apical leakage

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Apical Leakage of Resin Based Root Canal Sealers with aNew Computerized Fluid Filtration MeterHasan Orucoglu, DDS, PhD,* Abdulkadir Sengun, DDS, PhD, and Nihat Yilmaz, DDS, PhD

Abstract

In this in vitro study, the apical leakage of three root-canal sealers: AH Plus, Diaket, and EndoREZ was eval-uated using a new computerized fluid filtration meter.Forty-five extracted human premolar teeth with singleroot and canal were used. The coronal part of eachtooth was removed and the root canals were preparedusing GT Rotary files and crown-down technique. Theroots were randomly divided into three groups of 15samples, filled with one of the test materials and gutta-percha cones by the cold lateral condensation tech-nique and were stored at 37C and 100% humidity for

7 days. One-week later, apical parts of roots of 10 0.05 mm were attached to computerized fluid filtrationmeter. Apical leakage quantity was determined as l/cmH

2O/min1. Statistical analysis indicated that root

fillings with Diaket in combination with cold lateralcondensation technique showed lower apical leakagethan the others (p 0.05). In addition, this newcomputerized fluid filtration meter allowed quantitativemeasurement of leakage easily. As it is a newly devel-oped device to measure apical leakage of endodonticsealers, the reliability of it needed to be tested.

Key Words

Apical leakage, computerized fluid filtration meter, res-in-based root canal sealers.

From the *Department of Endodontics, Faculty of Den-tistry, Selcuk University, Konya, Turkey; Department of Oper-ative Dentistry, Faculty of Dentistry, Selcuk University, Konya,Turkey; and Department of Electrics and Electronics, Facultyof Engineering and Architecture, Selcuk University, Konya,Turkey.

Address requests for reprint to Dr. Hasan Orucoglu, De-partment of Endodontics, Faculty of Dentistry, Selcuk Univer-sity, Konya, Turkey. E-mail address: [email protected].

Copyright 2005 by the American Association ofEndodontists

The objectives of modern endodontic therapy are to clean and shape the root canalsystem removing all organic material and to seal this system with a permanentthree-dimensional filling that does not allow leakage (1, 2). The apical leakage of theendodontic sealers has been measured by degree of penetration of a dye (3, 4), radio-isotope penetration (5), bacterial penetration (6), electrochemical means (7), orscanning electron microscopy (8). Dye penetration techniques are the most frequentlymethods used (9, 10). These techniques require the destruction of the samples toobtain measurementsof leakage, thereby precludingthe measurement of changes in theapical seal over time in individualsamples. Also, these methods only indicate leakage inone plane and are not quantitative (11).

A method of measuring microleakage by fluid filtration method (12) overcomesthe disadvantages of previous methods. Samples are not destroyed, and it is possible toobtain measurements of microleakage at intervals over extended time periods. In ad-dition, conventional fluid filtration measurements reflect the leakage of the entire sam-ple and quantitative (10). However, the measurements are relatively subjective becauseof direct visual readings. A computerized, fully electronic, reliable, and digital airpressure checking system is required to remove these deficiencies.

Sealers available for the profession today are zinc oxide-eugenol based, calciumhydroxide based, resin based, glass ionomer based, or silicone based (13). Resin-based root canal sealers have been used for many years with clinical success (14, 15).There are a lot of resin-based root canal sealers. Well-known resin based root canalsealers are AH Plus (Dentsply DeTrey GmbH, Konstanz, Germany), AH 26 (DentsplyDeTrey GmbH, Konstanz, Germany), Endofill (Lee Pharmaceuticals, South El Monte,CA), and Diaket (Espe Dental, Seefeld, Germany). Recently, a new hydrophilic, ure-

thane-dimethacrylate-based resin sealer, EndoREZ (Ultradent, South Jordan, UT), hasbeen developed for use with a single, gutta-percha cone for canal obturation. To date,limited data is available about EndoREZs sealing properties.

The purpose of this in vitro study was to comparatively evaluate apical leakage ofthree root canal sealers using a new computerized fluid filtration meter with a lasersystem and a digital air pressure regulator and also to test statistical reliability of thisdevice.

Materials and MethodsForty-five extracted human noncarious single rooted premolar teeth were used in

this study. These teeth were extracted for various reasons, and none had receivedendodontic therapy before extraction. All teeth were stored in formalin immediately

after extraction.All soft tissues andcalculus were removed mechanically from the teeth.Allteethwere also radiographed from both bucco-lingual andmesio-distal directionstodetermine the number of the canals in each root.

The crowns of teeth were sectioned at the cemento-enamel junction using a lowspeed diamond saw (Buehler, Isomet, Lake Bluff, NY). A working length for each rootwas then established at 1 mm short of the apical foramen using a digital radiography(Gendex Visualix, Gendex Dental Systems, Milano, ltaly) and a #15 K-file. Root canalswere instrumented using GT Rotary files (Dentsply Maillefer, Ballaigues, Switzerland)and crown-down technique at the established working length. During instrumentation5.25% NaOCl was used for irrigation of each root, and upon completion of instrumen-tation root canals were flushed with 10 ml of 5.25% NaOCl. The patency of the apicalforamen was maintained with a #20 K file, and the teeth were stored in saline untilobturation.

Basic ResearchTechnology

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Forty-five teeth were randomly divided into one of three experi-mental groups of 15 teeth each. An additional six teeth were used forcontrol (three for negative control and three for positive control). Afterair drying, a #20 K file 2.0 mm longer than the working length waspassed through the apex of each tooth and with the file in place threecoats of nail polish were applied to external root surfaces to avoidsealing from the foramen after obturation. The negative control teethwere totally coated with three layers of nail polish, including the apicalforamina.

Each tooth was given a code number except for the positive con-trols and all roots were obturated with gutta-percha (Adentatec GmbH,Koeln, Germany) in combination with different root canal sealers usingcoldlateral condensation technique.Positive controls were leftunfilled.

After filling, the roots were stored at 37C and in a 100% humidityenvironment for 7 days. Seven days later, each root was allowed tobench cool for 1 h before testing, to reach room temperature.

For leakage study, apical roots of 10.00 0.05 mm were sec-tioned using low speed diamond saw. Root sections were inserted intothe plastic tube from the apical side andconnected to 18-gauge stainlesssteel tube. The cyanoacrylate adhesive (Zapit, Dental Venture of Amer-ica Inc., Anaheim Hills, CA) was applied circumferentially between theroot and plastic tube. A new computerized fluid filtration meter with a

laser system used in this study have had a 25-l micropipette (Micro-caps, Fisher Scientific, Philadelphia, PA) mounted in horizontally. O

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from a pressure tank of 120 kPa (1.2 atm) was applied at the apicalside. The pressure was constant throughoutthe experiment by means ofa digital air pressure regulator added to pressure tank. A 25-l mi-cropipette (Microcaps, Fisher Scientific, Pittsburgh, PA) connected tothe pressure reservoir by polyethylene tubing (Microcaps, Fisher Sci-entific). All pipettes, syringes and the plastic tubes at the apical side ofthe sample were filled with distilled water. Water was sucked back withthe microsyringe for approximately 2 mm. In this way, an air bubblecreated in the micropipette and the air bubble was adjusted to a suitable

position in the syringe. The new computerized fluid filtration meter wasbased on basically light refraction at starting and ending position of airbubble movement inside micropipette. Through one side of the mi-cropipette inside the device, an infrared light was passed. Two light-sensitive photodiode was arranged on the opposite side of the micropi-pette to detect any movement of an air bubble inside micropipette. Alloperations were controlled with PC-compatible software (Fluid Filtra-tion03, Konya, Turkey). A 5-min pressurization preload of the systemwas completed before taking readings. Measurements of fluid move-mentwereautomaticallymadeat2minduring8minforeachsamplebyusing PC-compatible software (Fluid Filtration03, Konya, Turkey). Thesoftware converts minute linear movement of the bubble into nanolitermovement at a rate of one measurement. This information is fed intoPC-compatiblesoftware. Leakage quantity was expressed asl/cmH

2O/

min1 and means determined.

Statistically Analysis

CronbachsAlpha test wasused to determine reliability of the com-puterized fluid filtration method (16, 17). Then, one-way ANOVA andpost hoc Tukey HSD Tests were used to determine whether differenceswere significant at the 95% confidence level.

Coefficient of Determination R2

The total variability in the dependent variable, the total sum ofsquares could be partitioned into the variability explained by the regres-sion line, theregression sum of thesquares and thevariabilityabout theregression line, the error sum of squares. The proportion of the totalvariability accounted for the regression line was the coefficient of de-termination that takes a value between zero and one (18).

ResultsCronbachs Alpha test method proven that this new computerized

fluid filtration meter was statistically a reliable method (R2 0.9962).

Figure 1. A new computerized fluid filtration meter.


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Mean microleakage measurements and standard errors, in l/cmH

2O/min1 1.2 atm, are shown in Table 1 for all materials. Diaket

demonstrated the least amount of microleakage among the tested ma-terials, resulting in 0.000135 0.000042 l/cmH

2O/min1 1.2 atm.

AH Plus proved to have the secondleast amount of microleakage amongthe tested materials, exhibiting 0.000356 0.000132 l/cmH

2O/

min1 1.2 atm. There was a significant difference between Diaket andAH Plus (p 0.05). Overall, The EndoREZ samples demonstrated thegreatest amount of microleakage, having 0.000756 0.000189 l/

cmH2O/min

1

1.2 atm. There were significant differences between AHPlus and EndoREZ, and between Diaket and EndoREZ (p 0.05, foreach).

The positive controls demonstrated extreme amounts of apicalleakage. Mean leakage for the positive controls was observed to be0.015 0.002 l/cmH

2O/min1 1.2 atm. The negative controls reg-

istered no detectable bubble movement at 1.2 atm, for a minimum of 5min before each data collected began.

In this study, all of the root canal sealers showed apical leakage atdifferent levels. Data indicated that thisnew computerized fluid filtrationmeter was a reliable method (R2 0.9962).

DiscussionIn thisin vitro study, the different root canal sealers apical leakage

was tested using a new computerized fluid filtration meter. In vitro dyestudies have been criticized because mean leakage values are derived

from a range of measurements andthe resultsand conclusions areofteninconsistent between studies. Such differences may be attributed tovariations in specimens, testing procedures, dental methods, and leak-age interpretations (3, 19). One of the major considerations in respectof dye penetration studies is that entrapped air in voids along the rootcanal fillingmay hinder movement of fluid (20). On the other hand, theposition of the root apex hasan effect in thetesting of apical root sealing(21).

Comparing dye penetration and fluid filtration method, it can be

considered that: a) Fluid filtration method suggests pathways betweenthe coronal and the apical end of a root filling; b)Fluid filtration methodvalues indicate the diameter and length of the void, rather than thelength of the void only (22). Dye penetration technique has the maindisadvantage of being semi-quantitative in during, often involving onlyone plane of view. Dye penetration techniques do not provide any in-formation concerning the volume of tracer that actually penetrates theinterface void.

Karagoz-Kucukay et al. (23) and Wimonchit et al. (19) reportedthat the clearing technique allows three-dimensional visualizationof thegutta-percha filling within the tooth structure with the aid of stereomi-croscope. In addition, the extent and distribution of the India ink couldalso be evaluated and measured. However, consequent storage of the

cleared specimens in methyl salicylate for a longer period causedthe sealer to overflow slightly through the apical foramen with a bub-bling action.However,the clearing systemcould not be used to measurethe volume of the tracer ingress. In an in vitro study by Youngson et al.(24), there was no statistically significant correlation between the fluidfiltration measurements and clearing technique measured by a scoringsystem. Fluid filtration was a more sensitive technique. Clearing, al-thoughvisually impressive, hasnever been satisfactorily verified to com-pletely demonstrate the pattern of the tracer penetration. It is difficult tomeasure precisely and the tracer may be lost during the tissue process-ing (4).

Another leakage testing method is electrochemical technique.Amditis et al. (25) claimed that accumulation of corrosion deposits onthe copper anodemay have caused a diffusionbarrier to theflowof ions

TABLE 1. Mean microleakage (l/cmH2O/min1 1.2 atm) value and SD for

experimental groups

Mean Microleakage

SealerNo. ofTeeth

(l/cmH2

O/min1 1.2 atm) SD

Diaket 15 0.000135a

0.000042

AH Plus 15 0.000356b

0.000132

EndoREZ 15 0.000756c

0.000189

Means with different superscript symbols indicate significant differences (p 0.05).

Figure 2. PC-compatible software.




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and thereby hindered leakage readings. Therefore, the longitudinalleakage results produced by the electrochemical technique may alsobecome unreliable.

The result of the present study support the previous studies results(10, 26) that the fluid filtration technique of measuring microleakageof endodontic fillings was a reliable method. This technique allowsquantitative measurements of microleakage without the destruction ofsamples.

The computerized fluid filtrationmeter used in this study hassomeadvantages over the conventional ones with computer controlling anddigital air pressure arrangement. Additionally the movement of air bub-ble can be observed by laser diodes computer controlled rather thanvisual following. In an vitro fluid filtration study, Pommel et al. (27)used an electronic flow detector that fluid movement was calculatedfrom the bubble movement, which was followed automatically by aninfrared light photodiode. However, in Pommel et al.s study the tech-nique was not tested with a statistically analysis that test reliability.

Reliability analysis is an important component of engineeringwork that draws on the areas of probability and statistics. Reliabilityanalysis is concerned with the investigation of the failure rates of com-ponents and systems that are typically represented as probabilities. The

reliability of a component, which can be denoted byr, can ingeneralbethought of as the probability that it performs a certain task. The com-plement of this probability is therefore the probability that the compo-nent fails to perform the required task or the probability that the com-ponent fails. A complex system may consist of a large number ofcomponents each with its own reliability value (18).

Reliability analysis allows studying the properties of measurementscales and the items that make them up, calculates a number of com-monly used measures of scale reliability and also provides informationabout the relationships between individual items in the scale. Intraclasscorrelation coefficients can be used to compute inter rater reliabilityestimates (18).

There are a lot of models of reliability analysis. These are Alpha(Cronbach), Split-half, Guttman, Parallel, and Strict parallel. Amongthese, Cronbach Alpha is a model of internal consistency, based on theaverage inter-itemcorrelation.Thatswhy, in thisstudy, Cronbach Alphatest method were used. All of the root canal sealers tested showedmeasurable leakage properties by computerized fluid filtration meter.According to this study, Diaket had lower apical leakage than the others.Similar results have been reported by Gerhards and Wagner (28). Theyconcluded that Diaket is a good sealer when used as a retrograde filling.Diaket is organic polyketone compound and polycarboxylate cements(29, 30). When mixed in two parts powder to one part liquid, it has anideal handling property. This material offered a firm working consis-tency and acceptable working time of 30 min or more, which wasconsistent with previous studies (31).

The manufacturers of AH Plus claim it to be an improved pastepaste material based on epoxy-amine resins, with more pronouncedradiopacity and faster setting than conventional AH26. As all specimenswere kept in 100% humidity, one can speculate that oil-based materialssuch as AH Plus could prevent complete wetting of the root-canal wallandadhere poorly to humid dentine. This may result in poor adaptationof the material to the root-canal wall (32).

Miletic et al. (33) examined the apical sealing ability of five rootcanal sealers (AH Plus, AH 26, Diaket, Ketac-Endo, Apexit) and foundthat, there were no significant differences in leakage of tested materials(p 0.05). However, these findings are in contrast with the results ofMiletic et al. (33). In our study, AH Plus showed more leakage thanDiaket. This can be explained by the faster setting time of AH Plus. Thismight have created stresses that cause earlier debonding from dentinal

walls. Also, some ingredients of AH Plus, such as silicone oilsmight alsohave an affect on the sealing ability of this material.

Relation of root canal filling material with the surface of the canalwall in the presence or absence of thesmear layer may be important forapical leakage. Cobankara et al. (34) indicated that removal of thesmear layer has a positive effect in reducing apical and coronal leakagefor both AH26 and Roekoseal root canal sealers. The present studysmear layer was notremoved. Removal of the smear layer may affect theresults of this study. Limited data are available about the sealing orothers properties of EndoREZ. Kardon et al. (35) observed the rootsobturated with EndoREZ and single cone of gutta-percha showed moreleakage than that of obturated with AH Plus and a single cone of gutta-percha. Therefore, in the present study, lateral condensation of gutta-percha technique was used. Facer and Walton (36) found that sealers(Roths, Sealapex and AH26) neither formed a continuous layer be-tween the gutta-percha obturant and the canal wall nor totally filled thespaces between cones. It appeared that, where portions of gutta-perchawere laterally condensed and closely adapted to the dentin wall, thissqueezed out the sealers, thusresultingin gutta-percha in direct contactwith the canal wall.

The result of this study indicated that EndoREZshowedthe greatestapical leakage. This situation can be either a result of the physical and

chemical characteristics of the materials that are used or the differenceof polymerization contractions.

ConclusionWith the limitations of this study, the following conclusions were

drawn:1. Diaket showed significantly less leakage than AH Plus and En-

doREZ.2. The computerized fluid filtration meter provides a simple and

convenient method for measurement of endodontic leakage.3. Further studies comparing traditional fluid filtration test and

computerized fluid filtration meter test are needed.

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