an in-vitro assessment of apical sealing …2018/05/04 · the sealers are absorbable when they are...

INTRODUCTION

he cleaning and shaping of root canal followed byits filling in all three dimensions is the primary

objective of contemporary endodontics1,2. If apical sealis inadequate, it can cause apical leakage and will allowthe microorganisms and their toxins to enter and disturbperiradicular tissues and can nnegatively effect theendodontic prognosis3.

The Root canal treatment fails if doesn't meet adequatestandard4. Endodontic treatment may fail due to proceduralerrors such as broken instruments, over or under fillings,perforations, ledges5. Presence of viable bacteria in thecanal and its improper obturation is one of the major causeof endodontic failure1,6.

Canal preparation technique may also influence theendodontic outcome. Literature is replete with reports ofsuperiority of Nickel-titanium rotary (NiTi) files overhand files of stainless steel (ss)7,8. Von Fraunhofer reported

JPDA Vol. 24 No. 02 Apr-June 201575

AN IN-VITRO ASSESSMENT OF APICAL SEALING ABILITYOF RESIN BASED ENDODONTIC SEALER AT VARIOUSTIME INTERVALS

INTRODUCTION: Primary objective of root canal therapy is to eradicate microorganisms followed by perfect sealobtained by obturation of the root canal. The purpose of doing this study was to find out quality of apical seal of rootcanal obturated by cold lateral technique. For obturation, epoxy resin based sealer was used and tested at variousinterval of time period of at 1 week,4 weeks and 8 weeks.METHODOLOGY: We selected 180 permanent extracted teeth with single root. x.smart protaper were used for canalinstrumentation, obturation was done by lateral cold condensation. Samples were stored for 24 hours in an incubator.Finally, prepared tooth sample were divided into two major group. Control gp [n=30] and experimental group[n=150].We sub divided the experimental group into further three sub group, containing fifty teeth each, representing theimmersion period of 1 week, 4weeks and 8 weeks in methylene blue 5% dye, at a constant temperature of 37º. Afterstorage the samples were sectioned and observed under stereomicroscope. Linear dye leakage was evaluated inmillimeters. Statistical analyses was done by using SPSS of Windows V. 16.0 .Descriptive statistics were shown asMean±SD in millimeters (mm).One Way ANOVA were used to evaluate the mean dye leakage value differences. Thesignificance level was set at 0.05.RESULT: Group A exhibited minimum leakage (2.53mm,SD ±0.87) followed by, Group B (2.69mm,SD±1.01) andGroup C (2.77mm, SD±1.02) respectively. The difference amongst all three groups was statistically insignificant.(p=0.468). However 50% teeth in Group C showed grade 3 dye penetration with comparison to 40% and 30% in GroupA and Group B.CONCLUSION: Every samples leakage.. A gradual increase in mean leakage value was observed as the storagetime increases. The differences amongst the groups remain insignificant (p=0.468).KEY WORDS: Apical seal, Apical microleakage, Resin based sealer.HOW TO CITE: Sardar PK, Abidi SYA, Iqbal W, Meo AA, Jawaed NA, Khan RSM. An In-vitro Assessment ofApical Sealing Ability of Resinbased Endodontic Sealer at Various Time Intervals. J Pak Dent Assoc 2015; 24(2):75-80.

1. Assistant Professor MDS Supervisor & Subject Coordinator. Department of Scienceof Dental Materials. Dr.Ishrat-ul-Ebad Khan Institute of Oral Health Sciences. DowUniversity of Health Sciences.2. Program Director MDS Program. Associate Professor, Incharge, Department ofOperative Dentistry, Supervisor MDS (Science of Dental Materials), Supervisor FCPS(Operative Dentistry), Dr.Ishrat-ul-Ebad Khan Institute of Oral Health Sciences. DowUniversity of Health Sciences.3. Assistant Professor, HOD Department of Science of Dental Materials. Dr.Ishrat-ul-Ebad Khan Institute of Oral Health Sciences. Dow University of Health Sciences4. Chairman, Department of Materials Engineering, NED University of Engineeringand Technology, Karachi.5. Department of Operative Dentistry. Dr.Ishrat-ul-Ebad Khan Institute of Oral HealthSciences. Dow University of Health Sciences6. Department of Science of Dental Materials.Dow International Dental CollegeDow University of Health Sciences Consultant Dental surgeon Aga Khan Hospital.Corresponding author: “Dr Khurrum Parvez Sardar”<[email protected] >

T

ORIGINAL ARTICLE

Khurram Parvez Sardar1 BDS, MDSSyed Yawar Ali Abidi2 BDS, FCPSWasif Iqbal3 BDS, MScAshraf Ali Meo4 B.E (Met.), PhD (UK)Noor-ul-Ain Jawaed5 BDS, FCPSRao Subhan Mustafa Khan6 DMD,DDS, MDS

JPDA Vol. 24 No. 02 Apr-June 2015 76

that irrespective of obturating technique used, the canalpreparation technique influenced apical leakage withcanals prepared with NiTi files exhibiting less leakage9.Amongst the obturation techniques used nowadays, coldlateral condensation is most widely taught and a goldstandard against which newer techniques are compared6,10.The root canal sealer plays an important role for theachievement of an impermeable tight seal. It fills the canalirregularities and discrepencies between the filling materialand canal wall11. It may also lubricate the core materialduring obturation12. The canals devoid of smear layer,may not only allow adhesion to dentine walls, sealer mayalso penetrate the patent tubules13.A sealer should be welltolerated and non toxic to the peri-radicular tissues, themajority of the sealers show toxicity however their toxicityis very much reduced during setting and the majority ofthe sealers are absorbable when they are in contact withtissue fluids14.

The sealers utilized in root canal system are generallydivided into groups depending on their components, forexample sealers based on calcium hydroxide, sealers basedon Zinc oxide-eugenol , glass ionomer cement (GIC)sealers, chloropercha, formaldehyde containing sealersas well as resin based sealers14. In this study we usedEpoxy resin based sealer.

Various methods of dye leakage have been reportedin the literature (linear measurement),e.g. methylene blue,eosin aqueous solutions, ink India , bacteria, radioisotopesas well as electro-chemical15-17. Other technique forevaluating the apical leakage consist of a vacuumenvironment technique, air bubble movement techniqueand fluid filtration17. The initial acceptable seal of thecanal may be challenged by length of time, solubility ofsealer, negative pH in periapex, presence of periapicalfluids, residual smear layer as well as by residual intra-canal medicament. All of these factors have beenextensively studied except for extended time duration.The physical deterioration of dental materials is timedependent. It was therefore, the aim of this study to studythe effect of extended storage of upto 8 weeks on apicalseal of root canals obturated with an epoxy resin sealer.

METHODOLOGY

This in vitro study was carried out at OperativeDentistry Department and in the Department of DentalMaterials at DIKIOHS,(DowUniversity of HealthSciences). Microscopic evaluation of samples was done

in the Department of Materials at NED University Karachi,Pakistan. The study was conducted over a duration of oneyear.

A total of 180 single rooted human teeth with nocaries or restoration present and extracted due to advancedperiodontitis were selected for the study. We excludedteeth that were cracked, broken down or has internal orexternal resorption.

ISO/TS 11405 standard were followed to Store andhandle the extracted teeth. Ultrasonic scalers were usedto remove all deposits and cleaned thoroughly.. The teethwere decoronated 1mm coronal to the CEJ and placed innormal saline. PA view X-ray (Kodak) was taken to assessthe approximate working length and patency of the rootcanal.A size K file ISO # 15 (MANI) was used forcalculating working lengths.

The canals were prepared protaper rotary NiTiinstruments (Dentsply/Maillefer) using the standardsequence. Sx was introduced first to widen the orifice,followed by S1 and S2 to prepare the coronal and middlethird. Apical third was gauged and prepared by F1, F2 orF3 according to manufacturers' instructions. The irrigationwas accomplished with a 27 gauge needle and sodiumhypochlorite (Sultan Healthcare Inc, USA) was used. 17%EDTA (Prime Dental Products of India) was used to smearlayer management followed by drying of canals withpaper points. Cold lateral condensation technique wasused for obturating the canals. An appropriate size ISOstandardized master gp was prefitted in the canal. If thegp point exhibited tug back at 0.5 to 1 mm from theworking length it was selected. The epoxy resin sealerwas mixed according to the manufacturers' instructions.The master gp was coated with sealer and inserted in thecanal. The gp was laterally condensed with a fingerspreader. Accessory gp's were subsequently filled untilthe whole of canal was obturated. The top protion of gp'swere seared off using a hot instrument and condensedwith a no. 4 hand plugger. Quality of the fill was assessedwith a radiograph and those deemed unsatisfactory wererefilled.. The cavity of access of all teeth were filled byusing Ketac Molar to make certain of a coronal seal.Samples were placed in distilled water and store up in anincubator for one day in the environment of 100% humidenvironment and at 37ºC to allow setting of a sealent.

The tooth samples (n=180) thus prepared were dividedinto an experimental group (n=150) and control group(n=30). We divided the experimental group into three sug-groups (n=50 each) that were kept in 5% methylene blue

Resin based Endodontic Sealer at Various Time IntervalsSardar PK / Abidi SYA / Iqbal W /Meo AA / Jawaed NA / Khan RSM


(MERCK) at 37°C for 1week (group 1) , 4weeks (group2) and 8 weeks (group 3) respectively. The control groupwas divided further into a positive (group D) (n=15) andnegative (Group E)(n=15) group.

Two coats of varnish/ nail polish were used to paintthe external surfaces of root samples in the experimentalgroups (A,B,C) and in positive control group (D), up tothe apical 2mm area , and completely in the negativegroup (E). As mentioned earlier, the sample belonging togroup A, B & C were kept in methylene blue dye for aperiod of 1, 4 & 8 weeks respectively. While the positiveand negative control (Group D & E) samples were furthersubdivided into smaller groups comprising of 5 sampleseach. Each sub group from group D 7 D were also keptin methylene blue for 1, 4 & 8 weeks.

After the prescribed incubation period the sampleswere washed, dried and varnish removed with a scalpel.The samples were subsequently sectioned horizontallywith the help of a sectioning disc (Noritake Dental SupplyCo. Ltd).

DATA COLLECTION PROCEDURE

Apical leakage was assessed by computing linearextention of the methylene blue dye infiltration inmillimeters in apico-coronal direction.

To eliminate bias, two evaluators made independentassessments and a mean of their readings was consideredas the final value. A stereo-microscope (Motic, HongKong) was used for visual analysis of sectioned specimens.Motic Image Plus 2.0 ML (Motic, Hong Kong) softwarewas used for measurement of linear dye leakage in allstudy groups.

DATA MANAGEMENT

A 3mm dye penetration was considered as an adequateseal, as reported earlier18.

The gradin method used in this study was modifiedfrom the one reported byKytridou and is presented intable no 119.

STATISTICAL ANALYSIS

SPSS version 16 was used for statistical analysis.Descriptive statistics was used to calculate mean andstandard deviation of dye leakage, whereas frequency ofleakage was calculated from the grading system. The

difference in mean of various groups was calculated usingthe ANOVA at a level of significance of 0.05.

RESULTS

There was no leakage in negative control group,whereas every sample in positive control group leaked.Group A demonstrated the least leakage value (2.53mm,SD ±0.87) followed by group B (2.69mm SD±1.01) andGroup C (2.77mm, SD±1.02). However, this differencewas statistically insignificant (p=0.468). (Table 2, Figure1). Table 3 represents the dye leakage in terms of ourgrading criteria mentioned in table 1. Almost half samplesof group C exhibited grade 3 leakage, whereas worst

Resin based Endodontic Sealer at Various Time Intervals

Table.1 Grading system that was used to evaluate penetrationof Methylene blue dye 19

Table.2 Mean depth of dye penetration in millimeters (mm)and Standard Deviation (±S.D)

Sardar PK / Abidi SYA / Iqbal W /Meo AA / Jawaed NA / Khan RSM


leakage (Grade 5 & 6) were very rare. Majority of samplesleaked at the interface of canal wall and root filling, whilesome samples leaked throughout the sealer.

DISCUSSION

We used an epoxy resin sealer (AH-26) in our studysince it is one of the most commonly used sealer in themarket20,21. This sealer is cost-effective and has a provenefficiency22.

AH plus may form a better adhesion with the rediculardentin due to its hypothesized formation of covalent bondwith amines of collagen23. In our study the samples thatleaked upto 3mm or less were considered as hermeticallysealed as reported by Freymann18. Majority of our samples(70% of group A and C and 62% of group B ) leaked3mm or less thus fulfilling the criteria for hermetic sealing.Thus an impervious seal was achieved in our samples foran extended period, however since we didn't compare AHplus with other sealers a generalization cannot be madeand it is one of the limitation of our study and a possiblefuture direction. We kept group C specimens in dye for8 weeks to assess the claim of De Munck that the bondof resin to radicular dentin deteriorates over an extendedexposure to dye. However, the results of our studydisagreed with these observations. This difference mightresult from a different methodology or types of sealerused in the previous study. On the other hand whenindividual leakage values are considered instead of groupmean, a trend of an increasing leakage with time can beobserved17.

In Group A, 30% of samples leaked more than 3mm,out of which 6% leaked more than 4mm. Whereas inGroup b, 40% samples leaked more than 3mm and only4% more than 4mm. Interestingly in this group 2%samplesshowed dye penetration of more than 5mm. In Group C,30% of samples leaked for more than 3mm while 12%leaked more than 4mm. Out of this 12% sample, 2%leaked more than 5mm and another 2% leaked more than6mm.

In spite of our insignificant findings, our resultssuggests that future researches may be planned keepingthese limitation in mind. We recommend using either adifferent methodology or a longer exposure time to dye.

We used a crown down technique to shape canals withNiTi instruments. Numerous in-vitro and in-vivo studieshave reported the superiority of NiTi over stainless steelfiles7,8.

Resin based Endodontic Sealer at Various Time Intervals

Table.3 Proportion of teeth with various Grades of dyepenetration in the experimental groups.

Dye

pen

etra

tion

(mm

)

Apical M

icroleakage

IMMERSION TIME PERIOD

Figure.1 The bar graph explains, mean values (mm) of theleakage of dye for the three experimental groups.

(a) After 7 days of Storage (b) 4 Weeks of Storage(c) 8 Weeks of Storage

Figure.2 leakage of dye value measured in millimeter with theuse of Stereomicroscope(D) Indicate Dentine, (M) Indicate

Methylene blue penetration.

Sardar PK / Abidi SYA / Iqbal W /Meo AA / Jawaed NA / Khan RSM


Another limitation of the study is that a comparisonamong instrument type, technique and methodology wasnot performed.

We used cold lateral condensation technique in ourstudy since it is considered to be a gold standard24.A variety of root canal obturation techniques and materialshave been reported in literature24. Similarly, a variety ofin-vitro studies have been conducted including but notlimited to coloured dye penetration, bacterial penetration,radiolabelled tracer penetration, dissolution of hard tissue,clearing of teeth, spectrometry of radioisotopes,electrochemical methods and gas chromatography25-27. Itmust however be noted that an ideal method of leakagedetection doesn't exist26.

Despite of the inaccuracy in dye penetration method,this technique is more commonly used in the analysis of coronal or apical leakage26 perhaps due to its simplicityof laboratory procedure and measurements. Literaturedemonstrate that 82% of leakage studies in root canalsystem used dye or radioisotope penetration technique27.Starkey28 concluded that methylene blue dye generallydemonstrate accurate apical leakage. According toAhlberg29 methylene blue dye is a satisfactory indicatorof leakage of microorganisms, large size endotoxins andtoxic agents with low molecular weight.

Methylene blue was used in the study because itshowed accurate results in previous studies28. It is easilyavailable, less expensive and simple. Our results suggestthat none of the samples had an impervious seal sincesome leakage was present in each group with a statisticallyinsignificant difference between the groups.According to Hovland and Dumsha, leakage is present inmost if not all the sealers in-vivo. It only becomespathological or symptomatic if it reaches a certain criticallimit resulting in apical periodontitis. The exact dynamicsof the leakage is complicated by the presence of manyinterfaces between canal wall, solid core and sealer.Dissolution of the sealer itself may enhance leakage30.Similarly, De Moor has reported that the use of a tracingmechanism and its observation by splitting a root may bea simple and efficient method to study leakage31.

In our study, in spite of non-significant findings thereis still a need for further work to compare different canalpreparation techniques, sealers and obturation techniquessince all of these variables may influence the final sealof the canal. It is also important not to overlook thebio-compatibility and cyto-toxicity and one should striveto strike a balance. Other reasons of leakage in our study

might be attributed to the presence of entrapped airor aberrant anatomy which was not studied in our workand hence the results of our study must be interpretedwith caution and may be topic of research in future studies.

CONCLUSION

We draw following conclusions on the basis of our results.. Leakage was present in all the samples. A gradual increase in mean leakage value was observedas the storage time increases.. The differences amongst the groups remaininsignificant (p=0.468).

REFERENCES

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an in-vitro assessment of apical sealing …2018/05/04 · the sealers are absorbable when they are...

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