A confocal laser scanning microscopy study

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higher sealer penetration than the PUI group (p < .05). The EAS and EVS groups achieved better degrees of tubular dentin sealer penetration, compared with ...
Received: 14 January 2018

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Accepted: 2 March 2018

DOI: 10.1002/jemt.23019

RESEARCH ARTICLE

Tubular dentin sealer penetration after different final irrigation protocols: A confocal laser scanning microscopy study Ricardo Machado1

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Alessandra Timponi Goes Cruz2 |

Bianca Marques de Mattos de Araujo2 | Adriane Antoniw Klemz2 | Hellen Pontes Klug2 | Ulisses Xavier da Silva Neto2 1 Clinical Practice Limited to Endodontics, Navegantes, Santa Catarina, Brazil 2 Department of Endodontics, School of Life Sciences, Pontifical Catholic University of Parana, Curitiba, Parana, Brazil

Correspondence Ricardo Machado, Rua Brasília, n. 300, Apto. 503, Centro, Navegantes, Santa Catarina, Brazil, CEP. 88.370-100. Email: [email protected] Review Editor: Dr. Paolo Bianchini

Abstract The aim of this study was to evaluate tubular dentin sealer penetration, comparing different final irrigation protocols using a conventional needle (CONV), EndoActivator system (EAS), EndoVac system (EVS), and ultrasound (PUI). Initially, fifty-two first maxillary molars with a single canal in the palatal root, without abrupt curvatures, resorptive processes, or previous endodontic treatment were selected for this study. Then, the crowns were sectioned to obtain palatal roots 15 mm in length. The root canals were prepared with the ProTaper Universal System and irrigated with 5% NaOCl. Afterwards, the specimens were divided into four groups (n. 13), according to the final irrigation protocol: CONV, EAS, EVS, and PUI. After filling, slices at 3 mm and 5 mm from the apex were obtained for analysis by confocal laser scanning microscopy. Two-way comparisons between the groups and the levels were performed with Games Howell’s test (p < .05). Tubular dentin sealer penetration was higher at 5 mm compared with 3 mm from the apex (p < .05). The EAS group showed a higher percentage of tubular dentin sealer penetration, compared with the CONV group, at both levels. At 3 mm, there was no statistically significant difference among EAS, EVS, and PUI; however, these groups showed better performance, compared with the CONV group. At 5 mm, there was no statistically significant difference between the EAS and EVS groups, but both showed higher sealer penetration than the PUI group (p < .05). The EAS and EVS groups achieved better degrees of tubular dentin sealer penetration, compared with the other groups.

KEYWORDS

confocal laser scanning microscopy, final irrigation protocol, sealer penetration

1 | INTRODUCTION

However, the use of files associated to irrigation solutions promotes the production of a smear layer, which is a 1- to 2-mm-thick

The main objectives of root canal treatment are to promote a signifi-

amorphous structure containing inorganic dentin debris, as well as

cant reduction in the microbial contingent present in the root canal

organic substances containing fragments of the odontoblastic process,

system, and to prevent against recontamination (Siqueira & Rocas,

microorganisms, and necrotic pulp tissue (Violich & Chandler, 2010).

2008). Although chemomechanical preparation reduces the bacterial

The smear layer may induce persistent infection due to its composition,

load significantly, complete disinfection is impossible due to the

and may also block the entrance of dentinal tubules and prevent proper

complex anatomy of the root canal system. Therefore, the need to

filling of the root canal system (Kokkas, Boutsioukis, Vassiliadis & Stav-

use irrigating solutions is uncontestable (Grayson, 2016; Haapasalo,

rianos, 2004; Kuci, Alacam, Yavas, Ergul-Ulger & Kayaoglu, 2014).

Shen, Qian & Gao, 2010; Haapasalo, Shen, Wang & Gao, 2014;

Tubular dentin sealer penetration is generally accepted as a favor-

Machtou, 1980; Machtou & Yana, 1990; Sinanan, Marshall &

able consequence of root canal filling, considering that the sealing abil-

Quinton-Cox, 1983).

ity and the force required to dislodge the filling material is improved by

Microsc Res Tech. 2018;1–6.

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mechanical interlocking between sealer and dentin substrate (Weis,

Specimens that had an anatomical diameter smaller than 10 and greater

Parashos & Messer, 2004). In addition, smear layer removal associated

than 20 were discarded and replaced.

to tubular dentin sealer penetration plays a relevant role in preventing

All the roots were prepared by using the ProTaper Universal Sys-

reinfection from the oral cavity, by incarcerating and depriving residual

tem (Dentsply-Maillefer), according to the manufacturer’s protocol, up

microorganisms of a nutrient source (Assouline, Fuss, Mazor & Weiss,

to F4 file (Mancini, Cerroni, Iorio, Dall’Asta & Cianconi, 2017; Saber Sel

2001).

& Hashem, 2011). Irrigation was performed at each change of file with

Several methods and devices have been used for irrigation, such as

rmula & Aç~ao, S~ 2.5mL of 5% NaOCl (Fo ao Paulo, SP, Brasil) and Navi-

conventional needles, EndoActivator, EndoVac, and ultrasound. They

Tip 29 gauge needles 25 mm in length (Ultradent Prod Inc, South Jor-

have also been used to carry out different final irrigation protocols,

dan, UT), calibrated to 1 mm short of the working length (Kuah, Lui,

aiming to potentiate the removal of the smear layer and to obtain

Tseng & Chen, 2009). After instrumentation, the specimens were

greater tubular dentin sealer penetration (Bolles, He, Svoboda, Schnei-

divided into four groups (n. 13) according to the final irrigation protocol

derman & Glickman, 2013; Chaudhry, Yadav, Talwar & Verma, 2017;

(Table 1).

Elnaghy, Mandorah & Elsaka, 2017; Kara Tuncer & Unal, 2014; Mancini

Afterwards, the specimens were dried with F4 sterile absorbent

et al., 2013; Mancini, Cerroni, Iorio, Dall’Asta & Cianconi, 2017; Suman,

paper points (Dentsply-Maillefer), and #40 master gutta-percha cones

Verma, Prakash-Tikku, Bains & Kumar-Shakya, 2017; Uroz-Torres,

(Tanari, S~ao Paulo, SP, Brasil) were selected. A #20 Lentulo file was

Gonzalez-Rodriguez & Ferrer-Luque, 2010).

then used to place 10 lL of AH Plus (Dentsply-DeTrey, Konstanz, Ger-

To the best of our knowledge, there are no studies comparing

many), labeled with 0.1% Rhodamine B dye (Sigma-Aldrich, St. Louis,

tubular dentin sealer penetration after applying different final irrigation

MO), into the root canals, using a counterclockwise rotation (Machado

protocols using a conventional needle, EndoActivator system, EndoVac

et al., 2014; Ordinola-Zapata et al., 2009). Next, master cones were

system and ultrasound. Therefore, the aim of this study was to evaluate

positioned, and the canals were filled using the lateral condensation

this variable by confocal laser scanning microscopy (CLSM), at 3 mm

technique. After cutting and vertical condensation of the filling material

and 5 mm from the apex. The null hypothesis tested was that there is no difference in tubular dentin sealer penetration, regardless of the method used.

2 | MATERIALS AND METHODS

with Paiva condensers (SS White, Rio de Janeiro, RJ, Brazil), the specimens were submitted to radiographic examination in both mesiodistal and buccolingual directions, to check the quality of the fillings. The

T AB LE 1

Groups according to final irrigation protocols

Group

Final irrigation protocol

2.1 | Specimen selection

a

After approval by the research ethics committee of the university (no.

CONV (n. 13)

2.5 mL of 17% EDTA applied to the canals with NaviTip 29-gauge needle 25 mm in lengthf, calibrated to 1 mm short of the working length for 60 seconds, followed by 2.5 mL of 5% NaOClb in the same manner

EASc (n. 13)

2.5 mL of 17% EDTA activated with EndoActivator system using large activator tip (35/0.04) calibrated to 1 mm short of the working length, at 10,000 cycles/min for 60 seconds, followed by 2.5 mL of 5% NaOClb in the same manner

EVSd (n. 13)

2.5 mL of 17% EDTA for 3 cycles of 20 seconds using EndVac system microcannula calibrated to 1 mm short of the working length, to perform simultaneous irrigation and aspiration, followed by 2.5 mL of 5% NaOClb in the same manner

PUIe (n. 13)

2.5 mL of 17% EDTA activated for 3 cycles of 20 seconds, using ultrasonic deviceg coupled to #25/0.00 taper, stainless-steel, noncutting ultrasonic tiph calibrated to 1 mm short of the working length, followed by 2.5 mL of 5% NaOClb in the same manner

0005439/11), fifty-two extracted human maxillary molar teeth with complete root formation were selected from the Bank of Human Teeth of the institution. All the specimens were X-rayed in both mesiodistal and buccolingual directions (Machado et al., 2014) to confirm the presence of a single canal in the palatal root, without abrupt curvatures, resorptive processes or previous endodontic treatment. Afterwards, all the teeth were kept in 0.1% thymol solution at 48C until use.

2.2 | Root canal preparation and filling Initially, the tooth crowns were sectioned with a low-speed steel cutting disk (Isomet-Buehler, Lake Bluff, IL), standardizing the palatal roots at 15 mm in length. Preparation of the root canal orifices were performed with 3082 (KG Sorensen, Barueri, SP, Brazil) and Largo #2 drills (Dentsply-Maillefer, Ballaigues, Switzerland). Cervical and middle thirds were prepared using Gates-Glidden #3, #2 and #1 drills (Dentsply Maillefer). Afterwards, the working lengths were established by

a

Conventional. Sodium hypochlorite. c EndoActivator (Dentsply, Tulsa, OK, USA). d EndoVac system (Discus Dental, Smart Endodontics, Culver City, CA, USA). e Passive ultrasonic irrigation. f Ultradent Prod Inc, South Jordan, UT, USA. g Pmax XS; Satelec, Merignac, France. h IrriSafe; Satelec, Acteon, Merignac, France. b

subtracting 1 mm from the point where a size 10 K file (Dentsply-Maillefer) was visible at the apical foramen. The anatomical diameter was determined by inserting K files # 10, 15 and 20 (Dentsply-Maillefer) in ascending order, until the first one fit the root canal at the working length (Barroso, Guerisoli, Capelli, Saquy & Pecora, 2005; Ibelli, Barroso, Capelli, Spano & Pecora, 2007).

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specimens were then stored at 378C and 100% humidity for 7 days to

Germany) (Figure 1). Measurements of the tubular dentin sealer pene-

allow the sealer to set completely.

tration were performed with AxioVision 4.5 software (Carl Zeiss). The following formula was used to calculate the tubular dentin

2.3 | Sealer penetration analysis by CLSM

sealer penetration:

All the specimens were embedded in crystal resin to obtain cross sec-

 Dentin area 5 Total area 2 root canal area

tions of 1.5 mm thickness at 3 and 5 mm from the apex, by using a dia-

 Percentage of tubular dentin sealer penetration 5 area filled by

mond cutting disk (127 vmm 3 0.4 vmm 3 12.7 vmm—Buehler Ltd.,

sealer 2 root canal area/dentin area 3 100

Lake Bluff, IL), coupled to an automatic precision cutter (Isomet 4000, Buehler Ltd., Lake Bluff, IL), at a speed of 5 mm/min, at 400 rpm rotational speed, under copious water cooling

2.4 | Statistical analysis

The cervical faces of each slice were then submitted to metallo-

Seeking to determine if there was a difference among the mean values

graphic treatment for visualization by optical microscopy, to determine

of the tubular dentin sealer penetration percentages in the four groups

the external root perimeters. The procedure was conducted by a ster-

and at the two levels, the normality of the data was initially tested

eomicroscope (Discovery V8, Carl Zeiss, Hallbergmoos, Germany) with

through the Kolmogorov-Smirnov, the Levene variance homogeneity,

Objective Plan S 1.0 x, coupled to a digital camera (AxioCam icc1, Carl

the two way ANOVA and the Tukey HSD multiple comparison tests.

Zeiss, Hallbergmoos, Germany) (Machado et al., 2014).

The two-way comparison between the groups and the levels was per-

One image was taken of each slice (at 3 and 5 mm from the apex) of each specimen, resulting in 26 per group and 104 in total. The exter-

formed by the Games Howell multiple parametric comparison test (p < .05).

nal root perimeters were measured using AxioVision 4.5 software (Carl Zeiss, Hallbergmoos, Germany) (Machado et al., 2014). Then, images

3 | RESULTS

were taken by confocal laser scanning microscope (CLSM Leica, Jena, Germany) for analysis of tubular dentin sealer penetration, using two

Tubular dentin sealer penetration was higher at 5 mm from the apex,

Ne-He laser beams excited at a wavelength of 568 nm. The specimens

compared with 3 mm (p < .05). The EAS group showed a higher per-

were scanned axially and laterally using the fluorescence mode, with a

centage of tubular dentin sealer penetration, compared with the CONV

resolution of 220 and 330 nm, respectively. The images were obtained

group at both levels (5 mm and 3 mm). At 3 mm, there were no statisti-

by Leica Microsystems LAS AF TCS MP5 software (Leica, Jena,

cally significant differences among EAS, EVS, and PUI; however, these

Representative confocal laser scanning microscopy images of slices from groups CONV, EAS, EVS, and PUI, at 3 mm (a, b, c, and d) and 5mm (e, f, g, and h) from the apex, respectively [Color figure can be viewed at wileyonlinelibrary.com]

FIGURE 1

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accordance with those of other studies, which have found significantly deeper penetration of an epoxy resin sealer into dentinal tubules at 5 mm, compared with 3 mm and 1 mm from the apex (Ordinola-Zapata et al., 2009; Weis, Parashos & Messer, 2004). This finding may be the result of the low number of dentinal tubules, lower tubule density, and the presence of more sclerotic dentin in the apical area than in the coronal dentin (Mjor, Smith, Ferrari & Mannocci, 2001). At 5 mm from the apex, there was no statistically significant difference between the EAS and EVS groups, but both showed higher sealer penetration than the PUI group (p < .05). Similar results were described by Rodig, Dollmann, Konietschke, Drebenstedt and Hulsmann (2010), who showed significantly greater smear layer removal when EAS was used, rather than ultrasonic agitation and a canal brush. The poor results found for PUI in the present study, compared with EAS and EVS at 5 mm from the apex, may be associated with three main factors: time of activation, size of the tip and power setting. The reduced time Percentage of tubular dentin sealer penetration considering the group and the level [Color figure can be viewed at wileyonlinelibrary.com]

FIGURE 2

groups showed better performance, compared with the CONV group. At 5 mm, there was no statistically significant difference between the EAS and EVS groups, but both showed higher sealer penetration than the PUI group (p < .05) (Figure 1).

of activation (1 min) may not have been sufficient to achieve adequate removal of the smear layer (Alacam, 1987; Cameron, 1983; Rodig et al., 2010). Moreover, the use of a small ultrasonic tip (25/00) in canals prepared up to a #40/06 file (F4) may also have contributed to these results (Saber Sel & Hashem, 2011). Additionally, the power setting used could have been too weak to allow proper acoustic streaming with this small tip. This corroborates the findings by Jiang et al. (2011), who demonstrated that higher ultrasonic intensity results in higher amplitude of oscillation, and, consequently, enhances the cleaning effi-

4 | DISCUSSION

cacy of PUI. However, the limitations associated with activation time, tip size and power setting seem to have been minimized in the apical

During the last few decades, tubular dentin sealer penetration has been recognized as a favorable feature, capable of improving both the sealability and the resistance to dislodgment of the filling material, by

third, based on the absence of statistically significant differences between EAS/EVS and PUI at 3 mm from the apex. This most likely occurred due to the smaller dimensions of the root canal in this region.

enabling close adaptation between the interfaces (Weis, Parashos &

Conversely, Uroz-Torres, Gonzalez-Rodriguez and Ferrer-Luque

Messer, 2004). In addition, smear layer removal associated to tubular

(2010) reported no significant improvement in smear layer removal

dentin sealer penetration plays a relevant role in preventing reinfection

with EAS. These findings could be attributed to the lower volume of

from the oral cavity, by incarcerating and depriving residual microor-

irrigant used for performing the final irrigation protocol, i.e., 1 mL 17%

ganisms of a nutrient source (Assouline, Fuss, Mazor & Weiss, 2001).

EDTA and 3 mL 4% NaOCl (Uroz-Torres, Gonzalez-Rodriguez &

Therefore, the aim of this study was to evaluate tubular dentin sealer

Ferrer-Luque, 2010), compared with both 2.5 mL of 17% EDTA and

penetration, comparing different final irrigation protocols using a

5% NaOCl used in the present study. Hence, in the study by Uroz-

conventional needle (CONV), EndoActivator system (EAS), EndoVac

Torres, Gonzalez-Rodriguez and Ferrer-Luque (2010), the root canals

system (EVS) and ultrasound (PUI). The null hypothesis was rejected,

were flushed during instrumentation with 1 mL of 4% NaOCl solution

because there were statistically significant differences among the

between files, using a plastic syringe with a closed-end needle (Hawe

groups at both levels analyzed (3 and 5 mm from the apex).

Max-I-probe; Dentsply Rinn) inserted as deeply as possible into the

The most common methods used to evaluate tubular dentin sealer

root canal without binding. In our research, the root canals were

penetration are scanning electron microscopy (Bolles, He, Svoboda,

flushed with 2.5 mL of 5% NaOCl solution between files, using a Navi-

Schneiderman & Glickman, 2013; Mamootil & Messer, 2007), optical

Tip 29 gauge needle 25 mm in length (Ultradent Prod Inc, South Jor-

microscopy (Stevens, Strother & McClanahan, 2006; Weis, Parashos &

dan, UT), calibrated to 1 mm short of the working length.

Messer, 2004) and CLSM (Kara Tuncer & Unal, 2014; Moon et al.,

The literature has shown that practically any form of activation of

2010). In the present study, CLSM was used, because it allows more

the irrigating solutions is more effective than its “static use.” The results

comprehensive assessments in the root thirds, and sample preparation

of this study also reiterate this finding, indicated mainly by the better

tends to produce fewer artifacts, as compared with other methodolo-

results showed by the EAS and the EVS groups, compared with the

gies (Kara Tuncer & Unal, 2014; Machado et al., 2017; Ordinola-Zapata

CONV group. Considering that the same amounts of the irrigation solu-

et al., 2009).

tions were used, and that all the systems were used at the same level

The results of the present study showed that tubular dentin sealer

(1 mm from the working length), it is plausible to consider that EAS and

penetration was higher at 5 mm from the apex. These results are in

EVS were able to promote better cleaning, thus boosting the action of

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the irrigating solution, and, ultimately, allowing greater tubular dentin sealer penetration. This finding is mainly related to the reduction in the root canal vapor lock, as corroborated by others studies (Buldur & Kapdan, 2017; Desai & Himel, 2009; Nielsen & Craig Baumgartner, 2007).

5 | CONCLUSIONS Within the limitations of this in vitro study, the EAS and EVS groups achieved better degrees of tubular dentin sealer penetration than the other groups.

C ONFLICT OF INT E RE ST S The authors certify that they have no commercial or associative interest that could represent a conflict of interest in connection with the manuscript.

OR CID Ricardo Machado

http://orcid.org/0000-0002-1901-7270

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Suman, S., Verma, P., Prakash-Tikku, A., Bains, R., & Kumar-Shakya, V. (2017). A comparative evaluation of smear layer removal using apical negative pressure (EndoVac), Sonic irrigation (EndoActivator) and Er: YAG laser - an in vitro SEM study. Journal of Clinical and Experimental Dentistry, 9, e981–e987. Uroz-Torres, D., Gonzalez-Rodriguez, M. P., & Ferrer-Luque, C. M. (2010). Effectiveness of the EndoActivator System in removing the smear layer after root canal instrumentation. Journal of Endodontics, 36(2), 308–311. Violich, D. R., & Chandler, N. P. (2010). The smear layer in endodontics a review. International Endodontic Journal, 43(1), 2–15.

Saber, S. E.-D., & Hashem, A. A. R. (2011). Efficacy of different final irrigation activation techniques on smear layer removal. Journal of Endodontics, 37(9), 1272–1275.

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How to cite this article: Machado R, Cruz ATG, de Araujo BM

Siqueira, J. F., Jr., & Rocas, I. N. (2008). Clinical implications and microbiology of bacterial persistence after treatment procedures. Journal of Endodontics, 34, 1291–1301. e1293. Stevens, R. W., Strother, J. M., & McClanahan, S. B. (2006). Leakage and sealer penetration in smear-free dentin after a final rinse with 95% ethanol. Journal of Endodontics, 32(8), 785–788.

de Mattos, Klemz AA, Klug HP, da Silva Neto UX. Tubular dentin sealer penetration after different final irrigation protocols: A confocal laser scanning microscopy study. Microsc Res Tech. 2018;00:1–6. https://doi.org/10.1002/jemt.23019