doi:10.1111/iej.12431
Comparison of two negative pressure systems and syringe irrigation for root canal irrigation: an ex vivo study
C. G. Adorno1, V. R. Fretes1, C. P. Ortiz1, R. Mereles1, V. Sosa1, M. F. Yubero2, P. M. Escobar3 & C. Heilborn3 1
Facultad de Odontologıa, Universidad Nacional de Asunci on, Asunci on; 2Departamento de Fısico-Quımica, Facultad de on, Paraguay Ciencias Quımicas, Universidad Nacional de Asunci on, Asunci on; and 3Private Practice Asunci
Abstract Adorno CG, Fretes VR, Ortiz CP, Mereles R, Sosa V, Yubero MF, Escobar PM, Heilborn C. Comparison of two negative pressure systems and syringe irrigation for root
canal
irrigation:
an
ex
vivo
study.
International
Endodontic Journal.
Aim To compare in a laboratory study two negative pressure systems and syringe irrigation, regarding the delivery of a contrast solution (CS) to working length (WL) and into simulated lateral canals and the effective volume of irrigant aspirated during negative pressure irrigation. Methodology Twenty single-canaled incisor training models were constructed with six simulated lateral canals each (2, 4 and 6 mm to WL) and a size 40, 0.04 taper apical size canal. Each model underwent all irrigation procedures (EndoVac at WL (EndoVac-0) and WL–2 mm (EndoVac-2), iNP needle with negative pressure (iNPn) and syringe irrigation with the iNP needle (iNPs) and a 30-G side-slot needle placed at WL (SI0) and WL–2 (SI2) mm in a crossover design. CS was delivered at 4 mL min 1 for 60 s with a peristaltic pump and a recovery device collected the volume (in mL) of irrigant suctioned by the negative pressure groups. The irrigation procedures were digitally recorded, and a still image of the 60-s time-point of irrigation was evaluated for CS distance
to WL (in millimetres) after irrigation and penetration into lateral canals (3-point scale). Statistical tests used were Kruskal–Wallis and Dunn’s test. Results EndoVac-0, iNPn and iNPs had median distances of CS to WL of 0 mm, followed by SI0 (0.2 mm), SI2 (0.7 mm) and EndoVac-2 (1.7 mm). There were no significant differences between EndoVac-0, iNPn, iNPs and SI0, but these were significantly different to SI2 and EndoVac-2 (P < 0.05). There were no significant differences between the volume of CS delivered by syringe irrigation and that collected by iNPn (4 mL), but these were significantly greater than EndoVac-0 (2.8 mL, P < 0.001) and EndoVac-2 (2.85 mL, P < 0.001), which were not different to each other (P = 1.0). The irrigation procedures were ineffective at penetration into lateral canals. Conclusion iNPn, EndoVac-0, iNPs and SI0 achieved greater irrigant penetration to WL. iNPn was able to collect a median volume of CS (4 mL) similar to that delivered by syringe irrigation (iNPp, SI0 and SI2). An adequate irrigant penetration into lateral canals could not be achieved by any of the systems. Keywords: lateral canals, negative pressure irrigation, root canal irrigation, volume, working length. Received 24 January 2014; accepted 23 January 2015
Introduction Correspondence: Carlos G. Adorno, Facultad de Odontologıa, Universidad Nacional de Asunci on, Avenida Espa~ na c/ Calle Brasil c.c. 517, Asuncion, Paraguay (Tel.: (+595) 971 232371; e-mail:
[email protected]).
© 2015 International Endodontic Journal. Published by John Wiley & Sons Ltd
The finding that at least 35% of the canal walls remain untouched by instrumentation (Peters et al. 2001) emphasizes the importance of chemical
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Comparison of negative pressure irrigating systems Adorno et al.
debridement and disinfection of the root canal system. The capacity of any kind of irrigation regime to reach every portion of the canal system will determine its mechanical and chemical effectiveness (Ciucchi et al. 1989). The ability to dissolve organic tissues, kill microbes, remove microbial by-products and remove the smear layer (Moorer & Wesselink 1982, Mader et al. 1984, Miller & Baumgartner 2010) are better achieved when the solutions are delivered to the most apical regions of the root canal system. However, when a disinfecting agent comes into contact with vital or necrotic tissue, debris and/or microbial cells a gradual weakening or inactivation of the disinfecting solution occurs (Haapasalo et al. 2007, Morgental et al. 2013). Therefore, to improve the effectiveness of the irrigant, frequent exchange and a greater volume of the solution are recommended (Baker et al. 1975, Baumgartner & Cuenin 1992, Morgental et al. 2013). In addition, smaller irrigating needles and deeper placement within the canal also increase the mechanical effectiveness of irrigation (Chow 1983, Sedgley et al. 2005, Boutsioukis et al. 2010b). However, the delivery of the solutions by syringe irrigation to the most apical parts of the root canal system is difficult and entails the possibility of inadvertent injection beyond the apical foramen (H€ ulsmann & Hahn 2000, Psimma et al. 2013). The apical negative pressure technique has been reported to provide better cleanliness (Shin et al. 2010), disinfection (Hockett et al. 2008), and less apical extrusion of irrigants (Fukumoto et al. 2006, Mitchell et al. 2010) when compared to syringe irrigation. Negative pressure irrigation allows potentially large volumes of irrigant to reach the apical region (Brunson et al. 2010) and better debridement of the apical root canal (Siu & Baumgartner 2010), in part attributed to its ability to displace the vapour lock (Tay et al. 2010). However, a recent study (Boutsioukis et al. 2014) provided experimental evidence showing that vapour lock removal was also achievable through syringe irrigation. To date, most, if not all, studies on negative pressure irrigation were performed with the EndoVac (SybronEndo, Orange, CA, USA) (Fig. 1b). Therefore, the introduction of new systems using the negative pressure concept warrants comparison to the EndoVac. A new apical negative pressure irrigating system, the intracanal negative pressure (iNP) needle (Mikuni Kogyo Co., Inc., Nagano, Japan), was recently developed (Fig. 1a). The main body of the 32-mm-
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(a)
(b)
(c)
Figure 1 Needles used in this study; (a) iNP (intracanal negative pressure) needle; (b) EndoVac microcannula; (c) 30-G side-vented closed-ended needle. Scale bar = 1 mm.
long iNP needle has an external and internal diameter of 0.65 and 0.50 mm, respectively. The 4 mm end of the iNP needle (enlargement) is swaged from 0.46 mm diameter that gradually narrows with the tip having an internal and external diameter of 0.25 and 0.36 mm (28G), respectively. The inner diameter would allow a high volumetric flow rate and the outer diameter a loose placement at 2 mm from the working length (WL) when the canal is enlarged to at least size 40, 0.04 taper. In contrast, EndoVac has a microcannula with a closed-ended 0.32-mm tip (30G) and an array of twelve 0.1 mm in diameter holes extending from 02– 0.7 mm from the tip. The EndoVac is placed at WL during irrigation ensuring irrigant penetration to the most apical level. Although both iNP and EndoVac adopt the negative pressure irrigation concept, the variable designs suggest different performances. Thus, the aim of this laboratory study was to compare several combinations of needles used for negative pressure or syringe irrigation regarding the delivery of a contrast solution (CS) to WL and into simulated lateral canals and the volume of CS that reaches the apical region of the canal. The null hypothesis tested was that there were no differences between the combinations of needles used for negative pressure or syringe irrigation in terms of contrast solution (CS) penetration to WL and into simulated lateral canals and the volume of CS that reaches the apical region of the canal.
© 2015 International Endodontic Journal. Published by John Wiley & Sons Ltd
Adorno et al. Comparison of negative pressure irrigating systems
Materials and methods
remained in the same position throughout the procedure.
Experimental set-up and sample size estimation Transparent single-canaled straight mandibular incisor custom-made training models (Toppy Co, D-Mec ltd., Tokyo, Japan) were used. The models were designed with the main canal having an apical preparation size 40, 0.04 taper and with 100 lm in diameter lateral canals at 2, 4 and 6 mm from the apex on both the lingual and buccal aspects. The apical foramen was located at 0.5 mm from the apex and was considered as the apical limit of the WL. The dimensions of the main canal was checked by introducing a size 40, 0.04 taper NiTi rotary file (Profile, Dentsply Maillefer, Ballaigues, Switzerland) to WL. Remaining plastic debris was removed from the models, and patency of the main and lateral canals was checked with a size 06, 0.02 taper K-file (Flexofile, Dentsply Maillefer). The exit portals of the lateral canals and the apical foramen were then sealed with dual-cure flowable resin to create a closed system. Sample size estimation was calculated a priori with G*Power 3.1.9.2. The variable selected was irrigant penetration to WL. A total of 90 specimens (6 groups of 15 specimens each) would be required to detect an effect size of 0.4 by a one-way ANOVA at 80% power and with a type I error of 0.05 (two-tailed). Twenty tooth models were used for each of the 6 groups explained below. The models were mounted horizontally on a custommade platform to ensure standardization and stability during irrigation procedures. Each model underwent all irrigation procedures in a randomized crossover design. The irrigation systems included in the study were negative pressure iNP needle (Fig. 1a) and EndoVac microcannula (Fig. 1b), and syringe irrigation performed with a 30-G side-vented closed-tip needle (Vista Dental Products, Racine, WI, USA) (Fig. 1c).
Negative pressure groups Group 1 (EndoVac-0): The microcannula was passively introduced into the canal at working length and remained in the same position throughout the procedure. Group 2 (EndoVac-2): Same as EV0 except the microcannula was placed at 2 mm short of the working length. Group 3 (iNPn): The iNP needle was introduced into the canal at 2 mm short of the working length and
© 2015 International Endodontic Journal. Published by John Wiley & Sons Ltd
Syringe irrigation groups Group 4 (iNPs): Same as group 3 except the contrast solution was expressed through the needle (syringe irrigation instead of negative pressure). Group 5 (SI0): The 30-G needle was passively introduced into the canal up to working length. Group 6 (SI2): Same as group 6 except the needle was placed 2 mm short of the working length.
Irrigation procedures For irrigation, 10 mL caries detector (S 52 acid red, Visucarie, Maquira, Maring a, Brazil) mixed with 1 L of saline solution was used as CS. Dynamic viscosity was measured by a Brookfield viscometer (RVT, Brookfield Engineering, Middleburg, MA, USA) and surface tension by the stalagmometric method. An analytic balance (Sartorius A 200 S, G€ ottingen, Germany) was used to measure the density of the contrast solution. A peristaltic pump delivered the CS at a flow rate of 4 mL min 1 for 60 s. The CS was deposited into the pulp chamber by a 27-G needle (groups 1–3) or directly delivered by the syringe irrigation needle (groups 4–6) connected to a peristaltic pump. Aspiration was achieved with a dental chair suction line calibrated at 21 kPa. A recovery device was used to measure the volume of CS collected from the apical region for groups 1–3 (Brunson et al. 2010, De Gregorio et al. 2013).
Positive and negative controls Positive controls for CS penetration to working length and into lateral canals were tested by confirmation of patency and permeability of the models without sealing the apical foramen or the lateral canals and applying vacuum to the external root surface whilst irrigating. This was carried out before each irrigating procedure. The apical foramen and lateral canals were sealed with the flowable resin to test negative controls (n = 20) for CS penetration to working length and into lateral canals and the CS delivered into the pulp chamber without aspiration from within the canal. Positive controls for volume consisted of measuring the volume of CS that the microcannula and the iNP needle were capable of suctioning 5 times each from
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an open vial during 1 min. Negative controls for irrigant volume consisted of placing each needle within a confined space, that is the iNP needle to working length with apically directed pressure, and microcannula was introduced into an uninstrumented canal until it wedged. The volume collected 5 times each during 1 min was measured.
Evaluation The irrigation procedures were recorded in video format (1280 9 720.mov files) using a macro lens (EF 100 mm F2.8 L IS USM; Canon Inc., Tokyo, Japan) attached to digital single reflex camera (EOS Kiss X3; Canon Inc.). A still image at the 60-s time-point from each video was coded and evaluated. CS distance to WL was measured in millimetres from the apical limit of the contrast solution up to WL using AutoCAD (Autodesk Inc., San Raphael, CA, USA) and treated as continuous data, and penetration into lateral canals as ordinal data (3 levels; 0: no penetration, 1: penetrated up to 1/2 of the lateral canal, 2: penetrated more than 1/2 into the lateral canal). A total of 120 lateral canals per group (40 at each level) were assessed. Using Photoshop CS3 (Adobe Systems Inc., San Jose, CA, USA), two blinded evaluators scored each specimen by superimposing a grid that divided each lateral canal in two equal parts on the image. The evaluators were trained endodontists, blinded to the irrigation system used. The selective colour adjustment was used to select the ‘red’ colour and increase the density of the magenta channel to 100%. These scores were compared for interobserver agreement. In case of discrepant scores, a consensus was reached by discussion. Thirty images were randomly selected after 4 weeks and submitted to a new assessment by the same evaluators in order to test for intra-observer agreement on CS penetration into lateral canals. The total volume delivered by the syringe irrigation groups (4 mL) was considered as effectively reaching the apical region and was added to the data obtained by the negative pressure groups. CS volume reaching the apical region was measured in mL and treated as continuous data.
Statistical analysis Statistical analysis was performed with IBM SPSS (v21, New York, NY, USA) statistical package. To test for normality, CS distance to WL and the CS volume reaching the apical region were subjected
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Shapiro–Wilk test and both were found to have a non-normal distribution. Therefore, a Kruskal–Wallis test was run to determine whether there were differences in median CS distance to WL and volume reaching the apical region. Similarly, differences in irrigant penetration into lateral canals were analysed by the Kruskal–Wallis test. If the previous tests revealed significant differences, follow-up tests were conducted to evaluate pairwise differences amongst the six groups (Dunn’s test) controlling for type I error across tests by using the Bonferroni approach. The median and mode were used to summarize the results of irrigant penetration into lateral canals at each level. Significance level was set at P = 0.05. Inter- and intra-observer agreement was determined using the kappa coefficient.
Results Exact P values are reported unless lower than 0.001. Dynamic viscosity, surface tension and density were 1.245 mPas, 0.079 N m 1 and 1005 kg m 3, respectively. The CS filled all lateral canals and the apical foramen in the positive control groups, but in the negative control groups, the CS did not penetrate into any lateral canals and did not reach working length. The mean volume of contrast solution aspirated per min in the positive control test was 3.14 mL and 14.85 mL for the EndoVac and the iNP, respectively. The mean volume for the negative control was 0.27 and 0.44 mL for the EndoVac and the iNP, respectively. Kappa coefficient for interobserver agreement was 0.88, and those for intra-observer agreement of both evaluators were 0.92 and 0.89. Regarding CS distance to WL (Fig. 2), the Kruskal– Wallis test found a significant difference between groups, v2(5) = 100.817; P < 0.001. Median distance of CS penetration to WL, the P values of pairwise comparisons and effect sizes of the comparisons when the difference was statistically significant are shown in Table 1. Median, 1st and 3rd quartile of CS volume collected by groups 1–3, and mode and median of irrigant penetration into lateral canals are summarized in Table 2. The differences between median volume reaching the apical region were significant (Kruskal– Wallis, v2(5) = 105.325; P < 0.001). Pairwise comparisons (Dunn’s test with Bonferroni correction) revealed no significant differences between the syringe irrigation groups (iNPp, SI0 and SI2) and iNPn (adj. P = 0.981), all of which had median volume of 4 mL. However, these were significantly different to
© 2015 International Endodontic Journal. Published by John Wiley & Sons Ltd
Adorno et al. Comparison of negative pressure irrigating systems
Figure 2 Boxplot of contrast solution distance to working length after 60-s irrigation. Dashed line indicates the working length (WL) and dots indicate the outliers.
Table 1 Median distance of contrast solution to working length (WL), WL penetration, P values of pairwise comparison (Dunn’s test with Bonferroni adjustment) and effect size of statistically significant pairwise comparisons Median distance to WL (1st–3rd quartile) (mm)
Reached WL
EV0
0.0 (0.0–0.0)
18/20
EV2
1.7 (1.6–1.8)
0/20
iNPn
0.0 (0.0–0.0)
18/20
iNPs
0.0 (0.0–0.0)
16/20
SI0 SI2
0.2 (0.0–0.3) 0.7 (0.6–0.8)
8/20 0/20
Group
Comparison (adj. P value) EV2 iNPn iNPs SI0 SI2 iNPn iNPs SI0 SI2 iNPs SI0 SI2 SI0 SI2 SI2
(
