Intracanal Bacterial Reduction Research Articles

Effects of Calcium Hydroxide Paste in Different Vehicles on Bacterial Reduction during Treatment of Teeth with Apical Periodontitis

IntroductionThis clinical study evaluated the antibacterial effects of calcium hydroxide associated with different vehicles during the treatment of infected teeth with apical periodontitis. MethodsBacteriologic samples were taken from 90 necrotic root canals of teeth with apical periodontitis before (S1) and after preparation with a rotary nickel-titanium instrument system and 2.5% sodium hypochlorite irrigation (S2). The teeth were distributed in 3 groups according to the intracanal medication used, which consisted of a calcium hydroxide paste in glycerin, camphorated paramonochlorophenol/glycerin (CHPG), or 2% chlorhexidine for 1 week, and then another sample was taken (S3). The frequency of bacteria-positive cases and the reduction of bacterial counts were evaluated by quantitative real-time polymerase chain reaction. ResultsSubstantial intracanal bacterial reduction was observed after preparation in the 3 groups (P < .001). After calcium hydroxide paste in glycerin medication, the number of bacteria-positive cases decreased from 20/29 (69%) to 17/29 (59%); however, the mean bacterial counts increased 8.4% from S2 to S3. Medication with CHPG reduced the number of bacteria-positive cases from 17/29 (59%) to 15/29 (52%), with a significant mean S2–S3 reduction of 71% (P < .05). In the chlorhexidine group, the number of bacteria-positive cases decreased from 21/30 (70%) to 17/30 (57%) after medication, with a mean S2–S3 reduction of 55%, which, however, was not statistically significant (P > .05). Intergroup comparisons showed no significant differences (P > .05). ConclusionComparison between the 3 calcium hydroxide pastes showed no significant differences in antibacterial effectiveness in the main root canal. However, only the CHPG paste showed a significant reduction in bacterial counts when postpreparation and postmedication samples were compared.

Enhancing the Intracanal Antibacterial Effects of Sodium Hypochlorite with Etidronic Acid or Citric Acid

IntroductionThis study evaluated the bacterial reduction promoted by root canal preparation using irrigation with sodium hypochlorite (NaOCl) alone, associated with etidronic acid (1-hydroxyethane 1,1-diphosphonic acid [HEDP]) or alternated with citric acid, and after a supplementary agitation step. MethodsExtracted mandibular premolars were selected and distributed into 3 groups based on anatomically paired micro–computed tomographic analyses. The canals were contaminated with Enterococcus faecalis for 30 days and then subjected to chemomechanical preparation with a reciprocating instrument under irrigation with NaOCl alone, mixed with HEDP (NaOCl/HEDP), or alternated with citric acid (NaOCl/CA). A supplementary agitation step with the XP-endo Finisher was performed in all groups. Intracanal bacteriological samples were taken before (S1) and after preparation (S2) and after the supplementary approach (S3). DNA was extracted from the samples and subjected to quantitative real-time polymerase chain reaction. ResultsIntragroup analyses revealed a substantial bacterial reduction from S1 to S2 or S3 in all groups (P < .01). The supplementary agitation resulted in S2-to-S3 bacterial reduction of 6%, 68%, and 80% in the NaOCl, NaOCl/HEDP, and NaOCl/CA groups, respectively. Irrigation with NaOCl alone resulted in 53% and 47% of samples negative for bacteria in S2 and S3, respectively. Corresponding figures for NaOCl/HEDP were 75% and 85%, and 44% and 72% for NaOCl/CA. Intergroup analyses of S2 samples showed that NaOCl/HEDP was significantly more effective than the other 2 in reducing the bacterial levels (P < .05). After the supplementary approach, both NaOCl/HEDP and NaOCl/CA were significantly more effective than NaOCl alone (P < .05), with no significant differences between them (P > .05). ConclusionsBoth the freshly combined NaOCl/HEDP solution and the alternate use of NaOCl and citric acid followed by XP-endo Finisher agitation resulted in significantly higher intracanal bacterial reduction than NaOCl alone.

Root Canal Disinfection by Single- and Multiple-instrument Systems: Effects of Sodium Hypochlorite Volume, Concentration, and Retention Time

IntroductionThis ex vivo study evaluated the intracanal bacterial reduction promoted by chemomechanical preparation using a single-file technique varying the volume, concentration, and retention time of sodium hypochlorite (NaOCl) irrigation in comparison with a multifile system. MethodsPalatal roots from extracted maxillary first molars were selected and anatomically matched based on microcomputed tomographic analysis for group distribution. The canals were contaminated with a fresh mixed bacterial culture grown in anaerobiosis and recently obtained from a tooth with apical periodontitis. Specimens were divided into 4 groups of 24 each according to the following preparation protocols: REC-6LOW (Reciproc R50 instrument [VDW, Munich, Germany], 6% NaOCl, low irrigant volume), REC-2.5LOW (R50, 2.5% NaOCl, low irrigant volume), REC-2.5HI (R50, 2.5% NaOCl, high irrigant volume), and BR-2.5HI (BioRaCe [FKG Dentaire, LaChaux-de-Fonds, Switzerland], 2.5% NaOCl, high irrigant volume). The total time of preparation was recorded. Intracanal bacteriologic samples were taken before and after preparation; DNA was extracted and subjected to quantitative polymerase chain reaction. ResultsBacteria were detected in 22 initial samples from the REC-2.5LOW group and in 23 from the other groups. Intragroup analysis showed that all tested preparation protocols were highly effective in significantly reducing the intracanal bacterial counts (P < .001). Intergroup comparison of bacterial reduction levels revealed a statistically significant difference between BR-2.5HI and REC-2.5LOW (P < .05). Counts of bacteria were 2.5 times significantly higher in REC-2.5LOW compared with BR-2.5HI. No other significant differences were found in quantitative findings (P > .05). ConclusionsThe concerted effects of multiple instruments, the high volume of irrigation, and the long retention time of NaOCl irrigant had a positive influence on intracanal disinfection during chemomechanical preparation.

Bacteria and Hard Tissue Debris Extrusion and Intracanal Bacterial Reduction Promoted by XP-endo Shaper and Reciproc Instruments

IntroductionThis study used a multipurpose analytic approach to compare the levels of apically extruded bacterial and hard tissue debris as well as intracanal bacterial reduction after root canal preparation with either XP-endo Shaper (FKG Dentaire, La Chaux-de-Fonds, Switzerland) or Reciproc (VDW, Munich, Germany) instruments. MethodsDistobuccal canals from extracted maxillary molars were contaminated with Enterococcus faecalis and randomly distributed into 2 groups according to the instrumentation system: the XP-endo Shaper or Reciproc. Teeth were mounted in an apparatus that simulates the apical resistance offered by the periapical tissues and permitted to collect debris extruded during preparation. Saline was used as the irrigant during preparation, and all treatment procedures were performed inside a cabinet under a controlled temperature of 37°C. DNA extracts from samples taken from the canal before and after preparation were subjected to quantitative real-time polymerase chain reaction for E. faecalis counting. The volume of extruded debris was evaluated by micro–computed tomographic imaging. DNA was extracted from the extruded hard tissue debris and analyzed by quantitative real-time polymerase chain reaction. ResultsMechanical intracanal bacterial reduction was significantly more pronounced when using the XP-endo Shaper (P < .001). Although both instruments produced a similar volume of extruded debris (P > .05), extruded bacteria counts were significantly lower with Reciproc than the XP-endo Shaper (P < .001). No correlation was observed between the extruded bacterial counts and debris volume. ConclusionsAlthough bacterial extrusion was lower with Reciproc, the intracanal bacterial reduction was higher with the XP-endo Shaper. Both techniques produced a similar volume of hard tissue debris extrusion.

Influence of the Apical Preparation Size and the Irrigant Type on Bacterial Reduction in Root Canal–treated Teeth with Apical Periodontitis

IntroductionThis clinical study evaluated the influence of the apical preparation size using nickel-titanium rotary instrumentation and the effect of a disinfectant on bacterial reduction in root canal–treated teeth with apical periodontitis. MethodsForty-three teeth with posttreatment apical periodontitis were selected for retreatment. Teeth were randomly divided into 2 groups according to the irrigant used (2.5% sodium hypochlorite [NaOCl], n = 22; saline, n = 21). Canals were prepared with the Twisted File Adaptive (TFA) system (SybronEndo, Orange, CA). Bacteriological samples were taken before preparation (S1), after using the first instrument (S2), and then after the third instrument of the TFA system (S3). In the saline group, an additional sample was taken after final irrigation with 1% NaOCl (S4). DNA was extracted from the clinical samples and subjected to quantitative real-time polymerase chain reaction to evaluate the levels of total bacteria and streptococci. ResultsS1 from all teeth were positive for bacteria. Preparation to the first and third instruments from the TFA system showed a highly significant intracanal bacterial reduction regardless of the irrigant (P < .01). Apical enlargement to the third instrument caused a significantly higher decrease in bacterial counts than the first instrument (P < .01). Intergroup comparison revealed no significant difference between NaOCl and saline after the first instrument (P > .05). NaOCl was significantly better than saline after using the largest instrument in the series (P < .01). ConclusionsIrrespective of the type of irrigant, an increase in the apical preparation size significantly enhanced root canal disinfection. The disinfecting benefit of NaOCl over saline was significant at large apical preparation sizes.

Influence of Taper of Root Canal Shape on the Intracanal Bacterial Reduction.

Objectives:Taper is a factor that determines final root canal dimensions and consequently, the space available for the cleaning action of irrigants. Therefore, the aim of this study was to investigate the influence of taper on intracanal bacterial reduction.Methods:Sterilized root canals of 25 mandibular incisors were inoculated with E. faecalis and then divided into two experimental groups and one control group (A= saline, B= NaOCl + EDTA and C= control, not prepared). Groups A and B were prepared to an apical size of #30/0.04, a culture was obtained and then prepared to #30/0.08 and cultured again. Final irrigation sequence was 30 ml of saline for group A and 10 ml of 17% EDTA followed by 10 ml of 2.5% NaOCl and 10 ml of saline for group B. The CFU ml-1 of the pre- and two post-operative samplings were recorded. Values were compared by performing ANOVA and FDR for multiple hypothesis testing.Results:No statistically significant difference between initial CFU ml-1 readings was recorded, whereas significant differences between group A and B at both 4% and 8% tapers were noted. Furthermore, a linear-dependent reduction of CFU ml-1 was recorded in each group from non-instrumented root canals to #30/0.04 and subsequently to #30/0.08. The positive control group shows the expected reduction of bacterial count.Conclusion:Chemomechanical instrumentation was more efficient at reducing E. faecalis when the taper of root canals increased from 4% to 8% and NaOCl plus EDTA led to a greater intracanal bacterial reduction than saline, regardless of the taper achieved.

Comparative evaluation of antimicrobial efficacy of three herbal irrigants in reducing intracanal E. faecalis populations: An in vitro study.

BackgroundThe present study aimed to evaluate the intracanal bacterial reduction promoted by chemomechanical preparation using three different herbal extracts named Ocimum sanctum (OS), Cinnamomum zeylanicum (CZ), Syzygium aromaticum (SA) against Enterococcus faecalis.Material and MethodsRoot canals from extracted teeth were contaminated with Enterococcus faecalis ATCC 29212 for 7 days and then randomly distributed into 3 experimental groups of 10 teeth each: which includes conventional irrigation with OS, CZ and SA. The control groups included 5 teeth each consisting of NaOCl (positive control) and distilled water (negative control). Samples taken before and after chemomechanical procedures were cultured, and the colony-forming units (CFUs) were counted. Bacterial identification was performed using Polymerase chain reaction technique. The statistical analyses were performed with various tests. ResultsReduction in the intracanal bacterial populations was highly significant for all the experimental groups. CZ and SA showed 80 to 85% intracanal bacterial reduction while O. Sanctum revealed only 70 to 75 % reduction. NaOCl showed 96 to 100 % bacterial reduction on the other hand distilled water showed very minimal bacterial reduction i.e 10 to 16%.ConclusionsCinnamomum zeylanicum, Syzygium aromaticum and Ocimum sanctum showed intracanal bacterial reduction against Enterococcus faecalis. The 3 experimental groups were less effective in terms of intracanal bacterial reduction as compare to NaOCl but more effective than distilled water. Key words:Antimicrobial activity, Cinnamomum zeylanicum, Enterococcus faecalis, Ocimum sanctum, Syzygium aromaticum, herbal extracts.

Efficacy of a Novel Rotary System in Reduction of Intracanal Bacteria: An in Vitro Study.

Introduction:This in vitro study aimed to assess the effectiveness of a single-file rotary system (OneShape) in reduction of intracanal bacteria. Methods and Materials:Eighty one single-rooted mandibular first premolars with single canals were used. Six samples were selected as aseptic control group. Seventy five remaining specimens were infected by Enterococcus faecalis and incubated for 72 h at 37°C. Then they were randomly divided into three groups (n=25). In each group, cleaning and shaping procedures were done using either two conventional rotary systems (ProTaper and iRace), or the single-file system (OneShape). Microbial samples from the intracanal environment were taken by paper points in two steps, before and after instrumentation. Then, they were diluted and plated in blood agar. In order to compare bacterial reduction and turbidity, the Kruskal-Wallis test was used followed by the Chi-Square and Mann-Whitney tests for pairwise comparison. The level of significance was set at 0.05. Results:The control group didn’t show any bacterial growth. The pre- and post-instrumentation samples were significantly different between three groups (P=0.02). Hence, there was no significant differences between turbidity of samples (P>0.05). Conclusion:OneShape system is efficient in bacterial reduction. In this regard ProTaper is the most effective system in intracanal bacterial reduction followed by iRaCe and OneShape, respectively.

Infection Control in Retreatment Cases: In Vivo Antibacterial Effects of 2 Instrumentation Systems

IntroductionThis in vivo study compared the antibacterial effects of 2 instrumentation systems in root canal–treated teeth with apical periodontitis. MethodsForty-eight teeth with a single root and a single canal showing post-treatment apical periodontitis were selected for this study. For retreatment, teeth were randomly divided into 2 groups according to the instrumentation system used: Self-Adjusting File (SAF; ReDent-Nova, Ra'anana, Israel) and Twisted File Adaptive (TFA; SybronEndo, Orange, CA). In both groups, 2.5% sodium hypochlorite was the irrigant. Bacteriological samples were taken before (S1) and after chemomechanical preparation (S2). In the TFA group, passive ultrasonic irrigation (PUI) was performed after instrumentation, and samples were also taken after this supplementary step (S2b). DNA was extracted from the clinical samples and subjected to quantitative real-time polymerase chain reaction to evaluate the levels of total bacteria, streptococci, and Enterococcus faecalis. Statistical analyses from quantitative real-time polymerase chain reaction data were performed within groups using the Wilcoxon matched pairs test and between groups using the Mann-Whitney U test and the Fisher exact test with the significance level set at P < .05. ResultsBacteria were detected in S1 samples from 43 teeth, which were then included in the antibacterial experiment. Both SAF and TFA instrumentation protocols showed a highly significant intracanal bacterial reduction (P < .001). Intergroup quantitative comparisons disclosed no significant differences between TFA with or without PUI and SAF (P > .05). PUI did not result in significant improvement in disinfection (P > .05). ConclusionsBoth instrumentation systems/treatment protocols were highly effective in significantly reducing the intracanal bacterial counts. No significant difference was observed between the 2 systems in disinfecting the canals of teeth with post-treatment apical periodontitis.

Correlative Bacteriologic and Micro–Computed Tomographic Analysis of Mandibular Molar Mesial Canals Prepared by Self-Adjusting File, Reciproc, and Twisted File Systems

IntroductionThis ex vivo study evaluated the disinfecting and shaping ability of 3 protocols used in the preparation of mesial root canals of mandibular molars by means of correlative bacteriologic and micro–computed tomographic (μμCT) analysis. MethodsThe mesial canals of extracted mandibular molars were contaminated with Enterococcus faecalis for 30 days and assigned to 3 groups based on their anatomic configuration as determined by μCT analysis according to the preparation technique (Self-Adjusting File [ReDent-Nova, Ra’anana, Israel], Reciproc [VDW, Munich, Germany], and Twisted File [SybronEndo, Orange, CA]). In all groups, 2.5% NaOCl was the irrigant. Canal samples were taken before (S1) and after instrumentation (S2), and bacterial quantification was performed using culture. Next, mesial roots were subjected to additional μCT analysis in order to evaluate shaping of the canals. ResultsAll instrumentation protocols promoted a highly significant intracanal bacterial reduction (P < .001). Intergroup quantitative and qualitative comparisons disclosed no significant differences between groups (P > .05). As for shaping, no statistical difference was observed between the techniques regarding the mean percentage of volume increase, the surface area increase, the unprepared surface area, and the relative unprepared surface area (P > .05). Correlative analysis showed no statistically significant relationship between bacterial reduction and the mean percentage increase of the analyzed parameters (P > .05). ConclusionsThe 3 instrumentation systems have similar disinfecting and shaping performance in the preparation of mesial canals of mandibular molars.

Antimicrobial efficacy of cryotreatment against Enterococcus faecalis in root canals

The purpose of this investigation was to evaluate intracanal bacterial reduction by cryotreatment using a dental instrument equipped with a duct and connected to a cryogenic fluid source. A total of 86 roots were infected with Enterococcus faecalis and incubated. After incubation, the contaminated roots were divided into three study groups: 35 roots irrigated with 2 ml of a 5% sodium hypochlorite (NaOCl) solution, 35 roots irrigated with 2 ml of a 5% NaOCl solution and further treated with cryo and 10 roots irrigated with 2 ml of saline solution, plus positive and negative controls. Subsequent to each irrigation treatment, the residual bacterial colonies were counted. The use of cryo-instrumentation in association with NaOCl irrigation significantly reduced the number of Ent. faecalis (P < 0·01) in the root canal compared with controls. The interesting potential of cryotreatment should be further investigated through clinical studies aimed to establish a correct irrigation protocol. Within the limits of the study, the cryotreatment seems to have a greater effect on the reduction in bacteria compared to a standard NaOCl irrigation.

Comparison of two mechanical instrumentation techniques in reducing root canal bacterial population

Microorganisms and their products play an important role in the pathogenesis of pulpal and periradicular diseases, so their elimination from root canal system as well as reinfection prevention are the main purpose of root canal treatment. This study was designed to compare the in-vitro efficiency of the Hero and M-Two rotary instruments in intracanal bacterial reduction. Fifty six human extracted teeth were divided into two equal experimental groups (n=25), Hero file as group 1 and M-Two file as group 2, and one control group (n=6). All samples were prepared by K-file No 20 and Gates Glidden No 2 and 3 before sterilization. The teeth were autoclaved and then were infected with Enterococcus faecalis . The experimental groups were instrumented either with Hero 4% or with M-Two files up to #30. To determine the level of remaining organisms, bacteria samples were collected after instrumentation. In the group 1, two samples and in the group 2, 12 samples represented complete elimination of bacteria. There was statistically significant difference between the two groups regarding the level of bacteria elimination (p<0/05). So using M-Two instrumentation technique reduces the intracanal bacteria more efficiently than Hero 4% instrumentation technique.

Evaluation of cleaning capacity and instrumentation time of manual, hybrid and rotary instrumentation techniques in primary molars

To compare the cleaning effectiveness of manual, hybrid and rotary instrumentation techniques in primary molar teeth. Fifteen primary molars were selected. After endodontic access, the teeth were immersed in a medium containing Enterococcus faecalis and divided into three groups, according to the root canal instrumentation technique: group 1 - manual, group 2 - hybrid and group 3 - nickel-titanium (NiTi) rotary files. For microbiological evaluation, comparisons before and after instrumentation were performed using the paired Student's t-test. One-way anova complemented with the Student's t-test was used to compare the percentage of microbial reduction. Instrumentation time was evaluated by Kruskal-Wallis and Student-Newman-Keuls tests. Images obtained under scanning electron microscopy were analysed by three blinded examiners, and kappa statistics was used to evaluate calibration among examiners. The most frequent results among examiners were analysed using Kruskal-Wallis and Student-Newman-Keuls tests. The hybrid technique required a significantly longer instrumentation time than the manual and rotary techniques (P < 0.05). All techniques tested were able to significantly reduce the number of E. faecalis (P < 0.05). The hybrid technique was associated with the highest intracanal bacterial reduction, with a statistically significant difference compared with manual instrumentation (P = 0.01). Manual instrumentation resulted in the lowest amount of debris and the highest amount of smear layer when compared with the rotary and hybrid techniques (P < 0.05). There was no difference between rotary and hybrid instrumentation in the removal of debris and smear layer. The use of NiTi rotary files is an option for root canal instrumentation in primary teeth.

Comparison of the Effectiveness of Three Irrigation Techniques in Reducing Intracanal Enterococcus faecalis Populations: An In Vitro Study

IntroductionSeveral irrigation techniques have been recently introduced with the main objective of improving root canal disinfection. This in vitro study aimed at comparing the intracanal bacterial reduction promoted by chemomechanical preparation with 3 different irrigation techniques. MethodsRoot canals from extracted teeth were contaminated with Enterococcus faecalis ATCC 29212 for 7 days and then randomly distributed into 3 experimental groups of 20 teeth each: group 1, conventional irrigation with NaviTip needles inserted up to 3 mm short of the working length; group 2, same as group 1, but supplemented with final irrigant activation by the EndoActivator system; and group 3, irrigation with the EndoVac system. NaOCl and ethylenediaminetetraacetic acid (EDTA) were the irrigants used in all experimental groups. The overall preparation time was kept constant for the groups, but the total volume ranged from 20 mL (groups 1 and 2) to 43 mL (group 3). The control group was irrigated with saline solution (total volume, 43 mL). Samples taken before and after chemomechanical procedures were cultured, and the colony-forming units (CFUs) were counted. ResultsReduction in the bacterial populations was highly significant for all groups. The 3 experimental groups with NaOCl and EDTA as irrigants were significantly more effective than the control group with saline in reducing CFU counts. There were no significant differences between the 3 techniques tested. ConclusionsThere was no evident antibacterial superiority of any of the irrigation techniques evaluated in the present in vitro model.

Efficacy of Instrumentation Techniques and Irrigation Regimens in Reducing the Bacterial Population within Root Canals

The purpose of this study was to compare the in vitro intracanal bacterial reduction produced by using two instrumentation techniques and different irrigation methods. Root canals inoculated with Enterococcus faecalis were prepared by using the following techniques and irrigants: alternated rotary motions (ARM) technique, hand nickel-titanium files and 2.5% sodium hypochlorite (NaOCl) as irrigant; ARM technique and combined irrigation with 2.5% NaOCl and citric acid; ARM technique and combined irrigation with 2.5% NaOCl and 2% chlorhexidine gluconate; and Greater Taper rotary files, using 2.5% NaOCl as irrigant. Controls were instrumented by using the ARM technique and irrigated with sterile saline. Canals were sampled before and after preparation. After serial dilution, samples were plated onto Mitis-Salivarius agar, and the colony forming units that were grown were counted. All test techniques and solutions significantly reduced the number of bacterial cells within the root canal (p < 0.05). There was no significant difference between the experimental groups (p > 0.05). Nonetheless, all of them were significantly more effective than the control group (p < 0.05). These findings support the importance of using antimicrobial irrigants during the chemomechanical preparation, regardless of the solutions or instrumentation techniques used.

Chemomechanical Reduction of the Bacterial Population in the Root Canal after Instrumentation and Irrigation with 1%, 2.5%, and 5.25% Sodium Hypochlorite

Given the importance of bacteria in the development of periradicular lesions, the eradication of the root canal infection is paramount in endodontic treatment. This study evaluated the in vitro intracanal bacterial reduction produced by instrumentation and irrigation with 1%, 2.5%, and 5.25% sodium hypochlorite (NaOCl) or saline solution. Root canals inoculated with Enterococcus faecalis were instrumented and irrigated with the solutions tested. Canals were sampled before and after preparation. After serial dilution, samples were plated onto Mitis salivarius agar, and the colony-forming units grown were counted. Inhibitory effects of the three NaOCl solutions on E. faecalis were also evaluated by means of the agar diffusion test. All test solutions significantly reduced the number of bacterial cells in the root canal (p < 0.05). There was no significant difference between the three NaOCl solutions tested (p > 0.05). Nonetheless, all NaOCl solutions were significantly more effective than saline solution in reducing the number of bacterial cells within the root canal (p < 0.05). The three NaOCl concentrations showed large zones of inhibition against E. faecalis. The results of this study suggest that regular exchange and the use of large amounts of irrigant should maintain the antibacterial effectiveness of the NaOCl solution, compensating for the effects of concentration.

Bacterial reduction with nickel-titanium rotary instrumentation

The purpose of this study was to compare intracanal bacterial reduction on teeth instrumented with 0.04 tapered nickel-titanium (NiTi) rotary instrumentation to bacterial reduction when using a stainless-steel K-file step-back technique using sterile saline irrigation. Forty-eight patients with apical periodontitis were randomly assigned treatment type. The canals were sampled before, during, and after instrumentation. The samples were incubated anaerobically for 7 days at 37 degrees C, colony-forming unit numbers calculated, and a log transformation performed to normalize the counts. Teeth exhibiting apical periodontitis were uniformly infected, whereas vital control teeth were not. A similar and uniform reduction occurred with progressive filing, regardless of technique (p < 0.0001). There was no detectable difference in colony-forming unit count after NiTi rotary or stainless-steel hand instrumentation (p = 0.42). Neither technique could predictably render canals free of bacteria. The results of this study indicate NiTi rotary and stainless-steel hand K-file step-back instrumentation techniques were not significantly different in their ability to reduce intracanal bacteria.

OR 12 Intracanal bacterial reduction with nickel-titanium rotary instrumentation

OR 12 Intracanal bacterial reduction with nickel-titanium rotary instrumentation