Quantitative Assessment of the Efficacy of Two Different Single-file Systems in Reducing the Bacterial load in Oval-Shaped Canals: A Clinical Study.

INTRODUCTION: This randomized clinical study compared the in vivo antibacterial efficacy of Reciproc Blue (RB), XP-endo Shaper (XP-S), and XP-endo Shaper associated with XP-endo Finisher (XP-F) systems in infected oval-shaped root canals with primary apical periodontitis. METHODS: In this study, 28 human teeth with a single root and a single canal were randomly assigned to 2 groups according to the instrumentation technique: group 1, RB (n = 14) and group 2, XP-endo (XP-S and XP-F, n = 14). The single-rooted teeth were prepared by reciprocating and rotary nickel-titanium instruments with 5.25% sodium hypochlorite irrigation. Samples were collected from the canal at the baseline (S1), after chemomechanical preparation (S2), and after XP-F instrumentation (S3). The DNA extracts were subjected to quantitative analysis for total bacterial counts by quantitative real-time polymerase chain reaction. The data were analyzed using the analysis of variance test, and the level of significance was set at 5%. RESULTS: All samples tested positive for the presence of bacteria at baseline, and the bacterial counts substantially reduced after treatment procedures (P < .01). The results showed no statistical difference between RB and XP-S instrumentation with respect to the bacterial reduction (P > .05). A marked bacterial reduction was observed after the use of the XP-F instrument (P < .01). CONCLUSIONS: The XP-S and RB systems sharply reduced the bacterial load in oval-shaped root canals with primary apical periodontitis. XP-F used as a supplementary instrument to chemomechanical preparation promoted a significantly higher bacterial reduction.

Resinous adhesive systems differentially affect the expression of cytokines by human monocytes stimulated or not with Streptococcus mutans in vitro.

OBJECTIVES: The polymerization of adhesive systems is incomplete and the residual monomers that have been released have a cytotoxic capacity. Some teeth develop into pulp necrosis after composite resin restorations. Considering frequent pulpal inflammation in response to cariogenic bacteria, substances released from the patches could affect the cells of the inflammatory infiltrate and interfere with the mechanisms of defense against microorganisms and protection of pulpal tissue. The aim of this study was to evaluate the effect of substances released by different resinous adhesive systems on cell viability and cytokine expression by human monocytes stimulated in vitro with Streptococcus mutans. DESIGN: Peripheral blood mononuclear cells from 10 healthy subjects were stimulated with S. mutans and then incubated with supernatants obtained from the Single Bond Universal (SBU) or Clearfil SE Bond (CSEB) adhesive systems for eight hours. Staining with Annexin V and 7AAD for analysis of apoptosis were performed and detection of monocytes expressing cytokines IL-1α, IL-6, IL-8, IL-10, IL-12 and TNF-α were performed by flow cytometry. RESULTS: No treatment significantly affected apoptosis in monocytes. SBU supernatant increased the frequency of monocytes expressing IL-8 and decreased the monocytes expressing IL-10. Considering S. mutans-stimulated cells, while SBU increased the frequency of IL-8+ monocytes, CSEB reduced the frequency of IL-6 and TNF-α positive monocytes. CONCLUSIONS: Products released from SBU seem to induce proinflammatory effects on monocytes while those from CSEB show an anti-inflammatory outcome. These effects may interfere in the control of cytokine-mediated immunoinflammatory pulp reactions, both in the presence and absence of stimulation by cariogenic bacteria.

Composition analysis of dental solid waste in Brazil.

When developing proper waste management strategies, it is essential to characterize the volume and composition of solid waste. The aim of this work was to evaluate the composition of dental waste produced by three dental health services in Belo Horizonte, Minas Gerais State, Brazil. Two universities, one public and one private, and one public dental health service were selected. Waste collection took place from March to November 2007. During this period, three samples were collected from each dental health service. The total amount of dental waste produced in one day of dental work was manually separated into three categories: infectious and potentially infectious waste, accounting for 24.3% of the total waste; non-infectious waste, accounting for 48.1%; and domestic-type waste, accounting for 27.6% (percentages are for mean weights of solid waste). Our results showed that most of the waste considered as biomedical may be misclassified, consequently making the infectious waste amount appear much larger. In addition, our results suggest that the best waste minimization method is recycling, and they help to define an appropriate waste management system in all three of the dental health services involved in this study.

Investigating cross-contamination by yeast strains from dental solid waste to waste-handling workers by DNA sequencing.

Trying to widen the discussion on the risks associated with dental waste, this study proposed to investigate and genetically compare yeast isolates recovered from dental solid waste and waste workers. Three samples were collected from workers' hands, nasal mucosa, and professional clothing (days 0, 30, and 180), and two from dental waste (days 0 and 180). Slide culture, microscopy, antifungal drug susceptibility, intersimple sequence repeat analysis, and amplification and sequencing of internal transcribed spacer regions were performed. Yeast strains were recovered from all waste workers' sites, including professional clothes, and from waste. Antifungal susceptibility testing demonstrated that some yeast recovered from employees and waste exhibited nonsusceptible profiles. The dendrogram demonstrated the presence of three major clusters based on similarity matrix and UPGMA grouping method. Two branches displayed 100% similarity: three strains of Candida guilliermondii isolated from different employees, working in opposite work shifts, and from diverse sites grouped in one part of branch 1 and cluster 3 that included two samples of Candida albicans recovered from waste and the hand of one waste worker. The results suggested the possibility of cross-contamination from dental waste to waste workers and reinforce the need of training programs focused on better waste management routines.

Exploring different photodynamic therapy parameters to optimize elimination of Enterococcus faecalis in planktonic form.

BACKGROUND: The failure of endodontic treatment is linked to the presence of Enterococcus faecalis in the root canals. The scope of this study was to evaluate the influence of the energy dose and frequency of photodynamic therapy (PDT cycles), as well as the volume of bacterial suspensions (BS) in the elimination of Enterococcus faecalis in planktonic form. METHODS: In four successive assays BS of Enterococcus faecalis ATCC 19433 were irradiated with a diode laser (40 mW) using the photosensitizer (PS) methylene blue (MB) (0.005 µg/mL). Group 1 - Effect of energy dose: 100 µâ€¯L of BS and 100 µâ€¯L of PS were irradiated by 1, 2.5, 5, 7.5 and 10 minute s. Group 2 - Effect of PDT cycles: The BS received 1, 2, 3 or 4 PDT cycles (in each cycle 100 m L of PS was added and irradiated by 2.5 minutes). Group 3 - Effect of energy dose and bacterial suspension volume: 10 µâ€¯L of BS and 10 µâ€¯L of PS were irradiated similar to group 1. Group 4 - Effect of energy dose, bacterial suspension volume and PDT cycles: 10 µâ€¯L of BS and 10 µL of PS were irradiated according to group 2. The laser source and MB isolated represented the controls. RESULTS: The mean log reduction after separate applying laser light and MB were 0.01 and 0.07, respectively. It was found that wells with 100 µâ€¯L of BS irradiated with 2.4 to 24 J of energy did not cause significant bacterial elimination (p > 0.05), on the other hand PDT cycles above 12 J increased significantly bacterial elimination (p < 0.05). In 10 µâ€¯L wells irradiation from 12 J of energy provided higher bacterial elimination (p < 0.05) which combined with PDT cycle resulted in the logarithmic elimination of E. faecalis (p < 0.05). CONCLUSIONS: The energy dose, the volume of the bacterial suspension and, especially, the PDT cycles optimized the bacterial elimination of Enterococcus faecalis in planktonic form.

Actinomyces israelii in radicular cysts: a molecular study.

OBJECTIVE: To investigate whether the microscopic filamentous aggregates observed in radicular cysts are associated with the molecular identification of Actinomyces israelii. Moreover, to verify whether this bacterium can be detected in radicular cyst specimens not presenting aggregates. STUDY DESIGN: Microscopic colonies suggestive of Actinomyces were found in 8 out of 279 radicular cyst samples (case group). The case and control groups (n = 12; samples without filamentous colonies) were submitted to the semi-nested polymerase chain reaction to test the presence of A israelii. DNA sequencing was performed to validate polymerase chain reaction results. RESULTS: Two and 3 samples in the case and control groups, respectively, did not present a functional genomic DNA template and were excluded from the study. A israelii was identified in all samples of the case group and in 3 out of 9 samples of the control group. CONCLUSIONS: Although A israelii is more commonly identified in radicular cysts presenting filamentous aggregates, it also appears to be detected in radicular cysts without this microscopic finding.

Monitoring the effectiveness of photodynamic therapy with periodic renewal of the photosensitizer on intracanal Enterococcus faecalis biofilms.

BACKGROUND AND OBJECTIVE: Photodynamic therapy (PDT) can eliminate microorganisms in a root canal. However, the parameters for disinfection remain undefined. This study assessed the effectiveness of a PDT protocol against intracanal Enterococcus faecalis biofilms. MATERIALS AND METHODS: Root canals were contaminated with E. faecalis for 21 days. The instrumentation was associated to irrigation with 0.85% saline or an alternate irrigation (AI) with 5.25% NaOCl and 17% EDTA. Complementary treatments included saline/PDT and AI/PDT. Four PDT cycles were performed using a diode laser (660nm, 40mW) delivered through a tapered optical fiber. In each cycle, the root canal was filled with 1.56µM/mL methylene blue and irradiated for 150s. Microbiological samples were collected before (S1) and after (S2) instrumentation; after PDT (S3); and daily over the course of 14 days (S4-S17). Colony-forming units (CFUs) were counted, positive cultures verified, and data subjected to parametric and proportion's tests. RESULTS: The highest bacterial load reduction was observed in S2. In regard to S3, Saline/PDT reduced 1.3 log(10) CFU counts (p=0.000 for S2) and no CFUs were recovered after AI/PDT treatment. All canals were CFU-free on the 14th day for saline/PDT, AI and AI/PDT. Positive cultures were observed in 60% of saline-irrigated canals on the 14th day, whereas the saline/PDT, AI and AI/PDT treatments resulted in germ-free canals after 10, 5 and 2 days, respectively. CONCLUSION: Our findings suggest immediate and delayed antibacterial effects using the PDT protocol tested.

Antiproliferative activity of Actinobacillus (Haemophilus) actinomycetemcomitans and Fusobacterium nucleatum in peripheral blood mononuclear cells.

Several studies indicate Actinobacillus (Haemophilus) actinomycetemcomitans and Fusobacterium nucleatum as etiologic agents of periodontal disease. Immunosuppressive factors produced by microorganisms probably contribute to the initiation and evolution of this disease. This study evaluated the antiproliferative activity of ammonium precipitate fractions of A. (H.) actinomycetemcomitans and F. nucleatum isolates from humans and marmosets both with and without periodontal disease. All A. (H.) actinomycetemcomitans and most F. nucleatum strains inhibited PBMC proliferation in a dose-dependent manner. The degree of cell proliferative inhibition of each bacterial species differed among the strains and was independent of host clinical status. The in vitro inhibition of stimulated lymphocyte proliferation induced by different A. (H.) actinomycetemcomitans and F. nucleatum isolates demonstrated the importance of this phenomenon in bacterial virulence, playing a possible suppressor role in host defense mechanisms in vivo. Moreover, our findings pointed out a marked difference between A. (H.) actinomycetemcomitans and F. nucleatum cytoplasmic extracts in their antiproliferative activity, regarding the antigen concentration required for maximum inhibition and their vulnerability to heating and proteolytic treatment.

Effectiveness of chemomechanical preparation with alternating use of sodium hypochlorite and EDTA in eliminating intracanal Enterococcus faecalis biofilm.

INTRODUCTION: The elimination of microorganisms from root canals is a critical step in endodontic treatment. We aimed to evaluate the antimicrobial effectiveness of an alternating irrigation regimen during chemomechanical preparation (CMP). METHODS: During 21 days, root canals of extracted human teeth were infected with Enterococcus faecalis, and colonization was confirmed by scanning electron microscopy (SEM). Canals were irrigated with saline solution (control group), with 5.25% NaOCl followed by a final rinse with 17% EDTA (conventional irrigation group), or with the alternating use of NaOCl and EDTA (alternating irrigation [AI] group). Samples were taken before treatment (S1), after CMP (S2), and during the following 14 days. Two specimens/group were analyzed by SEM. RESULTS: The AI group yielded negative agar and liquid cultures from immediately after CMP and from the 5th day on, respectively. SEM confirmed several bacterium-free sites in the AI group. CONCLUSION: The irrigation regimen based on the alternating use of NaOCl and EDTA seems to be a promising endodontic tool because it promoted the elimination of root canal E. faecalis biofilms throughout the experimental period.