Effect of calcium hydroxide intracanal dressing on the bond strength of a resin-based endodontic sealer

Evaluation of the efficacy of different irrigation activation techniques in removing of calcium hydroxide on teeth with the simulated internal root resorption cavity: a confocal laser scanning microscope analysis

The aim of this study is to evaluate the effect of different irrigation activation methods on root canal sealer penetration in teeth with simulated internal root resorption (IRR) and calcium hydroxide (CH) applied using a confocal laser scanning microscope (CLSM). 60 incisors with a single root and a single canal were included in the study. IRR cavities were created in the middle third of the root canal, and CH was placed. The samples were randomly divided into 4 groups (n = 15) according to the irrigation activation method to be tested: standard needle irrigation (SNI), sonic activation (EDDY), photon-induced photoacoustic flow (PIPS), and shock wave enhanced emission photoacoustic flow (SWEEPS). After irrigation activation applications, the root canals were obturated. Sections of 1.0 ± 0.1 mm were taken from the apical, middle, and coronal regions of each sample. The penetration area (µm2) and maximum penetration depth (µm) of the root canal sealer were examined by CLSM and analyzed using ImageJ software. Statistical analysis was performed with a one-way ANOVA and post-hoc Tukey test at the P < 0.05 significance level. Among all irrigation activation methods tested, both the penetration area and maximum penetration depth of the root canal sealer were greater in the coronal region than in the apical region (p < 0.05). In the IRR region, there was no difference in terms of maximum penetration depth between PIPS and SWEEPS (p > 0.05), it was highest in SWEEPS (p < 0.05). PIPS and SWEEPS were better than other irrigation activation methods in the penetration of root canal sealer in the resorption areas of teeth with IRR.

Effect of canal medicaments triple antibiotic paste, Bio-C Temp, and Nano-silver gel activated by visible blue light on canal dentin microhardness and extrusion bond strength of AH plus sealer: A SEM and EDX analysis

AIM

Assessment of contemporary canal medicaments (Triple antibiotic paste (TAP), Bio-C Temp, and Nano silver gel activated by visible blue light on the dentin microhardness (MH) and push-out bond strength (PBS) of AH plus endodontic sealer.

METHOD

Sixty extracted premolars were obtained and decontaminated. Canal cleaning and shaping were performed. The samples were randomly allocated into four groups based on the intracanal medicaments. Group 1= CH paste, Group 2= TAP, Group 3= Bio-C Temp, and Group 4= Nano-silver gel activated by visible blue light. MH assessment was performed using a Vickers Microhardness tester. Forty specimens, ten from each group underwent root canal obturation. PBS and failure mode evaluation were performed. ANOVA and Post Hoc Tukey test were utilized to conduct intra and inter-group comparisons.

RESULTS

The maximum outcome of surface hardness was presented by Group-3 (Bio-C Temp®) specimens. However, minimum scores of MH were displayed by Group 1 (CH) treated teeth. The highest outcomes of EBS were exhibited by the cervical third of Group 3 (Bio-C Temp®) samples. The apical section of Group 4 Teeth with Nano Silver gel activated by visible blue light revealed the lowest scores of bond integrity.

CONCLUSION

Bio-C Temp and TAP proved to be better intracanal medicament than other tested groups in terms of the push-out bond strength of the sealer. TAP displayed lower microhardness as compared to the Bio-C Temp.

Efficacy of 2% Paradichlorobenzene, 10% Citric Acid, 17% Ethylenediaminetetraacetic Acid, and 0.2% Chitosan at Removing Calcium Hydroxide From the Root Canals

INTRODUCTION

Chronic infections often require the use of an intracanal medicament. Calcium hydroxide is the most commonly used intracanal medicament. However, retrieval of calcium hydroxide (CH) medicaments is a challenge.

AIM

This study evaluated the efficacy of 2% paradichlorobenzene, 10% citric acid, 17% ethylenediaminetetraacetic acid (EDTA), and 0.2% chitosan in removing calcium hydroxide from the root canals.

METHODS AND MATERIALS

Forty single-rooted mandibular premolars extracted for orthodontic reasons were selected for the study. After access opening, cleaning and shaping were performed following a standardized irrigation protocol, and the samples were pre-weighed for baseline weight. CH was placed in canals until the apex, and the specimen was incubated at 37 °C and 100% relative humidity for seven days. These samples were weighed again for quantitative analysis and subjected to cone beam computed tomography (CBCT) for volumetric analysis using ITK SNAP software (Penn Image Computing and Science Laboratory (PICSL), University of Pennsylvania, Philadelphia, PA). The samples were randomly divided into four groups based on the irrigant used for the removal of medicament. Group 1: 2% paradichlorobenzene; group 2: 10% citric acid; group 3: 17% EDTA; and group 4: 0.2% chitosan, all in combination with sonic agitation. After the removal of CH, weight and volumetric analyses were repeated, and the percentage difference was calculated.

STATISTICAL ANALYSIS

Statistical analysis was done using the one-way ANOVA test for both weight and volumetric assessment, and the inter-group comparison was made using the post hoc Tukey test.

RESULTS

The maximum retrieval was observed with 2% paradichlorobenzene by both weight (96.75%) and volumetric (91.42%) assessment, with p=0.00 and p=0.01, respectively. This was followed by 0.2% chitosan, 10% citric acid, and the least, 17% EDTA.

CONCLUSION

Two percent paradichlorobenzene combined with sonic agitation was most efficient in removing CH, followed by 0.2% chitosan, 10% citric acid, and 17% EDTA chitosan.

Analysis of pH, calcium ion release, and energy dispersive spectroscopy of a bioceramic root canal dressing

This study compared the pH and calcium ion release of calcium silicate- (Bio-C Temp) and calcium hydroxide-based (Ultracal XS) medications. Intracanal remnants of both medications were also evaluated using SEM-EDS after the removal protocol. Thirty-five bovine teeth were prepared. Fifteen were filled with Bio-C Temp and 15 with Ultracal XS. Five remained without intracanal medication (control group). Five samples from each experimental time (i.e.. 24, 72, and 168 hours) were used to measure pH and calcium ions release using a digital pH meter and microplate reader, respectively. Afterward, the peaks of the chemical elements composing both medications were analyzed in SEM-EDS. One-way ANOVA and Tukey's post hoc test analyzed the pH and calcium ion release data. Student's t-test compared the medications in each experimental time. SEM-EDS described the percentage of chemical elements in the samples. Bio-C Temp and Ultracal XS showed a significant pH increase from 24 to 168 hours (p<0.05). Ultracal XS showed a higher pH value at 24 hours than Bio-C Temp (p<0.05) but were similar at 72 and 168h (p > 0.05). Calcium ion release did not depend on the experimental period (p > 0.05). Bio-C Temp showed lower calcium ions release than Ultracal XS at 24 hours (p<0.05). SEM-EDS analyses showed the remains of both medications, but the concentration of Si, Al, and W ions was present only in the calcium silicate-based medication. Bio-C Temp presented alkaline pH and a satisfactory calcium ion release over the time. The remaining of both medications were present after the protocols for paste removal.

The Bond Strength of Root Canal Filling after Calcium Hydroxide Removal with a Simple Apical Negative Pressure Kit in Oval-Shaped Root Canal

Background

The aim of this study was to evaluate the effect of a simple irrigating device, which produced from the apical negative pressure concept, as a final irrigating method after calcium hydroxide (CH) medication on the bond strength of epoxy resin-based sealer in the oval-shaped root canal.

Methods

Forty-eight single-rooted premolars with oval-shaped canals were included in the study. The crown was decoronized and canal instrumented with Mtwo (VDW GmbH, Munich, Germany) up to size 40/04. The specimens were assigned to four groups according to the irrigation protocol after 1 week of CH medication: control group (no medication) and three experimental groups conventional needle irrigation (CNI), passive ultrasonic irrigation (PUI), and simple apical negative pressure kit (sANP). The teeth were obturated with a warm vertical technique using epoxy resin-based sealers. After 1 week, the roots were transversally sectioned at coronal, middle, and apical thirds. A push-out test was performed by a universal testing machine, and statistical analysis was performed using One-Way ANOVA with Duncan's post hoc test.

Results

The bond strength in the control group was significantly higher than the CNI group in all root canal thirds (P < 0.05). At coronal third, sANP showed lower bond strength than PUI group (P < 0.05). However, the bond strength of sANP group was comparable to the control group (P > 0.05) which was significantly higher than the PUI group at apical third (P < 0.05).

Conclusion

A sANP enhanced the bond strength of epoxy resin-based sealer in the apical third of CH-medicated root canal in the oval-shaped canal.

Effects of calcium hydroxide intracanal medicament on push-out bond strength of endodontic sealers: A systematic review and meta-analysis

OBJECTIVE

To investigate the effect of calcium hydroxide intracanal medicament on the push-out bond strength of resin-based and calcium silicate-based endodontic sealers.

METHODS

A comprehensive search of was conducted for all relevant in-vitro studies. All randomized controlled in-vitro studies that evaluated the effect of calcium hydroxide on the push-out bond strength of resin-based or calcium silicate-based endodontic sealers were assessed. The variables of interest were extracted, and the risk of the included studies was evaluated. The standardized mean difference was calculated and the significance level was set at p value <0.05.

RESULTS

A total of 26 studies were eligible for analysis. There were 45 independent comparison groups and 1009 recruited teeth. The pooled data showed no significant difference in push-out bond strength between calcium hydroxide and control group in the resin-based group (SMD = 0.03; 95% CI = -0.55, 0.60; p = 0.93), and calcium silicate-based group (SMD = 0.02; 95% CI = -0.31, 0.35; p = 0.90). Most of the studies (21 out of 26) were at medium risk of bias and five studies showed a low risk of bias.

CONCLUSION

The available evidence suggests that calcium hydroxide used as intracanal medication does not influence the push-out bond strength of the resin- and calcium silicate-based endodontic sealers.

CLINICAL SIGNIFICANCE

The results of this meta-analysis suggest that calcium hydroxide used as intracanal medication does not influence the push-out bond strength of resin-based and calcium silicate-based endodontic sealers.

Efficacy of Laser-Activated Irrigation and Conventional Techniques in Calcium Hydroxide Removal from Simulated Internal Resorption Cavities: Micro-CT Study

Objective: This study aimed to evaluate the effectiveness of different irrigant-activation techniques for eliminating calcium hydroxide from an internal root canal resorption cavity by using microcomputed tomography (micro-CT). Background: Several techniques and irrigants are inadequate for the complete removal of calcium hydroxide from an internal root resorption cavity. Recently, a few studies have investigated the effectiveness of various methods, but there has been no micro-CT study that compares the effectiveness of photon-induced photoacoustic streaming (PIPS) and shock wave enhanced emission photoacoustic streaming (SWEEPS) techniques. Methods: Seventy single-canal mandibular premolar teeth were selected and divided into seven groups (n = 10) according to the techniques to be used: syringe irrigation (SI), passive ultrasonic irrigation (PUI), EndoActivator (EA), XP-Endo finisher file (XP), Er,Cr:YSGG laser-activated irrigation, PIPS, and SWEEPS. The root canals were instrumented using a rotary system and divided vertically. Internal resorption cavities were created and standardized through diamond burs. Calcium hydroxide was placed into the root canal space. All specimens were evaluated using micro-CT in two different periods. The initial and residual calcium hydroxide volumes in the simulated cavities were calculated. Data were analyzed using a Kruskal-Wallis H test. Results: SWEEPS and PIPS were significantly more effective than EA, Er,Cr:YSGG, PUI, XP, and SI (p < 0.05). There was no significant difference between the SWEEPS and PIPS groups (p > 0.05). SI and XP showed the least effective activity (p < 0.05). Conclusions: The SWEEPS and PIPS techniques were superior to the EA, Er,Cr:YSGG, PUI, XP, and SI techniques. None of the techniques used entirely removed the calcium hydroxide from the resorption cavities.

The effects of root canal perforation repair materials on the bond strength of fiber posts

INTRODUCTION

This study aimed to evaluate the effect of calcium hydroxide and bioceramics used in perforation repair on the bonding strength of fiber posts via a push-out test.

METHODOLOGY

This study used 106 extracted single-rooted human mandibular premolar teeth. Root canal preparations were performed with a rotary file system and perforations were created in the middle third of each tooth. The samples were randomized into two main experimental groups, one with calcium hydroxide and one without. Each group had four subgroups in which different bioceramic cements were applied (n = 11) and a control group (n = 9). The root canals perforations were repaired using MTA, Biodentine, Bioaggregate, and Endosequence BC root repair material. A fiber post was applied to each tooth and a push-out test was performed. The samples were examined at 40× magnification with a digital microscope in order to identify fracture type.

RESULTS

Bonding strength was calculated in MPa. A statistical analysis showed that the calcium hydroxide had no effect on the bonding strength of the fiber posts. A comparison of the perforation repair materials revealed that Biodentine in the calcium hydroxide group and Bioaggregate in both groups decreased the bonding strength compared to the other materials (p < 0.05). The most common failure type was adhesive failure between the dentin and resin cement (38.16%).

CONCLUSIONS

The use of different perforation repair materials can affect the bonding strength of fiber posts. Therefore, the choice of perforation repair material should be made on an individual basis.

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.

The Contribution of the Brazilian Dental Journal to the Brazilian Scientific Research over 30 Years

The Brazilian Dental Journal (BDJ) was officially launched in 1990, stimulated by the courage and boldness of researchers dedicated to teaching and research in dentistry. The journal was conceived in a worldwide coverage and universal language to allow publication of the results of Brazilian studies, which otherwise would not be accessible to the scientific dental community. In the year we celebrate the thirtieth anniversary of BDJ, this article presents a brief overview of Brazilian dental research and a bibliometric analysis of the articles published in this journal as a contribution to our readers and fellow researchers. The purpose was to identify the mot frequent categories of study, the most published areas of dentistry and BDJ's top 50 most-cited articles in the Scopus and Google Scholar databases. A search was performed on all BDJ online issues published from 1990 to 2019. In this period, BDJ published 1,710 articles. Based on their distribution by category of study, 557 articles were in the basic research/dental materials area, 527 in the basic research/biology area and 280 in the clinical research area. Eight articles were cited more than 100 times in the Scopus database and 266 times in the Google Scholar database. Endodontics was the most published area. This overview of BDJ production over those 30 years allows establishing a profile of the characteristics, impact and trends of the published studies, as well as the journal's contribution to the top 50 most-cited articles in the Scopus and Google Scholar databases.

Dentinal Tubule Penetration and Dislocation Resistance of a New Bioactive Root Canal Sealer Following Root Canal Medicament Removal Using Sonic Agitation or Laser-Activated Irrigation

Objective:

To investigate the influence of sonic agitation or laser-activated irrigation techniques on the removal chlorhexidine (CHX) and modified triple antibiotic paste (mTAP) on the sealer penetration depth and dislocation resistance of Guttaflow Bioseal.

Methods:

Single-rooted mandibular premolars (n=96) were prepared with rotary nickel titanium instruments and randomly divided into two groups (n=48) based on the intracanal medicaments used: Group 1, mTAP; Group 2, CHX gel. After 7 days, the specimens in each group were divided into three subgroups (n=16) based on the supplementary irrigation technique used to remove the medicaments: laser activated irrigation (Er, Cr: YSGG laser, Waterlase MD, Biolase Technology Inc., San Clemente, CA, USA), sonic agitation (EndoActivator, Dentslpy Sirona Endodontics, PA, USA) and syringe-and-needle irrigation (control) techniques. Canals were filled with single matched-taper gutta-percha cone and a calcium silicate-based sealer (GuttaFlow® Bioseal, Coltène/Whaledent, Langenau, Germany). At the end of three weeks, sealer penetration was investigated using confocal microscopy (n=6), and dislocation resistance was calculated by measuring the push-out bond strength (n=10). Statistical analysis was performed using three-way analysis of variance (ANOVA) and Tukey post-hoc test (P=0.05).

Results:

Laser activated irrigation resulted in significantly higher depth of sealer penetration compared to sonic agitation and syringe irrigation (P<0.01). The average sealer penetration depths were recorded as 846.6 µm, 786.5 µm and 505 µm in the Er, Cr: YSGG laser, EndoActivator and control groups, respectively. The mean bond strength obtained in group 3 (syringe-and-needle irrigation) was significantly less than the other groups (P<0.05). The mean values were 9.08 in the Er, Cr: YSGG laser group, 8.44 in the EndoActivator group and 5.08 in the needle group.

Conclusion:

Er,Cr;YSGG laser irrigation to remove the medicaments was advantageous to other irrigation techniques in sealer penetration and dislocation resistance of the sealer.

Smear Layer Removal and Microhardness Alteration Potential of a Naturally Occurring Antioxidant - An In Vitro Study

Introduction: It is well-known in the field of endodontics that the presence of a smear layer in the root canals can harbor bacteria and limit the penetration of irrigating solutions and intracanal medications into the dentinal tubules which, in turn, causes the failure of endodontic treatment. Removing the entire smear layer throughout the root canal is essential for the success of endodontic treatment and these chemical agents that facilitate the removal of the smear layer are called chelating agents. Ethylenediaminetetraacetic acid (EDTA), being the most widely used chelating agent, brings about increased reduction in the microhardness of the root dentin, thereby making it friable.

N-acetyl cysteine (NAC) is naturally occurring antioxidant that has various beneficial properties for the human being. Several studies have been done in determining the antimicrobial efficacy of NAC against various endodontic pathogens and concluded NAC to be advantageous. The chelating property of NAC has been utilized in heavy metal detoxification, where it binds to the metal ion and removes them from the human system. However, this chelating property has not been explored in the field of endodontics.

Aim: This study was aimed to compare the ability of N-acetyl cysteine with the conventional chelating agent in the removal of the smear layer and in altering the microhardness of root dentin.

Materials and Methodology: A total of 84 single-rooted human mandibular premolars with relatively similar dimension and morphology, freshly extracted with closed apices, were collected from adult patients. The crowns of all specimens were cut transversally at the cementoenamel junction (CEJ) with the double-faced diamond disc at low speed, with water coolant, to obtain a 12 mm root length. The root canals were randomly divided into three equal groups according to the final irrigation solutions: Group I: 17% EDTA, Group II: 20% NAC, and Group III: distilled water (control). They were then randomly divided into two parts: scanning electron microscope (SEM) analysis for the extent of smear layer removal and microhardness evaluation using the Vicker’s hardness test.

Results: The smear layer removal ability of EDTA and NAC were more effective in the coronal and middle thirds of the root canal. However, both groups showed less smear layer removal in the apical region. Specimens treated with distilled water showed the least reduction in the smear layer throughout the length of the root canals. Regarding the evaluation of microhardness, both EDTA and NAC had a significant reduction in root dentin microhardness. However, the percentage of dentin microhardness reduction was significantly more in the EDTA group (p < 0.05) than N-acetyl cysteine in the coronal, middle, and apical third of the root canals.

Conclusion: The chelating property of NAC is equally effective to that of EDTA in the smear layer from the root canal, and it induced a significantly lesser reduction in microhardness of root dentin than EDTA.

A Comparative Evaluation of Intracanal Calcium Hydroxide Removal with Hand File, Rotary File, and Passive Ultrasonic Irrigation: An In Vitro Study

Aim

The aim of this study was to compare the effectiveness of hand file (K-file), rotary file (HERO shaper), and passive ultrasonic irrigation (PUI; U-file) in removing Ca(OH)₂ from the root canal.

Materials and Methods

Thirty single-rooted teeth were collected and decoronated to standardize the length to 14 mm. Cleaning and shaping were conducted using HERO shaper rotary files (up to no. 25, 4% taper). Ca(OH)₂ powder was mixed with normal saline and filled into the canals using lentulo spiral and the orifice was sealed with zinc oxide eugenol. After 7 days of incubation, samples were divided into three groups of 10 samples each: Group I (hand files)-no. 20 K-file; Group II (rotary files)-no. 25, 4% HERO shaper; Group III (PUI)-no. 20 U-file. Ca(OH)₂ paste was removed using 2 mL of 3% sodium hypochlorite solution followed by 1-minute activation of the respective file system. All the samples were finally irrigated with 17% ethylenediaminetetraacetic acid and flushed with distilled water.

Results

Ultrasonic group was more effective in removing Ca(OH)₂ followed by HERO shaper and hand file.

Conclusion

It was concluded that PUI had the highest ability to remove Ca(OH)₂ from the root canal walls.

Efficacy of chlorhexidine as a final irrigant in one-visit root canal treatment: a prospective comparative study

AIM

To evaluate postoperative pain and radiographic evidence of periapical healing in teeth with apical periodontitis treated in one visit with an additional final irrigation using 2% chlorhexidine (CHX) and to compare the results with conventional two-visit root canal treatment (RCT) with an intracanal calcium hydroxide (CH) dressing as a control group.

METHODOLOGY

Ninety asymptomatic maxillary anterior teeth with periapical lesions were treated by a single operator. Root canals were prepared using the step-back technique with manual instrumentation with 2.5% NaOCl and 5% EDTA as irrigants. Half of the teeth were randomly assigned to the one-visit (OV) group and received an additional final rinse with 2% CHX before canal filling. The other teeth were treated in two visits (TV) with a CH paste made by mixing CH powder and distilled water as an interappointment dressing. All patients were recalled and investigated clinically and radiographically for 24 months. Postoperative pain at 24-48 h and changes in apical bone density indicating radiographic healing were evaluated statistically using the Mann-Whitney U-test followed by the Friedman and the Wilcoxon tests (α = 0.05).

RESULTS

There were no significant differences between two groups regarding the incidence of postoperative pain at 24 h (OV group 50% no pain, 47.6% mild, 2.4% moderate pain/TV group 55% no pain, 42.5% mild, 2.5% moderate pain) and at 48 h (OV group 95% no pain, 5% mild pain/TV group 98% no pain, 2% mild pain). None of the patients reported severe postoperative pain, swelling and/or flare-ups during the follow-up period. There was no significant difference in the radiographic healing rates (OV group 97.6% PAI 1 and/or PAI 2 and 2.4% PAI 3/TV group 95% PAI 1 and/or PAI 2 and 5% PAI 3; P > 0.05).

CONCLUSION

Both groups provided favourable and similar postoperative pain and periapical healing rates at 24 months. Thus, one-visit RCT with a final rinse with 2% CHX is an acceptable alternative to two-visit RCT with CH as temporary dressing in maxillary anterior teeth.

Biological Activities and Potential Oral Applications of N-Acetylcysteine: Progress and Prospects

N-Acetylcysteine (NAC), a cysteine prodrug and glutathione (GSH) precursor, has been used for several decades in clinical therapeutic practices as a mucolytic agent and for the treatment of disorders associated with GSH deficiency. Other therapeutic activities of NAC include inhibition of inflammation/NF-κB signaling and expression of proinflammatory cytokines. N-Acetylcysteine is also a nonantibiotic compound possessing antimicrobial property and exerts anticarcinogenic and antimutagenic effects against certain types of cancer. Recently, studies describing potentially important biological and pharmacological activities of NAC have stimulated interests in using NAC-based therapeutics for oral health care. The present review focused on the biological activities of NAC and its potential oral applications. The potential side effects of NAC and formulations for drug delivery were also discussed, with the intent of advancing NAC-associated treatment modalities in oral medicine.

Efeito da medicação intracanal na resistência de união de um cimento obturador endodôntico à dentina radicular

Objetivo: Este estudo teve como objetivo avaliar a influência da medicação intracanal na resistência de união de um cimento obturador endodôntico à dentina radicular. Métodos: Foram utilizadas 24 raízes bovinas unirradiculares que foram submetidas ao preparo químico-cirúrgico e divididas aleatoriamente em 4 grupos da seguinte forma: G1, (controle), sem medicação; G2, Hidróxido de Cálcio (Ca(OH)2) + Clorexidina (CHX); G3, bolinha de algodão embebida em Formocresol; e, G4, bolinha de algodão embebida em Paramonoclorofenol Canforado. As amostras ficaram armazenadas em temperatura ambiente e 100% de umidade por 1 semana. Logo após, foram obturadas com cimento endodôntico AH Plus e cones de guta-percha. Os dentes foram então fatiados transversalmente e o teste de push-out foi realizado. Os dados foram tabulados e submetidos à Análise de Variância. Resultados: As médias e seus respectivos desvios-padrão foram: G1, 2,42 (±1,45) ; G2, 1,81 (±1,04); G3, 2,21 (±1,14); e, G4, 2.63 (±1.32). Os resultados mostraram que não houve diferença estatisticamente significante entre os grupos em estudo. Conclusão: Pode-se concluir que as medicações intracanal utilizadas neste estudo não influenciaram na resistência de união do cimento obturador AH Plus à dentina radicular.

Effects of different intra canal medicaments on the push out bond strength of endodontic sealers

BACKGROUND

One of the essential properties of the root canal sealers is the adhesion to root canal dentin and their higher bond strength decreases the microleakage. The aim of the present study was to compare the effect of Different Intracanal medicaments on the push out bond strength of AH26 and MTA Fillapex sealers.

MATERIAL AND METHODS

A total of 104 one-rooted extracted human teeth were divided into 4 (n=26) experimental groups. After the cleaning and shaping, the root canals were filled with Ca(OH)2, triantibiotic paste (TAP), Metapex or 2% chlorhexidine gel for two weeks. Then, intracanal medicaments were rinsed away and the samples in the sub-groups were obturated with gutta-percha and AH26 or MTA Fillapex sealers. After two weeks incubation, 2-mm-thick middle section of each root was then subjected to push-out testing. Data were analyzed with two-way ANOVA and LSD test.

RESULTS

With all the intracanal medicaments, the overall mean of bond strength values were significantly higher with AH26 compared to MTA Fillapex (p<0.05). With the use of MTA Fillapex the maximum and minimum means of bond strength values were recorded with CHX and Metapex and for AH26 were recorded with Ca(OH)2 and chlorhexidine, respectively.

CONCLUSIONS

The bond strengths of sealers to dentin are under the influence of pre-treatment with intracanal medicaments. Under the limitations of the present study, the effect of TAP on the bond strength of endodontic sealers was not negative. Key words:AH26, medicament, MTA Fillapex, push-out bond.

Comparison of different techniques for removal of calcium hydroxide from straight root canals: an in vitro study

To compare four different techniques for removal of calcium hydroxide from straight root canals. The present study used the design suggested by Lee et al. (Int Endod J 37:607-612, 32) and van der Sluis et al. (Int Endod J 40:52-57, 17). One-hundred and ten extracted human teeth with straight root canals were prepared to ISO-size 50 and split longitudinally. Two lateral grooves were prepared, filled with calcium hydroxide and the root halves reassembled in a muffle. Calcium hydroxide was removed using one of five techniques: (1) passive ultrasonic irrigation, (2) hydrodynamic irrigation using RinsEndo^®, (3) sonic irrigation using the EndoActivator^®, (4) motor-driven plastic brush (CanalBrush™), and (5) manual irrigation with a syringe as the control group. Distilled water was used as irrigant. Cleanliness of the grooves was scored under a microscope with 40× magnification. For intraindividual reproducibility and interrater agreement, Cohens Kappa was calculated. Results of scoring were analyzed using a non-parametric test. Post hoc pairwise comparisons were used for irrigation techniques (α = 0.05). Passive ultrasonic irrigation performed significantly better than all other groups in the apical groove. Significant differences were found between RinsEndo and CanalBrush (P = 0.01855) and CanalBrush and syringe irrigation (P = 0.00021). In the coronal groove, passive ultrasonic irrigation performed significantly superior and hand irrigation performed significantly worse than all other groups. A statistically significant interaction was shown between irrigation technique and localization of the groove (P = 0.01358). The coronal grooves showed more remaining calcium hydroxide than the apical grooves. Complete removal of calcium hydroxide from the root canal could not be achieved with any of the techniques investigated. The highest degree of cleanliness resulted from the use of passive ultrasonic irrigation.

Removal of calcium hydroxide from Weine Type II systems using photon-induced photoacoustic streaming, passive ultrasonic, and needle irrigation: a microcomputed tomography study

Objective

This study compared the effectiveness of Er:YAG laser-activated irrigation (PIPS), passive ultrasonic irrigation (PUI) with EndoUltra and standard needle irrigation (SNI) in the removal of calcium hydroxide [Ca(OH)2] from the mesial roots of Weine Type II mandibular molars.

Material and Methods

Thirty mandibular molars were screened by µCT for the presence of mesial roots with complex intra-canal anatomy and a common apical foramen. The teeth were enlarged to a standardized 25/.06 preparation and filled with Ca(OH)2 paste. Specimens were divided into three groups (n=10) according to the technique used for Ca(OH)2 removal: PIPS, at 15 Hz and 20 mJ using a 9 mm long, 600 µm diameter tip; PUI using a 15/.02 tip; and SNI (30 Ga. side-vented needle). Equal volumes of 8.25% NaOCl and 17% EDTA were used in all groups. µCT was used to measure the initial amount of Ca(OH)2 present and to assess the residual volume of Ca(OH)2 following each irrigation protocol. Data were analyzed using Tukey HSD and Kruskal-Wallis tests (α=5%).

Results

The mean volume of Ca(OH)2 before removal was significantly higher in the coronal third than in the middle and apical third (p<0.001). Ca(OH)2 was similarly removed from the coronal and middle thirds with the three methods used (p>0.05). PIPS (median 0%; IQR: 0-0) showed significant higher Ca(OH)2 removal in the apical third than PUI (median 100%, IQR: 85-100) and SNI (median 47%; IQR: 16-72) (p<0.001).

Conclusions

PIPS laser-activation was more effective for the removal of Ca(OH)2 from mesial roots of mandibular molars with Weine Type II canal configurations than PUI with EndoUltra and SNI.

Comparison of efficiency of ethylenediaminetetraacetic acid, citric acid, and etidronate in the removal of calcium hydroxide intracanal medicament using scanning electron microscopic analysis: An in-vitro study

Context:

Being integral to root canal therapy, obturation can be performed adequately only after the removal of intracanal medicament. One technique involves the use of chelating agents such as ethylenediaminetetraacetic acid (EDTA) and citric acid. Etidronic acid, a relatively new chelator, has smear layer removal ability and lesser dentinal erosion. It is untested in calcium hydroxide (Ca[OH]₂) medicament removal.

Aim:

The aim of this study was to compare the efficiency of irrigation protocols (EDTA, citric acid, and etidronate) in Ca(OH)₂ removal.

Materials and Methods:

Forty-five single-rooted mandibular premolars were decoronated, instrumented, and filled with Ca(OH)₂. After 7 days incubation, Ca(OH)₂ was removed by three irrigation protocols (Group-I: 17% EDTA; Group-II: 10% citric acid; and Group-III: 18% etidronate). Roots were split and analyzed (scanning electron microscope, ×1500). Chelator solution pH was tested. Data were analyzed by Kruskal–Wallis ANOVA and Mann–Whitney U-test.

Results:

Group-III (coronal-third) and Groups-I and II (middle-third) had highest cleanliness scores; Groups-II and III (apical-third) had lowest scores. Comparing the thirds, all groups showed difference in scores. pH of Groups-I, II, and III were 6.8, 1.4, and 0.3, respectively.

Conclusion:

The solution pH of citric acid and etidronate impacts their Ca(OH)₂ removal efficiency in different ways: the highly alkaline pH of Ca(OH)₂ increases citric acid pH toward neutrality, where it becomes an inefficient chelator; on the contrary, high acidity of etidronate compensates for its weaker chelation. Etidronate may not require 5 min duration for Ca(OH)₂ removal due to the likelihood of dentinal erosion.

Efficacy of XP-endo finisher files in the removal of calcium hydroxide paste from artificial standardized grooves in the apical third of oval root canals

AIM

To compare the efficacy of the XP-endo finisher file (XP) (FKG Dentaire, La Chaux de Fonds, Switzerland) to that of passive ultrasonic irrigation (PUI) and conventional syringe and needle irrigation (SNI) in the removal of calcium hydroxide paste from an artificial standardized groove in the apical third of root canals.

METHODOLOGY

The root canals of 68 mandibular incisors with single oval canals were prepared using Mtwo instruments (VDW GmbH, Munich, Germany) up to size 40, .04 taper. Each tooth was split longitudinally, and in one half of the root, a standardized groove was prepared in the apical part of the specimen. The grooves were filled with Ca(OH)₂ , and the root halves were reassembled. The roots were randomly divided into two control groups (n = 4) and three experimental groups (n = 20) according to the Ca(OH)₂ methods used: XP, PUI and SNI. The amount of remaining medicament was evaluated under X25 magnification using a 4-grade scoring system. Kappa values were calculated for intra- and interobserver agreement evaluation. The differences in the Ca(OH)₂ scores amongst the different groups were analysed using the Kruskal-Wallis test.

RESULTS

None of the tested methods could completely clean the Ca(OH)₂ from the artificial standardized groove in the apical third of the root canals. XP and PUI removed significantly more Ca(OH)₂ than SNI (P < 0.001), with no significant differences between them (P = 0.238).

CONCLUSIONS

XP and PUI were more effective in removing Ca(OH)₂ from artificial standardized grooves in the apical third of root canals than SNI.

Effect of double antibiotic and calcium hydroxide pastes on dislodgement resistance of an epoxy resin-based and two calcium silicate-based root canal sealers

OBJECTIVES

The purpose of the present study was to determine the dislodgement resistance of AH Plus, MTA Fillapex, and Total Fill BC sealer to root canal dentin walls following placement of calcium hydroxide (CH) or double antibiotic paste (DAP) medicaments.

MATERIALS AND METHODS

Root canals of 90 single-rooted human mandibular premolar teeth were instrumented with Reciproc rotary instruments to a size R50. The teeth were randomly divided into two experimental groups: those receiving an intracanal medicament with either CH or DAP and a control group (n = 30). After 3 weeks, the medicaments were removed by irrigation with 5 mL of 2.5 % NaOCl, 5 mL 17 % EDTA, and 5 mL distilled water under sonic agitation. Each group was then subdivided into three subgroups (n = 10), and the canals were filled with either AH Plus, MTA Fillapex, or Total Fill BC sealer. After 1 week, a push-out test was applied to the specimens and the results were analyzed using one-way analysis of variance (ANOVA) and post hoc Tamhane's tests.

RESULTS

Regardless of the type of intracanal medicament used, Total Fill BC Sealer and MTA Fillapex showed the highest and lowest bond strength, respectively (P < 0.05). The use or absence of medicaments did not significantly affect the dislodgment resistance of root canal fillings (P > 0.05). Prior CH placement improved dislodgement resistance of all sealers without statistical difference (P > 0.05). Adhesive failure between core and sealer was the most frequent failure mode.

CONCLUSIONS

Prior application of CH or DAP did not significantly affect the adhesion of the AH Plus, MTA Fillapex, and Total Fill BC Sealers.

CLINICAL RELEVANCE

There is a little information about the influence of antibiotic medicaments on the bond strength of root canal sealer. These findings suggest that the use of DAP does not affect the adhesion strength of AH Plus, MTA Fillapex, and Total Fill BC Sealers.

Effect of Calcium Hydroxide, Chlorhexidine Digluconate and Camphorated Monochlorophenol on the Sealing Ability of Biodentine Apical Plug

INTRODUCTION

Teeth with immature apex are managed by establishing an apical plug using various materials and techniques. However, the use of previously placed intracanal medicament may affect the sealing ability of permanent filling material used as an apical plug.

AIM

To evaluate the effect of removal of previously placed Calcium Hydroxide, Chlorhexidine Digluconate and Camphorated Monochlorophenol as an intracanal medicament on the sealing ability of the Biodentine as an apical plug.

MATERIALS AND METHODS

A total of 72 recently extracted human permanent teeth with single root were selected and stored in saline at room temperature. The crown portion of each tooth was removed at the level of cemento enamel junction; 14mm root length was taken as standard length. All the roots were submerged in 20% sulphuric acid up to 3 mm from the apex, for four days for root resorption. One sample was cut longitudinally to look for root resorption under stereo microscope. The canal preparation was done; the roots were kept in moist gauze after instrumentation. A total of 71 roots were randomly divided into three groups. GROUP 1:Calcium hydroxide paste, GROUP 2: Chlorhexidine digluconate, GROUP 3: Camphorated Monochlorophenol (CMCP). The medicaments were removed with stainless steel hand files and 0.5% sodium hypochlorite irrigation. After removal of medicament Biodentine was placed in apical third of resorbed roots and the remaining portion of the canals was filled with gutta-percha. All the 71 roots were analysed with fluid filtration method for evaluating microleakage.

RESULTS

Comparing all the three groups statistically there was no significant difference. The mean values were found more for group 1 followed by group 2 & 3.

CONCLUSION

All the groups showed microleakage. Calcium hydroxide showed the maximum microleakage followed by Chlorhexidine digluconate and least with CMCP.

Effect of calcium hydroxide on the bond strength of two bioactive cements and SEM evaluation of failure patterns

The aim of this study was to assess the effect of calcium hydroxide on bond strength of two bioactive cements. One-mm thick longitudinal slabs of root dentin were obtained from freshly extracted human monorradicular teeth (n = 60). Simulated root perforations (1 mm in diameter) were prepared in radicular dentin. Thereafter, the specimens were randomly divided into two groups (n = 30), according to the repair material: MTA (n = 30) and Biodentine (BD) (n = 30). Next, the specimens in each group were further randomly divided into 4 equal subgroups (n = 15) according to the prior use of Ca(OH)2: MTA/Ca(OH)2 and BD/Ca(OH)2 groups: perforations were filled with calcium hydroxide [Ca(OH)2] and after 7 days, it was removed, and MTA and BD groups: calcium hydroxide dressing were not used. Push-out test was performed at a crosshead speed of 1 mm/min. Bond strength values were compared statistically using Kruskal-Wallis test and Dunn's post-test at a significance level of 5%. The failure analysis was performed using a stereoscopic and classified as adhesive, cohesive and mixed. The push-out bond strength of MTA and BD was not affected by the prior use of Ca(OH)2 (p > 0.05). BD yielded higher push-out bond strength values compared with those of MTA, regardless of the use of Ca(OH)2 (p < 0.05). Mixed failures were predominant in all groups. Ca(OH)2 placement for perforations sealing does not alter the bond strength of MTA and BD to the root dentin. BD presented higher bond strength values than MTA. SCANNING 38:240-244, 2016. © 2015 Wiley Periodicals, Inc.

The effect of N-acetylcysteine and calcium hydroxide on TNF-α and TGF-β1 in lipopolysaccharide-activated macrophages

OBJECTIVE

The present study was designed to evaluate the pro- and anti-inflammatory effects of NAC and calcium hydroxide (Ca(OH)2) on lipopolysaccharide-stimulated human macrophage cell lines.

DESIGN

THP-1 human monocyte precursor cells were differentiated into macrophage adherent cells. Cell cytotoxicity was measured by flow cytometry analysis. NAC and Ca(OH)2 were applied in the presence or absence of lipopolysaccharides (LPS) for time periods of 4, 8, and 24h. Protein and mRNA levels of tumor necrosis factor-alpha (TNF-α) and transforming growth factor-beta1 (TGF-β1) were determined using ELISA and qRT-PCR. The data were statistically analyzed by three-way ANOVA followed by Bonferroni test at α=0.05.

RESULTS

In LPS-stimulated cell lines, while the TNF-α protein and mRNA levels were reduced in the first 4h, only the TGF-β1 mRNA levels increased in the 24th hour following treatment with Ca(OH)2 and NAC when compared with the control group (p<0.001). In LPS-unstimulated cells, the TNF-α protein level was significantly decreased by NAC and Ca(OH)2 at the 4th hour. Additionally, while the TGF-β1 mRNA levels were significantly reduced, the protein level of TGF-β1 was increased at the 24th hour.

CONCLUSIONS

It was concluded that NAC, similar to Ca(OH)2, has anti-inflammatory properties and might be considered an alternate candidate therapeutical agent to Ca(OH)2.

Effectiveness of four different techniques in removing intracanal medicament from the root canals: An in vitro study

Aim:

To evaluate the effectiveness of different techniques in removing calcium hydroxide (Ca(OH)₂) from the root canal.

Materials and Methods:

Twenty-four freshly extracted mandibular premolars were instrumented using ProTaper rotary instruments. The teeth were longitudinally split into two halves, cleaned of debris. The two halves were then reassembled and filled with Ca(OH)₂ and were divided into four groups. In Group I, the teeth were irrigated with 5 mL of 2.5% sodium hypochlorite (NaOCl) and 5 mL of 17% of ethylenediaminetetraacetic acid. In Group II, the teeth were irrigated with 5 mL of 2.5% NaOCl and a rotary ProTaper F3 instrument was used. In Group III, the teeth were irrigated with 5 mL of 2.5% NaOCl and agitated using an ultrasonic unit. In Group IV, the teeth were irrigated with 5 mL of 2.5% NaOCl and a CanalBrush was used to remove Ca(OH)₂. The roots were disassembled, and photographs were taken. The amount of residual Ca(OH)₂ was calculated using an image analysis software as a percentage of the total canal surface area. The data were analyzed using one-way analysis of variance and post-hoc Tukey test.

Results:

CanalBrush and ultrasonic techniques showed significantly less residual Ca(OH)₂ than irrigants and rotary techniques. There was no significant difference between the rotary and irrigant techniques.

Conclusion:

None of the techniques used were completely able to remove Ca(OH)₂ from the root canals. But the CanalBrush and ultrasonic techniques were significantly better than the rotary instrument and irrigant groups.

Efficacy of Needle, Ultrasonic, and Endoactivator Irrigation and Photon-Induced Photoacoustic Streaming in Removing Calcium Hydroxide from the Main Canal and Isthmus: An In Vitro Micro-Computed Tomography and Scanning Electron Microscopy Study

OBJECTIVE

The aim of this in vitro study was to use high-resolution micro-computed tomography (micro-CT) and scanning electron microscopy (SEM) to compare the efficacy of four irrigation techniques [needle, ultrasonic, EndoActivator, and photon-induced photoacoustic streaming (PIPS)] in removing calcium hydroxide (Ca[OH]2) from the root canal and isthmus of maxillary premolars.

METHODS

Twenty-four maxillary first premolars were selected based on the presence of isthmus regions on micro-CT scans. Root canals were instrumented with an F2 file using ProTaper rotary instruments and filled with Ca(OH)2 paste. Samples were stored at 37°C and 100% humidity for 1 week and randomly divided into four groups (n=6 each), according to irrigation technique. Samples were scanned with micro-CT before instrumentation, after Ca(OH)2 filling, and after irrigation. Ca(OH)2 reduction in the coronal, middle, and apical thirds and in the isthmus were assessed with three-dimensional image analysis. Next, specimens were split longitudinally, and canal walls were examined with SEM for Ca(OH)2 residues. Data were statistically evaluated with the Kruskal-Wallis and Mann-Whitney tests (p=0.05).

RESULTS

The PIPS and ultrasonic groups showed greater Ca(OH)2 reduction in the apical third and higher cleanliness of the isthmus than the EndoActivator and needle irrigation groups (p<0.05). Ca(OH)2 residue scores in the PIPS and ultrasonic groups were significantly lower than those in the EndoActivator and needle groups in all regions of the root canals (p<0.05). There was no significant difference between PIPS and ultrasonic groups (p>0.05), or between EndoActivator and needle groups (p>0.05).

CONCLUSIONS

PIPS and ultrasonic irrigation more effectively removed Ca(OH)2 from the main canal and isthmus in maxillary premolars than did EndoActivator or needle irrigation.

Calcium hydroxide removal in curved root canals with apical transportation In Vitro

Calcium hydroxide (CH) is applied to improve disinfection of root canals in most root canal retreatment. This study aimed to analyze the CH removal efficacy using 7 different root preparing files (K file, pre-curved K file, EndoActivator, Ultrasonic file, pre-curved ultrasonic file, F file and needle irrigation alone) with apical transportation. Standardized models of curved canal with such apical transportation or not were set up before applying CH to root canal for 7 days. Seven techniques described above were used for its removal. Then the roots were disassembled and digital photos were taken. The ratio of residual CH in the overall canal surface was calculated using the image analyzer image pro plus 6.0. The data were analyzed using one-way ANOVA with post hoc Tukey test. Results revealed that CH was effectively removed (P<0.05) by using all 6 mechanical methods except irrigation alone. In curved root canals with apical transportation, EndoActivator, pre-curved ultrasonic file and F file were found to be more effective in removing CH than the other four file (P<0.001), while there was no significant difference among EndoActivator, pre-curved ultrasonic file and F file groups (P>0.05). The percentage of residual CH in the canal with apical transportation was higher than that in the canal without apical transportation (P<0.05). In conclusion, CH can be hardly removed completely. Canal with apical transportation will result in insufficient CH removal. EndoActivator, pre-curved ultrasonic file and F file are more effective in the curved root canal with apical transportation.

Effect of rotary instrument associated with different irrigation techniques on removing calcium hydroxide dressing

Calcium hydroxide [Ca(OH)2 ] residues in root canals may compromise sealing of filling and endodontic treatment success. The aim of this study was to compare the efficacy of using rotary instrument associated with EndoActivator, EndoVac, passive ultrasonic irrigation (PUI), and conventional needle irrigation (CNI), in Ca(OH)2 removal from root canal, by means of scanning electron microscopy (SEM) images. Sixty-six human canines were prepared with the Protaper system up to F5 and filled with Ca(OH)2 . After 7 days, Ca(OH)2 was removed with rotary instrument F5 associated with the irrigation techniques used in each group (n = 15): GI (CNI), GII (EndoVac), GIII (EndoActivator) and GIV (PUI). In all groups 15 mL of 2.5% NaOCl and 3 mL of 17% EDTA were used for Ca(OH)2 removal. The Ca(OH)2 residues was evaluated by SEM in the middle and apical third using a system of scores. The results were analyzed by the Kruskal-Wallis and Dunn tests (α = 0.05). None of the techniques completely removed the Ca(OH)2 from root canals. There was no difference between EndoActivator, EndoVac and PUI (P > 0.05), but the three techniques removed more Ca(OH)2 than the CNI (P < 0,05), in the middle and apical thirds of the root canal. It was concluded that the rotary instrument combined with EndoActivator, EndoVac, and PUI was shown to be more efficient than the rotary instrument combined with the CNI in removing Ca(OH)2 from the root canal.

Push-out bond strength of self-adhesive methacrylate resin-based sealers to root dentin

This study examined the adhesive strength of two self-adhesive methacrylate resin-based sealers (MetaSEAL and RealSeal SE) to root dentin and compared them with RealSeal and AH Plus in properties. A total of 48 extracted human single-rooted teeth were used to prepare the 0.9-mm thick longitudinal tooth slice (each per tooth). Standardized simulated canal spaces of uniform dimensions were prepared in the middle of radicular dentin. After treated with 5.25% sodium hypochlorite (NaOCl) and 17% EDTA, tooth slices were allocated randomly to four groups (n=12) in terms of different sealers used: MetaSEAL, RealSeal SE, RealSeal, and AH plus groups. The simulated canal spaces were obturated with different sealers in each group. There were 10 slabs with 20 simulated canal spaces (n=20) used in each group for push-out testing. The failure modes and the ultrastructures of fractured sealer-dentin interfaces were examined. The remaining 2 slabs in each group underwent partial demineralization for observation of the ultrastructure of resin tags. The results showed that the push-out bond strength was 12.01±4.66 MPa in MetaSEAL group, significantly higher than that in the other three groups (P<0.05). Moreover, no statistically significant differences were noted in the push-out bond strength between RealSeal SE (5.43±3.68 MPa) and AH Plus (7.34±2.83 MPa) groups and between RealSeal SE and RealSeal (2.93±1.76 MPa) groups (P>0.05). Mixed failures were predominant in the fractured sealer-dentin interfaces in MetaSEAL and AH Plus groups, while adhesive failures were frequently seen in RealSeal SE and RealSeal groups. In conclusion, after complete removal of the smear layer, MetaSEAL showed superior bond ability to root dentin. The RealSeal SE is applicable in clinical practice, with its adhesive strength similar to that of AH Plus. The self-adhesive methacrylate resin-based sealer holds promise for use in endodontic treatment.

Eficácia da irrigação ultrassônica passiva na remoção de hidróxido de cálcio

INTRODUÇÃO: Remanescentes de Hidróxido de Cálcio [Ca(OH)2] podem interferir na qualidade da obturação endodôntica. OBJETIVO : Avaliar a eficácia da Irrigação Ultrassônica Passiva (IUP) associada à técnica convencional na remoção de medicação intracanal à base de Ca(OH)2. METODOLOGIA: Trinta dentes humanos anteriores monorradiculares foram usados. Os canais radiculares foram preparados com instrumentos manuais tipo K e preenchidos com medicação intracanal à base de Ca(OH)2, contendo PMCC e propilenoglicol. Após sete dias, a pasta de Ca(OH)2 foi removida de todos os canais radiculares com um instrumento manual e irrigação de NaOCl 1% com seringa. Os espécimes foram randomizados em dois grupos (n=12) de acordo com a irrigação final: Irrigação Manual - agitação manual de EDTA 17 % e irrigação de NaOCl 1%; IUP - agitação ultrassônica de NaOCl 1% (três ativações de 20s) seguida da ativação de EDTA 17% por 1 min. O Grupo Controle (n=6) não recebeu medicação intracanal. Todos os espécimes foram clivados e a quantidade de Ca(OH)2 remanescente foi calculada com o auxílio do estereomicroscrópio (20×). Os testes Kruskall-Wallis e Wilcoxon foram utilizados para avaliar a porcentagem de Ca(OH)2 remanescente. RESULTADO: O grupo da IUP apresentou, estatisticamente, as menores porcentagens de Ca(OH)2 remanescente, quando comparado ao grupo da Irrigação Manual, independentemente dos terços analisados (P < 0,05). O terço apical apresentou a maior quantidade de medicação residual, em ambos os grupos (P < 0,05). CONCLUSÃO : A associação da IUP com a técnica convencional demonstrou ser mais eficiente na remoção de medicação intracanal à base de Ca(OH)2 do que a combinação da Irrigação Manual com a técnica convencional.

Comparison of calcium hydroxide removal by self-adjusting file, EndoVac, and CanalBrush agitation techniques: An in vitro study

Objectives:

This study comparatively evaluated the efficacy of self-adjusting file (SAF), Endovac, and CanalBrush irrigant agitation protocols in removing calcium hydroxide (Ca(OH)₂) from the root canals.

Materials and Methods:

Sixty extracted human mandibular canine teeth were instrumented with ProTaper rotary instruments to size #40 and dressed with Ca(OH)₂. The roots were randomly assigned to four groups according to irrigant agitation protocol used (n = 15). In Group 1: Conventional syringe irrigation (no activation, control); Group 2: Rotary brush agitation (CanalBrush); Group 3: Apical negative pressure irrigation (EndoVac system); and Group 4: Sonic agitation (SAF) were used. Scanning electron microscopic (SEM) evaluation was done for assessment of Ca(OH)₂ removal in the coronal and apical thirds. Statistical analysis was performed by Wilcoxon and Kruskal-Wallis tests.

Results:

There were statistically significant differences among the groups (P = 0.218). A statistically significant difference was seen between the test groups in Ca(OH)₂ removal from the apical third of the canal (P < 0.05). In the coronal third, there was no difference between the groups (P > 0.05). The most efficient Ca(OH)₂ removal in apical third was recorded in Group 3 (EndoVac) and Group 4 (SAF) (P < 0.05). In Group 4 (sonic agitation), there was no significantly difference between Ca(OH)₂ removal in coronal and apical thirds.

Conclusions:

SAF and EndoVac showed significantly better performance than CanalBrush and conventional syringe irrigation in removing Ca(OH)₂ from apical third of the root canals.

The effects of calcium hydroxide removal methods on bond strength of Epiphany SE with two irrigation protocols

OBJECTIVE

The purpose of this study was to compare the effects of five calcium hydroxide removal methods on the bond strength of Epiphany SE sealer after canal irrigation with NaOCl+EDTA or NaOCl+MTAD.

MATERIALS AND METHODS

The 120 roots were instrumented by using the ProTaper rotary system under irrigation with 2.5% sodium hypochlorite and randomly divided into two major groups according to the final irrigation: 1.3% NaOCl + MTAD and 5% NaOCl + 17% EDTA. For controls, 10 roots from each of the final irrigations with NaOCl + MTAD and NaOCl + EDTA (20 roots) were not filled with Ca(OH)2. The intra-canal paste, Ca(OH)2 was applied to each of the 100 remaining roots and stored at 37°C for 7 days. Each group was sub-divided into five sub-groups (n = 10) according to the removal technique for the intra-canal dressing: Group-1: recapitulation with size 30 K file + 3 ml of saline solution, Group-2: recapitulation with size 30 K file + 3 ml of 5% NaOCl, Group-3: using 5% NaOCl + 17% EDTA, Group-4: using 5%NaOCl + 15% citric acid, and Group-5: using 1.3% NaOCl + 5 ml MTAD. The root canals were filled with Resilon and Epiphany SE sealer. The bond strength was measured.

RESULTS

The mean bond strength of Epiphany SE to root dentine irrigated with NaOCl + MTAD was lower than that of NaOCl + EDTA. The highest bond strengths were 3.31 ± 0.057 and 2.60 ± 0.054 in the NaOCl + citric acid group when Ca(OH)2 was applied to roots treated with NaOCl + EDTA and NaOCl + MTAD, respectively (p < 0.05).

CONCLUSION

For root canals treated with NaOCl + EDTA or NaOCl + MTAD, the use of NaOCl + chelating agent for Ca(OH)2 removal does not adversely affect the bond strength of Epiphany SE to dentin.

Effect of endodontic irrigation and dressing procedures on the shear bond strength of composite to coronal dentin

This study aimed to evaluate the effects of three sodium hypochlorite (NaOCl)-endodontic irrigation procedures used alone or in combinations with two intermediate dressing materials on bond strengths of two adhesive composite systems to coronal dentin. Surfaces were treated with NaOCl or NaOCl–Glyde-File-Prep (H₂O₂ and EDTA) with or without chlorhexidine (CHX) as a final rinse. Intermediate dressing materials of calcium hydroxide (Ca(OH)₂) and sodium perborate (SP) were combined with surface treatments. Surface treatment groups (n = 10/group) included (1) distilled water (control), (2) 5.25% NaOCl (30 min), (3) NaOCl/Glyde (30 min), (4) NaOCl/Glyde (30 min) + CHX (2 min), (5) NaOCl/Glyde (30 min) + Ca(OH)₂ (5 days) + CHX (2 min), and (6) NaOCl/Glyde (30 min) + SP (9 days) + CHX (2 min). For each surface treatment group, dentin shear bond strengths of two different composite systems (Excite/Tetric Flow Chroma, [EX/TFC], and Clearfil Protect Bond/Protect Liner F [PB/PLF]) were evaluated. Median shear bond strengths (EX/TFC, PB/PLF) for each surface treatment group in MPa were (1) 21, 18; (2) 26, 18; (3) 21, 17; (4) 22, 16; (5) 17, 11; and (6) 14, 11, respectively. NaOCl significantly increased the bond strength of EX/TFC (p < 0.05), but did not significantly affect that of PB/PLF. The use of NaOCl/Glyde with CHX did not significantly affect EX/TFC (p > 0.05), whereas it significantly decreased PB/PLF (p < 0.05). Ca(OH)₂ and SP significantly decreased the bond strengths of both adhesive systems (p < 0.05). Adhesion to coronal dentin is dependent upon the irrigation regimen and the type of adhesive.

Effect of the smear layer in the removal of calcium hydroxide from root canal walls

Background:

The aim of this study was to investigate whether the smear layer influences the removal of calcium hydroxide from the root canal with manual or rotary instruments.

Materials and Methods:

The root canals of 48 freshly extracted single-rooted maxillary incisors were prepared to apical size 40 (n=40) and finally irrigated with sodium hypochlorite (group A), or ethylene diamine tetra acetic acid (EDTA) followed by sodium hypo chlorite (group B). 20 teeth were assigned to each group, while the remaining eight teeth served as positive and negative controls. Each group was divided into two subgroups of 10 teeth (subgroup I - calcium hydroxide was removed with master apical file; subgroup II - with profile file); and, in all removal procedures, citric acid was used for irrigation. The percentage of calcium hydroxide- [Ca(OH)₂] coated surface area was calculated by image processing analysis.

Results:

Considering the root canal as a whole, the removal of Ca(OH)₂ from the dentinal walls in group B showed significantly better results (P<0.05) as compared to group A.

Conclusions:

Under the conditions of this study, it can be concluded that the smear layer is important in the removal of calcium hydroxide.

Efficacy of NiTi rotary instruments in removing calcium hydroxide dressing residues from root canal walls

THE AIM OF THIS STUDY

was to evaluate the efficacy of three rotary instrument systems (K3, ProTaper and Twisted File) in removing calcium hydroxide residues from root canal walls. Thirty-four human mandibular incisors were instrumented with the ProTaper System up to the F2 instrument, irrigated with 2.5% NaOCl followed by 17% EDTA, and filled with a calcium hydroxide intracanal dressing. After 7 days, the calcium hydroxide dressing was removed using the following rotary instruments: G1 - NiTi size 25, 0.06 taper, of the K3 System; G2 - NiTi F2, of the ProTaper System; or G3 - NiTi size 25, 0.06 taper, of the Twisted File System. The teeth were longitudinally grooved on the buccal and lingual root surfaces, split along their long axis, and their apical and cervical canal thirds were evaluated by SEM (×1000). The images were scored and the data were statistically analyzed using the Kruskall Wallis test. None of the instruments removed the calcium hydroxide dressing completely, either in the apical or cervical thirds, and no significant differences were observed among the rotary instruments tested (p > 0.05).

Bond strength of different endodontic sealers to dentin: push-out test

Objective

The aim of this in vitro study was to evaluate the bond strength of different root canal sealers to dentin.

Material and Methods

Forty extracted single-rooted human teeth were examined and the coronal and middle thirds of the canals were prepared with a 1.50 mm post drill (FibreKor Post System, Pentron). The teeth were allocated in two experimental groups, irrigated with 2.5% NaOCl+17% EDTA or saline solution (control group) and instrumented using Race rotary files (FKG) to a size #40 at the working length. Then, the groups were divided into four subgroups and filled with Epiphany sealer (Group 1), EndoREZ (Group 2), AH26 (Group 3) and Grossman's Sealer (Group 4). After 2 weeks of storage in 100% humidity at 37ºC, all teeth were sectioned transversally into 2-mm-thick discs. Push-out tests were performed at a cross-head speed of 1 mm/min using a universal testing machine. The maximum load at failure was recorded and expressed in MPa.

Results

Means (±SD) in root canals irrigated with 2.5% NaOCl and 17% EDTA were: G1 (21.6±6.0), G2 (15.2±3.7), G3 (14.6±4.5) and G4 (11.7±4.1).Two-way ANOVA and Tukey's test showed the highest bond strength for the Epiphany's group (p< 0.01) when compared to the other tested sealers. Saline solution decreased the values of bond-strength (p<0.05) for all sealers.

Conclusion

Epiphany sealer presented higher bond strength values to dentin in both irrigating protocols, and the use of 2.5% NaOCl and 17% EDTA increased the bond strength values for all sealers.