Effect of Different Final Irrigation Methods on the Removal of Calcium Hydroxide from an Artificial Standardized Groove in the Apical Third of Root Canals

Introduction

The aim of this study was to compare the efficacy of conventional syringe, ultrasonic, EndoVac (Discus Dental, Culver City, CA), and Self-Adjusting File (SAF) (Re-Dent-Nova, Ra'nana, Israel) irrigation systems in removing calcium hydroxide (Ca[OH]₂) from simulated root canal irregularities.

Methods

The root canals of 88 extracted single-rooted teeth were prepared using ProTaper rotary instruments (Dentsply Maillefer, Ballagiues, Switzerland) up to size F4. The roots were split longitudinally, and a standardized groove was prepared in the apical part of 1 segment. The root halves were reassembled, and Ca(OH)₂ medicament was placed into the root canals using a Lentulo spiral. The roots were randomly divided into 4 experimental groups and 2 control groups according to the different irrigation systems used: conventional syringe irrigation, continuous passive ultrasonic irrigation (PUI), EndoVac irrigation, and SAF irrigation. Each group was then divided into 2 subgroups (n = 10) according to the irrigation protocol: subgroup 1: 10 mL 2.5% NaOCl and subgroup 2: 10 mL 17% EDTA + 10 mL 2.5% NaOCl. The amount of remaining medicament was evaluated under a stereomicroscope at 30× magnification using a 4-grade scoring system. The influences of the different Ca(OH)₂ medicament removal methods and irrigation protocols were statistically evaluated using 2-way analysis of variance and Tukey post hoc tests.

Results

In the NaOCl-irrigated groups, PUI removed significantly more Ca(OH)₂ medicament than the other techniques (P < .05). There was no significant difference among the other groups (P > .05). In the EDTA/NaOCl-irrigated groups, the SAF and PUI removed significantly more Ca(OH)₂ than the other techniques (P < .05).

Conclusions

The use of the SAF system with the combination of EDTA and NaOCl enhanced Ca(OH)₂ removal when compared with the use of only NaOCl irrigation with the SAF. Continuous PUI and SAF were more effective than EndoVac, and conventional syringe irrigation in the removal of the Ca(OH)₂ medicament from an artificial standardized groove in the apical part of the root canal.     

The efficacy of the self-adjusting file and ProTaper for removal of calcium hydroxide from root canals

Objective

The goal of this study was to evaluate the efficacy of the Self-Adjusting File (SAF) and ProTaper for removing calcium hydroxide [Ca(OH)₂] from root canals.

Material and Methods

Thirty-six human mandibular incisors were instrumented with the ProTaper system up to instrument F2 and filled with a Ca(OH)₂-based dressing. After 7 days, specimens were distributed in two groups (n=15) according to the method of Ca(OH)₂ removal. Group I (SAF) was irrigated with 5 mL of NaOCl and SAF was used for 30 seconds under constant irrigation with 5 mL of NaOCl using the Vatea irrigation device, followed by irrigation with 3 mL of EDTA and 5 mL of NaOCl. Group II (ProTaper) was irrigated with 5 mL of NaOCl, the F2 instrument was used for 30 seconds, followed by irrigation with 5 mL of NaOCl, 3 mL of EDTA, and 5 mL of NaOCl. In 3 teeth Ca(OH)₂ was not removed (positive control) and in 3 teeth canals were not filled with Ca(OH)₂ (negative control). Teeth were sectioned and prepared for the scanning electron microscopy. The amounts of residual Ca(OH)₂ were evaluated in the middle and apical thirds using a 5-score system.

Results

None of the techniques completely removed the Ca(OH)₂ dressing. No difference was observed between SAF and ProTaper in removing Ca(OH)₂ in the middle (P=0.11) and the apical (P=0.23) thirds.

Conclusion

The SAF system showed similar efficacy to rotary instrument for removal of Ca(OH)₂ from mandibular incisor root canals.     

HISTOMICROBIOLOGIC ASPECTS OF THE ROOT CANAL SYSTEM AND PERIAPICAL LESIONS IN DOGS' TEETH AFTER ROTARY INSTRUMENTATION AND INTRACANAL DRESSING WITH Ca(OH)2 PASTES

OBJECTIVE:

The purpose of this study was to evaluate the distribution of microorganisms in the root canal system (RCS) and periapical lesions of dogs'' teeth after rotary instrumentation and placement of different calcium hydroxide [Ca(OHy-based intracanal dressings.

MATERIALS AND METHODS:

Chronic periapical lesions were experimentally induced in 80 premolar roots of four dogs. Instrumentation was undertaken using the ProFile rotary system and irrigation with 5.25% sodium hypochlorite. The following Ca(OH)₂-based pastes were applied for 21 days: group 1 - Calen (n=18); group 2 - Calen+CPMC (n=20); group 3 - Ca(OH₂ p.a. + anaesthetic solution (n=16) and group 4 - Ca(OH₂ p.a.+ 2% chlorhexidine digluconate (n=18). Eight root canals without endodontic treatment constituted the control group. Histological sections were obtained and stained with Brown & Brenn staining technique to evaluate the presence of microorganisms in the main root canal, ramifications of the apical delta and secondary canals, apical cementoplasts, dentinal tubules, areas of cemental resorption and periapical lesions. The results were analyzed statistically by the Mann-Whitney U test (p<0.05).

RESULTS:

The control group showed the highest prevalence of microorganisms in all sites evaluated. Gram-positive cocci, bacilli and filaments were the most frequent morphotypes. Similar microbial distribution patterns in the RCS and areas of cementum resorption were observed in all groups (p>0.05). The percentage of RCS sites containing microorganisms in groups 1, 2, 3, 4 and control were: 67.6%, 62.5%, 78.2%, 62.0% and 87.6%, respectively.

CONCLUSION:

In conclusion, the histomicrobiological analysis showed that the rotary instrumentation and the different calcium hydroxide pastes employed did not effectively eliminate the infection from the RCS and periapical lesions. However, several bacteria seen in the histological sections were probably dead or were inactivated by the biomechanical preparation and calcium hydroxide-based intracanal dressing.     

INFLUENCE OF CALCIUM HYDROXIDE POINTS ON THE QUALITY OF INTRACANAL DRESSING FILLING

Purpose

The aim of this study was to evaluate, in vitro, the quality of calcium hydroxide [Ca(OH)₂] paste filling (Ultracal, Ultradent) associated or not with Ca(OH)₂-containing gutta-percha points (Calcium Hydroxide Plus Points™, Roeko) in curved root canals.

Material and Methods

One hundred and twenty roots of extracted human teeth, randomly divided into three curvature ranges (mild - 0 to 14°; moderate - 15° to 29°; severe - >30°) were used. After chemomechanical preparation, the roots were assigned to 4 groups (n=30), according to the technique of intracanal dressing placement: group 1 - Ca(OH)₂ paste was applied with a lentulo spiral; group 2 - Ca(OH)₂ paste was applied with a lentulo spiral and a Ca(OH)₂ point was inserted into the canal; group 3 - Ca(OH)₂ paste was applied with a Navitip™ tip (supplied with Ultracal system); group 4 - Ca(OH)₂ paste was applied with a Navitip™ tip and a Ca(OH)₂ point was inserted into the canal. The roots were cleared and the quality of apical third filling was assessed by a calibrated experienced examiner. The specimens were examined under stereomicroscopy and scored 1 to 4 (i.e., from inadequate to complete root canal filling). The results were analyzed statistically by ANOVA and Duncan''s post hoc test at 5% significance level.

Results

There were no statistically significant differences (p>0.05) among the curvature degrees in groups 1, 3 and 4. Severely curved roots in group 2 presented bordering significance (p=0.05). The groups that associated the use of Ca(OH)₂ paste and points (2 and 4) showed better apical filling than the other groups, but this difference was statistically significant (p<0.001) only for roots with severe curvature.

Conclusion

According to the results of this study, the curvature degree did not influence the quality of filling. The techniques that used Ca(OH)₂-containing gutta-percha points yielded better filling of the apical third in roots with severe curvature.     

The efficacy of three passive ultrasonic irrigation systems on intracanal medicament removal in a novel standardised three-dimensionally printed model

This study compared the efficacy of several passive ultrasonic irrigation (PUI) systems in removing intracanal medicament using 3-dimensionally printed root canal model assembled with dentin specimen. After the placement of the model in the agar container (37°C), the intracanal medicament was removed using three different PUI instruments including CK file, Irrisafe and Endosonic Blue. Then, the area coated by the medicament and the volumetric percentage of the remaining medicament was measured. Irrisafe and Endosonic Blue showed higher removal efficacy than CK and the control regarding both the coated area and remaining volume (p < 0.05). CK showed the lowest efficacy among the tested PUI systems (p > 0.05). Notably, Endosonic Blue group showed the smallest coated area among the tested groups (p < 0.05). Conclusively, PUI systems made of nickel-titanium alloy with small dimensions, such as Endosonic Blue, have advantages for the removal of intracanal medicaments from curved root canals.     

Incidence of postoperative pain after use of calcium hydroxide mixed with normal saline or 0.2% chlorhexidine digluconate as intracanal medicament in the treatment of apical periodontitis

Objective

To compare the incidence of postoperative pain after the use of calcium hydroxide powder mixed with normal saline or 0.2% chlorhexidine digluconate as intracanal medicament.

Participants

Fifty-five subjects aged 17–60 years with teeth diagnosed to have apical periodontitis.

Intervention

Two-visit conventional root canal treatment of seventy teeth. The teeth were divided by randomization (balloting) into two groups: control group and experimental group, each with thirty-five teeth treated with calcium hydroxide mixed with normal saline or with 0.2% chlorhexidine digluconate as intracanal medicament respectively. Incidence of postoperative pain was assessed using the universal pain assessment tool and whether or not analgesic was taken.

Main outcome measured

Incidence of post-operative pain.

Result

Postoperative pain occurred only at 1-day and 1-week reviews. In the control group, the overall incidence of pain was the same at both review periods (5.7%), while the experimental group showed a slight decrease in incidence between 1-day (17.2%) and 1-week (11.4%) reviews. Incidence of flare-ups was more in the experimental group (11.4%) than in the control group (5.7%). No significant statistical differences between the two groups were observed (p > 0.05).

Conclusion

The incidence of postoperative pain was lower in the normal saline treatment group, but the difference was not statistically significant.     

Monitoring the effectiveness of root canal procedures on endotoxin levels found in teeth with chronic apical periodontitis

Objective:

The aim of this study was to monitor the effectiveness of root canal procedures by using different irrigants and intracanal medication on endotoxin levels found in root canals of teeth with chronic apical periodontitis.

Material and Methods:

Thirty root canals of teeth with pulpal necrosis associated with periapical lesions were selected and randomly divided into groups according to the irrigants used: GI - 2.5% NaOCl, GII - 2% chlorhexidine (CHX) gel, and GIII - saline solution (SS) (all, n=10). Samples were collected with sterile/apyrogenic paper points before (S1) and after root canal instrumentation (S2), after use of 17% ethylenediaminetetraacetic acid (EDTA) (S3), and after 30 days of intracanal medication (Ca(OH)₂+SS) (S4). A turbidimetric kinetic Limulus Amebocyte Lysate assay was used for endotoxin measurement.

Results:

Endotoxins were detected in 100% of the root canals investigated (30/30), with a median value of 18.70 EU/mL. After S2, significant median percentage reduction was observed in all groups, irrespective of the irrigant tested: 2.5% NaOCl (99.65%) (GI), 2% CHX (94.27%) (GII), and SS (96.79%) (GIII) (all p<0.05). Root canal rinse with 17% EDTA (S3) for a 3-minute period failed to decrease endotoxin levels in GI and a slight decrease was observed in GII (59%) and GIII (61.1%) (all p>0.05). Intracanal medication for 30 days was able to significantly reduce residual endotoxins: 2.5% NaOCl (90%) (GI), 2% CHX (88.8%) (GII), and SS (85.7%) (GIII, p<0.05). No differences were found in the endotoxin reduction when comparing s2 and s4 treatment groups.

Conclusion:

Our findings demonstrated the effectiveness of the mechanical action of the instruments along with the flow and backflow of irrigant enduring root canal instrumentation for the endotoxin removal from root canals of teeth with chronic apical periodontitis. Moreover, the use of intracanal medication for 30 days contributed for an improvement of endotoxin reduction.     

Efficacy of self‐adjusting file,XP‐endo finisher and passive ultrasonic irrigation on the removal of calcium hydroxide paste from an artificial standardized groove

The purpose of this study was to compare the effectiveness of self‐adjusting file (SAF), XP‐endo finisher (XP), passive ultrasonic irrigation (PUI) and conventional syringe and needle irrigation (SNI) in the removal of Ca(OH)₂ from an artificial groove. Eighty mandibular incisors with single oval canals were prepared to size 40/0.04 and split longitudinally. A standardised groove was prepared in the apical third and filled with Ca(OH)₂. The root halves were reassembled and divided into two control groups (n = 4) and four experimental groups (n = 18) according to the removal methods used. The amount of residual Ca(OH)₂ was evaluated using a four‐grade scoring system. The differences among the groups were analysed using the Kruskal–Wallis test (P < 0.05). SAF, XP and PUI removed significantly more Ca(OH)₂ than SNI (P < 0.001), although there were no significant differences among them (P = 0.209). None of the tested methods could completely clean Ca(OH)₂ from the groove.     

Efficacy of sonic and ultrasonic activation for removal of calcium hydroxide from mesial canals of mandibular molars: a microtomographic study

Background

The purpose of this study was to use micro-computed tomography (micro-CT) scanning to evaluate the efficacy of sonic and passive ultrasonic irrigation (PUI) on calcium hydroxide (Ca[OH]₂) removal and to measure the volume and percentage of Ca(OH)₂ remaining in the root canal system.

Methodology

The root canals of 46 extracted human mandibular molar teeth were prepared with rotary instruments and randomly assigned to two experimental groups (n = 40) as well as positive and negative controls (n = 6). In each experimental group, 20 teeth were assigned to each irrigation protocol, sonic or passive ultrasonic irrigation. All experimental teeth and the positive controls were filled with Ca(OH)₂, whereas the negative control teeth did not receive Ca(OH)₂. All teeth were scanned using micro-CT scanning to determine the dressing volume. After 7 days, the Ca(OH)₂ was removed in the experimental groups using rotary instrumentation only, and the teeth were again scanned using micro-CT scanning to calculate volume and percentage of Ca(OH)₂ removed. Positive control teeth were not subjected to rotary instrumentation. Experimental samples were then irrigated using either sonic or passive ultrasonic and the volume of remaining Ca(OH)₂ was calculated using micro-CT.

Results

Remnants of Ca(OH)₂ were found in all experimental groups. No Ca(OH)₂ was found in the negative controls, whereas a mean of 8.7 mm³ of Ca(OH)₂ was recorded in the positive controls. Rotary plus passive ultrasonic irrigation removed significantly more Ca(OH)₂ (85.7%) than rotary plus sonic irrigation (71.5%) (p < 0.001).

Conclusions

The combination of rotary instrumentation and passive ultrasonic activation for 3 periods of 20 seconds results in significantly lower amounts of Ca(OH)₂ remnants in the canal compared with sonic irrigation.     

Removal efficacy of various calcium hydroxide/chlorhexidine medicaments from the root canal

Aim To compare the efficiency of removing calcium hydroxide [Ca(OH)₂]/chlorhexidine (CHX) (gel), Ca(OH)₂/CHX (solution) and Ca(OH)₂/saline pastes with the use of instrumentation and irrigation with sodium hypochlorite and ethylene diamine tetraacetic acid (EDTA) solutions. Moreover the role of the patency file in the cleanliness of the apical third of the root canal was evaluated. Methodology Sixty‐four human single‐rooted teeth with straight canals were used. Root canal preparation was performed with a stepback technique using Hedström (H) files. Teeth were randomly assigned to three groups and subsequently filled with one of the pastes: Ca(OH)₂/CHX (gel), Ca(OH)₂/CHX (solution) and Ca(OH)₂/saline paste. The medicaments were removed 10 days later using instrumentation and irrigation with 1% sodium hypochlorite and 17% EDTA, with or without obtaining patency of the apical foramen with a size 10 H‐file. The crowns were removed at the cemento‐enamel junction and the roots were grooved longitudinally and split into halves. Images of all halves were acquired with the use of a flatbed scanner. A scoring system of 1 to 4 was used to assess the amount of residue on the cervical, middle and apical third of the canal. Data were subjected to statistical analysis using Kruskal–Wallis and Mann–Whitney tests, with Bonferroni correction, at 95% confidence level (P < 0.05). Results Remnants of medicament were found in all experimental teeth regardless of the experimental material used and the use of the patency file. When examining the root canal as a whole, Ca(OH)₂/CHX (gel) paste was associated with significantly larger amount of residue, whereas the Ca(OH)₂/CHX (solution) paste was associated with less amount (P < 0.05) than the other two medicaments with or without the use of a patency file. Conclusions None of the techniques used in this study removed the inter‐appointment root canal medicaments effectively; the use of the patency file facilitated removal of more of the medicament in the apical third of those straight canals.     

ANTIMICROBIAL ACTIVITY OF SODIUM HYPOCHLORITE ASSOCIATED WITH INTRACANAL MEDICATION FOR Candida albicans AND Enterococcus faecalis INOCULATED IN ROOT CANALS

Objective:

The purpose of this study was to evaluate the action of sodium hypochlorite (NaOCl) associated with an intracanal medication against Candida albicans and Enterococcus faecalis inoculated in root canals.

Material and Methods:

Thirty-six human single-rooted teeth with single root canals were used. The canals were contaminated with C. albicans and E. faecalis for 21 days and were then instrumented with 1% NaOCl. The roots were divided into 3 groups (n=12) according to the intracanal medication applied: calcium hydroxide paste, 2% chlorhexidine (CHX) gel, and 2% CHX gel associated with calcium hydroxide. The following collections were made from the root canals: a) initial sample (IS): 21 days after contamination (control), b) S1: after instrumentation, c) S2: 14 days after intracanal medication placement; S3: 7 days after intracanal medication removal. The results were analyzed statistically by the Kruskal-Wallis test at 5% significance level.

Results and Conclusions:

Both 1% NaOCl irrigation and the intracanal medications were effective in eliminating E. faecalis and C. albicans inoculated in root canals.     

Comparison of final irrigation techniques in removal of calcium hydroxide

The aim of this study was to compare new irrigation systems with a conventional irrigation technique for the removal of inter‐appointment calcium hydroxide [Ca(OH)₂]. Forty‐seven extracted human single‐rooted teeth were instrumented, and Ca(OH)₂ paste was placed into root canals by using a lentulo spiral at the apical third. Teeth were randomly divided into three groups according to different irrigation protocols using a 30‐gauge slot‐tipped needle, EndoVac system and ProUltra® PiezoFlow? ultrasonic irrigation system. Scanning electron microscopic images of the selected root canal surfaces (cervical, middle and apical third) were evaluated using a 5‐grade scale. The influence of the irrigation system was evaluated using a two‐way analysis of variance test and Tukey's test. The EndoVac and PiezoFlow groups demonstrated the lowest scale values (cleanest canals); however, there was no statistical difference between these two groups. The conventional irrigation group exhibited significantly higher scores (P < 0.05). The conventional needle irrigation was not sufficient to remove Ca(OH)₂ from the root canal system. Irrigation with EndoVac and PiezoFlow? ultrasonic irrigation systems improved the removal of the intracanal medicament resulting in cleaner root canal walls.     

The influence of the ultrasonic intensity on the cleaning efficacy of passive ultrasonic irrigation

Introduction

It is not clear whether increasing the ultrasonic intensity would enhance the cleaning efficacy of passive ultrasonic irrigation (PUI) inside a root canal. The aim of this study was to evaluate the effect of the ultrasonic intensity on PUI to remove dentin debris and whether there is any lateral effect beyond the ultrasonic tip.

Methods

Each of 15 in vitro root canal models with four standard depressions in the apical part of one canal wall were filled with dentin debris and received PUI repeatedly. The most apical depression was localized apically from the ultrasonic tip. The highest intensity was applied in group 1, the lowest intensity was applied in group 3, and syringe irrigation was performed in group 4 as a control. Before and after irrigation, images of the canal wall with depressions were taken and compared. The removal of dentin debris in the depressions was categorized as clean or not clean. The data were analyzed by means of the chi-square test. The oscillation amplitude of the ultrasonic file at each intensity was recorded in vitro using time-resolved high-speed imaging.

Results

Group 1 (highest intensity) exhibited significantly better cleaning than all the other groups (P < .05); no significant difference was found between the four levels of the depressions within any of the four groups. High-speed imaging showed that the amplitude of the oscillating file increased as the intensity went up, which leads to a higher velocity of the irrigant around the file.

Conclusions

Higher ultrasonic intensity resulted in a higher amplitude of the oscillating file and, consequently, enhanced the cleaning efficacy of PUI.     

Effect of Calcium Hydroxide Dressing on the Dentinal Tubule Penetration of 2 Different Root Canal Sealers: A Confocal Laser Scanning Microscopic Study

Introduction

The purpose of this study was to evaluate the effect of calcium hydroxide (Ca[OH]₂) dressing on the dentinal tubule penetration of epoxy resin–based sealer (AH 26; Dentsply Maillefer, Ballaigues, Switzerland) and tricalcium silicate–based sealer (BioRoot RCS; Septodont, Saint Maurdes Fosses, France).

Intermittent or continuous ultrasonically activated irrigation: micro-computed tomographic evaluation of root canal system cleaning

Objectives

The aim of this study was to evaluate the efficacy of two passive ultrasonic irrigation (PUI) methods and conventional manual irrigation (CMI) in root canal system (RCS) cleaning.

Materials and methods

Artificial single-rooted teeth were used. Four lateral canals were made 2 and 7 mm short from the apex. Root canals were filled with a contrast solution. The specimens were divided into four groups (n = 8): PUI1—intermittent flushing; PUI2—continuous flushing; CMI1—at 1 mm; and CMI2—at 3 mm. Micro-computed tomographic images were obtained. New images were taken after the irrigation protocols enabling the evaluation of the contrast solution volume (in mm³) within RCS (main and lateral root canals) in comparison to the initial analysis. The comparison among groups was performed using ANOVA and Tukey’s tests with 5 % significance level.

Results

There was no difference among PUI1, PUI2, and CMI1 regarding the contrast solution removal from RCS (p > 0.05). These methods demonstrated greater cleaning than CMI2. At the apical third, CMI2 showed lower cleaning capacity when compared to the other methods (p < 0.05).

Conclusions

PUI with intermittent or continuous flushing and CMI with the needle placed 1 mm from the working length were efficient in cleaning the main and lateral root canals.

Clinical relevance

Root canal irrigation plays an important role in cleaning and disinfection of the RCS. Effective apical irrigation is an important procedure during root canal treatment. PUI and CMI (at 1 mm short) were effective in cleaning of the main and simulated lateral root canals.

     

Evaluation of Triple Antibiotic Paste Removal by Different Irrigation Procedures

Introduction

Regenerative endodontics aims to re-establish a functional pulp-dentin complex. First, the root canal system is disinfected primarily by irrigants and medicaments. Triple antibiotic paste (TAP), a commonly used intracanal medicament, has been shown to be directly toxic to stem cells at concentrations greater than 0.1 g/mL. Thus, its complete removal is a crucial step in regenerative endodontic procedures. We hypothesized that currently used irrigation techniques do not completely remove TAP from root canal system.

Methods

TAP was radiolabeled by the incorporation of I¹²⁵, and calcium hydroxide (Ultracal; Ultradent, South Jordan, UT) was radiolabeled with Ca⁴⁵. The intracanal medicaments were placed into standardized human root segments and incubated for 28 days at 37°C. Then, canals were irrigated with EndoActivator (Dentsply, Tulsa, OK), passive ultrasonic irrigation, EndoVac (SybronEndo, Coppell, TX), or a syringe/Max-i-Probe needle (Dentsply Rinn, Elgin, IL) using a standardized irrigation protocol in a closed system. Radioactivity levels (counts per minute values) were measured for each tooth before and after the irrigation protocols. Furthermore, the canals were sequentially enlarged and dentin samples collected and evaluated for radioactivity. Data were analyzed with analysis of variance and Bonferroni post hoc testing (P < .05).

Results

Approximately 88% of the TAP was retained in the root canal system regardless of the irrigation technique used (no difference among groups). Furthermore, approximately 50% of the radiolabeled TAP was present circumferentially up to 350 μm within the dentin. Conversely, up to 98% of the radiolabeled intracanal calcium hydroxide was removed, and most residual medicament was found present in the initial 50 μm of dentin.

Conclusions

Current irrigation techniques do not effectively remove TAP from root canal systems, possibly because of its penetration and binding into dentin. However, calcium hydroxide is effectively removed with significant less residual presence.     

Effect of Dentin Conditioning with Intracanal Medicaments on Survival of Stem Cells of Apical Papilla

Introduction

Regenerative endodontics is a valuable treatment modality for immature teeth with pulpal necrosis. A common feature in regenerative cases is the use of intracanal medicaments. Although these medicaments are chosen because of their antibacterial properties, their enduring effect on dentin (conditioning) and the subsequent impact on stem cell survival has never been evaluated. In this study, we hypothesized that triple antibiotic paste (TAP), double antibiotic paste (DAP), or Ca(OH)₂ has an indirect adverse effect on the survival of stem cells of apical papilla (SCAP) by dentin conditioning.

Methods

Human dentin disks were created with a standardized root canal diameter of 3.2 mm. The disks were then exposed to either TAP or DAP (at concentrations of 1 mg/mL or 1000 mg/mL), Ca(OH)₂ (Ultracal), or Hank's balanced salt solution for 7 or 28 days. Next, the medicaments were removed with copious irrigation, followed by placement of SCAP in a Matrigel scaffold in the lumen of the disks. The bioengineered constructs were cultured for 7 days, followed by determination of cellular viability by using the CellTiter-Glo luminescence assay. Data were analyzed using 1-way analysis of variance with Bonferroni post hoc test.

Results

Exposure of dentin to TAP or DAP at 1000 mg/mL resulted in no viable SCAP, whereas the use of these medicaments at 1 mg/mL had no adverse effect on cell viability. In contrast, Ca(OH)₂ treatment significantly increased SCAP survival and proliferation when compared with the control group.

Conclusions

Dentin conditioning with TAP and DAP at commonly used clinical concentration (approximately 1000 mg/mL) alters dentin in such a way as to prevent SCAP survival. This lethal indirect effect of both TAP and DAP can be largely avoided if these medicaments are used at the 1 mg/mL concentration. Conversely, dentin conditioning with Ca(OH)₂ promotes SCAP survival and proliferation.     

Apical transportation associated with ProTaper? Universal F1, F2 and F3 instruments in curved canals prepared by undergraduate students

Objective

This study evaluated apical transportation associated with ProTaper^® Universal Fl, F2 and F3 rotary files in curved canais prepared by undergraduate students.

Material and Methods

Twenty mesial roots of mandibular molars with curvatures ranging between 25° and 35° were selected. Mesiobuccal canals were instrumented by twenty students with the ProTaper^® system (Dentsply-Maillefer, Ballaigues, Switzerland) according to the manufacturer''s instructions. Pre-fiaring was performed with Sl and SX files. A #15 K-file was inserted into the root canal up to the working length (WL), and an initial digital radiograph was taken in a buccolingual direction (baseline). Afterwards, the S1, S2, F1, F2, and F3 files were employed up to the WL. Other radiographies were taken in the same orientation of the baseline after the use of the Fl, F2, and F3 files, with each file inserted into the root canal. The radiographic images were overlapped, and the Image J software was used to measure the distance between the rotary files'' ends and the #15 K-file''s end, characterizing the apical transportation. Data were analyzed by Repeated Measure ANOVA and by the SNK post hoc test (P<0.05).

Results

It was verified that file size affected apical transportation significantly (P<0.001). The F3 file showed higher apical transportation than Fl and F2, while between these last files there was no difference.

Conclusion

The undergraduate students produced lower apical transportation in curved canals when they did not use the F3 rotary file.     

Spectrophotometric Determination of Irrigant Extrusion Using Passive Ultrasonic Irrigation,EndoActivator, or Syringe Irrigation

Introduction

Sodium hypochlorite (NaOCl) irrigation is critical to endodontic success, and several new methods have been developed to improve irrigation efficacy (eg, passive ultrasonic irrigation [PUI] and EndoActivator [EA]). Using a novel spectrophotometric method, this study evaluated NaOCl irrigant extrusion during canal irrigation.

Methods

One hundred fourteen single-rooted extracted teeth were decoronated to leave 15 mm of the root length for each tooth. Cleaning and shaping of the teeth were completed using standardized hand and rotary instrumentation to an apical file size #40/0.04 taper. Roots were sealed (not apex), and 54 straight roots (n = 18/group) and 60 curved roots (>20° curvature, n = 20/group) were included. Teeth were irrigated with 5.25% NaOCl by 1 of 3 methods: passive irrigation with needle, PUI, or EA irrigation. Extrusion of NaOCl was evaluated using a pH indicator and a spectrophotometer. Standard curves were prepared with known amounts of irrigant to quantify amounts in unknown samples.

Results

Irrigant extrusion was minimal with all methods, with most teeth showing no NaOCl extrusion in straight or curved roots. Minor NaOCl extrusion (1–3 μL) in straight roots or curved roots occurred in 10%–11% of teeth in all 3 irrigant methods. Two teeth in both the syringe irrigation and the EA group extruded 3–10 μL of NaOCl.

Conclusions

The spectrophotometric method used in this study proved to be very sensitive while providing quantification of the irrigant levels extruded. Using the PUI or EA tip to within 1 mm of the working length appears to be fairly safe, but apical anatomy can vary in teeth to allow extrusion of irrigant.     

Effectiveness of Final Irrigant Protocols for Debris Removal from Simulated Canal Irregularities

Introduction

The aim of this in vitro study was to compare the effectiveness of saline, 2.5% sodium hypochlorite, and 2% chlorhexidine, with or without passive ultrasonic irrigation (PUI), in debris removal from simulated canal irregularities within prepared root canals.

Methods

Ninety bovine lateral incisors were randomly divided into 3 main groups (n = 30) based on the irrigant and prepared with hand files attached to an oscillating handpiece (NSK, Tokyo, Japan) up to a size #80 K-file. Next, the teeth were split longitudinally, and a standardized groove was prepared into the apical third and filled with dentin debris. After the halves were reassembled, they were placed in a muffle. Each main group was randomly subdivided into 2 groups (n = 14) and was treated with different final irrigation protocols. In the sodium hypochlorite/PUI, chlorhexidine/PUI, and saline/PUI groups, the solution was ultrasonically activated 3 times for 20 seconds. In the remaining groups, PUI was not performed. Specimens were scored for debris removal and analyzed under a scanning electron microscope.

Results

An association was observed between the score of debris removal and protocols using PUI (P < .05). No association was observed between the scores of debris removal and the irrigants (P = .87).

Conclusions

Final irrigation protocols that used PUI were more effective in removing debris from simulated canal irregularities into the apical third than those that did not use it.