Cytotoxicity and Antimicrobial Effects of a New Fast-Set MTA.

Purpose. To compare the biocompatibility and antimicrobial effectiveness of the new Fast-Set MTA (FS-MTA) with ProRoot MTA (RS-MTA). Methods. The agar overlay method with neutral red dye was used. L929 mouse fibroblast cells were cultured. The liquid and oil extracts and solid test material were placed on the agar overlay, four samples for each material. Phenol was used as the positive control and cottonseed oil and MEM extracts were used as negative controls. Cytotoxicity was examined by measuring the zones of decolorization and evaluating cell lysis under an inverted microscope using the established criteria after 24 and 48 hours. The antimicrobial test was performed using the Kirby-Bauer disk-diffusion method against S. mutans, E. faecalis, F. nucleatum, P. gingivalis, and P. intermedia. The size of the zone of inhibition was measured in millimeters. Results. There was no zone of decolorization seen under or around the test materials for FS-MTA and RS-MTA at 24 and 48 hours. The antimicrobial test demonstrated no inhibitory effect of FS-MTA or RS-MTA on any bacterial species after 24 and 48 hours. Conclusions. There was no cytotoxicity or bacterial inhibition observed by the new Fast-Set MTA when compared to the ProRoot MTA after setting.

Effect of opposing implant prostheses on periodontal pathogens in dentures: A pilot study.

STATEMENT OF PROBLEM: An understanding of the presence of periodontal pathogens in denture plaque is important for the treatment of patients with edentulism. However, current data are limited and inconclusive. PURPOSE: The purpose of this pilot clinical study was to investigate whether opposing implant prostheses affect the presence of periodontal pathogens in maxillary complete dentures. MATERIAL AND METHODS: Twenty adult participants were enrolled in the study. The complete denture (CD/CD) group included 7 participants with complete maxillary and mandibular dentures. The implant overdenture (CD/IOD) group included 13 participants with maxillary complete-denture opposing implant overdentures. Plaque from maxillary complete dentures was collected and genomic DNA was extracted. Periodontal pathogens included Aggregatibacter actinomycetemcomitans, Eikenella corrodens, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, and Tannerella forsythia, and the total bacteria numbers were determined by real-time polymerase chain reaction (PCR) assay. A comparison of the detection rates and levels of periodontal pathogens between the 2 groups was performed using the chi-square test and the Mann-Whitney U test, respectively. Associations among these pathogens were determined using the Spearman rank correlation coefficient. RESULTS: No significant differences (P>.05) in detection rates were found between the CD/CD and CD/IOD groups for A actinomycetemcomitans (100% versus 100%, respectively), E corrodens (71.4% versus 76.9%, respectively), F nucleatum (100% versus 69.2%, respectively), Porphyromonas gingivalis (100% versus 100%, respectively), P intermedia (57.1% versus 84.6%, respectively), and T forsythia (100% versus 92.3%, respectively). No significant differences in periodontal pathogen levels (P>.05) were observed between the 2 groups. Significant positive associations were observed (P<.05) between F nucleatum and P intermedia, F nucleatum and T forsythia, F nucleatum and P gingivalis, P intermedia and P gingivalis, P intermedia and A actinomycetemcomitans, T forsythia and P gingivalis, T forsythia and A actinomycetemcomitans, and P gingivalis and A actinomycetemcomitans. CONCLUSIONS: Six investigated periodontal pathogens were widely present in denture plaque. Wearing opposing implant overdentures did not affect the presence and levels of the periodontal pathogens.

Real-time PCR quantification of six periodontal pathogens in saliva samples from healthy young adults.

OBJECTIVE: The use of saliva as a diagnostic fluid for the evaluation of periodontal health has gained attention recently. Most published real-time PCR assays focused on quantification of bacteria in subgingival plaque, not in saliva. The aims of this study were to develop a real-time PCR assay for quantification of six periodontal pathogens in saliva and to establish a relationship between the amount of DNA (fg) and colony-forming unit (CFU). MATERIALS AND METHODS: TaqMan primers/probe sets were used for the detection of Aggregatibacter actinomycetemcomitans (Aa), Eikenella corrodens (Ec), Fusobacterium nucleatum (Fn), Porphyromonas gingivalis (Pg), Prevotella intermedia (Pi), Tannerella forsythia (Tf), and total bacteria. Six periodontal pathogens and total bacteria in saliva from 24 periodontally healthy individuals were determined. The relationship between the amount of DNA (fg) and CFU was established by measuring the concentrations of extracted bacterial DNA and CFU per milliliter of bacteria on agar plates. RESULTS: Fn, Ec, and Pi were detected in all saliva samples, while 58.5, 45.8, and 33.3% were detected for Tf, Pg, and Aa, respectively. Numbers of Ec and Fn in saliva were highly correlated (R(2) = 0.93, P < 0.01). The values of DNA (fg) per CFU ranged from 64 for Ec to 121 for Pg. CONCLUSION: The real-time PCR assay in combination with the relationship between DNA (fg) and CFU can be used to quantitate periodontal pathogens in saliva and estimate the number of live bacteria (CFU). CLINICAL RELEVANCE: This real-time PCR assay in combination with the relationship between DNA (fg) and CFU has the potential to be an adjunct in evaluation of periodontal health status.

Therapeutic effect of TSG-6 engineered iPSC-derived MSCs on experimental periodontitis in rats: a pilot study.

BACKGROUND: We derived mesenchymal stem cells (MSCs) from rat induced pluripotent stem cells (iPSCs) and transduced them with tumor necrosis factor alpha-stimulated gene-6 (TSG-6), to test whether TSG-6 overexpression would boost the therapeutic effects of iPSC-derived MSCs in experimental periodontitis. METHODS: A total of 30 female Sprague-Dawley (SD) rats were randomly divided into four groups: healthy control group (Group-N, n = 5), untreated periodontitis group (Group-P, n = 5), iPS-MSCs-treated and iPSC-MSCs/TSG-6-treated periodontitis groups (Group-P1 and P2, n = 10 per group). Experimental periodontitis was established by ligature and infection with Porphyromonas gingivalis around the maxillae first molar bilaterally. MSC-like cells were generated from rat iPSCs, and transducted with TSG-6. iPSC-MSCs or iPSC-MSCs/TSG-6 were administrated to rats in Group-P1 or P2 intravenously and topically, once a week for three weeks. Blood samples were obtained one week post-injection for the analysis of serum pro-inflammatory cytokines. All animals were killed 3 months post-treatment; maxillae were then dissected for histological analysis, tartrate-resistant acid phosphatase (TRAP) staining, and morphological analysis of alveolar bone loss. RESULTS: Administration of iPSC-MSC/TSG-6 significantly decreased serum levels of IL-1ß and TNF-α in the Group-P2 rats (65.78 pg/ml and 0.56 pg/ml) compared with those in Group-P (168.31 pg/ml and 1.15 pg/ml respectively) (p<0.05). Both alveolar bone loss and the number of TRAP-positive osteoclasts showed a significant decrease in rats that received iPSC-MSC/TSG-6 treatment compared to untreated rats in Group-P (p<0.05). CONCLUSIONS: We demonstrated that overexpression of TSG-6 in rat iPSC-derived MSCs were capable of decreasing inflammation in experimental periodontitis and inhibiting alveolar bone resorption. This may potentially serve as an alternative stem-cell-based approach in the treatment and regeneration of periodontal tissues.

Comparison of efficacy of pulverization and sterile paper point techniques for sampling root canals.

INTRODUCTION: The purpose of this study was to compare the efficacy of the pulverization and sterile paper point techniques for sampling root canals using 5.25% NaOCl/17% EDTA and 1.3% NaOCl/MTAD (Dentsply, Tulsa, OK) as irrigation regimens. METHODS: Single-canal extracted human teeth were decoronated and infected with Enterococcus faecalis. Roots were randomly assigned to 2 irrigation regimens: group A with 5.25% NaOCl/17% EDTA (n = 30) and group B with 1.3% NaOCl/MTAD (n = 30). After chemomechanical debridement, bacterial samplings were taken using sterile paper points and pulverized powder of the apical 5 mm root ends. RESULTS: The sterile paper point technique did not show growth in any samples. The pulverization technique showed growth in 24 of the 60 samples. The Fisher exact test showed significant differences between sampling techniques (P < .001). The sterile paper point technique showed no difference between irrigation regimens. However, 17 of the 30 roots in group A and 7 of the 30 roots in group B resulted in growth as detected by pulverization technique. Data showed a significant difference between irrigation regimens (P = .03) in pulverization technique. CONCLUSIONS: The pulverization technique was more efficacious in detecting viable bacteria. Furthermore, this technique showed that 1.3% NaOCl/MTAD regimen was more effective in disinfecting root canals.

Dynamic model of hydrogen peroxide diffusion kinetics into the pulp cavity.

AIM: To measure the time course hydrogen peroxide penetration into the pulp cavity and evaluate short-term tooth color changes after bleaching. MATERIALS AND METHODS: Twenty extracted human canines were sectioned, pulp tissue removed and the cavity enlarged. Teeth were painted with nail varnish to leave a 6-mm diameter circle on the buccal surface. Baseline color was measured spectrophotometrically. Teeth were randomized into a control group (n = 10) treated with 30 µl of glycerin base and a bleaching group (n = 10) exposed to 30 µl of 40% hydrogen peroxide for 1 hour. A linear low density polyethylene wrap was placed to prevent evaporation of the material. Acetate buffer was placed into the cavity and replenished every 10 minutes and placed into plastic tubes. Hydrogen peroxide amount was estimated spectrophotometrically using leukocrystal violet and horseradish peroxidase. Specimen color was remeasured immediately after bleaching, 1 hour, 1 day 1, 2 and 6 weeks postbleaching. Color change was measured per Commission Internationale de l'Eclairage methodology. Mann-Whitney procedure was used to assess baseline color measurements and total hydrogen peroxide penetration amount. Friedman's test was used to assess within group differences for color change and hydrogen peroxide penetration. RESULTS: There was significantly greater hydrogen peroxide penetration in the bleaching group (p < 0.05). Hydrogen peroxide penetration levels were constant throughout the 1-hour evaluation period in the bleaching group. The groups showed no difference at baseline with respect to any of L*a*b color measurements (p > 0.05). The postbleaching color measurement showed an increase of change in overall color (ΔE) and lightness (ΔL) up to 1 week followed by a gradual stabilization up to 6 weeks. CONCLUSION: This dynamic model provided information about the time course diffusion kinetics into the pulp cavity, demonstrating constant penetration of hydrogen peroxide into the pulp cavity during a 1-hour bleaching session. CLINICAL SIGNIFICANCE: A prolonged application of 40% hydrogen peroxide bleaching material for 1 hour produces constant penetration of hydrogen peroxide into the pulp cavity in vitro.

Minimum contact time and concentration of sodium hypochlorite required to eliminate Enterococcus faecalis.

INTRODUCTION: The purpose of this investigation was to determine the concentration of sodium hypochlorite and the irrigation time required to disinfect dentin cylinders infected with Enterococcus faecalis. METHODS: Four hundred fifty dentin cylinders (5 mm in diameter and 4 mm in height) with a lumen (2-3 mm in width) were prepared from freshly extracted bovine incisors. The cementum and predentin were then removed. The tubules were opened by using a 4-minute application with 17% ethylenediaminetetraacetic acid and 5.25% NaOCl and then exposed to E. faecalis (ATCC 4082) for 3 weeks in brain-heart infusion broth. The cylinders were then divided into 3 groups, and a 1.3%, 2.5%, or 5.25% concentration of NaOCl was applied in 5-, 10-, 15-, 20-, 25-, 30-, 35-, and 40-minute intervals for a total of 30 subgroups including positive and negative controls. Each test sample was placed into a tube of 2 mL brain-heart infusion broth and incubated for 72 hours. Absence of turbidity demonstrated no bacterial growth, whereas turbidity indicated presence of remaining viable bacteria. RESULTS: The most effective irrigation regimen was 5.25% at 40 minutes, whereas irrigation with 1.3% and 2.5% NaOCl for this same time interval was ineffective in removing E. faecalis from infected dentin cylinders. CONCLUSIONS: High concentration and long exposure to NaOCl are needed for elimination of E. faecalis contaminated dentin.

Recovery of putative pathogens from paper point sampling at different depths of periodontal lesions.

BACKGROUND: The aim of this study was to compare the recovery of three putative periodontal pathogens from periodontal lesions in samples using paper points inserted to different depths of the lesions. METHODS: Twenty 6-8 mm deep periodontal lesions with bleeding on probing were studied. Microbial samples were obtained using paper points inserted to three different depths of the lesions: orifice of lesion; 2 mm into the lesion; and to the base of lesion. Culturing was used for recovery and identification of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia. RESULTS: The recovery of each of the three putative periodontal pathogens was similar following sampling at the various depths of the lesions. CONCLUSIONS: The findings may be explained by the fact that the paper points become saturated as they pass through the orifice of the lesion. Absorption of microorganisms will therefore primarily occur at the orifice. It is also conceivable that the pathogens may be present in similar proportions throughout the various depths of the periodontal lesions.

Antiplaque/antigingivitis efficacy and safety of a cetylpyridinium chloride/zinc gluconate mucoadhesive gel. Results of a 6-month clinical trial.

This article presents the results of a controlled clinical trial evaluating a new at-home treatment to improve gingival health. Designed for overnight application at the gingival margins and in the interproximal spaces, the product is a mucoadhesive gel containing 0.10% cetylpyridinium chloride (CPC) and 0.592% zinc gluconate (ZG). The authors assessed the efficacy and safety of the CPC/ZG gel in adults with low-to-moderate gingival and plaque index scores by comparing clinical and laboratory findings for subjects using the CPC/ZG gel with those for subjects using the control gel (0% CPC and 0.592% ZG). Clinical findings at 3 and 6 months showed statistically significant improvements in two of the three major indices of gingival health in the CPC/ZG group compared with the control group. The performance of the treatment gel was supported by results of microbial analyses of plaque samples.

The antimicrobial effect of biopure MTAD on eight strains of Enterococcus faecalis: an in vitro investigation.

The purpose of this investigation was to determine the antimicrobial effect of MTAD as a final irrigant on eight strains of Enterococcus faecalis (E. faecalis) and to measure the minimum inhibitory concentration (MIC) and the minimum lethal concentration (MLC) of MTAD. The roots of 240 extracted human teeth were instrumented using 1.3% NaOCl and 17% EDTA. The roots were divided into eight groups and contaminated with one of eight strains of E. faecalis. After irrigating with 1.3% NaOCl, the root canal and the external surfaces were exposed to MTAD for 5 minutes. Roots or dentin shavings were cultured to determine the growth of E. faecalis. The results showed that this treatment regimen was effective in completely eliminating growth in seven of eight strains of E. faecalis. The MIC/MLC tests showed that MTAD inhibited most strains of E. faecalis growth when diluted 1:8192 times and killed most strains of E. faecalis when diluted 1:512 times.

The antimicrobial effect of MTAD: an in vitro investigation.

Pulp and periradicular diseases are of microbial origin. To effectively clean the root canal system a disinfecting agent must be able to penetrate into difficult-to-reach areas and kill microorganisms with minimal damage to the host tissues. The purpose of this investigation was to test the ability of a mixture of a tetracycline isomer, an acid, and a detergent (MTAD) to kill Enterococcus faecalis and compare its efficacy to that of sodium hypochlorite (NaOCl) and ethylene diamine tetraacetic acid (EDTA). The zones of inhibition and minimum inhibitory concentrations were measured for these solutions. Measurement of zones of inhibition and determination of the minimum inhibitory concentrations showed that MTAD is as effective as 5.25% NaOCl and significantly more effective than EDTA (p < 0.0001). Furthermore, MTAD is significantly more effective in killing E. faecalis than NaOCl when the solutions are diluted (p < 0.0001). Measurement of the minimum inhibitory concentrations demonstrated that although MTAD is still effective in killing E. faecalis at 200x dilution, NaOCl ceases to exert its antibacterial activity beyond 32x dilution. EDTA did not exhibit any antibacterial activity. Based on the results of this study, it seems that MTAD is an effective solution in eradicating E. faecalis.