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Cairo Dental Journal (25)
Number (3), 323:328
September, 2009
The INflUeNCe Of MTAD IRRIgANT
ON The ApICAl MICROleAkAge
Of ObTURATeD ROOT CANAlS
Mohamed M. Ibrahim;(1) Naguib M. Abul Enein;(2) Abdalla M. Shahin(3) and Amany E. Badr(4) 1. Assistant lecturer, Conservative Dentistry Department, Faculty of Dentistry, Mansoura Univerisity.
2. Professor, Head of Endodontic Department, and Vice Dean of Faculty of Dentistry, Suez Canal University.
3. Professor, Geology Department, Faculty of Science, Mansoura University.
4. Associate Professor of Endodontics, Conservative Dentistry Department, Faculty of Dentistry, Mansoura University.
. AbstrAct
Recently a mixture of a tetracycline isomer, an acid, and a detergent, combined in a product called MTAD has been suggested as a final rinse to remove the smear layer from the surface of instrumented root canals. The purpose of this study was to investigate the influence of MTAD and alternate use of EDTA and MTAD with NaOCl on the apical microleakage of obturated root canals. In this study 60 maxillary central incisors were decoronated at cemento-enamel junction. The roots were divided into six groups of ten teeth each according to irrigation regimens used during preparation of root canals as follows: Saline, NaOCl, MTAD, NaOCl / EDTA, NaOCl / MTAD, and NaOCl / EDTA / NaOCl. After cleaning and shaping, roots were obturated with gutta percha and Endofill root canal sealer using lateral condensation technique and incubated at 370C for 48 hours. The roots were coated by nail varnish and immersed in india ink then rendered clear by using 10% nitric acid and methyl salcilate. Dye-penetration extent was measured using stereomicroscope. The results of this study showed that roots irrigated with NaOCl / MTAD had a significantly least mean extent of dye-penetration values compared with all irrigating regimen except NaOCl / EDTA. In conclusion the final rinse with either MTAD or EDTA following 2.5% NaOCl irrigation could reduce the root apical microleakage. . INTRODUCTION
The smear layer is formed of inorganic and organic substances, which include fragments of odontoblastic The main objectives of root canal therapy are removal processes, microorganisms and necrotic materials3. of diseased tissue, elimination of microorganisms present Whereas the smear layer itself may be infected, it also in the canals and dentinal tubules, and prevention of may protect the bacteria already present in the dentinal recontamination after treatment1. The current techniques tubules from the action of the antimicrobial agents4-6. Its removal from infected root canals may lead to better of root canal debridement produce smear layer and penetration of intracanal medications into the dentinal leave some areas of the root canal system completely tubules and more effective disinfection of the root canal The most popular and advocated irrigant is sodium . MATeRIAlS AND MeThODS
hypochlorite (NaOCl). It has several properties that Sodium hypochlorite (NaOCl) at 2.5%, 17% EDTA contribute to achieve chemical debridement of the , MTAD (Dentsply, Tulsa) were used in this study as root canal system8. NaOCl has an antibacterial and intracanal irrigants. Sixty recently extracted human lubricant effect, and has the capability of dissolving maxillary central incisors were used in this study. After tissue remnants and flushing out loose debris but it does cleaning they were rinsed and stored in thymol till time not remove the smear layer from the dentin wall9-11. Currently, a combination of solutions such as ethylene diamine tetra-acetic acid (EDTA) and NaOCl is used to The crowns of the teeth were decapitated at the remove the smear layer from root canal walls12.
cemento-enamel junction with a diamond disk under Some Studies suggested that removal of smear layer water coolant. The roots were randomly divided into six groups of ten teeth each according to irrigation regimens the treatment with EDTA may leave a chelated layer of used during preparation of root canals as follows: dentine at the dentine-root filling interface. Residual group I: (Saline) Irrigation with 1 ml saline was used
EDTA inside the dentinal tubules, which was measured to be up to 3.8% of the originally applied volume, may group II: (NaOCl) Irrigation with 1 ml of 2.5% NaOCl
contribute additionally to ongoing demineralization, resulting in further increase of apical-leakage15-17. Residual EDTA also may interact with the sealer, group III: (MTAD) Irrigation with 1 ml of MTAD
which has been demonstrated with zinc-oxide eugenol containing sealers17. Because of these limitations, a group IV: (NaOCl / EDTA) Irrigation with 1 ml of
search for a better root canal irrigant is not stopping.
2.5% NaOCl was used after each file followed by Various acids , ultrasonic instruments , and lasers a final rinse with EDTA for 3 min at the end of have been tried to remove the smear layer18-20. Recently a mixture of a tetracycline isomer, an acid, and a detergent, group V: (NaOCl / MTAD) Irrigation with 1 ml of
combined in a product called MTAD has been suggested 2.5% NaOCl was used after each file followed by as a final rinse to remove the smear layer from the surface a final rinse with MTAD for 3 min at the end of of instrumented root canals. The experimental studies showed many favorable results of MTAD, as it has the ability of dissolving inorganic and organic content of group VI: (NaOCl / EDTA / NaOCl) Irrigation with 1 ml
dentin, and to remove the smeared layer completely21,22. It of 2.5% NaOCl was used after each file followed also has been shown to have low degree of cytotoxicity23.
by irrigation with EDTA for 3min and a final rinse with NaOCl for 2 min. The controversial suggestions about the effect of removal of smear layer on apical microleakage using The working length of all roots was visually different irrigating solutions may need more research to determined by subtracting 1 mm from the length of a size study their effect and to reach the most suitable regimen 15 K-file (Dentsply, Maillefer, Ballaigues, Switzerland) at of irrigation. Accordingly this study was conducted the apical foramen. All roots were prepared at the coronal to investigate the influence of MTAD and alternate two thirds using size 2-4 Gates Glidden burs (MANI, use of EDTA and MTAD with NaOCl on the apical INC, Japan) followed by apical preparation using step- microleakage of obturated root canals.
back technique to the size 50 K-file. Final flush of root canal of all groups were performed with 5 ml distilled NaOCl / EDTA / NaOCl with the highest extent of dye water to remove any traces of irrigants and dried with penetration(3.760mm ± 0.898) Fig. (1) One way ANOVA paper points. The roots were obturated with gutta percha test showed significant difference among groups (p < and Endofill root canal sealer using lateral condensation 0.05). LSD test showed significant difference between technique and the root canal orifices were filled with group V and groups (I, II, III and VI). The test also Cavit and then were kept in an incubator at 37oC and showed significant difference between group IV and 100% humidity for 48 hours to ensure complete setting group VI. Representative photographs of the extent of dye-penetration in each group are shown in (Fig. 2). Assessment of Apical microleakage
Dye penetration and clearing Technique
The external surfaces of all roots were coated by two successive layers of nail varnish except the apical 2 millimeters. The roots were held vertically with the help of meshwork in a plastic box containing 2 mm depth of India ink, so that only the apical 2 mm of each root were immersed in the dye. The roots were left in the dye for three days, after which they were removed, washed and the nail varnish was removed with scalpel. fig. (1) A bar chart represents the mean values (in millimeters)
The roots were subjected to decalcification using 10% and standard deviation (SD) of apical microleakage as nitric acid for 3 days, followed by washing with tap water to remove remaining acid. After that, the roots were dehydrated in increasing alcohol concentrations (60, 70, 80, 90 and 100%) and immersed in methyl salicilate, to render it transparent, until the time of image analysis. The binocular stereomicroscope (Olympus Zoom Stereomicroscope, Sz 40-45, Japan) were used to measure extent of dye- penetration up to the most coronal mark in millimeters (at magnification of X20). The data were collected and subjected to statistical analysis using ANOVA and LSD tests. . ReSUlTS
The apical microleakage was presented as mean extent of dye-penetration in millimeters. Roots irrigated with NaOCl / MTAD had the least mean extent of dye-penetration values (1.5 mm ± 0.577). Fig. (2) Stereomicroscopic photographs showing the extent of In increasing order, it was followed by NaOCl / dye-penetration in obturated samples of (a) Saline (3.5 EDTA (2.440mm ±0.702), MTAD (2.888mm±1.059), mm), (b) NaOCl (3 mm), (c) MTAD (2.7 mm), (d) NaOCl / EDTA (2 mm), (e) NaOCl / MTAD (1 mm), and NaOCl (3.125 ±0.85), Saline (3.570±1.1) and finally . DISCUSSION
rinse has less apical microleakage than those irrigated Recently, an alternative endodontic irrigant contain- with either saline or NaOCl. Also, several studies of coro- ing 3% doxycycline, 4.25% citric acid and 0.5% tween 80 nal microleakage indicated a reduction of leakage using detergent is being commercialized as Biopure MTAD EDTA or MTAD as a final rinse following NaOCl12,30-32. This irrigant is recommended to be used as the final rinse In contrast to our results other investigators33-36 showed that there is no significant improvement in microleakage well-conducted studies, MTAD has been shown to be after removal of smear layer. Timpawat and coworkers37 are the only investigators who have reported that removal of the smear layer has adverse effect on microleakage of 21 endodontic irrigant with potential sustained obturated root canals. These conflicting results might be because of differences in types of sealers and obturation Accordingly this study was conducted to investigate techniques, means of producing a smear layer, and the the influence of MTAD and alternate use of EDTA diversity of methodologies used to assess microleakage and MTAD with NaOCl on the apical microleakage of under various laboratory conditions.
obturated root canals. The clearing technique used in this On the other hand, canals irrigated with NaOCl / study for evaluating apical microleakage showed a good EDTA / NaOCl showed maximum leakage values. This three dimensional view of the root canal system; so that; may be attributed to the action of EDTA which is not measuring the apical leakage of ink around the filling selective for the smear layer. Its demineralizing effect was facilitated and comparison between the groups using also acts on the walls of root canals and these demineral- different irrigating regimens became easier. ized matrices produced by EDTA are removed by NaOCl The results of apical microleakage indicated that when used as a final rinse. This procedure inadvertent- root canals irrigated with NaOCl / MTAD results in the ly creates highly irregular, eroded canal dentin surface least leakage among all regimens used. This reduction in which may prevent proper adaptation of the filling mate- leakage may be attributed to increased surface contact rial to the canal wall38. Under the condition of this study, between the dentin and the sealer, and penetration of the final rinse with either MTAD or EDTA following irri- obturation materials into the open dentinal tubules28. gation with 2.5% NaOCl could reduce the apical micro- This proper adaptation may be related to previously proved very high capability of MTAD in removing the smear layer. Also the presence of lubricant (Tween 80) . RefeReNCeS
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