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Year : 2014  |  Volume : 4  |  Issue : 1  |  Page : 13-17

Evaluation of calcium hydroxide removal using EndoActivator system: An in vitro study

1 Department of Dental, King Abdulaziz Armed Forces Hospital, Dhahran, Saudi Arabia
2 Department of Restorative Dental Science, Division of Endodontics, College of Dentistry, Riyadh, Saudi Arabia
3 Department of Preventive Dental Sciences and Biostatistics, King Saud University, Riyadh 11545, Saudi Arabia

Date of Web Publication28-Feb-2014

Correspondence Address:
Saad Al-Shahrani
Department of Restorative Dental Science, Division of Endodontics, College of entistry, King Saud University, P.O. Box 60169, Riyadh 11545
Saudi Arabia
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1658-5984.127981

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Aim: The aim of this study was to compare the calcium hydroxide (Ca(OH) 2 ) removal efficacy of the EndoActivator system with that of conventional irrigation with a syringe and hand file manipulation. Materials and Methods: A total of 44 extracted human single-rooted mandibular premolars were used. The root canal systems of all teeth were cleaned and shaped, then filled with Ca(OH) 2 paste. The teeth were divided into two groups: Ca(OH) 2 was removed using ethylenediaminetetraacetic acid (EDTA) and sodium hypochlorite (NaOCl) with hand filing and irrigation (Group 1) or the EndoActivator system (Group 2). Each tooth was split into two halves and examined under a scanning electron microscope. Results: Ca(OH) 2 particles were completely removed at the coronal level in both experimental groups. More Ca(OH) 2 particles were present in the apical third than in the middle-third in both groups. No significant interaction was observed between the two experimental groups or among the three examined levels (P > 0.05). Conclusion: Agitation with NaOCl and EDTA improved Ca(OH) 2 removal only in the coronal third of the root canal. Use of the EndoActivator system did not improve the efficacy of Ca(OH) 2 removal in the middle and apical thirds.

Keywords: Calcium hydroxide, ethylenediaminetetraacetic acid, EndoActivator system, hand instrument, sodium hypochlorite

How to cite this article:
Al-Garni S, Al-Shahrani S, Al-Nazhan S, Al-Maflehi N. Evaluation of calcium hydroxide removal using EndoActivator system: An in vitro study. Saudi Endod J 2014;4:13-7

How to cite this URL:
Al-Garni S, Al-Shahrani S, Al-Nazhan S, Al-Maflehi N. Evaluation of calcium hydroxide removal using EndoActivator system: An in vitro study. Saudi Endod J [serial online] 2014 [cited 2023 Mar 22];4:13-7. Available from: https://www.saudiendodj.com/text.asp?2014/4/1/13/127981

  Introduction Top

Microorganisms play major roles in pulpal and periapical diseases. [1],[2],[3] Root canal treatment aims to eliminate bacteria from the root canal system and prevent reinfection. Although cleaning and shaping have been shown to greatly reduce the number of bacteria in infected canals, complete disinfection of canals is difficult to achieve. [4],[5],[6],[7],[8],[9] Bacteria left in the root canals may survive, resulting in the failure of root canal treatment. [5] In an effort to further reduce the microbial population in the canal, many authors have advocated the use of an intracanal dressing, like calcium hydroxide (Ca(OH) 2 ). [5],[6]

Calt and Serper [10] reported that complete removal of intracanal Ca(OH) 2 is essential before root canal filling. Failure to achieve this goal enables remnants of Ca(OH) 2 to block the dentinal tubules, preventing the penetration of root canal sealer cements and hindering the bonding of resin sealer to dentin; [11] these remnants may also interact with root canal sealers. [12]

The combined use of 15% of ethylenediaminetetraacetic acid (EDTA) and sodium hypochlorite (NaOCl) solutions has been shown to improve the removal of intracanal Ca(OH) 2 in comparison with the use of one of these agents alone. [12] Calt and Serper [10] found that Ca(OH) 2 could be removed completely from the root canal by irrigation with 17% EDTA followed by 5% NaOCl, applied in 10-ml volumes.

The activation of irrigation solution has been shown to produce sufficient shear forces to remove debris and achieve cleaner canals. [13] The EndoActivator system (Dentsply Tulsa Dental Specialties, Tulsa, OK, USA) is a sonically driven canal irrigation system that was introduced to improve the irrigation phase. Its activation produces vigorous intracanal fluid agitation. [14] The system consists of a portable handpiece and three types and sizes of disposable flexible polymer tip. Its design allows for the safe activation of various intracanal reagents and the production of vigorous intracanal fluid agitation. [15] The EndoActivator system has been shown to better irrigate simulated lateral canals at 4.5 and 2 mm from the working length, compared with traditional needle irrigation alone. [16]

The aim of this study was to use scanning electron microscopy (SEM) to compare the effectiveness of the EndoActivator system versus hand filing in the removal of intracanal Ca(OH) 2 .

  Materials and Methods Top

A total of 44 extracted human single-rooted mandibular premolars were selected for this study. The tooth crowns were removed with a diamond disks to a standardized length of 15 mm. Longitudinal grooves were made on the buccal and lingual surfaces of each tooth to facilitate halving before scanning. Access cavities were prepared in all teeth. The working length of each tooth was established by subtracting 1 mm from the length at which the file first appeared at the apical foramen. Cleaning and shaping were performed with 0.04 rotary files (ProFile; Tulsa Dentsply) using a crown-down technique until the size 40/04 master apical file was reached. Irrigation with 5.25% NaOCl was applied during cleaning and shaping. To remove the smear layer, the root canals were irrigated with 5 ml 17% EDTA, followed by a final rinse with 5 ml 5.25% NaOCl.

After the canals were dried with paper points, a premixed Ca(OH) 2 solution (Calasept; JB Dental, Ridgefield, CT, USA) was applied using a Lentulo spiral. Ca(OH) 2 filling was checked radiographically in the buccolingual and mesiodistal directions. The teeth were then stored at 37°C and 100% humidity for 7 days.

The specimens were randomly assigned to two groups (n = 20 each). In both groups, a size 10 k-file was introduced into the canal to loosen the Ca(OH) 2 . Irrigation was performed with a side-vented Max-I-Probe (Dentsply International, York, PA, USA) to 1 mm short of the working length using the following sequence: 5 ml 5.25% NaOCl was dispensed in the canal over a 1-min period with intermittent circumferential filing with a size 35 k-file (Group 1) or intermittent use of the EndoActivator system with a #20/02 polymer tip for 1 min (Group 2), followed by irrigation with 5 ml 17% EDTA and intermittent circumferential filing or agitation with the EndoActivator for 1 min. A size 10 k-file was intermittently passed 0.5 mm beyond the working length to assure patency and to dislodge any Ca(OH) 2 blocking the foramen. No restoration was placed in the access cavity and the teeth were allowed to dry for 3 days.

Specimens in the negative control group (n = 2) were cleaned and shaped, but no Ca(OH) 2 was applied to ensure that analysis of these clean canals will not produce false-positive results. Teeth in the positive control group (n = 2) were cleaned and shaped and Ca(OH) 2 dressing was applied but not removed to ensure that Ca(OH) 2 would be uniformly present throughout the lengths of the canals and that its quantity would differ significantly from any amount remaining after removal attempts.

  Sem Evaluation Top

Each tooth was split along the buccolingual plane using a mallet and chisel applied to the previously made groove. The halves were coated with gold-palladium particles (20 nm) for SEM evaluation (JSM 6360 LV; JEOL, Tokyo, Japan) at ×1000-2000 magnification.

The presence of Ca(OH) 2 remnants in the coronal, middle and apical thirds of the canals of both halves was assessed. Two calibrated examiners evaluated the cleanliness of root canal walls using the scoring system proposed by Kuga et al., [17] (0) Absence of residue; (1) small amount of residue (covering ≤20% of the surface); (2) moderate amount of residue (covering 20-60% of the surface); and (3) large amount of residue (covering >60% of the surface). Data were examined using one-way analysis of variance (ANOVA) and means were compared using Tukey's honestly significant difference (HSD) test. All the statistical analyses were performed using Statistical Package for the Social Sciences software (version 16.0.1 for Windows; SPSS Inc., Chicago, IL, USA).

  Results Top

SEM examination of the negative control specimens showed patent dentinal tubules at the three levels [Figure 1]. The dentinal tubules of positive control specimens were blocked with Ca(OH) 2 particles [Figure 2]. Irrigation of the Ca(OH) 2 dressing with NaOCl, followed by EDTA, resulted in the complete removal of Ca(OH) 2 particles from the coronal level in both experimental groups [Figure 3]. Ca(OH) 2 particles were clearly present in the middle and apical thirds in both experimental groups, with more Ca(OH) 2 particles observed in the apical third than in the middle-third [Figure 4].
Figure 1: Scanning electron microscopy images of a negative control specimen. Dentinal tubules are patent (Score 0) in the middle (a) and apical (b) thirds

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Figure 2: Scanning electron microscopy images of a positive control specimen. Dentinal tubules are blocked with Ca(OH)2 particles (Score 3) in the middle (a) and apical (b) thirds

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Figure 3: Scanning electron microscopy images of coronal thirds treated with the EndoActivator system (a) dentinal tubules are patient (Score 0) hand filing (b) dentinal tubules are patient (Score 1)

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Figure 4: (a) Scanning electron microscopy (SEM) image of the middle third of a specimen treated with the EndoActivator system, showing partial blockage of the dentinal tubules with Ca(OH)2 particles (Score 1) (b) SEM image of the apical third of a specimen treated with hand filing, showing blockage of the dentinal tubules with more Ca(OH)2 particles (Score 2)

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One-way ANOVA [Table 1] revealed no significant interaction between the two experimental groups or among the three examined levels (P > 0.05). No significant difference between experimental groups was observed at any level (independent t-test, P > 0.147). Mean scores in the EndoActivator (1.58 ± 0.86) and hand filing (1.61 ± 0.83) groups indicated moderate Ca(OH) 2 removal, with no significant difference between groups (P = 0.802). However, significant differences were observed among examined levels (one-way ANOVA, P = 0.000). Mean scores did not differ significantly between the coronal (1.26 ± 0.65, moderate) and middle (1.44 ± 0.809, moderate) levels (Tukey's HSD test for multiple comparisons, P = 0.122). However, the mean score for the apical level (2.09 ± 0.84, high) was significantly higher than those for the coronal and middle levels [Tukey's HSD test for multiple comparisons, P < 0.001; [Table 2].
Table 1: Tests of between-subjects effects

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Table 2: Post-hoc test level

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  Discussion Top

Ca(OH) 2 paste is an inorganic material that is commonly used as an intracanal medication during root canal therapy, due to its antimicrobial efficacy and biological properties. The only problem associated with Ca(OH) 2 use is the accumulation of particles on the root canal wall. Failure to remove these particles increases canal permeability, which may interfere with the sealing ability of endodontic sealer, potentially leading to the failure of treatment. [18],[19] In addition, Ca(OH) 2 remnants may cause an adverse chemical reactions with root canal sealer, rendering prognoses unpredictable.

Kim and Kim [11] demonstrated that the use of a zinc oxide-eugenol sealer increased apical leakage of Gutta-percha root filling. This procedure caused the formation of calcium eugenolate, which hindered penetration of the zinc oxide-eugenol cement into the dentin tubules. [12] On the other hand, Wang et al. [20] found that the use of Resilon did not affect root canal sealing. Wuerch et al. [21] reported similar results when canals were filled with Gutta-percha and AH Plus sealer after Ca(OH) 2 removal. These findings indicate that the effects of Ca(OH) 2 intracanal medications on apical sealing depend on the type of root canal sealer used. Kim and Kim [11] recommended the use of a sealer cement that binds to the root canal wall when Ca(OH) 2 is used as an intracanal medicament. Resilon and AH Plus bind to the root canal wall. [22],[23]

Several root canal irrigants and techniques for the complete removal of Ca(OH) 2 from root canals have been tested. In this study, hand filing and the EndoActivator system were used in combination with NaOCl and EDTA irrigation. Margelos et al. [12] found that hand instrumentation improved the efficiency of Ca(OH) 2 removal from root canals, but did not achieve complete elimination.

Uroz-Torres et al. [24] used SEM to compare the EndoActivator system with conventional Max-I-Probe irrigation with NaOCl and EDTA. The system did not enhance removal of the smear layer compared with NaOCl and EDTA. The authors concluded that final irrigation with at least 1 ml 17% EDTA solution was necessary to remove the smear layer after rotary instrumentation of the root canal, with or without the use of the EndoActivator system. They also found that smear layer removal was more complete in the coronal and middle-thirds than in the apical third of the root canal. Similar findings regarding Ca(OH) 2 removal were obtained in this study.

Most published studies, including ours, have noted the difficulty of removing the smear layer and debris from the apical region. [25],[26] Rödig et al. [27] attributed this difficulty to the amount of irrigant used. They reported that the use of a large volume of irrigant provided more effective removal of the smear layer and debris in the apical regions of straight root canals and that this effectiveness was further enhanced by ultrasonic agitation. Conversely, additional ultrasonic irrigation was not shown to improve smear layer removal significantly in other studies. [28],[29]

The effectiveness of Ca(OH) 2 removal may depend on the type of solution used. The use of viscous vehicles, such as propylene glycol, methylcellulose and silicone oil, complicates Ca(OH) 2 removal. [26],[27],[28],[29],[30] In this study, Calasept (containing 41.07 g Ca(OH) 2 , 8.33 g barium sulfate and 50.60 g sterile isotonic saline solution) was used. According to Onoda et al., [30] the combination of Ca(OH) 2 with saline solution facilitated removal from root canals in comparison with propylene or polyethylene glycol. Our SEM observations showed that Ca(OH) 2 particles remained on root canal walls after hand filing or use of the EndoActivator system. The EndoActivator system removed only loose debris.

  Conclusion Top

The removal of Ca(OH) 2 from root canals is difficult, if not impossible. Agitation of NaOCl and EDTA improved Ca(OH) 2 removal only in the coronal third of the root canal. Use of the EndoActivator system did not improve the efficacy of Ca(OH) 2 removal. An effective irrigating solution that is able to dissolve the inorganic components of Ca(OH) 2 materials is needed.

  References Top

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4]

  [Table 1], [Table 2]

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