In Vitro Evaluation of Different Irrigation Protocols on Intracanal Smear Layer Removal in Teeth with or without Pre-Endodontic Proximal Wall Restoration

Comparative Evaluation of the Effect of Different Chelating Agents on Mineral Content and Erosion of Radicular Dentine: A FESEM-EDS Analysis

OBJECTIVE

Irrigating solutions play an important role in the debridement and disinfection of the root canal space, and thus, it is crucial to comprehend their effects on the composition and surface structure of radicular dentine. This study evaluated and compared the effects of 17% ethylenediaminetetraacetic acid (EDTA), 9% 1-hydroxyethylidene-1,1-bisphosphonate (HEBP) and 0.2% chitosan on the mineral content and erosion of radicular dentine when used as a final rinse.

METHODS

Sixty extracted human mandibular premolar teeth were decoronated and instrumented to ProTaper size F2. After final instrumentation, the samples were randomly divided into 4 groups (n=15) according to the type of final irrigant used: Normal saline (control), 17% EDTA, 9% HEBP and 0.2% chitosan. Field emission scanning electron microscopy was used to assess the erosion of radicular dentine, and energy dispersive X- ray spectroscopy was used to quantify the radicular dentine mineral composition at the coronal, middle and apical levels of all the prepared samples after final irrigation. The one-way analysis of variance was used for intra-group and inter-group comparisons of means, the Kruskal Wallis test for intra-group and inter-group comparisons of medians and Tukey's post hoc test for pairwise comparisons.

RESULTS

There was no significant difference in the levels of calcium (Ca), phosphorus (P) and Ca/P ratio after final rinse with 17% EDTA, 9% HEBP and 0.2% chitosan at all three root levels (p>0.05); except at the coronal level, where 0.2% chitosan caused significantly less alteration in Ca levels and Ca/P ratio than 17% EDTA and 9% HEBP respectively (p<0.05). 17% EDTA, 9% HEBP and 0.2% chitosan caused no erosion at the middle and apical levels. Meanwhile, 17% EDTA and 9% HEBP caused moderate erosion at the coronal level.

CONCLUSION

Alternatives to 17% EDTA during final irrigation can be 9% HEBP and 0.2% chitosan. (EEJ-2023-06-078).

The Contribution of Various In Vitro Methodologies to Comprehending the Filling Ability of Root Canal Pastes in Primary Teeth

A void-free obturation during root canal treatment on primary teeth is currently very difficult to attain. In this study, the pulpectomy filling abilities of Bio-C Pulpecto (Angelus, Basil, Londrina, Paraná, Brazil) and of zinc oxide eugenol, or "ZOE" (DenPro, Prevest, New York, NY, USA), were compared using several in vitro techniques. Therefore, 30 primary anterior teeth were used in the present in vitro study. Analysis of variance (ANOVA), including a multiple comparison procedure (Holm-Sidak method, Dunn's Method, or Tukey test), was used. On micro-CT, Bio-C Pulpecto exhibited higher void percentages than did ZOE (10.3 ± 3.8%, and 3.5 ± 1.3%), respectively (p < 0.05). With digital microscopy, higher total void percentages were found in the BC (13.2 ± 26.7%) group compared to the ZOE (2.7 ± 2.8%) group (p < 0.05). With the CLSM, mean tubular penetration depths were higher for Bio-C Pulpecto than for ZOE in all canal thirds (p < 0.05). SEM images demonstrated no tags into dentinal tubules in either group throughout the three thirds. Moreover, higher statistically significant flowability was found for Bio-C (2.657 ± 0.06 mm) compared to ZOE (1.8 ± 0.13 mm) (p < 0.05). The findings of this study indicate that neither ZOE nor Bio-C Pulpecto appears to meet the criteria for an ideal root canal filling paste for primary teeth. This study laid the groundwork for future research by determining how micro-CT, digital microscopy, SEM, and CLSM contribute to our understanding of the filling process of primary teeth. More thorough research on the mechanism of root canal obturation on primary teeth is required to achieve a long-term successful root canal therapy in young children.

Effect of Passive Ultrasonic Irrigation, Er,Cr:YSGG Laser, and Photon-Induced Photoacoustic Streaming against Enterococcus faecalis Biofilms in the Apical Third of Root Canals

PURPOSE

This study aimed to compare the antibacterial effectiveness of passive ultrasonic irrigation (PUI), Er,Cr:YSGG laser (WTL), and photon-induced photoacoustic streaming (PIPS) using an Er:YAG laser against Enterococcus faecalis biofilms in the apical third of root canals.

METHODS

Root canals of 70 single-rooted human teeth were instrumented and infected with E. faecalis for 3 weeks to form biofilms. The samples were randomly divided into five groups as follows: (i) PUI + 3% NaOCl (n = 16); (ii) Er,Cr:YSGG laser (n = 16); (iii) PIPS + 3% NaOCl (n = 16); (iv) positive control group (n = 10); and (v) negative control group (n = 10). The bacterial content in the root canal was sampled using (a) the paper-point sampling method before (S1) and after (S2) treatment and (b) pulverising the apical 5 mm of the root. The number of bacteria recovered from each group was counted as colony-forming units (CFUs). The amount of reduction between the groups was compared with the Kruskal-Wallis test and post-test Dunn's multiple comparisons tests. The significance level was set at 5% (p < 0.05).

RESULTS

The samples from the paper-point sampling method showed that the amount of bacteria before (S1) and after treatment (S2) was significantly different between PIPS and WTL, as well as between the PUI and WTL groups. In contrast, no significant difference was found between the PIPS and PUI groups. From the pulverised samples, the results indicated no significant difference among all experimental groups in the amount of bacterial reduction in the apical 5 mm of the root.

CONCLUSIONS

PUI and PIPS showed a significantly greater reduction in bacterial content within the main root canal compared with the WTL. There was no difference among all experimental groups in the apical third of the root.

Stronger than Ever: Multifilament Fiberglass Posts Boost Maxillary Premolar Fracture Resistance

This paper investigates the influence of cavity configuration and post-endodontic restoration on the fracture resistance, failure mode and stress distribution of premolars by using a method of fracture failure test and finite elements analysis (FEA) coupled to Weibull analysis (WA). One hundred premolars were divided into one control group (G_contr) (n = 10) and three experimental groups, according to the post-endodontic restoration (n = 30), G₁, restored using composite, G₂, restored using single fiber post and G₃, restored using multifilament fiberglass posts (m-FGP) without post-space preparation. Each experimental group was divided into three subgroups according to the type of coronal cavity configuration (n = 10): G_1O, G_2O, and G_3O with occlusal (O) cavity configuration; G_1MO, G_2MO, and G_3MO with mesio-occlusal (MO); and G_1MOD, G_2MOD, and G_3MOD with mesio-occluso-distal (MOD). After thermomechanical aging, all the specimens were tested under compression load, and failure mode was determined. FEA and WA supplemented destructive tests. Data were statistically analyzed. Irrespective of residual tooth substance, G₁ and G₂ exhibited lower fracture resistance than G_contr (p < 0.05), whereas G₃ showed no difference compared to G_contr (p > 0.05). Regarding the type of restoration, no difference was highlighted between G_1O and G_2O, G_1MO and G_2MO, or G_1MOD and G_2MOD (p > 0.05), whereas G_3O, G_3MO, and G_3MOD exhibit higher fracture resistance (p < 0.05) than G_1O and G_2O, G_1MO and G_2MO, and G_1MOD and G_2MOD, respectively. Regarding cavity configuration: in G₁ and G_2, G_1O and G_2O exhibited higher fracture resistance than G_1MOD and G_2MOD, respectively (p < 0.05). In G₃, there was no difference among G_3O, G_3MO and G_3MOD (p > 0.05). No difference was found among the different groups and subgroups regarding the failure mode. After aging, premolars restored with multifilament fiberglass posts demonstrated fracture resistance values comparable to those of an intact tooth, irrespective of the different type of cavity configuration.

Cleaning efficacy of EDDY versus ultrasonically-activated irrigation in root canals: a systematic review and meta-analysis

BACKGROUND

Ultrasonically-activated irrigation (UAI) is effective in root canal irrigation but may damage canal walls. EDDY is a sonic activation system with flexible working tips that cause no harm to dentinal walls. This review explores the intracanal cleaning efficacy of EDDY compared with UAI in vitro.

METHODS

The systematic review was registered in the PROSPERO database (CRD42021235826). A literature search was conducted in six electronic databases. In vitro studies that compared the removal of smear layer, debris, soft tissue or microbes in root canals between EDDY and UAI were included. Data extraction and quality assessment were performed. Meta-analyses were conducted on smear layer removal and debris elimination with the standardized mean difference (SMD). Heterogeneity was measured using the I² test and the Chi² test. The random-effect model was used when I² > 50%, or p < 0.1, otherwise the fixed-effect model was applied. The level of significance was set at p < 0.05.

RESULTS

19 articles were included in this systematic review and 7 articles were included in meta-analyses. Meta-analyses on smear layer removal showed unimportant differences between EDDY and UAI at any canal third (coronal [SMD = 0.08, 95% confidence interval (95%CI): -0.29 to 0.45; p = 0.44, I² = 0%]; middle [SMD = 0.02, 95% CI: -0.44 to 0.47; p = 0.94, I² = 0%]; apical [SMD = 0.01, 95%CI: -0.35 to 0.38; p = 0.70, I² = 0%]). Meta-analyses on debris removal evaluated by scanning electron microscope (coronal [SMD = 0.03, 95% CI: -0.41 to 0.46; p = 0.27, I² = 23%]; middle [SMD = -0.24, 95% CI: -0.83 to 0.35; p = 0.80, I² = 0%]; apical [SMD = 0.24, 95%CI: -0.20 to 0.67; p = 0.36, I² = 2%]) and micro-CT (SMD = 0.36, 95% CI: -0.67 to 1.40; p = 0.03, I² = 70%) both found insignificant differences. No meta-analysis was undertaken on soft-tissue removal and disinfection due to the various study designs, but the qualitative analyses implied that EDDY achieved similar performance to UAI in both aspects.

CONCLUSIONS

Limited evidence indicated that EDDY was comparable to UAI in removing smear layer, debris, soft tissue and microbes ex vivo. Considering UAI may damage canal walls, EDDY might be a substitute for UAI in irrigation activation. But more randomized clinical trials are required to explore the clinical extrapolation of the results in this review.

Effectiveness of Two Endodontic Instruments in Calcium Silicate-Based Sealer Retreatment

The objective of the present in vitro work was to investigate the effectiveness and time required for the removal of calcium silicate-based sealer using two rotary retreatment systems. Sixty extracted, single-canal, lower premolars were used. After obturation using the single-cone technique with calcium silicate-based sealer, samples were divided into four groups according to the technique of desobturation: Group 1 (G1): D-Race; Group 2 (G2): D-Race followed by the use of XP–Endo Finisher R; Group 3 (G3): Protaper Universal Retreatment; and Group 4 (G4): Protaper Universal Retreatment followed by the use of XP–Endo Finisher R. Cone beam computed tomography (CBCT) images were used to calculate the remaining filling materials at the middle and apical thirds. Times required to perform each method were recorded. Scanning electron microscopy (SEM) and digital microscopy were used to evaluate the remaining filling materials. Data were statistically analyzed using the t-test and one way ANOVA on ranks tests. No statistically significant difference was found between G1 and G3 after CBCT observations (p > 0.05). Xp-Endo Finisher R significantly increased the ability to remove materials regardless of the initially used retreatment system (p < 0.05). Statistically significant longer time was found in G3 and G4 compared to G1 and G2, respectively (p < 0.05), to reach the full working length. No retreatment system was able to totally remove the calcium silicate-based sealer from the root canal at the middle and apical thirds (p > 0.05). Digital microscopy demonstrated that the residual materials were the remaining sealers on the canal walls. SEM showed the mineral depositions of calcium silicate materials onto the canal walls and into the dentinal tubules. However, that calcium silicate materials provide mineral deposition into the dentinal tubules might indicate that the traditional irrigants could not be sufficient to remove calcium silicate-based materials from the root canal, and other agents should be used to make retreatment considerably easier.

Modern Therapeutic Strategies in Endodontics and Restorative Dentistry

Modern endodontics aims to reduce or eliminate bacterial load inside root canals [...].

Peptides in Dentistry: A Scoping Review

Currently, it remains unclear which specific peptides could be appropriate for applications in different fields of dentistry. The aim of this scoping review was to scan the contemporary scientific papers related to the types, uses and applications of peptides in dentistry at the moment. Literature database searches were performed in the following databases: PubMed/MEDLINE, Scopus, Web of Science, Embase, and Scielo. A total of 133 articles involving the use of peptides in dentistry-related applications were included. The studies involved experimental designs in animals, microorganisms, or cells; clinical trials were also identified within this review. Most of the applications of peptides included caries management, implant osseointegration, guided tissue regeneration, vital pulp therapy, antimicrobial activity, enamel remineralization, periodontal therapy, the surface modification of tooth implants, and the modification of other restorative materials such as dental adhesives and denture base resins. The in vitro and in vivo studies included in this review suggested that peptides may have beneficial effects for treating early carious lesions, promoting cell adhesion, enhancing the adhesion strength of dental implants, and in tissue engineering as healthy promotors of the periodontium and antimicrobial agents. The lack of clinical trials should be highlighted, leaving a wide space available for the investigation of peptides in dentistry.

Smear Layer and Debris Removal from Root Canals Comparing Traditional Syringe Irrigation and 3D Cleaning: An Ex Vivo Study

Background: Endodontic treatment objectives comprise eliminating or decreasing bacterial load inside the complex endodontic space. Removing the smear layer and debris becomes mandatory to achieve good three-dimensional (3D) cleaning. Aim: This study assesses the difference in smear layer removal using the 3D cleaning technique and traditional syringe needle irrigation. The 3D cleaning technique includes the ultrasonic activation of intracanal-heated NaOCl. Materials and Methods: Our current study used single-rooted human mandibular premolar teeth to test the earlier-mentioned technique (n = 30). Initially, an endodontic access cavity was performed. Consequently, specimens were randomly distributed into three study groups according to irrigation protocol. The groups were Group 1, where the traditional syringe needle irrigation system was applied; Group 2, where the 3D cleaning technique was performed; and Group 3, in which teeth remained uncleaned as it was regarded as the control group. Once the experiment was completed, the teeth were decoronated at the cementoenamel junction (CEJ) and examined using scanning electron microscopy (SEM). Debris and smear layers were viewed in 1000× magnification and scored. Results: Statistical analysis was performed with a standard statistical software package (SPSS, version 28.0; SPSS IBM, Armonk, NY, USA). Data were analyzed with a nonparametric analysis of variance (Kruskal−Wallis ANOVA) among the groups tested and among the thirds of the canals. The level of significance was set at p < 0.05. A statistically significant (p < 0.05) lower mean smear layer and debris score was observed in both study groups compared to the control group. Group 2 showed better results compared to Group 1. Conclusions: The present study concluded that the 3D cleaning technique is an effective irrigation method for removing debris and smear layers. Future research, such as CLSM (Confocal Laser Scanning Microscopy) and Histological study, should be employed to confirm this study’s conclusion.

Evaluating the Effectiveness of Different Irrigant Activation Techniques in Removing the Smear Layer and Opening the Dentinal Canals: A Scanning Electron Microscopic Study

Background Although irrigation is one of the most important stages during root canal treatment, it is not possible to guarantee the entry of irrigants to all the areas in the root canal, especially in the apical third. Therefore, the activation of irrigants can stimulate and help the irrigants to access hard-to-reach places within the root canal system. Therefore, this study aimed to evaluate the opening of the dentinal canals with scanning electron microscopy (SEM) using different irrigant activation techniques, such as intracanal heating activation, sonic activation, and ultrasonic activation, along the walls of the root canals in the coronal, middle, and apical thirds. Methodology The study sample consisted of 36 single-canal premolars, which were randomly divided into the following three equal groups according to the method of activation used: group 1 (n = 12), which involved heating activation inside the root canals, group 2 (n = 12), which involved sonic activation, and group 3 (control; n = 12), which involved ultrasonic activation. Afterward, dental crowns were cut to standardize the working length by 18 mm and were then prepared using the ProTaper Next system up to size X2. Moreover, the irrigant was activated for each group separately, and the teeth were extracted and prepared for SEM. Three images were taken for each sample (i.e., coronal third, middle third, and apical third) at ×2,000 magnification. Data were analyzed using the Mann-Whitney U test. Results When studying the removal of the smear layer and the opening of the dentinal canal under ×2,000 magnification, there were no statistically significant differences in the coronal and middle third between the three studied groups. However, statistically significant differences were found in the apical third, where the ultrasonic activation group was the best, followed by the sonic activation group, and the heating activation group. Conclusions All methods of activation were effective in removing the smear layer and opening the dentinal canals with the advantage of ultrasonic activation in the rest of the groups. The intracanal heating irrigant activation proved to be similar to the effectiveness of sonic activation and close to ultrasonic activation.

Special Issue "Recent Advances in Biomaterials and Dental Disease" Part I

Oral cavities provide an entry point for food and nutrients [...].

Modern Endodontics

The goal of modern endodontics is the complete removal of damaged tissue and bacteria from the endodontic space [...].

Physicochemical and Mechanical Properties of Premixed Calcium Silicate and Resin Sealers

The aim of the present in vitro study was to evaluate specific mechanical and physicochemical properties of two calcium silicate based sealers, (AH Plus Bioceramic “AHPB”; Well-Root ST “WRST”), and a conventional resin sealer (AH Plus “AHP”). These aims were accomplished by assessing the porosity, pH, compression strength, roughness, wettability and cell attachment of the tested materials. The results were compared statistically using the one-way ANOVA test. Higher pH values were obtained in both AHPB and WRST compared to AHP at 3, 24 and 72 h (p < 0.05). A greater level of porosity and wettability was detected for both AHPB and WRST compared to the resin sealer AHP (p < 0.05). Evident cell growth characterized by elongated morphology was observed on the surface of AHPB and WRST, while only a thin layer of cells was seen on the surface of AHP. A significant lower compression strength and modulus were obtained in the specimens created using AHPB compared to those made with AHP and WRST (p < 0.05). The removal of calcium silicates may be quite tricky during endodontic retreatment. In conclusion, considering the limitations of the present in vitro study, both calcium silicate sealers demonstrated good physicochemical properties. However, the lower compression strength and modulus of AHPB may facilitate its removal and make the retreatment procedures considerably easier.

Intentional Replantation of Single-Rooted and Multi-Rooted Teeth: A Systematic Review

The technique of intentional replantation can provide a second chance to save teeth that would be destined for extraction. Therefore, the present systematic review aimed primarily to estimate tooth survival after intentional replantation and secondarily to compare treatment outcomes in single-rooted and multi-rooted teeth. The study protocol was developed before the analysis according to the Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines. Articles were electronically searched in PubMed/MEDLINE, the COCHRANE library and Google Scholar by two independent reviewers, and those that met the eligibility criteria were included. A statistical analysis using the chi-square test with a p-value of <0.05 was performed on the reported outcomes of intentional replantation. A total of 44 single-rooted replanted teeth with five failures (11.36%) and 42 multi-rooted replanted teeth with six failures (14.28%) were reported in the literature, corresponding to a survival rate of 88.64% and 85.57%, respectively. The overall survival rate for the replantation procedure was 86.7%, indicating that intentional replantation can be considered a safe therapeutic choice, with no statistically significant difference between the survival rates of single-rooted and multi-rooted replanted teeth.

The Effectiveness of Different Irrigation Techniques on Debris and Smear Layer Removal in Primary Mandibular Second Molars: An In Vitro Study

AIMS

The aim of the present in vitro study was to compare the effectiveness of passive ultrasonic irrigation (PUI), sonic irrigation, and mechanic dynamic activation on the removal of debris and smear layer from primary mandibular second molars during pulpectomy.

MATERIALS AND METHODS

Mesial roots of 48 primary mandibular second molars were prepared with an R-motion 21 mm file (30/0.04) (FKG Dentaire SA, La Chaux-de-Fonds, Switzerland), irrigated with 1% sodium hypochlorite (NaOCl) and 17% ethylenediaminetetraacetic acid (EDTA), and divided into four groups (n = 24 canals) according to the final irrigation activation technique: control group without activation, PUI with Ultra-X (Eighteeth, Changzhou, China), mechanical activation with XP-endo Finisher (FKG), and sonic irrigation with EQ-S (Meta Biomed, Chungcheongbuk-do, Korea). The roots were split longitudinally and analyzed using scanning electron microscopy (SEM). The presence of debris and smear layer was assessed using a 5-grade scoring scale with 200× and 1000× magnification, respectively. The Kruskal-Wallis and Friedman tests were used for data analysis.

RESULTS

The activation of the irrigant significantly improved debris and smear layer removal (p < 0.001). There was no significant difference between Ultra-X, XP-endo Finisher, and EQ-S (p > 0.05). No activation technique was able to completely eliminate debris and smear layer from the root canals of primary mandibular second molars.

CONCLUSIONS

During pediatric pulpectomy, the irrigation protocol must include activation of the irrigation solutions using either ultrasonic, sonic, or mechanical activation techniques to enhance the removal of debris and smear layer for a better prognosis.

CLINICAL SIGNIFICANCE

During root canal treatment on primary teeth, the clinician must incorporate an activation technique in the irrigation protocol to enhance the removal of debris and smear layer and increase the success of the treatment.

Comparative Study Assessing the Canal Cleanliness Using Automated Device and Conventional Syringe Needle for Root Canal Irrigation-An Ex-Vivo Study

The success of endodontic treatment relies on both apical and coronal sealing. To achieve a good three-dimensional seal, the removal of the smear layer becomes mandatory. This study aims to assess the difference in debris accumulation and smear layer formation while using automated root canal irrigation and conventional syringe needle irrigation. Single-rooted human mandibular premolar teeth (n = 30) which were indicated for orthodontic extractions were selected. An endodontic access cavity was prepared, and a glide path was created. Based on the irrigation protocol decided upon for the study, the teeth were randomly allocated into three study groups, namely Group 1, where the manual syringe needle irrigation method was adopted; Group 2, in which automated root canal irrigation was undertaken; and Group 3, in which teeth remained un-instrumented as it was considered the Control group. The teeth were decoronated at the cement-enamel junction (CEJ) and were subjected for scanning electron microscopy (SEM) examination. Debris and smear layers were viewed in 1000× magnification and scored. A statistically significant (p < 0.05) lower mean debris and smear layer score (p < 0.05) was observed in both study groups when compared with the control group. However, no significant difference (p > 0.05) in the debris and smear layer was observed between the manual syringe needle irrigation and automated irrigation, although automated irrigation devices can be a potential alternative. The present study concluded that the efficacy of smear layer removal remained the same with both automated irrigation and manual syringe irrigation.

The antimicrobial peptides secreted by the chromaffin cells of the adrenal medulla link the neuroendocrine and immune systems: From basic to clinical studies

The increasing resistance to antibiotic treatments highlights the need for the development of new antimicrobial agents. Antimicrobial peptides (AMPs) have been studied to be used in clinical settings for the treatment of infections. Endogenous AMPs represent the first line defense of the innate immune system against pathogens; they also positively interfere with infection-associated inflammation. Interestingly, AMPs influence numerous biological processes, such as the regulation of the microbiota, wound healing, the induction of adaptive immunity, the regulation of inflammation, and finally express anti-cancer and cytotoxic properties. Numerous peptides identified in chromaffin secretory granules from the adrenal medulla possess antimicrobial activity: they are released by chromaffin cells during stress situations by exocytosis via the activation of the hypothalamo-pituitary axis. The objective of the present review is to develop complete informations including (i) the biological characteristics of the AMPs produced after the natural processing of chromogranins A and B, proenkephalin-A and free ubiquitin, (ii) the design of innovative materials and (iii) the involvement of these AMPs in human diseases. Some peptides are elective biomarkers for critical care medicine, may play an important role in the protection of infections (alone, or in combination with others or antibiotics), in the prevention of nosocomial infections, in the regulation of intestinal mucosal dynamics and of inflammation. They could play an important role for medical implant functionalization, such as catheters, tracheal tubes or oral surgical devices, in order to prevent infections after implantation and to promote the healing of tissues.

Effectiveness of the REvision System and Sonic Irrigation in the Removal of Root Canal Filling Material from Oval Canals: An In Vitro Study

This study aimed to evaluate the effectiveness of the Endostar REvision system (Poldent, Warsaw, Poland) in the removal of filling materials from oval root canals using sonic irrigation as an additional cleaning method. Thirty human-extracted mandibular premolars with oval canals were prepared using the ProTaper Universal system (Dentsply Maillefer, Ballaigues, Switzerland) up to instrument F1 (20/.07), and then filled by the continuous wave vertical compaction technique using pulp canal sealer EWT (Sybron Dental Specialties, Orange, CA, USA). The teeth were randomly divided into two groups (n = 15) according to the instrumentation system and the additional cleaning method, as follows: REvision (30/.08, 25/.06) with EQ-S sonic activation (Meta Biomed, Chungcheongbuk-do, Korea), REvision (30/.08, 25/.06) without additional activation. All specimens were sectioned longitudinally at 3 and 7 mm from the apex, and analyzed using digital microscopy (KEYENCE, Osaka, Japan) to measure the total area of the residual obturation materials, followed by SEM analysis. The data on the percentage of remaining filling material were analyzed by Kruskal−Wallis one-way Analysis of Variance on ranks. None of the retreatment protocols completely removed the filling material from the root canals (p > 0.05); the retreatment technique using sonic activation showed statistically less residual filling materials than the retreatment technique using irrigants without activation at the coronal third (p < 0.05), whilst no significant difference was found between both tested groups at the apical and middle thirds (p > 0.05). The REvision system showed promising results in the removal of filling materials from oval canals.

Does Multi-Fiber-Reinforced Composite-Post Influence the Filling Ability and the Bond Strength in Root Canal?

The purpose of the present in vitro study was to investigate the bond strength of root canal dentin and the filling ability of a new multi-fiber-reinforced composite post (mFRC) compared to a conventional single fiber-reinforced-composite post (sFRC). Twenty-eight freshly maxillary first permanent single-rooted premolars were instrumented and divided into groups (n = 14). Group 1: single-fiber-reinforced composite (sFRC), group 2: multi-fiber-reinforced composite (mFRC). Bonding procedures were performed using a dual-cure universal adhesive system and resin cement. All specimens were sectioned so that seven discs of 1 mm of thickness were obtained from each root. An optical microscope was used before the push-out test to measure the total area of the voids and to determine the length of the smaller/bigger circumferences. The push-out bond strength (PBS) test was performed using an Instron universal testing machine. Data were then compared by one-way ANOVA on ranks (α = 0.05). The dentin–cement–post interface was observed using scanning electron microscopy (SEM). At the coronal third, a significantly higher bond strength (p < 0.05) was obtained in the sFRC group (44.7 ± 13.1 MPa) compared to the mFRC group (37.2 ± 9.2 MPa). No significant difference was detected between the groups at the middle third (sFRC group “33.7 ± 12.5 MPa” and mFRC group “32.6 ± 12.4 MPa”) (p > 0.05). Voids were significantly lower in the mFRC compared to those observed in the sFRC group (p < 0.05) at the coronal third. Whereas, no significant difference was found at the middle third (p > 0.05) between the tested groups. Filling ability was overall improved when employing mFRC, although such technique might have characteristic limitations concerning the bond strength to dentin.

Current strategies for conservative endodontic access cavity preparation techniques-systematic review, meta-analysis, and decision-making protocol

OBJECTIVES

To assess related studies and discuss the clinical implications of endodontic access cavity (AC) designs.

MATERIALS AND METHODS

A systematic review of studies comparing the fracture resistance and/or endodontic outcomes between different AC designs was conducted in two electronic search databases (PubMed and Web of Science) following the PRISMA guidelines. Study selection, data extraction, and quality assessment were performed. Meta-analyses were undertaken for fracture resistance and root canal detection, with the level of significance set at 0.05 (P = 0.05).

RESULTS

A total of 33 articles were included in this systematic review. The global evaluation of the risk of bias in the included studies was assessed as moderate, and the level of evidence was rated as low. Four types of AC designs were categorized: traditional (TradAC), conservative (ConsAC), ultraconservative (UltraAC), and truss (TrussAC). Their impact on fracture resistance, cleaning/disinfection, procedural errors, root canal detection, treatment time, apical debris extrusion, and root canal filling was discussed. Meta-analysis showed that compared to TradAC, (i) there is a significant higher fracture resistance of teeth with ConsAC, TrussAC, or ConsAC/TrussAC when all marginal ridges are preserved (P < 0.05), (ii) there is no significant effect of the type of AC on the fracture resistance of teeth when one or two marginal ridges are lost (P > 0.05), and (iii) there is a significantly higher risk of undetected canals with ConsAC if not assisted by dental operating microscope and ultrasonic troughing (P < 0.05).

CONCLUSIONS

Decreasing the AC extent does not necessarily present mechanical and biological advantages especially when one or more surfaces of the tooth structure are lost. To date, the evidence available does not support the application of TrussAC. UltraAC might be applied in limited occasions.

CLINICAL RELEVANCE

Maintaining the extent of AC design as small as practical without jeopardizing the root canal treatment quality remains a pragmatic recommendation. Different criteria can guide the practitioner for the optimal extent of AC outline form which varies from case to case.

Effectiveness of XP-Endo Finisher and passive ultrasonic irrigation on intracanal medicament removal from root canals: a systematic review and meta-analysis

Background

XP-Endo Finisher (XPF) and passive ultrasonic irrigation (PUI) are commonly used in intracanal medicament removal. The effectiveness of these two techniques needs to be compared, and evidence-based research should be conducted.

Methods

A comprehensive literature search was conducted in PubMed, Web of Science, Embase, Cochrane Library, and Google Scholar up to December 20th, 2020. The outcomes of the included trials were pooled into the Cochrane Collaboration’s Review Manager 5.3 software. Cochrane’s risk-of-bias tool 2.0 was applied to assess the risk of bias.

Results

Nine articles were included in this systematic review and processed for data extraction, and eight studies were identified for meta-analysis. In general, the use of PUI showed better medicament removal effectiveness than XPF (odds ratio [OR]: 3.09; 95% confidence interval [CI], 1.96–4.86; P < 0.001). PUI was also significantly more efficient than XPF in the apical third (OR: 3.42; 95% CI, 1.32–8.84; P = 0.01). For trials using sodium hypochlorite (NaOCl) alone, PUI was also significantly more effective than XPF on intracanal medicaments removal (OR: 5.23; 95% CI, 2.79–9.82; P < 0.001). However, there was no significant difference between PUI and XPF when NaOCl and ethylenediaminetetraacetic acid (EDTA) were used in combination (OR: 1.51; 95% CI, 0.74–3.09; P = 0.26). In addition, for studies whose intracanal medicament periods were two weeks, the effectiveness of PUI was statistically better than the XPF (OR: 7.73; 95% CI, 3.71–16.07; P < 0.001). Nevertheless, for trials whose intracanal medicament time was one week or over two weeks, no differences between the XPF and PUI were found (OR: 1.54; 95% CI, 0.74–3.22; P = 0.25) (OR: 1.42; 95% CI, 0.44–4.61; P = 0.56).

Conclusions

The meta-analysis is the first study to quantitatively compare the effectiveness of XPF and PUI techniques on intracanal medicaments removal. With rigorous eligibility criteria, the study only included high-quality randomised controlled trials. The study indicated that PUI might be superior over XPF techniques for removing intracanal medicaments from artificial standardized grooves and cavities in the root canal system. The anatomical areas, irrigation protocol, and intracanal medicaments time may influence the cleaning efficacy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01644-7.