moreover, if both bacteria were detected or only S. mutans was detected on a root surface at its entry into the study, that surface had a greater risk for developing a root lesion. However, the tests could not predict which root surfaces within the mouths of caries-active subjects were to become carious. Analysis of the data suggests that simple microbiological detection tests may be useful in identifying patients at high risk of root caries.

CLINICAL SCIENCE Longitudinal Microbiological Investigation of a Hospitalized Population of Older Adults with a High Root Surface Caries Risk

Intact root surfaces of chronically hospitalized subjects were sampled periodically to enumerate bacterial species believed to be associated with root caries. Bacteria were cultivated and enumerated using a series of selective and enriched media. Microbial counts, isolation frequencies, and percent cultivable flora data were analyzed for caries-active and caries-free surfaces and subjects. S. mutans, S. sanguis, A. viscosus, A. naeslundii, total lactobacilli, and Veillonella accounted for a mean of less than 20% of the cultivated flora, with mitis salivarius agar cultivable streptococci averaging less than 5%. The microbial count data were highly variable, precluding the finding of significant differences in caries association for either subjects or sites. Streptococci, especially S. mutans, correlated highly with lactobacilli in the samples.

Clinical Science A Longitudinal Study of Root Caries: Baseline and Incidence Data

A 34-month clinical investigation of root caries was conducted using a hospitalized, chronically-ill population. Forty-five subjects with 150 caries-free surfaces were observed for at least 12 consecutive months. Clinical measurements included diagnosis of new root and coronal caries, gingival inflammation, pocket depth, recession, and distance of new lesions from the gingival margin. The overall root caries attack rate was 1.90 lesions per 100 person-months at risk, with the greatest rate occurring during the first year of study. Mesial and facial surfaces accounted for 84% of all new lesions. Sixteen subjects accounted for 26 new lesions; nine subjects had two or more new lesions. Subjects with new root lesions were found to have lower enamel caries experience but higher root caries experience at baseline and higher scores for gingival inflammation, pocket depth, and recession compared with those who did not develop root caries.

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.

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.

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.