: 2022  |  Volume : 34  |  Issue : 4  |  Page : 236--241

Comparative evaluation of efficacy of XP Endo Finisher, sonic, and ultrasonic irrigation in removal of calcium hydroxide and subsequent adaptation of gutta percha in simulated internal resorption cavity - An in vitro study

Sonali Taneja, Pragya Kumar, Akriti Dheer 
 Department of Conservative Dentistry and Endodontics, I. T. S. Centre for Dental Studies and Research, Ghaziabad, Uttar Pradesh, India

Correspondence Address:
Dr. Sonali Taneja
Department of Conservative Dentistry and Endodontics, T. S. Centre for Dental Studies and Research, Ghaziabad, Uttar Pradesh


Aim: The study aims to comparatively evaluate various irrigating techniques in removing calcium hydroxide (CH, aqueous/silicon oil based) from simulated internal resorptive cavity and subsequent adaptability of thermoplasticized gutta percha (GP) to root canal walls. Methods: One hundred and sixty extracted human mandibular second premolars with single root were chemomechanically prepared to a size F3 (size 30, 6% taper). Standardized internal root resorption cavities were prepared, and samples were randomly divided into two main groups (n = 80) according to type of CH medicament used: Group I - silicon oil based (Metapex) and Group II - aqueous based (RC Cal) and four subgroups (n = 20) according to the technique used for removal of CH: Subgroup A - passive ultrasonic irrigation, Subgroup B - XP Endo Finisher (XP), Subgroup C - sonic irrigation, Subgroup D - conventional syringe irrigation. Half of the samples were evaluated for the quantity of remaining CH and the remaining half were evaluated for the adaptability of thermoplasticized GP under a stereomicroscope. The statistical analysis of the obtained scores was done using a nonparametric test, Kruskal–Wallis test, followed by Mann–Whitney U-test. Results: XP showed maximum removal of CH and adaptation of GP in both the groups. Adaptability of GP to the dentinal wall was better in Group II than in Group I. Conclusions: Complete removal of CH (both formulations) was not possible with either of the experimental irrigation techniques from simulated internal root resorptive defects.

How to cite this article:
Taneja S, Kumar P, Dheer A. Comparative evaluation of efficacy of XP Endo Finisher, sonic, and ultrasonic irrigation in removal of calcium hydroxide and subsequent adaptation of gutta percha in simulated internal resorption cavity - An in vitro study.Endodontology 2022;34:236-241

How to cite this URL:
Taneja S, Kumar P, Dheer A. Comparative evaluation of efficacy of XP Endo Finisher, sonic, and ultrasonic irrigation in removal of calcium hydroxide and subsequent adaptation of gutta percha in simulated internal resorption cavity - An in vitro study. Endodontology [serial online] 2022 [cited 2023 Jan 28 ];34:236-241
Available from: https://www.endodontologyonweb.org/text.asp?2022/34/4/236/365818

Full Text


Root resorption is a physiologic or pathologic dental condition which commonly results in loss of dentin, cementum, and bone. Generally, root resorption is classified as external root resorption and internal root resorption (IRR). IRR is identified by the depletion of dental hard tissues by increased activity of clastic cells due to pulpal inflammation. Literature has proven that treatment of internal resorption is very challenging in terms of achieving adequate disinfection of pulp space, removal of intracanal medicament, and subsequent three-dimensional adaptations of obturating material to irregular root canal walls.[1]

Calcium hydroxide (CH) paste is commonly used medicament in IRR as it arrests inflammatory response, but it should be removed completely before obturation. Various studies have reported that CH remnants in the root canal react with sealers, alter the setting reaction, and prevent the sealer penetration into dentinal tubules, leading to voids at sealer–dentine interface, interfering in the adaptation of gutta percha (GP) to the root canal wall, thus reducing the long-term prognosis of root canal therapy.[2],[3]

Various irrigants, irrigation protocols, and activation techniques have been studied for the thorough removal of CH from the root canal. Passive ultrasonic irrigation (PUI) utilizes ultrasonic tips and transmits acoustic energy from an oscillating endodontic file to an irrigant in the root canal. Sonic irrigation (SI)-based device Endo-Activator (Dentsply, York, PA, USA) is a handpiece available with three polymer activator tips (yellow 15/02, red 25/04, blue 35/04). The file system used in this study is XP Endo Finisher (XP) (FKG Dentaire, La Chaux-de-Fonds, Switzerland). It is a novel instrument used in final disinfection protocol. XP is a size #25 nontapered instrument, remains centered in the canal, and effectively disinfects irregularities of the root canal walls.[4] The curved bulb of XP expands its extent 6 mm in diameter if the file is squeezed in the root canal 100 times of corresponding sized file.[5]

Clinicians encounter many problems in obturating internally resorbed pulp space in terms of obtaining a three-dimensional impermeable seal due to the presence of irregularities in the root canal wall. Thermoplasticized compaction technique has been proven to be better when compared to lateral and vertical compaction techniques for obturation of internally resorbed areas.[6]

Till date, no study has comparatively evaluated the efficacy of various irrigating techniques on the removal of CH as well as subsequent adaptation of thermoplasticized GP on simulated internal resorptive cavities of the canal. Thus, the study was done to comparatively evaluate conventional syringe irrigation, XP, SI, and PUI in removing CH paste (water/oil based) from root canals with simulated internal resorption along with the adaptability of thermoplasticized GP to the root canal walls. The null hypotheses of the study were: (1) all irrigation devices were capable of removing CH (oil based and water based) from the internal resorptive cavity and (2) the adaptability of GP was same in all the groups and subgroups.

 Materials and Methods

Selection and preparation of the specimen

The ethical clearance for this study was taken from the Institutional Ethical Review Board (L/2019/135). One hundred and sixty extracted single-rooted human mandibular second premolars with no root caries, fractures, calcification, or internal/external resorption, and completely formed apices were selected. Preoperative radiographs both in mesiodistal and buccolingual direction were taken to confirm single, patent, and straight canal. Four sets of 40 teeth each with approximately similar thickness of radicular dentin at 3 mm, 6 mm, and 9 mm from the apex were selected using the EasyDent V4 Simple Viewer software (Value Added Technology Co Ltd, Gyeonggi Korea, Republic of (South)). The sample size was calculated using Open Epi version 3 (Emory University, Atlanta Georgia). The samples were stored in 0.01% thymol solution until use.

The samples were decoronated to obtain a standardized root length of 15 mm. An ISO size 10 K-stainless steel file was introduced in the root canal to a length that the tip of the file was just exposed from the apex. Working length was recorded by reducing 1 mm from the visible length. The root canals were prepared chemomechanically with the ProTaper Next rotary files (Dentsply Maillefer, Ballaigues, Switzerland) to a size F3 (size 30, 6% taper) used with endodontic motor (X-Smart Plus, Dentsply Maillefer). The irrigation was done with 2 ml of 2.5% NaOCl solution followed by 2 ml of saline for 30 s, respectively, after every change of instrument using a 30-gauge endodontic irrigation needle (Kerr Hawe SA, Switzerland) placed 1 mm short of working length (WL). Final irrigation was done with 5 ml 17% EDTA alternated with 5 ml 2.5% NaOCl for 1 min each. Final flushing was done with 2 ml of saline for 2 min.[7]

On both buccal and palatal/lingual root surfaces, longitudinal grooves were prepared with a fine diamond disc without affecting the inner layer of dentin. The specimen roots were split longitudinally using a chisel and a hammer with light strokes and precision. The standardized site of the resorption cavity was determined by measuring the lengths of the two root canal halves using a digital caliper. Standardized simulated internal root resorption cavities with 1.4 mm in diameter and 0.7 mm in depth were prepared using No. 4 round bur (Mani Dental Bur) 6 mm from the anatomic apex. The dimension of grooves was checked under a stereomicroscope at ×20 magnification. The debris from the internal resorptive cavities was removed with the help of a micro brush (MK Life, Porto Alegre, RS, Brazil) and 17% EDTA. 10 ml of distilled water was used as the final irrigant to flush the debris from the cavities.

After reassembling the two halves with sticky wax, the samples were divided into two groups (n = 80) according to the type of CH-based intracanal medicament used. In Group I, oil-based CH, i.e., Metapex (META BIOMED, Chungbuk, Korea), was injected into the canal until it was extruded through the apex. In Group II, RC Cal (Prime Dental products, Mumbai, India) was injected into the canal until it was extruded through the apex. The apical foramen was secured with two layers of utility wax to prevent subsequent apical extrusion of medicament, while the coronal portion was restored with interim restoration (Cavit, 3M ESPE, Seefeld, Germany). The specimens were kept in complete darkness for 1 week at 37°C in 100% relative humidity to stimulate clinical conditions. After 1 week, 15 K-file (Dentsply Maillefer) was introduced into the canal to loosen intracanal medicament and create a space for irrigation needle. All the specimens of both the groups were further subdivided into four subgroups (n = 20) depending on the technique of removal of CH.

In Subgroup A (PUI), passive ultrasonic agitation of the irrigant was done in two cycles using an ultrasonic Irrisafe (Satelec) ultrasonic tip (25/.00) that was inserted in the canal 1 mm short of WL, without touching the walls, enabling it to vibrate freely. In the first cycle, the canals were irrigated using 10 ml of 3% NaOCl for 1 min, and in the second cycle, 2 ml of 17% EDTA was used for 1 min. The ultrasonic tip was activated through a 5.5 W, 30 kHz piezoelectric ultrasound unit Suprasson P5 Booster (Satelec).

In Subgroup B (XP), the rubber stopper of the file was set at 1 mm short of the WL with a gentle up and down motion, flushing the canals with 10 ml 3% NaOCl, followed by a final flush using 2 ml 17% EDTA for 1 min. Endodontic motor (X-Smart Plus, Dentsply Maillefer) was set at 800 rpm speed and 1 Ncm torque.

In Subgroup C (SI), 10,000 cycles of sonic vibrations was generated by Endo Activator in a minute, activating irrigant. Size 0.04/25 tip was placed 2 mm short of WL; 10 ml of 3% NaOCl was used followed by 2 ml of 17% EDTA for 1 min, with a final rinse of 2 ml saline for 1 min.

In Subgroup D (CSI), irrigation was done with 10 mL 3% NaOCl for 1 min using a 30 gauge needle placed 1 mm short of WL. The final irrigation was completed using 2 ml of 17% EDTA for 1 min. During irrigation, the needle was constantly moved inward and outward within the canal.

The files (XP) and irrigants were kept in warm water bath to maintain the temperature at 37°C.[8]

Evaluation of remaining calcium hydroxide and adaptability of injectable thermoplasticized gutta percha

After the irrigation procedure, ten samples of each subgroup were used to evaluate remaining CH. The root halves of these samples were separated and digital images of simulated internal resorptive cavity of each root were captured at ×20 magnification attached to a stereomicroscope. Two images of each subgroup were obtained [Figure 1]. The sequence of all pictures was randomized, and an independent calibrated clinician who was blinded to the experimental groups used the scoring criteria described by van der Sluis et al.[9] for the evaluation of remaining amount of CH in resorptive cavity.{Figure 1}

Score 0: the cavity is free of CH, Score 1: Less than the half of the cavity is filled with CH, Score 2: More than the half of the cavity is filled with CH, and Score 3: The cavity is filled with CH completely.

The remaining ten samples of each subgroup were used to evaluate the adaptability of injectable thermoplasticized GP. 95% ethyl alcohol is used as final irrigant to dry the canal.[10] After irrigation, canals were dried using 30.6% paper points till it was completely dry. A 30.06 autofit GP cone was used to fill the apical root canal with a down-pack motion and sealer cement. Further, these samples were obturated using thermoplasticized injectable GP (BeeFill) in two increments. Heat plugger 40/.03 (BeeFill) followed by Finger pluggers (Dentsply #4) were used in between to condense the GP. The sectioning of the samples was done at middle of resorptive cavity and these sections were examined under the stereomicroscope to measure the adaptibility of GP to the wall [Figure 2]. In each image, space between the GP mass and the root canal walls was scored according to the scoring criteria given by Villegas et al.[11]{Figure 2}

Score 0: No spaces, Score 1: 0–1 mm space present, Score 2: 1–2 mm space present, Score 3: 3 mm space present.

Statistical analysis

All the collected data were entered into MS Excel and analyzed. The statistical analysis was done by SPSS Version 21.0 software (SPSS Inc., Chicago, IL USA). The normality of data was tested by Shapiro–Wilk test and found not normal. The statistical analysis was done using a nonparametric test, Kruskal–Wallis test, followed by Mann–Whitney U-test. The level of significance was set at 0.05.


Complete removal of CH (both formulations) from the resorptive cavities was not achieved by any of the irrigation technique used in this study. In both the groups, Subgroup B (XP) showed significantly higher removal of CH as well as superior GP adaptability as compared to all other subgroups (P < 0.05), followed by Subgroups A, C, and D in the decreasing order [Table 1]. However, the difference between Subgroups C and D was insignificant in case of Group I; and in case of Group II, the difference between Subgroups A and B was insignificant (P > 0.05).{Table 1}

Hence, overall removal of CH removal and GP adaptability was in the order of:

For Group I: Subgroup B > Sub group A > Subgroup C ≥ Subgroup DFor Group II: Subgroup B ≥ Subgroup A > Subgroup C > Subgroup D.


Disinfection of internal resorptive cavities is a challenging task due to the presence of irregular complexities in root canal walls. CH was used in our study because it enhances the disinfection procedure, controls bleeding, and necrotizes the residual pulp tissue.[1],[12],[13]

In this study, simulated resorption cavities of standardized dimensions were prepared to obtain uniform and exact dimension of the resorptive cavity in all specimens so as to standardize the quantity of the CH in them.[7],[14] The root canal samples were filled with CH (both formulation) to ensure that they simulated clinical scenario.

Thorough removal of CH from canal complexities such as internal resorption before obturation is very important to ensure the three-dimensional sealing of root canal system. The effective cleaning of irrigation technique depends on mechanical agitation, volume, and chemical composition of irrigant.[15]

NaOCl alone is very effective in eliminating organic debris than dissolving inorganic substances (calcium) while chelators such as EDTA have shown to be significantly more efficient in removing CH.[16] Therefore, in this study, both NaOCl and EDTA were used because various studies have proven that the use of NaOCl followed by EDTA shows superior efficiency in removal of CH as compared to other irrigants.[2]

The results of study showed that none of the irrigation techniques could completely remove CH from the resorption cavity as well as could achieve complete gutta percha adaptation to the dentin wall. Therefore, both the null hypotheses were rejected. The results of this study are supported by various studies reporting that no irrigation technique could completely remove all residues of intracanal medicaments from IRR cavities.[17],[18]

Intersubgroup comparison showed that XP showed maximum efficacy in removal of CH irrespective of vehicle (aqueous/silicon oil based), compared to all other subgroups, followed by PUI, then SI, and finally, CSI. These results are in accordance with Keskin et al.[18] and Marques-da-Silva et al.[19] concluded that XP and PUI were more effective in removing CH than CSI and Endo Activator.

Better efficacy of XP file can be attributed to its property of phase transformation (from martensitic to austenitic phase), which causes the file to expand and adapt to the resorptive cavity thus effectively cleaning the root canal. To simulate oral conditions, all specimens, files, and irrigants were kept in water bath at 37°C for Subgroup B because, at this temperature, XP removes significantly more CH than at room temperature.[20] Leoni et al.[21] reported that the use of XP eliminated 89.7% of accumulated hard tissue debris due to its alloy properties, small core size, and zero taper. Elnaghy et al.[22] and Wigler et al.[23] also supported the claim of XP in removing debris and the smear layer in moderate to severely curved root canals.

PUI performed better in both groups when compared with SI and CSI. These findings might be due to delivering of the acoustic energy by the ultrasonic tip at frequencies of 25–39 kHz, which creates cavitation bubbles by activating the irrigant solution.[8] The ultrasonic tip remains passive without contacting the root canal walls.[8] The agitation increases the penetration of irrigant into the irregular canal areas in turn increasing the CH removal capacity. Cavitation and microstreaming effects produced during PUI might even stream the solution from the apex, coronally.[24]

Capar et al.[14] and Ahmetoğlu et al.[25] also reported that PUI was more effective than CSI in removing CH from artificial groove.

Contradictory to our results, the study performed by Kirar et al.[26] suggested that CH removal efficacy of SI was better than PUI followed by CSI although the difference between SI and PUI was insignificant.

Sonic irrigation was found to work better at debriding the canal than CSI because of its mechanism of action which involves acoustic streaming which enhance debridement and disruption of microbial biofilm.[27] Activated fluids promote deep cleaning and disinfection. In our study, sonic irrigation showed better results than syringe irrigation in Group II while they were comparable in Group I. Arslan et al.[28] also reported that sonic irrigation performed better than needle irrigation in the removal of CH.

Irrespective of the irrigation technique used for removal of CH, the removal of Metapex (oil based) was difficult compared to RC Cal (water based) from the resorptive cavity. Nandini et al.[29] reported that in oil-based formulation of CH there is lesser penetration of chelating and irrigating solution through the silicone oil layer, thus making it difficult to remove.

In this study, following the various irrigation activation techniques, canals were obturated with thermoplasticized GP. Sealer was not used during obturation as only the adaptation of the GP to the dentine walls after irrigation was evaluated in the study and not the sealer distribution or the film thickness.[30] Subgroup B (XP) showed better results for adaptability of GP among other irrigation techniques due to its high efficacy to remove CH (both formulation) from the resorption cavities.


XP was most effective followed by PUI, SI, and CSI techniques in terms of CH (aqueous/silicon oil based) removal and adaptation of thermoplasticized GP to the stimulated resorptive canal walls.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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