OBJECTIVETo evaluate in vitro the antibacterial effectiveness of sodium hypochlorite on Enterococcus faecalis (E. faecalis) within root canals.

METHODSRoots inoculated with E. faecalis were divided into six groups, which underwent different root canal irrigation and treatment: Group 1: 5.25% NaOCl, Group 2: 2.5% NaOCl, Group 3: 0.9% NaCl, Group 4: root canal preparation + 5.25% NaOCl, Group 5: root canal preparation + 2.5% NaOCl, Group 6: root canal preparation + 0.9% NaCl. Microbiological samples were collected from root canals at three time points (before irrigation, immediately after irrigation and three days after irrigation).

RESULTSThe numbers of E. faecalis in root canal in each of the six groups were effectively reduced. Group 1 and 2 were statistically more effective than Group 3. Group 4 was statistically more effective than Group 5 and 6. Group 5 was statistically more effective than Group 6. Bacterial survival was observed in all canals of each group after a 3-day-incubation.

CONCLUSIONS2.5% NaOCl was highly effective for root canal irrigation. However residual bacteria remained in the root canals after chemical irrigation by NaOCl and mechanical preparation.

Dental Pulp Cavity ; microbiology ; Enterococcus faecalis ; drug effects ; Humans ; In Vitro Techniques ; Root Canal Irrigants ; pharmacology ; Sodium Hypochlorite ; pharmacology

OBJECTIVETo compare the antimicrobial efficacy of four endodontic irrigants using an in vitro model infected by Enterococcus faecalis (Ef).

METHODSThe root canals of fifty extracted teeth were infected by Ef in vitro. The test groups were irrigated with 3% H(2)O(2), 2.5% sodium hypochlorite (SH), 2% chloramine-T (CR), and 2% chlorhexidine (CHX), respectively, and the control group was irrigated with 0.9% NaCl. The concentration of Ef in canals of each group was calculated before and after irrigation. The residual bacteria within the dentinal tubules and vitalities of the residual bacteria were also examined.

RESULTSAll chemical irrigants were significantly more effective than 0.9% NaCl (P < 0.05); 2.5% SH and 2% CHX were statistically more effective than 3% H(2)O(2) (P < 0.05). Residual bacteria could be found in the dentinal tubules and propagated 72 h after.

CONCLUSIONS2% CR and 2% CHX had almost the equivalent antimicrobial effect as 2.5% SH, but 3% H(2)O(2) was less effective.

Chloramines ; pharmacology ; Chlorhexidine ; pharmacology ; Dental Pulp Cavity ; microbiology ; Enterococcus faecalis ; drug effects ; Humans ; Hydrogen Peroxide ; pharmacology ; In Vitro Techniques ; Root Canal Irrigants ; pharmacology ; Sodium Hypochlorite ; pharmacology ; Tosyl Compounds ; pharmacology

OBJECTIVE: To construct a model of Enterococcus faecalis (E. faecalis) infection in dentinal tubules by gradient centrifugation and to evaluate the antibacterial effect of low-temperature plasma on E. faecalis in dentinal tubules. METHODS: Standard dentin blocks of 4 mm×4 mm×2 mm size were prepared from single root canal isolated teeth without caries, placed in the E. faecalis bacterial solution, centrifuged in gradient and incubated for 24 h to establish the model of dentinal tubule infection with E. faecalis. The twenty dentin blocks of were divided into five groups, low-temperature plasma jet treatment for 0, 5 and 10 min, calcium hydroxide paste sealing for 7 d and 2% chlorhexidine gel sealing for 7 d. Scanning electron microscopy and confocal laser scanning microscope were used to assess the infection in the dentinal tubules and the antibacterial effect of low-temperature plasma. RESULTS: The results of scanning electron microscopy and confocal laser scanning microscopy showed that after 24 h of incubation by gradient centrifugation, E. faecalis could fully enter the dentinal tubules to a depth of more than 600μm indicating that this method was time-saving and efficient and could successfully construct a model of E. faecalis infection in dentinal tubules. Low-temperature plasma could enter the dentinal tubules and play a role, the structure of E. faecalis was still intact after 5 min of low-temperature plasma treatment, with no obvious damage, and after 10 min of low-temperature plasma treatment, the surface morphology of E. faecalis was crumpled and deformed, the cell wall was seriously collapsed, and the normal physiological morphology was damaged indicating that the majority of E. faecalis was killed in the dentinal tubules. The antibacterial effect of low-temperature plasma treatment for 10 min exceeded that of the calcium hydroxide paste sealing for 7 d and the 2% chlorhexidine gel sealing for 7 d. These two chemicals had difficulty entering deep into the dentinal tubules, and therefore only had a few of antibacterial effect on the bacterial biofilm on the root canal wall, and there was also no significant damage to the E. faecalis bacterial structure. CONCLUSION Gradient centrifugation could establish the model of E. faecalis dentin infection successfully. Low-temperature plasma treatment for 10 min could kill E. faecalis in dentinal tubules effectively, which is superior to the calcium hydroxide paste sealing for 7 d and the 2% chlorhexidine gel sealing for 7 d.
Chlorhexidine/pharmacology* ; Calcium Hydroxide/pharmacology* ; Enterococcus faecalis/physiology* ; Temperature ; Dentin ; Biofilms ; Anti-Bacterial Agents/pharmacology* ; Root Canal Irrigants/pharmacology* ; Dental Pulp Cavity

FOR smear layer removal from root canal walls, ethylenediaminetetraacetic acid (EDTA) is an effective chelating agent and its efficiency depends upon a lot of factors such as concentration, pH, duration of application, the type of the solution, the root canal length, penetration depth of the material, and hardness of the dentin.The aim of this scanning electron microscopic study was to evaluate the effectiveness of 19% EDTA gel on smear layer removal at different time periods when used as a final step in the irrigation regime.
Chelating Agents ; pharmacology ; Dental Pulp Cavity ; drug effects ; ultrastructure ; Edetic Acid ; pharmacology ; Gels ; Humans ; In Vitro Techniques ; Microscopy, Electron, Scanning ; Root Canal Irrigants ; pharmacology ; Smear Layer ; Therapeutic Irrigation

The purpose of this investigation was to elucidate the effects of superoxide dismutase (SOD) on the induced periapical periodontitis in rat, and to shed light on the possible mechanism involved in root canal therapy. 48 Wistar rats with induced periapical periodontitis were randomly divided into 3 groups; their root canals of molar teeth were prepared; and the root canals were filled with SOD, CH, and nothing, respectively. At 1, 2, 3 and 5 weeks after operation, 4 animals were killed respectively. Periapical roentgenogram and periapical pathological slices were made. The results were analyzed statistically by F test and t test with SPSS12.0 software package. After root canal therapy, mild inflammatory infiltration was observed in SOD and CH groups at 1 week. At 2 weeks, periapical periodontitis was improved. After 3 weeks, there was no inflammatory cell observed in SOD/CH group. At 3 and 5 weeks, no significant difference in periapical radiographic findings was noted between the experimental groups and normal group (P > 0.05). The periapical radiographic lesion in control group was larger than that in SOD and CH groups (P < 0.01). The results showed that SOD could control periapical inflammation and induce the proliferation of dentin and cementum. Therefore, SOD might be an ideal biocompatible material for root canal therapy.
Animals ; Female ; Male ; Periapical Periodontitis ; drug therapy ; Random Allocation ; Rats ; Rats, Wistar ; Root Canal Irrigants ; administration & dosage ; Superoxide Dismutase ; administration & dosage ; pharmacology

This study investigated the efficacy of calcium hydroxide and chlorhexidine gel for the elimination of intratubular Candida albicans (C. albicans). Human single-rooted teeth contaminated with C. albicans were treated with calcium hydroxide, 2% chlorhexidine gel, calcium hydroxide plus 2% chlorhexidine gel, or saline (0.9% sodium chloride) as a positive control. The samples obtained at depths of 0-100 and 100-200 µm from the root canal system were analyzed for C. albicans load by counting the number of colony forming units and for the percentage of viable C. albicans using fluorescence microscopy. First, the antimicrobial activity of calcium hydroxide and the 2% chlorhexidine gel was evaluated by counting the number of colony forming units. After 14 days of intracanal medication, there was a significant decrease in the number of C. albicans colony forming units at a depth of 0-100 µm with chlorhexidine treatment either with or without calcium hydroxide compared with the calcium hydroxide only treatment. However, there were no differences in the number of colony forming units at the 100-200 µm depth for any of the medications investigated. C. albicans viability was also evaluated by vital staining techniques and fluorescence microscopy analysis. Antifungal activity against C. albicans significantly increased at both depths in the chlorhexidine groups with and without calcium hydroxide compared with the groups treated with calcium hydroxide only. Treatments with only chlorhexidine or chlorhexidine in combination with calcium hydroxide were effective for elimination of C. albicans.
Antifungal Agents ; administration & dosage ; pharmacology ; Calcium Hydroxide ; administration & dosage ; pharmacology ; Candida albicans ; drug effects ; Chlorhexidine ; administration & dosage ; pharmacology ; Colony Count, Microbial ; Coloring Agents ; Dental Pulp Cavity ; microbiology ; Drug Combinations ; Humans ; Microbial Viability ; drug effects ; Microscopy, Electron, Scanning ; Microscopy, Fluorescence ; Root Canal Irrigants ; administration & dosage ; pharmacology ; Root Canal Preparation ; methods ; Smear Layer ; Time Factors