Passive ultrasonic irrigation in root canal: systematic review and meta-analysis

Cleaning and disinfection of the root canal system provided by four active supplementary irrigation methods

This in vitro study evaluated the bacterial reduction provided by the EndoActivator (EA), Easy Clean (EC), passive ultrasonic irrigation (PUI), and XP-Endo Finisher. Eight-four mesial roots of mandibular first molars were instrumented, inoculated with Enterococcus faecalis, and divided into four groups (n. 20). Bacterial reduction in the main canals and dentinal tubules were respectively determined by MTT assays and Live/Dead BackLight technique through confocal laser scanning microscopy (CLSM) at 50, 100, and 150 µm in-depth (n. 10 per group). Statistical analyses were conducted following a significance level of 95% (P < 0.05). A significant statistical difference was just identified between XPF and EC in the main canals. In the dentinal tubules from the main root canals, at 100 and 150 µm in-depths, significant statistical differences were only observed between XPF and EC (P = 0.027) for the former and between XPF and EC (P = 0.011) and XPF and PUI (P = 0.021) for the latter. In the dentinal tubules from the isthmus, at 100 µm in-depth, statistically relevant differences did occur between XPF and EC (P = 0.038) and EC and EA (P = 0.029). At 150 µm in-depth, these differences were only significant by comparing XPF and PUI (P = 0.025) and XPF and EC (P = 0.036). Although no irrigation method could thoroughly disinfect the RCS, bacterial reduction indexes were generally better after using XPF.

Comparison of Easydo Activator, ultrasonic and needle irrigation techniques on sealer penetration and smear layer removal in vitro

The effects of Easydo Activator (EA), a new sonic irrigation system, on sealer penetration at the root apex were compared to needle irrigation (NI) and passive ultrasonic irrigation (PUI) in this study. Forty-two single-rooted teeth were prepared and randomly divided into three groups (n = 14): group 1: NI; group 2: PUI; and group 3: EA. A solution of 3% sodium hypochlorite (NaOCl) was used for irrigation. Nine teeth in each group were filled with AH Plus sealer mixed with CY5 fluorescent dye and a single gutta-percha cone. The sealer penetration area, maximum penetration depth and percentage of sealer penetration at 5 mm and 1 mm from the apex were analyzed by confocal laser scanning microscopy (CLSM). The remaining 5 teeth in each group were subjected to test smear layer scores by scanning electron microscopy (SEM). The CLSM evaluation showed that increases in the area, depth and percentage of sealer penetration were detected at 1 and 5 mm from the root apex in the PUI group compared with the NI group, and greater increases were observed in the EA group (P < 0.05). The SEM experiment showed that the lowest scores for the smear layer and debris removal were achieved by the EA group when compared with the PUI and NI groups (P < 0.05). In conclusion, EA was superior to PUI and NI regarding sealer penetration at the root apex during endodontic treatment, and it could provide a new technical idea for clinical root canal therapy.

Can Heated Distilled Water Effectively Prevent Precipitate Formation between NaOCl and CHX?

Introduction

The present study aimed to investigate the capacity of different irrigation protocols using heated distilled water at 65°C (HDW), in preventing the formation of the brown-orange precipitate observed after the interaction between sodium hypochlorite (NaOCl) and chlorhexidine (CHX).

Methods

Forty human canines were selected, prepared, and cleaved in two halves. Images of delimited areas in each root canal thirds were obtained through a stereomicroscope (16x and 40x). After reassembly, the teeth were distributed into four groups (n = 10) according to the final irrigation protocol: G1 (no HDW): EDTA + NaOCl + CHX with conventional irrigation (CI); G2 (HDW + CI): EDTA with passive ultrasonic irrigation (PUI) + NaOCl (PUI) + HDW (CI) + CHX (PUI); G3 (HDW + PUI): EDTA + NaOCl + HDW + CHX with PUI; G4 (HDW + CUI): EDTA (PUI) + NaOCl (PUI) + HDW with continuous ultrasonic irrigation (CUI) + CHX (PUI). After irrigation, the teeth were re-separated and images of the same delimited areas were obtained again. Scores were assigned according to the amount of precipitate observed, comparing the initial and final images. The data were submitted to Kruskal-Wallis, Dunn and Friedman statistical tests (α = 5%).

Results

G1(no HDW) showed the highest scores in the analysis between groups (p < 0.001), with a greater amount of precipitate in the cervical and medium thirds (p < 0.001). The thirds of the other experimental groups did not differ from each other (p > 0.05).

Conclusion

The intermediate irrigation with heated distilled water at 65°C prevented the formation of brown-orange precipitate, regardless of the use of ultrasonic activation (PUI or CUI).

Effectiveness of adjunct therapy for the treatment of apical periodontitis: A systematic review and meta-analysis

BACKGROUND

Adjunct therapy refers to any intracanal procedure going beyond chemomechanical preparation with instruments and traditionally delivered irrigants (excluding interim dressings). It is not clear whether and which of these adjunct therapies have a significant impact on the outcome of root canal treatment [healing of apical periodontitis (AP) and other patient-related outcomes].

OBJECTIVES

This systematic review aimed to analyse available evidence on the effectiveness of adjunct therapy for the treatment of AP in permanent teeth, according to a population, intervention, comparison, outcome, time and study design framework formulated a priori by the European Society of Endodontology.

METHODS

Five electronic databases (PubMed, Embase, Scopus, Cochrane and Web of Science) were searched up to October 2021 to identify clinical studies comparing adjunct therapy to no adjunct therapy in adult patients with AP. Animal studies, reviews, studies with less than 10 patients per arm and studies with a follow-up time of less than 1 year, or less than 7 days for postoperative pain, were excluded. The quality of the included studies was appraised by the appropriate tools [Risk of Bias 2 (RoB2) for randomized clinical trials (RCTs) and Newcastle-Ottawa Scale for observational studies]. Meta-analysis was performed using a random-effects model. The certainty of the evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach.

RESULTS

Fourteen studies (13 RCTs and one retrospective cohort) fulfilled the inclusion criteria for this review. They evaluated different types of adjunct therapy: antimicrobial photodynamic therapy (aPDT; three studies), diode laser canal irradiation (3), Nd:YAG laser canal irradiation (2), Er;Cr:YSGG laser canal irradiation (1), ozone therapy (2) and ultrasonically activated irrigation (UAI) (4). Radiographical healing was reported in seven studies, but meta-analysis was only possible for UAI (two studies), showing no statistically significant difference in healing after 12 months. Pain after 7 days was reported in seven studies. Meta-analysis on three studies that used aPDT and on two studies using diode laser irradiation showed no significant difference in the prevalence of pain after 7 days between the control and adjunct therapy. According to RoB2 tool, six studies had a high risk of bias, five studies had some concerns, and two studies low risk of bias. The GRADE assessment revealed a very low strength of evidence for diode laser, and low strength of evidence for PDT, ozone and UAI studies.

DISCUSSION

The included studies displayed significant heterogeneity in terms of type of adjunct therapy, technical details per adjunct therapy, outcome reporting and several combinations of these, limiting the potential for meta-analysis.

CONCLUSIONS

There is insufficient evidence to recommend any adjunctive therapy for the treatment of apical periodontitis.

REGISTRATION

Prospero CRD42021261869.

Antimicrobial effectiveness of ultrasonic irrigation in root canal treatment: a systematic review of randomized clinical trials and meta-analysis

OBJECTIVE

The objective of this systematic review and meta-analysis (SRM) was to answer the question as to whether the use of ultrasonic irrigation (UI) results in better antimicrobial activity in root canal disinfection compared to conventional irrigation (CI).

METHODS

A literature search was performed in the main scientific databases, carried out until October 2021. The eligibility criteria were randomized clinical trials (RCTs). Two meta-analyses were conducted using R software with the "META" package. The mean difference (MD) and odds ratio (OR) measure of effect were calculated. The fixed effect model was applied with a 95% confidence interval. The Cochrane collaboration scale was used to assess risk of bias and the GRADE tool to assess the quality of evidence.

RESULTS

A total of 1782 records were screened, and 12 studies meeting the criteria were included in this review. A low risk of bias was observed for most domains, except allocation concealment that was considered unclear. The certainty of evidence was classified as moderate in the OR meta-analyses and low in the MD meta-analyses. Ultrasonic irrigation resulted in a better antimicrobial effect in both meta-analyses, MD 1.42 [1.60; 1.23] p < 0.0001, I² = 80%; and OR 3.86 [1.98; 7.53] p< 0.0001, I² = 28.7%.

CONCLUSION

Within the limitations of this SRM, UI presented better antimicrobial efficacy than CI.

CLINICAL RELEVANCE

UI should be used by clinicians as it promotes better antimicrobial efficacy in patients undergoing endodontic treatment.

Outcomes reporting in systematic reviews on non-surgical root canal treatment: A scoping review for the development of a core outcome set

BACKGROUND

Studies related to non-surgical root canal treatment are amongst the most frequently performed clinical studies in endodontics. However, heterogeneity in reporting outcomes and lack of standardization is a significant challenge to evidence synthesis and guideline development.

OBJECTIVES

The aims of the present scoping review were to (a) identify outcomes reported in systematic reviews evaluating non-surgical root canal treatment; (b) identify how and when the reported outcomes were measured; (c) assess possible selective reporting bias in the included studies. The information obtained in this study should inform the development of a core outcome set (COS) for non-surgical root canal treatment.

METHODOLOGY

Structured literature searches were performed to identify systematic reviews on non-surgical root canal treatments published in English between January 1990 and December 2020. Two reviewers undertook study selection and data extraction. Outcomes were categorized according to a healthcare taxonomy into five core areas (survival, clinical/physiological changes, life impact, resource use, and adverse events). The outcome measurement tools and length of follow-up were recorded.

RESULTS

Seventy-five systematic reviews were included, of which 40 included meta-analyses. Most reviews reported on physiological and clinical outcomes, primarily pain and/or radiographic assessment of periapical status, and a variety of measurement tools and scales were used. Few reviews focused on tooth survival, life impact, resources, and adverse events. The heterogeneity amongst the reviews was large on all parameters. Less than 40% of the reviews assessed the risk of selective reporting.

DISCUSSION

Overall aims of the included reviews were highly heterogenic; thus, outcomes and how they were measured also varied considerably. Patient-centred outcomes and the use of resources were rarely reported on.

CONCLUSIONS

Most studies reported on physiological and clinical outcomes, in particular pain and/or radiographic healing. Measurement tools, scales, thresholds, and follow-up periods varied greatly within each outcome, making comparison across studies complicated. Less than 40% of the reviews assessed risk of selective reporting; thus, selective bias could not be ruled out. The presented information on reported outcomes, measurement tools and scales, and length of follow-up may guide the planning of future research and inform the development of a COS for non-surgical root canal treatment.

Recovery in water polo: how much do we have to know? A systematic review

Water polo (WP) is a high-intensity intermittent aquatic sport, with a predominance of swimming skills and nonswimming activities and incomplete recovery periods. Consequently, recovery after exercise is a fundamental part of sports performance. The main purpose of this systematic review was to evaluate the effects of different recovery strategies in WP performance. The studies were found by searching in the databases of PubMed, Web of Science, and Scopus. Methodological quality and risk of bias were assessed in accordance with the Cochrane Collaboration Guidelines samples. A summary of results including five studies was followed. The results show that supplementation with cherry juice before training does not imply improvements in recovery; the full-body photobiomodulation therapy reduces muscle damage; reducing training load during the season increased the natural logarithm of the root mean square of successive differences and perceived state of recovery, and the heart rate variability stabilizes and could progressively increase at the end of a tournament; and when an increase in internal training load is less than 60%–70% autonomic cardiac disturbances during preseason training do not occur. Recovery in WP is a very limited field of study that needs future research in active recovery, hydrotherapy, massage, rest and sleep to help coaches formulate recommendations.

Sonic irrigation for removal of calcium hydroxide in the apical root canal: A micro-CT and light-coupled tracking analysis

Objective

This study aimed to evaluate the efficacy of three sonic irrigation systems for removal of calcium hydroxide dressing from the apical root canal.

Materials and methods

A total of 96 single-rooted teeth in three categories of root canal curvatures (straight: 0–5°, moderate: 6–20°, and severe: > 20°) were allocated to four groups: conventional needle irrigation, EndoActivator, EQ-S, and Vibringe. The root canals were instrumented using Protaper NEXT and filled with calcium hydroxide. After removal of calcium hydroxide, the remaining volume of calcium hydroxide was measured by micro-CT analysis. Data were compared among root canal curvatures and irrigation systems using the Kruskal-Wallis test and Mann-Whitney test (p < .05). The oscillating range of each irrigation system was measured using light-coupled motion tracking.

Results

The volumes of calcium hydroxide remaining in the canals with severe curvature were significantly higher than in those of straight curvature (p < .05). In the canals of moderate or severe curvature, EQ-S showed the highest removal percentage, followed by EndoActivator, Vibringe, and needle irrigation (p < .05). Light-coupled tracking showed the largest oscillating range in EQ-S (p < .05).

Conclusions

Sonically activated irrigation systems with a flexible tip can be beneficial for calcium hydroxide intracanal dressing removal in the curved apical canals.

The Effect of Irrigation with Citric Acid on Biodentine Tricalcium Silicate-Based Cement: SEM-EDS In Vitro Study

There are various factors that may interfere with the activity of biomaterials during endodontic therapy. One of them is the canal system irrigation procedure with different rinsing solutions performed after the placement of bioactive cements. The authors investigate the influence of citric acid, a chelating agent, on the surface and the chemical composition of Biodentine tricalcium silicate-based cement using a multimethod approach. Twenty samples were divided into two groups based on the material setting time. They were subjected to citric acid irrigation with or without ultrasonic activation for 5 and 20 min. The chemical analysis was made with energy dispersive spectroscopy (EDS). The visual assessment of Biodentine surface was carried out in scanning electron microscope (SEM). The volume of material loss during the procedure was measured with Keyence optic microscope and dedicated digital software. Statistical analysis was performed. The results of the study show that the irrigation with citric acid influenced the surface appearance of the material and changed its chemical composition in both investigated groups. The ultrasonic activation (US) of the liquid has also aggravated its impact. Further research is needed to assess if that fact may change the sealing properties of the material influencing the long-term clinical outcome.

Efficacy of sonic and ultrasonic activation during endodontic treatment: a Meta-analysis of in vitro studies

OBJECTIVE

To ensure a successful endodontic treatment, it is important to have a proper disinfection of the root canal. The current study compares the root canal cleanliness and smear layer score between sonic and ultrasonic activation.

METHOD

Systematic literature review was implemented, using 12 databases. All in vitro studies comparing the efficacy of sonic and ultrasonic activation and reporting at least one outcome of interest were included.

RESULTS

At the apical level, pooling the data in the random-effects model (I²=64%, p = .1) revealed a statistically significant lower smear layer score within the sonic activation group (MD-0.48; 95% CI-0.92, -0.04; p = .03). Furthermore, there was a statistically significant lower push-out bond strength value among the sonic group, in contrast to the ultrasonic group at the middle (MD-0.69; 95% CI-1.13, -0.25; p = .002) and at the apical levels (MD-0.78; 95% CI-1.09, -0.46; p < .0001) of the root canal.

CONCLUSIONS

Sonic activation accomplished advancement relative to ultrasonic agitation in removing the smear layer, while ultrasonic activation resulted in significant cohesion between the sealers and the dentine tubules, decreasing the vulnerability of apical leakage and tooth fracture.

Quantification of Bacterial DNA from Infected Human Root Canals Using qPCR and DAPI after Disinfection with Established and Novel Irrigation Protocols

The removal of bacterial infections within the root canal system is still a challenge. Therefore, the cleansing effect of established and new irrigation-protocols (IP) containing silver diamine fluoride (SDF) 3.8% on the whole root canal system was analyzed using quantitative PCR (qPCR) and 4′,6-diamidino-phenylindole-(DAPI)-staining. Extracted human premolars were instrumented up to F2 (ProTaper Gold) under NaCl 0.9% irrigation and incubated with Enterococcus faecalis for 42 days. Subsequently, different ultrasonically agitated IP were applied to the roots: control (no irrigation), 1. NaOCl 3%, EDTA 20%, CHX 2%, 2. NaOCl 3%, EDTA 20%, 3. NaOCl 3%, EDTA 20%, SDF 3.8%, 4. SDF 3.8%, and 5. NaCl 0.9%. One half of the root was investigated fluorescent-microscopically with DAPI. The other half was grinded in a cryogenic mill and the bacterial DNA was quantified with qPCR. The qPCR results showed a statistically significant reduction of bacteria after the application of IP 1, 2, and 3 compared to the control group. While IP 4 lead to a bacterial reduction which was not significant, IP 5 showed no reduction. These data corresponded with DAPI staining. With qPCR a new molecular-biological method for the investigation of the complete root canal system was implemented. The novel IP 3 had an equally good cleansing effect as the already established IP.

The applications of ultrasound, and ultrasonography in dentistry: a scoping review of the literature

OBJECTIVES

This scoping review aims to summarize the available literature on the clinical applications of ultrasonography and ultrasound in diagnostic, therapeutic, and interventional dental applications.

MATERIALS AND METHODS

We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, Extension for Scoping Reviews checklist and conducted a protocol-driven scoping review of randomized controlled trials, cohort studies, cross-sectional studies, case-control studies, and case series that assessed ultrasonography or ultrasound use as a stand-alone diagnostic, therapeutic, and interventional tool in dentistry. We included studies published after 1980, study samples ≥ 10, with diagnostic, concordance, or therapeutic outcomes. We searched Ovid MEDLINE, Embase, and others (up to April 2021) and extracted information regarding study level, patient level, test or treatment level, and outcome level data.

RESULTS

Five interventional studies (related to oral medicine, temporomandibular disorders, and dental anesthesia), eight therapeutic studies (related to surgery and orthodontics), and seventy-five diagnostic studies (related to orthodontics, surgery, endodontics, oral medicine, temporomandibular disorders, restorative dentistry, and periodontology) were identified and presented in this review.

CONCLUSION

Ultrasonography has a well-established niche in diagnostic dentistry, while therapeutic and interventional ultrasounds have a smaller, yet present, niche in dentistry. However, further research is needed to report the precise estimates of the diagnostic, therapeutic, and interventional effects.

CLINICAL SIGNIFICANCE

Dentists are mostly unfamiliar with ultrasonography and ultrasound and their potential uses. This review maps the diagnostic and therapeutic applications of ultrasonography and ultrasound technology in dentistry and highlights the current challenges, gaps of knowledge, and research status of ultrasound technology in this regard.

Novel laser activated photoacoustic streaming for removing pulp remnants from round root canals after single file reciprocating instrumentation: Photoacoustic streaming for removing pulp

BACKGROUND

This study evaluated the efficacy of a new laser-assisted irrigation system, the shock wave enhanced emission photo-acoustic streaming (SWEEPS) technique in removing pulp tissue from single-rooted premolars.

METHODS

Freshly extracted mandibular premolars with round root canals (n=40), scanned using cone beam computed tomography, were randomly divided into control and four experimental (according to the irrigation technique used) groups (n=8/group). Groups 1, 2, and 3 were instrumented using Reciproc Blue (RB25/.06) followed by final irrigation protocol (FIP), activated by SWEEPS, ultrasonically activated irrigation (UAI), and conventional irrigation (CI), respectively. In these groups, 7 mL 3% NaOCl in total was used during instrumentation; for FIP, 3% NaOCl (60 s), ethylenediaminotetraacetic acid (60s), and 3% NaOCl (30s). In group 4, SWEEPS activation of 3% NaOCl for 6 × 30 s alone was performed. The untreated control group specimens were processed for histological evaluation of remaining pulp tissue (RPT) in each canal third. The results were analyzed using the Mann-Whitney U test (α =0.05).

RESULTS

Significant differences were observed between the control group and the experimental groups (p<0.05). In the middle third, the UIA and SWEEPS showed similar efficacy (p=0.171), superior to CI and SWEEPS without instrumentation (p<0.05). In the apical third, SWEEPS was the most efficient (p=0.002), and UIA and CI showed no difference (p=0.643).

CONCLUSION

SWEEPS was superior to UIA and CI in removing RPT in the apical region of round canals after single instrument root canal preparation; SWEEPS without instrumentation was inefficient in removing pulp tissue.

Clinical and microbiological effects of ultrasonically activated irrigation versus syringe irrigation during endodontic treatment: a systematic review and meta-analysis of randomized clinical trials

This study aimed to systematically review clinical and microbiology-related effects of ultrasonically activated irrigation (UAI) compared to syringe irrigation (SI) during endodontic treatment. Electronic databases searching and manual searching were conducted. Only randomized clinical trials (RCTs) were included comparing UAI to SI. The RoB 2.0 Cochrane tool was used for risk-of-bias (RoB) assessment. The main outcomes were postoperative pain, treatment failure, and microbiology-related outcomes. Qualitative and quantitative analyses, wherever applicable, were performed. Risk ratios (RR) and [standardized] mean differences {[S]MD} were calculated for dichotomous and continuous outcomes, respectively. Certainty of evidence (CoE) was assessed using GRADE tool. Ten RCTs were included. UAI reduced pain incidence within the first 24 h (RR 0.50, 95% CI 0.35-0.71, 308 teeth) and microbial counts (SMD_pooled - 0.40, 95% CI [- 0.78, - 0.02], I² = 0%, 126 teeth) than SI in non-vital teeth with apical periodontitis (AP). Both groups, however, had similar effects regarding pain intensity, lipopolysaccharide amounts, and the incidence of rescue-analgesic intake, treatment failure, and microbial presence (p > 0.05). CoE ranged from low to very low. Very limited evidence suggests that UAI could reduce postoperative-pain risk within the first 24 h and microbial counts for non-vital teeth with AP compared to SI. Most meta-analyses, however, are based on very few studies, mostly low-powered, with an overall very-low-to-low CoE. Further well-designed, larger RCTs are, thus, required.

Evaluation of Ozone Therapy in Endodontic Treatment of Teeth with Necrotic Pulp and Apical Periodontitis: A Randomized Clinical Trial

INTRODUCTION

The aim of this study was to compare the effect of different application techniques of ozone on the prevalence of postendodontic pain in patients undergoing single-visit root canal treatment.

METHODS

hundred eight patients with necrotic pulp in single-rooted teeth and apical periodontitis participated in the trial. A standard single-visit endodontics protocol was followed with 5.25% sodium hypochlorite and rotary nickel-titanium files. After shaping and cleaning, patients were randomly allocated into the following groups: group 1 (n = 21), ozone treatment with no activation (NA); group 2 (n = 22), ozone treatment with manual dynamic activation (MDA); group 3, (n = 21), ozone treatment with passive ultrasonic activation (PUA); group 4 (n = 23), ozone treatment with sonic activation (SA); and group 5 (n = 21), no ozone treatment (the control group). Patient levels of discomfort were recorded at 6 different time intervals using the visual analog scale (VAS). Comparison of the mean difference between the groups and time intervals was performed using 2-way analysis of variance followed by a post hoc Bonferroni test. The level of significance was set at 5%.

RESULTS

VAS scores were highest for the control > NA > MDA > SA > PUA groups. A statistically significant reduction in VAS scores was observed in the PUA and SA groups in comparison with the NA, control, and MDA groups. Timewise comparison showed a highly significant decline in VAS scores at all time intervals (P < .001).

CONCLUSIONS

Ultrasonic and sonic activation of ozone resulted in less pain in patients undergoing single-visit endodontics compared with no ozone treatment.

Efficacy of a Nickel-Titanium Ultrasonic Instrument for Biofilm Removal in a Simulated Complex Root Canal

This study evaluated the effectiveness of NiTi ultrasonic tips for Enterococcus faecalis (E. faecalis) biofilm removal in simulated complex root canals. Sixty root canal models consisting of a 30-degree curved main canal and two lateral canals were constructed from polydimethylsiloxane and incubated with E. faecalis. Irrigants in root canals were activated using a manual syringe (SI), a stainless steel (SS) instrument, a nickel-titanium (Ni-Ti) ultrasonic instrument, or a sonic instrument (EA). Instruments of SI, SS, and NiTi-9 groups were placed 9 mm from the apex, whereas those in NiTi-2 and EA groups were placed 2 mm from the apex. The efficacy of each method was determined as the ratio of fluorescence concentration before and after activation. In the apical curved canal, the highest efficacy was found in the NiTi-2 group (99.40%), followed by SI (84.25%), EA (80.38%), SS (76.93%), and NiTi-9 (67.29%) groups. In lateral canals 1 and 2, the efficacy was the highest in the NiTi-2 group and the lowest in the SI group. The NiTi ultrasonic instrument could effectively remove biofilms in the curved canal and lateral canals. This instrument should be introduced close to the working length. An up-and-down motion of the activation instrument is recommended.

Pattern of Disinfection of Root Canal Dentin by Alternated Acid-Base Irrigating Regimen

Objective

To quantify Enterococcus faecalis density in root canal dentin after chemomechanical preparation (CMP) using alternated irrigating regimen.

Methodology

Root canals (RC) were contaminated with E. faecalis (ATCC 19433) for 3 weeks and evident biofilms were obtained. After initial sampling (S1), the CMP was aided by irrigants: saline solution (control; n=12), a conventional regimen (CR) (group 1; n=12) using 5.25% NaOCl and a final rinse with 17% EDTA, and an alternating regimen (AR) of intercalated use of NaOCl and EDTA (group 2, n=12), followed by a second sampling (S2). After 2 weeks, S3 was obtained. Two roots were analyzed by scanning electron microscopy. Each root was divided into cervical, mild, and apical segments and sampling of the superficial (n=90) and deep (n=90) dentin layers was obtained using Gates-Glidden burs. The E. faecalis density (CFU/mg) in log₁₀ was categorized as residual (0 > 0.2), moderate (0.2 ≥ 0.5), or elevated (> 0.5). The prevalence of positive samples in BHI and BHI-A was analyzed by Pearson's chi-square test. The data were normalized by a log₁₀ transformation of CFU and were analyzed by one-way ANOVA and Tukey's tests.

Results

Biofilms were observed only in the control root canal walls. Topographically, the controls and CR showed similar distributions of E. faecalis in the dentin. Microbiologically positive root canals harbored much E. faecalis in the adjacent dentin (p < 0.05). Irrigating saline provided moderate density of E. faecalis in the dentin while CR and AR resulted in a residual density of microorganisms (p < 0.05).

Conclusions

The Enterococcus faecalis density in dentin was influenced by the irrigating regimen and the microbiological status of the root canal. The CMP aided by the alternating regimen interfered with the recolonization of the root canal and topographic distribution of Enterococcus in root dentin.