Clinical Implications and Microbiology of Bacterial Persistence after Treatment Procedures

Evaluation of 2% Chlorhexidine and 2% Sodium Fluoride as Endodontic Irrigating Solutions on Root Dentine Microhardness: An In Vitro Study

Objectives  The aim of this study was to evaluate the effects of 2% chlorhexidine gluconate (CHG) and 2% sodium fluoride (NaF) as endodontic irrigants on microhardness of root dentin.

Materials and Methods  In this in vitro study, access cavity and root canal preparations were done on 24 freshly extracted anterior teeth. After sectioning into 24 dentin discs using hard tissue microtome in 2 mm thickness, all samples were immersed in solutions of 17% ethylenediamine tetra-acetic acid (EDTA) (2 minutes) followed by 2.5% of sodium hypochlorite (NaOCl) (10 minutes). Then samples were randomly divided into three groups based on the irrigant used: Group I: saline (control group); Group II: 2% NaF; Group III: 2% CHG for two minutes each. Dentin microhardness was measured before (pretreatment), during (after treatment with 17% EDTA and 2.5% NaOCl), and after the experimental period (after treatment with saline, 2% NaF, and 2% CHG) using a Vickers indenter. Statistical evaluation of the data was done using one-way analysis of variance (ANOVA) and the Student’s t -test, and the values are tabulated.

Results  Specimens rinsed in 2% CHG showed a significant increase in Vickers hardness number (VHN) values ( p < 0.05), as compared with EDTA and NaOCl groups, whereas saline and 2% NaF groups showed no significant difference.

Conclusions  NaF did not show any significant effect on microhardness of the root dentin. CHG as an irrigant was seen to have a strengthening effect on dentin microhardness in comparison to NaOCl and EDTA, which has decreased the strength of root dentin.

Clinical influence of calcium hydroxide and N-acetylcysteine on the levels of resolvins E1 and D2 in apical periodontitis

AIM

To investigate the presence of resolvins E1 (RvE1) and D2 (RvD2) in teeth with primary endodontic infections and apical periodontitis, and to assess the influence of calcium hydroxide medication [Ca(OH)₂ ], in association with 2% chlorhexidine gel (2% CHX gel), and N-acetylcysteine (NAC) on the levels of RvE1 and RvD2 in periapical tissues.

METHODOLOGY

Thirty-six single-rooted teeth with primary endodontic infections and apical periodontitis were selected and randomly divided into three groups according to the medication: [Ca(OH)₂ ] + saline solution (SSL) [Ca(OH)₂  + SSL group] (n = 12), Ca(OH)₂  + 2% chlorhexidine gel [Ca(OH)₂  + 2% CHX gel group] (n = 12) and NAC [NAC group] (n = 12). Samples were collected from the periapical interstitial fluid at two different sampling times: before (S1) and after 14 days of intracanal medications (S2). Resolvins were measured using the enzyme-linked immunosorbent assay. Data were analysed using paired t-test, Wilcoxon test and Kruskal-Wallis test, followed by Dunn's post hoc test; all statistical tests were performed at a significance level of 5%.

RESULTS

RvE1 and RvD2 were detected in 100% of the samples (36/36) at S1 and S2. Ca(OH)₂ medication did not increase the levels of RvE1 or RvD2 (both P > 0.05); however, NAC significantly increased the levels of RvE1 and RvD2 after 14 days of treatment (P < 0.05).

CONCLUSIONS

RvE1 and RvD2 were detected in periapical tissues from teeth with root canal infections. Moreover, calcium hydroxide medication did not increase the levels of resolvins in apical periodontitis. In contrast, the use of NAC intracanal medication significantly increased the levels of RvE1 and RvD2 after 14 days of treatment.

Association between genetic polymorphisms in the promoter region of the defensin beta 1 gene and persistent apical periodontitis

AIM

To evaluate the association between the promoter region of defensin beta 1 (DEFB1) genetic polymorphisms and persistent apical periodontitis (PAP) in Brazilian patients.

METHODOLOGY

Seventy-three patients with post-treatment PAP (PAP group) and 89 patients with root filled teeth with healed and healthy periradicular tissues (healed group) were included (all teeth had apical periodontitis lesions at the beginning of the treatment). Patients who had undergone at least 1 year of follow-up after root canal treatment were recalled, and their genomic DNA was extracted from saliva. Two single nucleotide polymorphisms (SNPs) in DEFB1 at the g. -52G>A (rs1799946) and g. -20G>A (rs11362) positions were analysed using real-time polymerase chain reaction. The chi-squared test was performed, and the odds ratios were calculated using Epi Info 3.5.2. Logistic regression analysis in the codominant model, using the time of follow-up as a variable, was used to evaluate the SNP-SNP interaction. All tests were performed with an established alpha of 0.05 (P = 0.05).

RESULTS

For the rs11362 polymorphism in the codominant and recessive models, patients who carried two copies of the T allele had a significantly lower risk of developing PAP (P = 0.040 and P = 0.031, respectively). For the rs1799946 polymorphism in DEFB1 in the codominant and recessive models, carrying one copy of the T allele significantly increased the risk of developing PAP (P = 0.007 and P = 0.031, respectively). In the logistic regression, both polymorphisms were associated with PAP as well as the SNP-SNP interaction (P < 0.0001).

CONCLUSIONS

Polymorphisms in DEFB1 genes were associated with the development of post-treatment persistent apical periodontitis.

Micro-computed Tomographic Assessment of Supplementary Cleaning Techniques for Removing Bioceramic Sealer and Gutta-percha in Oval Canals

INTRODUCTION

The aim of this study was to conduct a micro-computed tomographic assessment of the effectiveness of 3 supplementary cleaning techniques in reducing the residual volume of gutta-percha and a bioceramic sealer after performing endodontic retreatment procedures in teeth with oval canals.

METHODS

Thirty-six mandibular premolars were instrumented with the ProTaper Next system (instruments X1-X3; Dentsply Maillefer, Ballaigues, Switzerland) and filled with gutta-percha and Bio-C Sealer (Angelus, Londrina, PR, Brazil) using the single-cone technique. The teeth were reinstrumented with the Reciproc R40 instrument (VDW, Munich, Germany) and divided into 3 groups according to the supplementary cleaning technique used (n = 12): ultrasonic-assisted irrigation (UAI), EndoActivator (Dentsply Tulsa Dental Specialties, Tulsa, OK) irrigation (EAI), or the XP-endo Finisher R system (XPR; FKG Dentaire, La Chaux-de-Fonds, Switzerland). Micro-computed tomographic imaging was used to quantify the residual volume of filling material. One-way analysis of variance complemented by the Tukey test was used to perform the statistical analysis (P < .05).

RESULTS

Significant reductions were obtained in the residual filling material after supplementary cleaning (P < .05). XPR (47.5%) led to significantly greater (P < .05) filling material removal than UAI (16.6%) or EAI (22.6%). The removal values of the 2 latter systems were not significantly different.

CONCLUSIONS

XPR was more effective than UAI and EAI in removing filling material in mandibular premolars with oval canals. None of the tested supplementary cleaning techniques completely removed the residual filling material.

Current status on minimal access cavity preparations: a critical analysis and a proposal for a universal nomenclature

In the last decade, several access cavity designs involveing minimal removal of tooth tissue have been described for gaining entry to pulp chambers during root canal treatment. The premise behind this concept assumes that maximum preservation of as much of the pulp chamber roof as possible during access preparation would maintain the fracture resistance of teeth following root canal treatment. However, the smaller the access cavity, the more difficult it may be to visualize and debride the pulp chamber as well as locate, shape, clean and fill the canals. At the same time, a small access cavity may increase the risk of iatrogenic complications as a result of poor visibility, which may have an impact on treatment outcome. This study aimed to critically analyse the literature on minimal access cavity preparations, propose new nomenclature based on self-explanatory abbreviations and highlight the areas in which more research is required. The search was conducted without restrictions using specifics terms and descriptors in four databases. A complementary screening of the references within the selected studies, as well as a manual search in the highest impact journals in endodontics, namely International Endodontic Journal and Journal of Endodontics, was also performed. The initial search retrieved 1831 publications. The titles and abstracts of these papers were reviewed, and the full text of 94 studies was assessed. Finally, a total of 28 studies were identified as evaluating the influence of minimally invasive access cavity designs on the fracture resistance of teeth and on the different stages of root canal treatment (orifice location, canal shaping, canal cleaning, canal filling and retreatment). Overall, the studies had major methodological drawbacks and reported inadequate and/or inconclusive results on the utility of minimally invasive access preparations. Furthermore, they offered limited scientific evidence to support the use of minimally invasive access cavities to improve the outcome of root canal treatment and retreatment; they also provided little evidence that they preserved the fracture resistance of root filled teeth to a greater extent than traditional access cavity preparations. It was concluded that at present, there is a lack of supporting evidence for the introduction of minimally invasive access cavity preparation into routine clinical practice and/or training of undergraduate and postgraduate students.

Current trends in endodontic irrigation amongst general dental practitioners and dental schools within the United Kingdom and Ireland: a cross-sectional survey

Aims To investigate current trends in endodontic irrigation amongst general dental practitioners (GDPs) and dental schools within UK and Ireland. Secondly, to evaluate if significant differences exist between the irrigant practices of National Health Service (NHS) and private GDPs.Methodology In 2019, an online questionnaire was distributed to the 18 dental schools within the UK and Ireland and 8,568 GDPs. These surveys explored current trends in teaching and usage of endodontic irrigants. Chi-squared tests were performed to make comparisons between NHS and private GDPs (α <0.01).Results All 18 dental schools (100%) and 495 GDPs (6%) returned valid questionnaires. Three hundred and thirty (66.7%) practitioners were NHS and 165 (33.3%) were private. There was strong consensus on irrigation teaching amongst dental schools. These results aligned with GDP responses in terms of irrigant selection (sodium hypochlorite [NaOCl]); NaOCl concentration (≤3%); ethylenediaminetetraacetic acid (EDTA) contact time (>0-5 minutes); final rinse protocols (penultimate EDTA rinse); irrigant temperature (room); and agitation techniques (manual dynamic activation; >0-60 seconds). There was, however, considerable variation in NaOCl contact time and GDPs infrequently used chelating agents or agitation techniques. Compared with private practitioners, NHS GDPs used significantly lower NaOCl contact times and concentrations, less EDTA and activation techniques, and more chlorhexidine (P <0.01).Conclusions Overall, irrigation teaching within the UK and Ireland is consistent and evidence-based. Furthermore, trends in irrigant usage amongst UK GDPs are now more aligned with these teaching practices. Significant differences were, however, observed between NHS and private practitioners.

Improving the Efficiency of Photodynamic Chemotherapy in Root Canals against Enterococcus faecalis In Vitro

The aim of this study was to evaluate the effect of photoactivated chemotherapy (PACT) on Enterococcus faecalis (E. faecalis) biofilms in root canals using an 90% isopropanol (IPA)-based photosensitizer and removing excess photosensitizer before light incubation. Three hundred and seven extracted human teeth with one root canal were infected with E. faecalis for 72 h and treated in groups: IPA irrigation; PACT; PACT and final rinse with IPA; PACT with photosensitizer removal using either 0.9% NaCl solution or sterile paper points or both; PACT using IPA-based photosensitizer with and without a final rinse of IPA. Root canals were sampled using sterile paper points and dentin chips collected from the root canal walls. Additionally, SEM (Scanning Electron Microscopy) images of the specimens were taken to evaluate the root canal walls for residue bacterial contamination. In all antimicrobial treatment groups treatments E. faecalis counts were significantly reduced in the root canals. Using IPA-based photosensitizer the antimicrobial effect of PACT was significantly enhanced. Irrigation with IPA alone or after PACT significantly increased the antimicrobial effect compared to PACT alone. The collected dentin chips revealed the highest amount of culture negative root canals (10%) after PACT using IPA-based photosensitizer. In the other groups, the culture negative samples ranged from only 0–2 specimens of 30 specimens. REM images show remaining E. faecalis cells on the root canal wall and inside dentin tubules. Using IPA-based photosensitizer significantly enhanced the antimicrobial effect of PACT against E. faecalis in the root canals.

Acute endodontic and dental trauma provision during the COVID-19 crisis

COVID-19 (also known as coronavirus) has had a profound impact on dentistry, with all elective treatment grinding to a halt initially and a slow phased return to normal services. The guidance available regarding treating dental emergencies is currently advice, analgesia and antimicrobials, where indicated in the first instance. Some patients cannot be managed successfully with this approach and require face-to-face consultation. Unless dental practices have the appropriate PPE and follow strict infection prevention and control guidance, face-to-face consultation may not be possible. If treatment is required, this is based on minimum intervention and avoidance of aerosol generating procedures (AGPs) on patients who are free of COVID-19. COVID-19-positive or suspected patients still require treatment at designated Urgent Dental Care centres.The aim of this article is to provide an insight into the COVID-19 pandemic and its implications on current emergency dental care. Commonly presenting dental conditions which require endodontic management will be discussed. Finally, an endodontic management protocol is suggested. The intention of the protocol is to describe practical techniques to minimise potential viral load and reduce risk of COVID-19 transmission when AGPs are instigated.

An In Vitro Evaluation Study of the Geometric Changes of Root Canal Preparation and the Quality of Endodontic Treatment

Introduction

The geometry of root canals differs in different parts, especially in the apical region, and it is affected by different preparation techniques. The aim of this study was to evaluate the geometric changes of root canal preparation by general dentists regardless of the endodontic instrumentation systems and to study the quality of endodontic treatment by evaluating the untouched areas after mechanical preparation and the smear layer removal.

Materials and Methods

100 extracted maxillary canines were collected for the in vitro study from 10 dentists, and the dentists were asked to treat the teeth endodontically. The teeth then were separated and examined under an optical microscope to evaluate the root canal final diameter and the untouched areas. Then, the teeth were examined under a scanned electronic microscope to evaluate the smear layer in coronal, middle, and third parts of the canal. Statistical significance was set as P < 0.05.

Results

The mean diameter of the root canal after instrumentation in the coronal and middle thirds was 2.50 ± 1.12 and 1.75 ± 1.24 mm, respectively, and the untouched area percentage observed in the apical thirds was 71%. For smear layer removal, it was better in the coronal and middle thirds than in the apical (P < 0.05).

Conclusion

The changes in the diameter of the root canal, the percentage of untouched areas after mechanical preparation, and the percentage of smear layer were observed in a higher percent in the apical third than in the coronal and middle thirds, and this raises the question of changing the technique of processing the root canal, especially in the apical third.

Comparison of the Self-Adjusting File and Hedström File Used as Supplementary Instruments for the Remaining Filling Material Removal During Retreatment of C-Shaped Canals: A Micro-CT Study

Objective:

The aim of this study was to evaluate the use of Self-adjusting file (SAF) system and Hedström (H) file for removing remaining filling material (RFM) from C-shaped canals.

Methods:

20 C-shaped mandibular second molars with C1 configurations were instrumented, filled with tagger´s hybrid technique. Samples were divided into 2 groups (n=10). Reciproc R25 and a Mtwo 35/04 file were used for retreatment in both groups. Then, a 2.0 SAF file (group I) and a #35 H file (group II) were used as supplementary steps for RFM removal. Micro-CT scanning was performed after every procedure. Total volumes were calculated and converted into percentages. Also, the minimum wall thickness at 3, 5, 7 mm from apex was calculated. The Prism 7.0 software was used as the analytical tool with a significance of 5%.

Results:

Initial obturation removal was approximately 64% in group I and 67% in Group II. The apical third had the highest values of RFM. The use of a H file significantly reduced the RFM compared to SAF in the total canal length respectively (30% vs 18%) and at 1-3 mm and 3-6 mm when compared to the use of SAF. A statistically significant decrease of RFM and minimum wall thickness were observed in both groups (P<0.05).

Conclusion:

None of the retreatment techniques completely removed RFM. The apical region was the more unaffected area. Also, the SAF file was less effective than the H file in removing the RFM. Although C-shaped canals possesses thinner dentinal wall thickness, no excessive dentine removal was observed after each instrument use.

Microbial Association with Genus Actinomyces in Primary and Secondary Endodontic Lesions, Review

The main reason for root canal treatment failure is the persistence of microorganisms after therapy, or the recontamination of the root canal system due to an inadequate seal. In the mouth, Actinomyces spp. constitute a significant part of the normal flora, which is indicative of their ability to adhere to oral tissue and resist cleansing mechanisms, such as salivary flow. This review, performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA), aims to clarify the prevalence of microbial genera that are associated with the genus Actinomyces in primary and secondary endodontic infections (primary outcome), and to identify the most prevalent species of the Actinomyces genus in endodontic lesions (secondary outcome). A total of 11 studies were included in the qualitative and quantitative analysis, and a total of 331 samples were analyzed. Bacteria of the genus Actinomyces were found in 58 samples, and 46 bacterial genera were detected in association with bacteria of the genus Actinomyces. Bacteria of the genus Streptococcus and Propionibacterium were those most frequently associated with Actinomyces in the endodontic lesions considered, and Actinomyces israelii was the most frequently involved species.

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.

Coronal Bacterial Penetration after 7 days in class II endodontic access cavities restored with two temporary restorations: A Randomised Clinical Trial

The aim of this in vivo randomised clinical trial was to assess coronal bacterial penetration after placement of Cavit G and IRM temporary restorations in Class II endodontic access cavities. After completion of endodontic treatment, placement of an orifice seal and disinfection of the operating field, sterile cotton pellets were placed in the pulp chamber and the cavities were restored with Cavit G or IRM. After 7 days, coronal and proximal restoration thickness was measured by digital radiographs. Cotton pellet was evaluated by culture methods and polymerase chain reaction assay and bacterial species identified. Bacterial growth was observed in 5 of the 27 (18%) Cavit G samples and in 11 of the 27 (40%) IRM samples which was not significant. Coronal restoration thickness of 4-5 mm and proximal restoration thickness of more than 2.15 mm for Cavit G and 2.35 mm for IRM are recommended to prevent bacterial penetration over 7 days. Adequate restoration thickness is critical to prevent bacterial penetration.

Evaluation of various irrigation activation systems to eliminate bacteria from the root canal system: A randomized controlled single blinded trial

OBJECTIVE

To evaluate the effect of NaOCl irrigant activation using passive ultrasonic activation, F-files, XP-endo Finisher files and or needle irrigation alone on the reduction of intracanal bacteria from root canals in teeth undergoing root canal treatment.

METHODS

Eighty patients with asymptomatic apical periodontitis were randomly divided into four groups. Access cavities were prepared and pre-treatment samples were taken (S1). Canals were then prepared and post-instrumentation samples (S2) taken. NaOCl was then activated with the various irrigant activation systems and post-irrigation samples (S3) taken. The samples were processed and colony forming units (CFUs) of bacteria were determined. The reduction in CFUs among the experimental groups were analysed using the Kruskal Wallis test and pairwise comparisons with the Mann-Whitney test. The Friedman test was used to compare the differences in the reduction of CFUs within the groups.

RESULTS

Overall, for all groups there was a significant reduction in the CFUs from S1 to S2 (P < 0.05) and from S2 to S3 (P < 0.05). Both XP-endo Finisher and passive ultrasonic activation techniques were associated with the greatest reduction in CFUs with no significant difference between them (P = 0.24). However, both were associated with significantly lower CFUs when compared to F-file activation and needle irrigation (P < 0.05). F-file activation reduced the CFUs significantly more compared to needle irrigation (P = 0.04).

CONCLUSIONS

XP-endo Finisher file activation and passive ultrasonic activation were equivalent in terms of reduction in CFUs. F-file activation did not reduce the CFUs to the same extent as the XP-endo Finisher file and ultrasonic activation but reduced the CFUs more than needle irrigation.

CLINICAL SIGNIFICANCE

The present study highlights the effect of new XP-endo Finisher file and passive ultrasonic activation in reducing the bacterial load from the root canal system which is important for the success of root canal treatment.

Comparison of antibacterial effectiveness of three rotary file system with different geometry in infected root canals before and after instrumentation-a double-blinded randomized controlled clinical trial

Introduction

To compare the antibacterial effectiveness of three rotary file systems i.e., ProTaper Next, ProTaper Gold and XP-endo Shaper in root canals of teeth with asymptomatic apical periodontitis by using the real-time polymerase chain reaction.

Materials and methods

Root canals from single or multi-rooted teeth (straight canals) with necrotic pulps and asymptomatic apical periodontitis were instrumented using either ProTaper Next (n = 20), ProTaper Gold (n = 20) and XP-endo Shaper (n = 20) under irrigation with 3% sodium hypochlorite. Samples obtained before and after instrumentation were subjected to DNA extraction, amplification and quantitation of total amount of bacteria by using the real-time polymerase chain reaction.

Results

Samples were taken before preparation (S1) were positive for presence of bacteria, with mean numbers of 9.94 × 10⁷, 20.4 × 10⁷ and 9.20 × 10⁷ bacterial cells for the ProTaper Next, ProTaper Gold and XP-endo Shaper groups, respectively. After preparation (S2) with ProTaper Next, ProTaper Gold, and XP-endo Shaper, root canals still had bacteria with mean counts of 11.8 × 10⁵, 87.2 × 10⁵ and 4.52 × 10⁵ bacterial cells, respectively. Both XP-endo Shaper (99.50%) and ProTaper Next (98.81%) were effective in reducing total bacterial count, and there was no statistically significant difference between them (P > 0.05). XP-endo Shaper succeeded in reducing total bacterial count than ProTaper Gold (95.72%) and there exists statistically significant difference between them (P < 0.05).

Conclusions

XP-endo Shaper was highly effective in reducing total bacterial count from root canals of teeth with asymptomatic apical periodontitis than ProTaper Gold. ProTaper Next also showed improved microbial reduction percentage as compared with ProTaper Gold.

Effectiveness of Various Final Irrigation Techniques on Sealer Penetration in Curved Roots: A Confocal Laser Scanning Microscopy Study

Objective

To compare the efficacy of various techniques used for final irrigation on sealer penetration in the apical one-third of curved root canals. Material and Methods. Sixty-five freshly extracted maxillary first molar teeth with mesiobuccal roots having more than 20° of root curvature were used. The root canals were instrumented and randomly divided into four experimental groups and one control group. In the 4 experimental groups, 3 ml of 17% EDTA followed by 3 ml of 5.25% NaOCl was delivered with the use of the following protocols: Group 1: manual dynamic activation (MDA), Group 2: sonic irrigation (SI), Group 3: passive ultrasonic irrigation (PUI), and Group 4: conventional needle irrigation (CI). All teeth were obturated with gutta-percha and AH Plus sealer labeled with fluorescent dye. Transverse sections at 2 mm and 4 mm distance from the root apex were examined with the aid of confocal laser scanning microscopy. Total percentage (%) and maximum depth (μm) of sealer penetration were measured.

Results

All the experimental groups exhibited significantly higher penetration rates than the control group at both sections (p < 0.05). However, no significant differences were found in the penetration depth and percentage among the four experimental groups evaluated at both sections (p > 0.05).

Conclusion

PUI, SI, and MDA did not significantly improve sealer penetration in the apical portion of curved root canals when compared to conventional needle irrigation.

Sonic irrigant activation for root canal disinfection: power modes matter!

BACKGROUND

Sonic irrigant activation has gained widespread popularity among general dentists and endodontists alike in recent years. This in vitro study aimed to evaluate the impact of three power modes of a sonic activation device (EDDY) on its antimicrobial effectiveness in infected root canals.

METHODS

The root canals of straight, human roots (n = 120) were prepared to size 40/.06. In a short-term infection experiment, the root canals were inoculated with different microbial species for three days. The following irrigation protocols, using 4 ml of normal saline as irrigant, were performed: negative control, manual rinsing, sonic irrigant activation at power modes "low", "medium" and "high". In a second, long-term experiment, testing the same irrigation protocols, inoculation lasted 21 days and sodium hypochlorite was used as irrigant. Sequential infection control samples were assessed using culture assays. The statistical analysis included one-way analysis of variance of log₁₀-scaled counts of colony-forming units (CFU) with post-hoc comparisons using Bonferroni corrections and Chi² tests (α = 0.05).

RESULTS

In the short-term experiment, the sonic irrigation protocols decreased the number of CFUs by 1.88 log₁₀ units compared with the negative control (p < 0.001). The power modes "medium" and "high" achieved the most effective reduction of the microbial load. In the long-term experiment, microbial regrowth occurred after 7 days unless the device was used at its highest power setting.

CONCLUSIONS

The power modes of the sonic irrigation device have a significant impact on the effectiveness for endodontic disinfection. The sonic irrigation device should always be used at the highest power setting in order to maximize its antimicrobial effectiveness.

Detection, treatment and prevention of endodontic biofilm infections: what's new in 2020?

Endodontic disease, a biofilm infection of the root canal space, is a significant cause of dental morbidity worldwide. Endodontic treatment, or root canal treatment, as it is commonly known is founded on the ability to eradicate microbial biofilm infection and prevent re-infection of the highly complex root canal space. Despite many "advances" in clinical endodontics we have seen little improvement in outcomes. The aim of this critical review paper is to provide a contemporary view of endodontic microbiology and biofilm polymicrobiality, provide an understanding of the host response, and how together these impact upon clinical treatment. Ultimately, it is intended to provide insight into novel opportunities and strategies for the future diagnostics, treatment, and prevention of endodontic disease.

The effect of smear layer on bacterial penetration through roots obturated using zinc oxide eugenol-based sealer

BACKGROUND

Smear layer removal has been shown to reduce bacterial penetration through root canal obturations when resin-based endodontic sealer is used. The purpose of this in vitro study was to test this effect when a non-resin-based sealer is used.

MATERIAL AND METHODS

Thirty root segments were assigned to the following groups: Smear layer removed (n = 8); smear layer retained (n = 8); negative controls (n = 10; 5 with smear layer, 5 without); and positive controls (n = 4; 2 with smear layer, 2 without). After rotary instrumentation, smear layers were removed in the treatment group and half of controls using 17% ethylenediamenetetraacetic acid (EDTA) prior to obturation. Each obturated root was affixed into a dual-chamber leakage model employing Streptococcus mutans. Roots were incubated at 37 °C for 120 d. Days until lower chamber turbidity occurred was recorded for each sample, and data were analyzed using Kaplan-Meier survival curve analysis (p = 0.05).

RESULTS

No negative controls leaked, while all positive controls were turbid within 1 day. Mean days to leakage for roots with smear layer intact was 82.75 (+/- 33.29, 95% CI), although three never leaked. Mean days to leakage through roots with smear layer removed was 46.25 (+/- 26.67, 95% CI), and all leaked. Treatment survival curves were significantly different (p = 0.048).

CONCLUSIONS

Under the conditions and limitations of this study, retaining the smear layer reduced the rate of bacterial penetration through canals which had been obturated using zinc oxide eugenol (ZOE) -based sealer.

Cone Beam Computed Tomography-aided Endodontic Management of Second Maxillary Molar with Two Separate Palatal Roots: A Case Report

An infected human root canal system harbors harmful microbiota that needs to be eliminated by root canal therapy. But the human root canal system is known to have a complex anatomy. Hence, the knowledge of a possibly aberrant anatomy is deemed necessary before carrying out a root canal therapy. Usually, the maxillary second molars have three roots and three or four root canals (a second mesiobuccal canal as the fourth canal). The presence of a second palatal root and a second palatal root canal is very rare (1.4% incidence). Failure to locate and treat such aberrant external and internal anatomy results in a compromised root canal therapy. With the introduction of advanced imaging and visualization techniques such as cone beam computed tomography (CBCT) and dental operating microscopes, the variations in root anatomy have been successfully detected and treated. This case report describes the endodontic management of a second maxillary molar with two palatal roots and four separate canals, performed with the help of CBCT.

Effects of Contemporary Irrigant Activation Schemes and Subsequent Placement of an Interim Dressing on Bacterial Presence and Activity in Root Canals Associated with Asymptomatic Apical Periodontitis

New tools for activating endodontic irrigants have evolved, yet their impact on root canal disinfection, in comparison to the passive placing of an inter-visit medication, have not yet been fully elucidated. The use of DNA- and rRNA-based methods may cast some new light on this issue, as they allow a comparison to be made between microbial presence and activity. Therefore, the aim of this single-arm intervention trial is to evaluate the antibacterial effect of endodontic procedures using both molecular methods. Root canal samples were obtained from 20 patients with asymptomatic apical periodontitis after each treatment step: access cavity, chemo-mechanical preparation, adjunctive procedures (XP-endo Finisher file and passive ultrasonic irrigation), calcium hydroxide medication, and 2nd-visit root canal preparation. DNA and cDNA from the samples were subjected to quantitative polymerase chain reaction with universal primers for the bacterial 16S rRNA gene. Chemo-mechanical preparation promoted a drastic reduction in bacterial levels and activity, whereas the adjunctive procedures did not make a significant contribution to further disinfection. At the 2nd visit, bacteria were active after the use of calcium hydroxide medication; however, they were significantly reduced after a 2nd-visit preparation. Consequently, the lowest bacterial levels were found at the end of the treatment. This clinical trial, which used an rRNA and rDNA combined approach, confirmed previous studies showing that root canal preparation represents the main strategy for root canal disinfection.

The Influence of Enterococcus faecalis as a Dental Root Canal Pathogen on Endodontic Treatment: A Systematic Review

Endodontic treatment failure may occur due to different causes such as persistence of bacteria, root canals that are poorly cleaned and obturated, improper coronal seal (leakage), and untreated canals (missed canals). The main reason for endodontic failure is the presence of some species of bacteria inside the root canal system such as Enterococcus (E.) faecalis. Those bacteria are more resistant to disinfection agents, causing a persistent intra-radicular or extra-radicular infection.

The current review aims to compile all the current studies concerning Enterococcus faecalis as a dental root canal pathogen that causes endodontic failure. In this systemic review, two databases, PubMed and Google Scholar, were searched using specific inclusion and exclusion criteria. Among 2943 studies, only 11 met the inclusion criteria and were included in the review for further analysis.

The 11 studies give prominence to the high distribution of Enterococcus faecalis within the root canal system. These studies investigated different aspects of Enterococcus faecalis, including its prevalence, resistance mechanisms, characteristics, express survival genes, and treatment.

The compiled data observed that most of the studies highlight Enterococcus faecalis as the primary pathogen associated with endodontic treatment. It has characteristic proprieties that make it capable of escaping disinfection means. Furthermore, clinical trials are required to examine E. faecalis and may provide valuable information about novel microbial detection methods to decrease the number of E. faecalis within the root canal system.

Outcome of endodontic treatment with chlorhexidine gluconate as main irrigant: A case series

This study evaluated the overall endodontic therapy success using 0.12% or 2% chlorhexidine gluconate as main irrigant. Seventy-two teeth diagnosed as vital, necrotic or previously treated teeth with apical periodontitis that were consecutively treated by orthograde therapy. All cases were followed clinically and radiographically for at least 1-year period. Success was established in teeth without signs or adverse clinical symptoms and complete or incomplete radiographic healing. Failure was determined in teeth with any sign or adverse clinical symptoms and a new, unchanged or enlarged radiographic periapical lesion. The data were analysed using chi-square and Fischer's exact tests. The overall success rate for teeth undergoing vital pulp was 84.6%, 76.2% as for the necrotic teeth and 84% for the retreatment cases. No significant differences were observed between groups (P > 0.05). Cases treated with CHX as main irrigant showed a high overall endodontic therapy success rate.

The antibiofilm and collagen-stabilizing effects of proanthocyanidin as an auxiliary endodontic irrigant

AIM

To evaluate the antibiofilm effect of proanthocyanidin (PA) solution as an irrigant against Enterococcus faecalis (E. faecalis) and its influence on the mechanical properties and biodegradation resistance of demineralized root dentine.

METHODOLOGY

Enterococcus faecalis were introduced into human root dentine tubules by a serial centrifugation method and grown for 1 week. Dentine blocks infected with 1-week-old E. faecalis biofilms were treated with the following irrigants: sterile water (control), 2% chlorhexidine (CHX), 2% PA, 5% PA and 10% PA. After treatment, the live and dead bacteria proportions within E. faecalis biofilms were analysed using confocal laser scanning microscopy. To evaluate the biostability of fully demineralized dentine treated by the aforementioned irrigants, the elastic modulus and hydroxyproline release of human dentine incubated in collagenase solution were tested at baseline, after irrigant treatment and after biodegradation, respectively. Furthermore, the surface chemical bond of demineralized dentine collagen treated by various irrigants was characterized by X-ray photoelectron spectroscopy (XPS). Statistical analysis was performed using one-way anova and Tukey's post hoc multiple comparisons with the significance level at 5%.

RESULTS

The proportion of dead E. faecalis volume was significantly higher in the PA and CHX groups than that in the control group (P < 0.05). PA irrigation significantly increased the mechanical properties of demineralized dentine (P < 0.05), and the effect was enhanced with increasing PA concentration. CHX and PA groups had significantly less elasticity loss and hydroxyproline release (P < 0.05). The biomodification of dentine collagen by PA was verified by increased C-O/C-N peak percentage under C1s and C-O peak percentage under O1s narrow-scan XPS spectra.

CONCLUSIONS

Proanthocyanidin killed E. faecalis within biofilms and enhanced the biostability of the collagen matrix of demineralized root dentine. It might be used as an auxiliary endodontic irrigant with antibiofilm and collagen-stabilizing effects.

In Vitro Comparison of Efficacy of Neolix and ProTaper Universal Retreatment Rotary Systems in Removal of Gutta-Percha Combined with Two Different Sealers

Statement of the Problem

The complete removal of filling material is an important step to regain access to the entire canal and facilitate the disinfection of the root canal system. Rotary nickel-titanium (NiTi) instruments systems have been proposed as an effective removal technique for root canal retreatment.

Purpose

The aim of this study was to evaluate the efficacy of Neolix rotary system and ProTaper Universal retreatment system in the removal of gutta-percha combined with two different sealers.

Materials and Method

In vivo study, eighty extracted human permanent mandibular premolars were prepared using the ProTaper Universal rotary system to an apical size 30 (F3/0.06). The specimens were randomly divided into 4 groups (n=20) and subsequently filled with lateral condensation of gutta-percha and two sealers: AH-26 and Sure-Seal Root. The teeth were stored for 4 weeks at 37°C and 100% humidity and then retreated by one of the following rotary systems: Neolix or ProTaper Universal retreatment system. Teeth were then grooved and monitored under a stereomicroscope with 8× magnification. The images were transferred to the computer and the amount of filling material that remained on the root canal walls was scored using AutoCAD 2017 version 1.1software. Results were analyzed using one-way analysis of variance test and post hoc Tukey-HSD test (p< 0.05).

Results

The mean percentage of remaining gutta-percha and sealer was significantly higher in apical third in all groups (p< 0.01). Post hoc Tukey test showed that there is significantly higher residual filling material in the group filled with gutta-percha and Sure-Seal Root sealer and retreated by Neoniti rotary system compared with other groups in both coronal and middle third of the canal.

Conclusion

The Neoniti rotary system was as effective as ProTaper Universal retreatment system in retreatment of gutta-percha and AH-26 sealer but was significantly less effective in groups obturated with Sure-Seal Root sealer.

Antimicrobial effectiveness of grape seed extract against Enterococcus faecalis biofilm: A Confocal Laser Scanning Microscopy analysis

This study evaluated the antimicrobial effectiveness of 6.5% Vitis vinifera grape seed extract (GSE) against Enterococcus faecalis biofilm using confocal laser scanning microscopy (CLSM). Saline solution (SS), 5.25% sodium hypochlorite (NaOCl) and 2% chlorhexidine (CHX) were used for comparison. Dentin discs were inoculated with E. faecalis strain establishing a 3-week-old biofilm. Discs (n = 10) were exposed to 5.25% NaOCl, 2% CHX, 6.5% GSE and SS (negative control) for 10 min. Discs were stained with the fluorescent LIVE/DEAD-BacLight™ dye and analysed using CLSM. The proportion of dead cells in biofilm was analysed using one-way anova and Tukey tests (P < 0.05). A higher proportion of dead cells was found in GSE group compared with CHX and SS (P < 0.05). NaOCl group was associated with the highest proportion of dead cells (P < 0.05). GSE presented antimicrobial activity against E. faecalis; however, NaOCl was the most effective irrigant solution. GSE was more effective than CHX and SS.

Effect of passive ultrasonic activation on microorganisms in primary root canal infection: a randomized clinical trial

OBJECTIVE

This clinical study sought to evaluate the effectiveness of passive ultrasonic activation (PUA) in eliminating microorganisms in primary endodontic infection (PEI) after instrumentation of root canals using microbiological culture and checkerboard DNA-DNA hybridization.

METHODOLOGY

Twenty root canals with PEI and apical periodontitis were selected. The root canals were instrumented and then randomly divided into 2 groups, according to the irrigation method: PUA and conventional needle irrigation (CNI). Microbiological samples were collected before instrumentation (S1), after instrumentation (S2) and after irrigation with 17% EDTA (S3). The samples were subjected to anaerobic culture technique and checkerboard DNA-DNA hybridization analysis.

RESULTS

A statistically significant difference was found between CNI (23.56%) and PUA (98.37%) regarding the median percentage values for culturable bacteria reduction (p<0.05). In the initial samples, the most frequently detected species was S. constellatus (50%), and after root canal treatment was E. faecalis (50%).

CONCLUSION

Both treatments significantly decreased the number of bacterial species compared with the initial sample. However, no statistical difference in the total microbial load between PUA and CNI groups was detected. The number of cultivable anaerobic bacteria reduced significantly using PUA, and the bacterial composition and number of bacterial species after using either CNI or PUA was similar.

Significance of oral health in adult patients with congenital heart disease

Due to improved diagnosis and treatment life expectancy of patients with congenital heart disease is steadily increasing resulting in a growing portion of adult patients. When entering, adulthood patients commonly show a shift in their specific needs for medical care. Since the treatment is mostly not curative many patients have life-long cardiovascular anomalies, among others, entailing high risk for the development of infective endocarditis. Several oral diseases, i.e., caries, apical periodontitis and periodontitis show a very high overall prevalence. These entities are primarily initiated by bacterial infections. Hence, they cause an inherent risk for bacteremia and subsequently for infective endocarditis in patients with congenital heart disease during professional dental care and various daily activities. Conversely congenital heart disease seems to be inevitably associated with considerable impairment of oral health resulting in a tight interrelation between both entities. Different preventive strategies are available to address the elevated risk for infective endocarditis due to oral diseases in patients with congenital heart disease during professional dental care and routine daily activities. This review delineates the current evidence regarding the issue of oral health in adult patients with congenital heart disease.