Removal of Radioactively Marked Calcium Hydroxide from the Root Canal: Influence of Volume of Irrigation and Activation

The effect of different irrigation activation methods on the penetration of the irrigation solution into the dentinal tubules in teeth with calcium hydroxide applied and oval-shaped canals: Confocal laser scanning microscope analysis

This study aimed to evaluate the efficacy of different irrigation techniques including standard needle irrigation (SNI), passive ultrasonic irrigation (PUI), EndoActivator (EA), XP-Endo Finisher (XPF), photon-induced photoacoustic streaming (PIPS), and shock wave enhanced emission photo-acoustic streaming (SWEEPS) systems on the penetration of irrigation solutions into dentinal tubules in teeth with calcium hydroxide (CH) applied and oval-shaped canals by confocal laser scanning microscope (CLSM). Ninety mandibular incisor teeth with oval-shaped canals were included in this study. After the preparation of teeth using Resiproc Blue R25 (VDW, Munich, Germany) canals were filled with a paste based on CH. The teeth were stored in 100% humidity at a temperature of 37°C for 14 days. According to the irrigation activation systems, the teeth were divided into six groups (n = 15); SNI, PUI, EA, XPF, PIPS, and SWEEPS. In each group, 3 irrigation/activation cycles of 20 s of irrigation and 20 s of activation were performed with the relevant activation method. The root canals were filled with fluorescein sodium (Sigma, Alldrich Co., St. Louis, MO, USA) and activated with the relevant activation method for 30 s. Specimens were sectioned horizontally to 1 ± 0.1 mm at 2, 5, and 8 mm from the apex and then examined under the CLSM. Maximum penetration depth, maximum penetration area and penetration percentage were measured by using Image J software. Data were analyzed using a two-way analysis of variance (ANOVA) and posthoc Tukey tests (p = .05). No difference was found between the activation systems in terms of maximum penetration depth and maximum penetration area of irrigation solutions in the apical section (p > .05). The penetration percentage of irrigation solutions was higher in PUI and PIPS compared with EA and XPF at the apical section (p < .05). No difference was found between SNI, PUI, PIPS, and SWEEPS in terms of the penetration percentage of irrigation solutions in all sections (p > .05). The penetration percentage of irrigation solutions was higher in the middle and coronal sections compared to the apical section in EA and XPF (p < .05). Tubule penetration of irrigation solutions in SNI was similar between sections. The Tubule penetration area of irrigation solutions in PUI, EA, XPF, PIPS, and SWEEPS was lower in the apical section than in the middle and coronal sections. RESEARCH HIGHLIGHTS: The tubule penetration depth and area of the irrigation solutions were similar between the activation systems tested in the apical sections. The Tubule penetration area of irrigation solutions in middle and coronal sections was higher in PUI and PIPS than in SNI.

Mechanical activation with Easy Clean device enhanced organic tissue removal from simulated internal root resorption in a laboratory evaluation

BACKGROUND

Considering the irregular shape of the root canal, removing inflamed pulp and granulation tissue completely from internal resorption cavities during chemomechanical preparation can be challenging. This study aimed to evaluate the effectiveness of passive ultrasonic irrigation (PUI) compared to mechanical activation with Easy Clean in the removal of organic tissue from simulated areas of internal root resorption.

METHODS

The root canals of 72 extracted single-rooted teeth with oval canals were instrumented with Reciproc R25 instruments. After root canal preparations, the specimens were split longitudinally, and semicircular cavities were prepared using a round bur on each half of the roots. Samples obtained from bovine muscle tissue were weighed and adapted into semicircular cavities. The roots were reassembled and joined, and the teeth were divided into six groups (n = 12) according to the irrigation protocol: Sodium hypochlorite (NaOCl) without activation; NaOCl + PUI; NaOCl + Easy Clean; distilled water without activation; distilled water + PUI; and distilled water + Easy Clean. After irrigation protocols, the teeth were disassembled, and the remaining organic tissue was weighed. Data were analyzed by two-way ANOVA and Tukey's post hoc test (p < 0.05).

RESULTS

None of the experimental protocols totally removed the bovine tissue from simulated cavities. Tissue weight reduction was significantly affected by the activation method (p < 0.05) and by irrigation solution (p < 0.05). Groups with NaOCl irrigation presented higher tissue weight loss when compared to distilled water, for all irrigation methods (p < 0.05). The use of Easy Clean resulted in the greatest tissue weight loss (42.0%-Distilled water/45.5%- NaOCl) compared to those of PUI (33.3%-Distilled water/37.7%- NaOCl) and no activation (33.4%-Distilled water/38.8%- NaOCl) (p < 0.05). However, no differences were observed between PUI and no activation groups (p > 0.05).

CONCLUSIONS

Mechanical activation with Easy Clean enhanced organic tissue removal from simulated internal resorption more effectively than PUI. Easy Clean for agitation of the irrigating solution is effective in removing simulated organic tissues from artificial internal resorption cavities, being an alternative to the use of PUI.

Efficacy of five irrigation techniques in removing calcium hydroxide from simulated S-shaped root canals

Background/purpose

Calcium hydroxide [Ca(OH)₂], a wildly used intracanal medicament, should be completely removed from the root canal before obturation to avoid negative effects on the treatment. This study evaluated the effectiveness of conventional needle irrigation (CNI), passive ultrasonic activation (PUI), photon-induced photoacoustic streaming (PIPS), XP-endo Finisher (XP) and EDDY for the removal of Ca(OH)₂ from S-shaped root canal.

Materials and methods

Eighty-four S-shaped root canals in resin blocks were prepared using Protaper Gold up to size #25/0.08 and filled with Ca(OH)₂. Five groups were established according to the removal techniques (n = 16): CNI, PUI, PIPS, XP and EDDY group. The positive and negative control group (n = 2) were also established. Sodium hypochlorite 3% was used as the irrigant. Digital radiographs were used to measure the remaining Ca(OH)₂. Statistical analysis of the data was performed by using the Kruskal–Wallis test, followed by Dunn's post hoc test with Bonferroni correction (α = 0.05).

Results

All the tested techniques completely removed Ca(OH)₂ from the straight portion and coronal curve of the S-shaped root canal in 100% of cases. Regarding the apical curve, PUI, EDDY, PIPS and XP removed significantly more Ca(OH)₂ than CNI (P < 0.05), with no significant differences among these four groups (P > 0.05). The complete clearance of Ca(OH)₂ from the apical curve was observed in 75%, 62.5%, 56.3%, 43.8% and 0% of cases of PUI, EDDY, PIPS, XP and CNI group, respectively.

Conclusion

Irrigant activation enhanced Ca(OH)₂ removal from the apical region of the S-shaped root canal. CNI was significantly less effective than all activation techniques.

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.

Efficacy of glycolic acid for the removal of calcium hydroxide from simulated internal Resorption cavities

OBJECTIVES

This study evaluated the efficacy of 5% and 10% glycolic acid solutions for the removal of calcium hydroxide medicament from artificial internal resorption cavities.

MATERIALS AND METHODS

A total of 170 human maxillary premolars were selected and artificial internal resorption cavities were prepared using round burs and 37% orthophosphoric acid in the apical third of the root halves. Entire canal and resorption cavity were filled with calcium hydroxide paste. Then, the specimens were assigned to 2 control groups or ten experimental groups according to the irrigating solutions used for medicament removal with and without activation with ultrasonic energy as following: 5% glycolic acid, 10% glycolic acid, 17% EDTA, and 10% citric acid and distilled water. The resorption cavities were examined under different magnifications using stereomicroscopy and scanning electron microscopy (SEM). The calcium hydroxide remnants in the resorption cavity were scored by 2 evaluators using a 4-scoring scale. The data were analyzed with Kruskal-Wallis H tests with 5% significance threshold.

RESULTS

There was no significant difference regarding the distribution of removal scores among non-activated solutions (P > 0.05). In activated groups, 10% glycolic acid irrigation removed significantly more amount of calcium hydroxide than EDTA and distilled water (P < 0.05). No significant difference was found between the efficacy of 10% glycolic and citric acid (P > 0.05). Citric acid, 5% glycolic acid, and EDTA showed similar removal scores (P > 0.05). Passive ultrasonic irrigation significantly improved calcium hydroxide removal scores in 10% glycolic acid, citric acid, and EDTA groups (P < 0.05). The SEM examination revealed that the specimens that were scored 0 are not entirely free of calcium hydroxide remnants.

CONCLUSION

Concentration of 10% glycolic acid removed significantly more calcium hydroxide paste from resorption cavities than EDTA when used with passive ultrasonic irrigation. Although passive ultrasonic irrigation favored medicament removal in all irrigating solutions, complete elimination of medicament remnants was unattainable.

CLINICAL RELEVANCE

This study showed the improved efficacy of ultrasonically activated 10% glycolic acid in removing the calcium hydroxide medicament from the internal resorption cavity.

Final Endodontic Irrigation with 70% Ethanol Enhanced Calcium Hydroxide Removal from the Apical Third

INTRODUCTION

The purpose of this study was to evaluate the cleanliness of root canal walls and dentinal tubules after attempting to remove the calcium hydroxide dressing with different irrigant solutions and the use of nonactivated irrigation or passive ultrasonic irrigation (PUI).

METHODS

After root canal instrumentation, 80 single-rooted teeth were filled with calcium hydroxide mixed with propylene glycol and 0.1% rhodamine B dye and inserted into canals with a Lentulo spiral. The calcium hydroxide dressing was initially removed with 10 mL saline solution and reinstrumentation with the master apical file. Then, the samples were randomly assigned into 8 experimental groups (n = 10) according to the irrigant solution with or without PUI: 2.5% sodium hypochlorite, 17% ethylenediaminetetraacetic acid + 1.25% sodium lauryl ether sulfate (EDTA-T), 37% phosphoric acid, or 70% ethanol. A final flush with 5 mL saline solution was performed. The percentage of clean root canal walls and the depth of clean dentinal tubules were measured with images of confocal laser scanning microscopy. The groups were compared using the 2-way analysis of variance test with the Bonferroni post hoc test for depth analysis and the Kruskal-Wallis with Dunn post hoc test for the perimeter analysis.

RESULTS

Irrigation with 70% ethanol presented a significantly higher percentage of clean root canal walls and a higher depth of clean dentinal tubules when compared with irrigation with 2.5% sodium hypochlorite and 17% EDTA-T for both irrigation methods (P < .05). No differences were observed between nonactivated irrigation or PUI protocols (P > .05).

CONCLUSIONS

Seventy percent ethanol enhanced calcium hydroxide removal from the apical root third compared with 2.5% sodium hypochlorite or 17% EDTA-T.

Do Contaminating Substances Influence the Rheological Properties of Root Canal Sealers?

INTRODUCTION

This study evaluated the effect of residual substances derived from irrigant solutions and intracanal medications on the rheological properties of a silicone, gutta-percha, and bioactive glass-based sealer in comparison with an epoxy resin-based sealer.

METHODS

Thin films of contaminants (0.5 μL) (3% sodium hypochlorite [NaOCl], chlorhexidine digluconate [CHX], 17% EDTA, calcium hydroxide, 40% citric acid, or distilled water [DW]) were applied along with freshly mixed GuttaFlow Bioseal (GFB; Coltene/Whaledent, Langenau, Germany) or AH Plus Jet (Dentsply DeTrey, Konstanz, Germany) on the lower plate of a dynamic rheometer. Rheological measurements were performed in oscillating mode at the strain amplitude, angular frequency, and constant temperature of 0.01%, 10 rad/s, and 37°C, respectively. Samples without contaminants served as controls. All measurements were performed 5 times. The Kolmogorov-Smirnov test and 1-way analysis of variance followed by the Student-Newman-Keuls test were performed to analyze the results (P < .05).

RESULTS

The contaminants did not alter the setting time of GFB compared with the controls; however, CHX and calcium hydroxide decreased its complex viscosity (ƞ*) (P < .05). The setting time of AH Plus Jet was increased by DW, CHX, citric acid, and EDTA (P < .05). All contaminants decreased its ƞ* at the setting point (P < .05). NaOCl led to the greatest alteration of its rheological parameters.

CONCLUSIONS

Irrigant solutions and intracanal medications adversely affected at least 1 of the tested rheological properties of both sealers, except for DW and 3% NaOCl, which did not alter any rheological property of GFB.

An in vitro study on the efficacy of removing calcium hydroxide from curved root canal systems in root canal therapy

To compare the efficacy of various irrigants (citric acid, ethylenediaminetetraacetic acid (EDTA) and NaOCl) and techniques in removing Ca(OH)₂ in two types of curved root canal systems, simulated root canals with specific curvatures were used to investigate the effects of different irrigants and instruments on Ca(OH)₂ removal. The optimal methods were verified on extracted human teeth. Simulated root canals were assigned to one of two groups based on the irrigation solution: 10% citric acid or 2.5% NaOCl. Each group was divided into four subgroups according to the technique used to remove Ca(OH)₂. The percentage of Ca(OH)₂ removal in different sections of root canals was calculated. On the basis of the results obtained for the simulated canals, 10% citric acid and 17% EDTA were applied to remove Ca(OH)₂ from the extracted human teeth with curved root canal systems. The teeth were scanned by micro computed tomography to calculate the percentage of Ca(OH)₂ removal in the canals. In simulated root canals, we found that 10% citric acid removed more Ca(OH)₂ than 2.5% NaOCl in the 0–1 mm group from the apex level (P<0.05). Ultrasonic and EndoActivator activation significantly removed more Ca(OH)₂ than a size 30 K file in the apical third (P<0.05). However, there were no significant differences in any sections of the canals for 10% citric acid or 17% EDTA in removing Ca(OH)₂ in extracted human teeth. We concluded that it was effective to remove residual Ca(OH)₂ using the decalcifying solution with EndoActivator or Passive Ultrasonic Irrigation in a curved root canal system. A protocol for Ca(OH)₂ removal was provided based on the conclusions of this study and the methods recommended in previous studies.

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.

A novel model for testing the efficiency of removal of calcium hydroxide from complex root canal anatomies

The purpose of this study was to evaluate the efficacy of several irrigation protocols in the removal of calcium hydroxide [Ca(OH)₂ ] from simulated internal root resorption cavities in a complex root canal anatomy model. The 20° to 35° curved mesiobuccal roots of 94 maxillary molars were sectioned longitudinally; internal resorption cavities were prepared in the apical third of the canal walls. Calcium hydroxide was placed into the cavities and the root halves reassembled. Four teeth were used as controls, and 90 teeth were randomly divided into six experimental groups (n = 15), according to the irrigation protocols used: syringe irrigation; H₂ O₂ (HP); Navitip FX; Vibringe-syringe; Vibringe-NaviTip FX; ultrasonically activated irrigation (UAI) using an ultrasonic K-file. In the HP group, 2.5% NaOCl and 3% H₂ O₂ were used, while 2.5% NaOCl and 17% EDTA were used in the remaining groups. Stereomicroscope images and radiographs were used to measure the remaining Ca(OH)₂ . The model proved to be suitable for simulating complex anatomy. Positive correlation was found between stereomicroscope and radiographic analyses (P < 0.05). UAI removed significantly more Ca(OH)₂ than the other experimental groups (P < 0.05). The HP group was the least efficient protocol (P < 0.05). It would appear that a reliable model has been developed that simulates complex root canal anatomy. Irrigant activation protocols enhanced Ca(OH)₂ removal.