Assessment of the Antibacterial Effects of Bismuth Nanoparticles against Enterococcus faecalis.

INTRODUCTION: Enterococcus faecalis (E. faecalis) is the most important species in dentistry and plays a significant role in the etiology of persistent apical lesions after root canal treatment. Up to date, the intracanal application of 2% chlorhexidine for 7 days is the best way to eliminate E. faecalis. However, due to the ability of this bacterium to persist and survive in harsh environments, many studies have been directed towards finding an alternative strategy for prevention or eradication of it. This study was conducted to investigate the effect of bismuth nanoparticles on E. faecalis, as an etiologic factor in recurrent root canal infections. METHODS: Forty patients, referred to Endodontic Ward of Shiraz University of Medical Science for endodontic pretreatment, provided root canal samples. First, all samples were transferred in Enterococcosel broth and incubated. Then, samples which showed growth were plated on blood agar plates and incubated for further PCR procedure. Nanoparticle powder was dissolved in high-purity water, and the final concentration of bismuth nanoparticles (BiNPs) was measured by the spectrophotometer. Minimum inhibitory concentration (MIC) of BiNPs against E. faecalis was determined by microbroth dilution method according to methods for antimicrobial susceptibility tests. Also, bactericidal assays were conducted in Mueller-Hinton broth medium and reported as the concentration of BiNPs that reduced the viable bacterial count by 99.9%. RESULTS: Of all samples, 77.5% revealed the presence of E. faecalis by PCR. Also, E. faecalis growth inhibition was observed at concentrations ranging from 0.625 µg/ml to 20 µg/ml (geometric mean: 2.337 µg/ml), and the MBC values were between 1.25 µg/ml and 40 µg/ml (geometric mean: 4.781 µg/ml), which in comparison with chlorhexidine, these values were about one-eighth of chlorhexidine. CONCLUSION: The experimental data suggest that bismuth nanoparticles could be an interesting alternative to combat E. faecalis, which, in view of the advantages mentioned for bismuth nanoparticle like inhibiting Streptococcus mutans biofilm formation and higher antibacterial activity compared to chlorhexidine, can be suggested to be used in different fields of dentistry.

Assessment of the functional efficacy of root canal treatment with high-frequency waves in rats.

The purpose of this study was to develop a high-frequency wave therapy model in rats and to investigate the influence of high-frequency waves on root canal treatment, which may provide a novel strategy for treating apical periodontitis. Root canal treatments with and without high-frequency wave irradiation were performed on the mandibular first molars of 10-week-old male Wistar rats. The mesial roots were evaluated radiologically, bacteriologically, and immunohistochemically. At 3 weeks after root canal treatment, lesion volume had decreased significantly more in the irradiated group than in the non-irradiated group, indicating successful development of the high-frequency therapy model. The use of high-frequency waves provided no additional bactericidal effect after root canal treatment. However, high-frequency wave irradiation was found to promote healing of periapical lesions on the host side through increased expression of fibroblast growth factor 2 and transforming growth factor-ß1 and could therefore be useful as an adjuvant nonsurgical treatment for apical periodontitis.

Observer variation in the assessment of root canal curvature.

AIM: To evaluate the inter- and intra-observer agreement between training/trained endodontists regarding the ex vivo classification of root canal curvature into three categories and its measurement using three quantitative methods. METHODOLOGY: Periapical radiographs of seven extracted human posterior teeth with varying degrees of curvature were exposed ex vivo. Twenty training/trained endodontists were asked to classify the root canal curvature into three categories (<10°, 10-30°, >30°), to measure the curvature using three quantitative methods (Schneider, Weine, Pruett) and to draw angles of 10° or 30°, as a control experiment. The procedure was repeated after six weeks. Inter- and intra-observer agreement was evaluated by the intraclass correlation coefficient and weighted kappa. RESULTS: The inter-observer agreement on the visual classification of root canal curvature was substantial (ICC = 0.65, P < 0.018), but a trend towards underestimation of the angle was evident. Participants modified their classifications both within and between the two sessions. Median angles drawn as a control experiment were not significantly different from the target values (P > 0.10), but the results of individual participants varied. When quantitative methods were used, the inter- and intra-observer agreement on the angle measurements was considerably better (ICC = 0.76-0.82, P < 0.001) than on the radius measurements (ICC = 0.16-0.19, P > 0.895). CONCLUSIONS: Visual estimation of root canal curvature was not reliable. The use of computer-based quantitative methods is recommended. The measurement of radius of curvature was more subjective than angle measurement. Endodontic Associations need to provide specific guidelines on how to estimate root canal curvature in case difficulty assessment forms.

Efficiency and effectiveness evaluation of three glass fiber post removal techniques using dental structure wear assessment method.

AIM: This study evaluated the efficiency and effectiveness of three glass fiber post removal techniques. MATERIALS AND METHODS: Forty-five extracted maxillary teeth were endodontically treated and cross-sectioned in thirds. Presence of cementing agent and dental structure wear were assessed by analyzing images taken before luting of glass fiber post and after removal procedure. Teeth were divided into 3 groups: Group 1 - diamond bur + Largo reamer; Group 2 - ultrasonic insert; Group 3 - carbide bur + ultrasonic insert. Time spent on removal procedures, dental structure wear and amount of remaining cement agent were recorded and results submitted to ANOVA, Kruskal Wallis and Tukey-Kramer tests. RESULTS: Group 1 - 16'46", 33.33% and 6.99%; Group 2 - 12'31", 40% and 7.86%; and Group 3 - 10'24", 80% and 8.14%. Group 3 presented the most effective removal of glass fiber posts. CONCLUSION: There was no significant difference in efficiency among the evaluated techniques.

Assessment of smear layer removal protocols in curved root canals.

This study sought to assess if the final rinse protocol interferes with the smear layer removal in the apical area of curved canals. Sixty-four extracted human mandibular molars with curved mesial roots were instrumented with rotary files and divided into six experimental groups for final rinse: 1EDTA (syringe irrigation with 1 mL of 17% ethylenediaminetetraacetic acid (EDTA) ), 5EDTA (syringe irrigation with 5 mL of 17% EDTA), 1EDTA-P (syringe irrigation with 1 mL of 17% EDTA + pumping with gutta-percha point), 5EDTA-P (syringe irrigation with 5 mL of 17% EDTA + pumping with gutta-percha point), 1EDTA-EA (syringe irrigation with 1 mL of 17% EDTA + EndoActivator) and 5EDTA-EA (syringe irrigation with 5 mL of 17% EDTA + EndoActivator). Final rinsing was carried out over 3 min. The specimens were split lengthwise and observed under a scanning electron microscope using a score criterion. Comparison among the groups showed statistically significant difference only between the 5EDTA-EA group and the other groups (Kruskal-Wallis and Dunn's post-hoc tests, P < 0.05). The combination of 5 mL of 17% EDTA and 3 mL of 2.5% sodium hypochlorite (NaOCl) with the EndoActivator removed smear layer from the apical area of curved root canals more effectively than the other protocols used.

Assessment of apically extruded debris produced by the self-adjusting file system.

INTRODUCTION: This study was designed to quantitatively evaluate the amount of apically extruded debris by the Self-Adjusting-File system (SAF; ReDent-Nova, Ra'anana, Israel). Hand and rotary instruments were used as references for comparison. METHODS: Sixty mesial roots of mandibular molars were randomly assigned to 3 groups (n = 20). The root canals were instrumented with hand files using a crown-down technique. The ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) and SAF systems were used according to the manufacturers' instructions. Sodium hypochlorite was used as an irrigant, and the apically extruded debris was collected in preweighted glass vials and dried afterward. The mean weight of debris was assessed with a microbalance and statistically analyzed using 1-way analysis of variance and the post hoc Tukey multiple comparison test. RESULTS: Hand file instrumentation produced significantly more debris compared with the ProTaper and SAF systems (P < .05). The ProTaper system produced significantly more debris compared with the SAF system (P < .05). CONCLUSIONS: Under the conditions of this study, all systems caused apical debris extrusion. SAF instrumentation was associated with less debris extrusion compared with the use of hand and rotary files.

Assessment of the separation incidence of mtwo files used with preflaring: prospective clinical study.

INTRODUCTION: The Mtwo rotary system was designed to be used at full length without performing previous cervical enlargement or creating a manual glide path. However, to our knowledge, no study has investigated whether preflaring influences instrument fatigue. The purpose of this clinical study was thus to evaluate the incidence of separation of Mtwo instruments during the preparation of mandibular and maxillary molars and bicuspids that was preceded by cervical preflaring. METHODS: A total of 556 treatments were performed by 6 endodontists after calibration. Cervical enlargement and exploration with hand files were undertaken before using the rotary files. The canals were negotiated with small K-type hand files. Cervical and middle thirds were prepared with hand files and Gates-Glidden burs. Irrigation was performed with 2 mL of 2.5% NaOCl after each instrument. The working length was established, and the apical third was prepared with Flexofiles until a #15 file could reach the working length, establishing a glide path. The Mtwo instruments were used following manufacturer's recommendations and disposed of after being used in 5 teeth. Each file was examined under ×8 magnification after use. In cases of file deformation or separation, the entire file kit was no longer used, except when using the 10.04 file. Because of its high failure rate, which is well-established in the related literature, this instrument could be replaced at any time. RESULTS: Separation and deformation rates were 1.98% and 28.78%, respectively. Ten of the total separations observed occurred with the 10.04 file (90.01%) and one with the 15.05 file (9.09%). CONCLUSIONS: The use of Mtwo rotary instruments preceded by cervical preflaring with manual files and Gates-Glidden burs provides a low separation incidence.

[The accidental detection of apical periodontitis]. / De toevallige vondst van een parodontitis apicalis.

Accidental detection of an asymptomatic apical periodontitis raises the question whether this lesion should be treated or not. Arguments favouring treatment are that the inflammation may cause pain in the future, may enlarge or may negatively affect the host's resistance. Reasons for not treating may be that treatment weakens the tooth, may cause iatrogenic damage and that treatment is expensive and burdensome for the patient and does not lead in all cases to complete healing. Scientific evidence supporting either choice, whether treating the lesion or not, is lacking. In making such decisions, therefore, personal judgments by the patient and the dentist concerning the impact on the quality of life of the patient play an important role.

[The role of panoramic radiography in assessing the risk of injury to the inferior alveolar nerve before the extraction of mandibular wisdom teeth. The effect of the extent of root curvature and inferior alveolar canal-root tip overlap on the risk assessment]. / A panorámaröntgen szerepe a nervus alveolaris inferior sérülések várható kockázatában alsó bölcsességfogak eltávolítása elôtt. A gyökérgörbület és a gyökércsúcs-canalis mandibulae átfedésének hatása a rizikóbecslésre.

The aim of the present study was to determine on panoramic radiographic images the effect of the distance between the root curvatures and inferior alveolar canal (IAC) root tip overlap on the surgeon's risk assessment predicting inferior alveolar nerve (IAN) paresthesia after lower third molar removal. In this case-control study 41 cases with postoperative IAN paresthesia and 359 controls without any postoperative complications were involved. Demographic data, root curvatures and the extent of IAC-root tip overlap were registered. The cases of major curvature--larger than 90 degrees (P=0.015; odds ratio [OR]=2.65), the "deepest" superimposition (P<0.001; OR=1.96), female gender (P=0.020) and increased age (P=0.008) were significantly associated with IAN paresthesia. Assessing root curvatures and the extent of IAC-root tip overlap for predicting IAN paresthesia after mandibular third molar removal should help to improve risk assessment.

DIAGNOdent laser fluorescence assessment of endodontic infection.

INTRODUCTION: Real-time assessment of the microbial status of the root canal system would be useful in clinical endodontic practice for determining endpoints of biomechanical treatment. This laboratory study used an existing laser fluorescence device, the DIAGNOdent (KaVo, Biberach, Germany), in a proof-of-concept study. METHODS: Visible laser red light (wavelength 655 nm) was used to elicit fluorescence emissions in the near-infrared range from infected and uninfected root canals. A prototype sapphire tip designed for periodontal assessment was used to analyze the pulp chamber and coronal third of the root canal system in extracted teeth. The fluorescence properties of bacterial cultures, monospecies biofilms in root canals, pulpal soft tissues, and sound dentin were also evaluated, together with 50 extracted teeth with known endodontic pathology. RESULTS: Sound dentin and healthy pulpal soft tissue gave an average fluorescence reading of 5 (on a scale of 100), whereas biofilms of Enterococcus faecalis and Streptococcus mutans established in root canals showed a progressive increase in fluorescence over time. Fluorescence readings reduced to the "healthy" threshold reading of 5 when root canals were endodontically treated, and the experimentally created bacterial biofilms were removed completely. High fluorescence readings were recorded in the root canals and pulp chambers of extracted teeth with radiographic evidence of periapical pathology and scanning electron microscopy evidence of bacterial infection. CONCLUSIONS: The use of the DIAGNOdent fluorescence approach for the assessment of the status of the pulp chamber and root canal system holds promise for clinical application; once more, flexible tips can be developed for gaining greater penetration into middle and apical thirds of the root canal.

Assessment of the deviation after biomechanical preparation of the coronal, middle, and apical thirds of root canals instrumented with three HERO rotary systems.

The aim of the present study was to assess the risk of deviation of the root canals prepared by 3 HERO rotary systems, used solely or in association, by means of preoperative and postoperative imaging of a cross-section of their coronal, middle, and apical thirds. Fifty mesiobuccal canals of human first molars were randomly divided into 5 groups of 10 specimens each: group A, HERO 642; group B, HERO 642 + HERO Apical; group C, HERO Shaper; group D, HERO Shaper + HERO Apical; group E (control), NitiFlex files. Fisher exact test showed that the differences between the percentages of the presence of deviation and the differences observed between the proportions of instrumented and noninstrumented walls were not statistically significant. No system presented absolute effectiveness, because each of them produced morphologic changes and failed to instrument all the walls of the root canals. A level of significance of .05 was adopted.

The microscope and endodontics.

The incorporation of the microscope in clinical endodontics has had profound effects on the way endodontics is done and has changed the field fundamentally. This article outlines the key prerequisites for the use of the microscope in nonsurgical endodontic procedures, discusses which procedures benefit from using the microscope, and addresses the issue of cost versus patient benefit.

National survey of endodontics in general dental practice in France.

The purpose of this paper was to gather both qualitative and quantitative information on endodontic treatments performed by French dental practitioners, and to identify the factors influencing the duration of endodontic procedures. A questionnaire was addressed in a two-rounds distribution to 2000 dentists selected by the quotas method in the whole country. A total of 790 (39.5%) questionnaires containing useful information were returned. The duration of endodontic treatment increases according to the number of roots to treat. The pulpal preoperative status has an influence on the duration of treatment, which is longer for a tooth with a necrotic pulp. Three variables strongly influence the duration of endodontic treatment: the number of patients attended per day, the number of appointments required for this treatment and the presence of a wage earner in the office. Continuing education also seems to be a variable having some influence on the duration of treatment. Financial considerations are also taken into account and there was general agreement that the current remuneration system of the French Health National Insurance is inadequate. Further, when one compares the total cost of an endodontic treatment with the fees fixed by the Health Insurance, it is clear that such procedures afford no positive financial return for a majority of practitioners. Moreover, the return becomes even more negative for teeth with a necrotic pulp. The findings presented in this study constitute the first stage of the medico-economic analysis concerning the endodontic practices in France. Prospective studies to gather precise information on the duration of endodontic treatments and a cost-analysis of endodontic practices could assist in the decision making process for practitioners or for the policy makers in the formulation of policies regarding application and reimbursement of endodontic treatment.

A histobacteriological assessment of nonvital teeth after ultrasonic root canal instrumentation.

The purpose of this study was to evaluate and discuss the bactericidal effect of ultrasound when applied in the root canal of teeth with necrotic pulp and periapical lesions. Twenty newly extracted teeth were instrumented with an ultrasonic unit and K-files using 0.5% sodium hypochlorite as irrigating solution. Compacted debris and micro-organisms were frequently observed in the apical region and in dentinal tubules of the root canal wall. Overinstrumentation that sometimes occurred led to contamination of the periapical lesions with micro-organisms and debris from the root canal.