The accuracy of three different electronic root canal measuring devices: an in vitro evaluation

Transcription

1 91 Journal of Oral Science, Vol. 44, No. 2, 91-95, 2002 Original The accuracy of three different electronic root canal measuring devices: an in vitro evaluation Ali Cemal Tinaz, Murat Maden, Cumhur Aydin and Emin Tiirkoz Department of Operative Dentistry and Endodontics, Faculty of Dentistry, Gazi University, Ankara, Turkey (Received 3 September 2001 and accepted 23 May 2002) Abstract: The main objective of this in vitro study was to evaluate the effects of the operator's experience level and pre-flaring on the accuracy of the results of three different brands of a new generation of root canal measuring devices, as well as the comparison among them. Extracted human teeth were prepared and then actual length and electronic length measurements were made by three different operators according to a double-blind technique. Three different operators performed electronic measurements on each specimen separately with three different electronic root canal measuring devices using in vitro models. Measurements were repeated by all operators after the pre-flaring. Taking the clinical tolerance of } 0.5 mm into account, there was no statistically significant difference between the accuracy of the instruments (P > 0.01). However, the results obtained from the Bingo electronic apex locator in pre-flared canals by the beginner operator were statistically significant (P < 0.01). All of the instruments had a clinically acceptable result at the tolerance of } 0.5 mm. If the instruments are used in accordance with the manufacturer's instructions, experience with electronic root canal measurement is not essential. However, the operator has to be more careful when working on pre-flared canals. (J. Oral Sci. 44, 91-95, 2002) Key words: apex locator; working length. Correspondence to Dr. A. Cemal Tinaz, Department of Operative Dentistry and Endodontics, Faculty of Dentistry, Gazi University, 82. Sokak, Emek, 06510, Ankara, Turkey Tel: actinaz@yahoo.com Introduction A successful long-term root canal treatment depends on the true determination of working length (1). The ideal root canal preparation and obturation should be established at the apical constriction. While there are two different distances between the radiographic apex and major and minor foramens to be determined, it is not possible to locate these points accurately by radiographic or tactile methods (2). Although the distance between the major foramen and radiographic apex is usually 2 mm, the distance between the apical constriction and major foramen may vary by 1 mm or more (3). Electronic root canal length measuring devices have been developed in order to determine the location of the apical constriction and major foramen. The former generations of these devices were easily affected by various contents of the root canal. The manufacturers of recently introduced new generation apex locators claim a consistent accuracy regardless of irrigants or other fluids present in the canals. Fouad et al. (4) showed that the new generation devices can accurately determine the apical constriction, even in the presence of various liquids. In another in vivo study, Shabahang et al. (5) tested the accuracy of the new generation apex locator Root ZX and found an accuracy rate of 92.6%, within a tolerance of } 0.5 mm. Alternatively, De Moor et al. (6) studied another new generation apex locator device, the Apex Finder AFA Model 7005, and found it the most accurate one in comparison with the others in their study. Stabholdz et al. (7) analyzed the effect of pre-flaring of the canals, which might have an effect on the tactile sensitivity of an operator who attempts to locate the apical constriction manually. They emphasized the tightening of

2 92 Fig. 1 The alginate in vitro model for electronic measurements. files in the coronal third of canals and stated that files should pass the apices more easily if canal orifices were enlarged by the crown-down technique. On the other hand, the experience of the operator who has to use these sophisticated electronic root canal measuring devices might have an effect on the accuracy of the results and it should also be investigated. The main objective of this in vitro study was to evaluate the effect of the experience level of the operator and preflaring on the accuracy of the results of three different brands of new generation root canal measuring devices as well as the comparison among them. Materials and Methods Thirty-nine single rooted teeth with one canal were collected for use in this study. The crowns of the teeth were removed by cutting the teeth with a water-cooled high-speed diamond bur (North Bel Int.I S.r.I. Italy) at their cementenamel junctions. The contents of root canals were removed with a convenient barbed broach. In order to standardize the apical pattencies, a #20 K type file (Zipperer UDM West Palm Beach, FL) was used under ~ 10 magnification (Olympus, SZ-PT, Japan) and the file was immediately back drafted after extending it 1 mm beyond the apical foramen. The teeth having an obstruction in their apical foramens were excluded as well as those with an open apex which let the # 20 file pass the apical foramen very easily final number of teeth to be tested was 32. The actual length measurement of these prepared. The specimens. A K type # 20 file that was inserted into the canal up to its major apical foramen to measure the actual length. The file was retracted to the minor apical foramen with the help of a ~ 10 magnifying microscope and it was, marked with a stopper at the cut surface. The length between the tip and the lower side of the stopper was measured to the nearest 0.02 mm and recorded as the actual length. Three different operators, using a doubleblind technique, repeatedly performed the measurements and thus three separate actual length measurements from each specimen were completed. The first operator was an expert (E) on electronic measurements, the second one was a familiar (F) with such procedures and the last one was a beginner (B). Then the lip-clip of the device and all of the roots were embedded up to their cement-enamel junctions into unset alginate (Blue Print, Dentsply Ltd., De Trey Div., Weybridge, Surrey, England) which was freshly prepared according to the manufacturer's instructions and poured into a plastic container (Fig. 1). The alginate was then left to set. The specimens were kept continually moist and refrigerated until testing. Root ZX (Morita Corp., Tokyo, Japan), Apex Finder AFA Model 7005 (EIE Analytic Technology, Orange, CA, USA) and Bingo 1020 (Tel Aviv, Israel) electronic root canal measuring devices were adjusted to the "0" mark which indicates the major apical foramen, and electronic measurements of each specimen were performed separately by three different operators with each electronic root canal measuring device. These measurements were performed according to the manufacturer's instructions in the presence of 2.65% Na0C1 in the root canals and the results were recorded to the nearest 0.02 mm. Pre-flaring of all specimens was performed with a.06 tapered rotating Quentec (Analytic Endodontics, Glendora, CA, USA) nickel titanium instrument followed the electronic measurements. All operators repeated electronic measurements after the pre-flaring and these results were also recorded. The actual length measurements were taken as the controls and the results obtained by electronic measurements were compared with the control group with a Student's t test. The differences between the operators were evaluated with the Friedman test. Results The means of the differences of flared and non-flared experimental groups relative to the control group are given in Table 1. The sign of (-) preceding the numbers means that the file was passed beyond the apical foramen. Taking the clinical tolerance of } 0.5 mm into regard there was no difference between the instruments either in non-flared canals and pre-flared canals (P > 0.01) (Table 1). However, when the tolerance in the periapical region was diminished to } 0.1 mm, more accurate measurements were obtained

3 93 with the Apex-Finder AFA 7005 and Bingo, relative to those with Root ZX in the non-flared group, while more accuracy was obtained with Root ZX compared to other two instruments in the pre-flared specimens. Additionally, there was no statistically significant difference among operators in the non-flared groups (Tables 2-4). When the results obtained with the different operators were compared, there was only one statistically significant finding (P < 0.01) and it was the result obtained from Bingo by the beginner operator (B) on pre-flared specimens (Table 3). Discussion In this study, the accuracies of three different brands of electronic apex locating devices of the same generation were compared, as well as the effect of the experience level of the operator. When determining the length of tooth roots, the results of all devices were comparable. The difference of the operators and their experience levels also was not associated with statistically significant differences in the results. This can be related to the effectiveness of the multi frequency property of new generation devices. Table 1 Means of the differences between the control group and non-flared (x) and pre-flared (y) specimens for three electronic apex locators, together with the maximum and minimum values (n = 32) Table 2Means of the results obtained with Root ZX by three different operators on non-flared (x) and pre-flared canals (y) (n = 32) Table 3Means of the results obtained with Bingo by three different operators on non-flared (x) and pre-flared (y) canals (n = 32)

4 94 On the other hand, the effect of a rotary instrument,.06 tapered Quentec, which is suggested for accessment to the root canal, on electronic root length measurement was also evaluated. Although the usage of this instrument is generally for the package of dentine debris and thus obstructing apical one third of the root canal, there was no such obstruction in any of the specimens. The records obtained by the beginner with Bingo after flaring was the only significantly different result of this study, but contrary to common accusations, it was a negative value and the instrument passed the apical third easily, instead of tightening there. This finding is in a concordance with the result of the study of Reddy and Hiks (8), in which they compared the step-back technique with rotary instruments. Additionally they are in an agreement with the results of Ibarrola et al. (9). It was interesting that the Bingo and Apex Finder AFA Model 7005 instruments were more accurate without flaring while Root ZX was more successful after flaring. No exact explanation could be made for this situation, but we thought that it was likely attributed to the properties of the frequencies produced by these instruments. This suggests that these instruments should also be compared using the science of physics. Additionally, the values obtained by Bingo and Apex Finder AFA Model 7005 became negative after flaring (Table 1); that is, they extended beyond the apical foramen. This means flaring helps the files to progress more easily in the canal. While we were able to measure the length before and after flaring in the same teeth, we think this finding has completed and confirmed the statement of Ibarrola et al. (9) and therefore we are in an absolute agreement with them. As all discussions in the above paragraphs were made based on the results obtained according to the tolerance level of } 0.1 mm, it becomes a necessity to say some words on this: endodontic disciplines usually accept the tolerance level of } 0.5 mm and therefore all of the instruments tested are clinically acceptable. However, while the theme of this investigation is accuracy and comparison, we believe that the results obtained with the tolerance level of } 0.1 mm are meaningful and it is obvious that it will be helpful to an operator in decision making. Some discussion might be needed on the method followed and especially the model used in this study; the method suggested by Katz et al. (10) was preferred in the study. There are only a few methods and models to be used in such investigations. In one of these a colloidal liquid is used as an electrically conduction medium. But the liquids are easily penetrated into the canal and this situation can produce misleading results. In another one, gelatin agar is used as the embedding medium, and this method was not found appropriate due to our previous experiences of gaps (11) in it, which mislead the electrical circuit evaluations. The last one of the modeling methods for this purpose is the method suggested by Katz et al. (10). In this method, alginate is used as the embedding medium which does not penetrate into canals because of its high viscosity and because it has more resemblance to oral tissues than a liquid or a gelatin medium. While the prepared specimens were kept in a moist medium, the possibility of the loss of conductivity was also eliminated. Therefore, we can strongly claim that the method and the model used in this study produced the least effects on the electrical evaluations as we had demonstrated in another study (11). Finally, we have to conclude that all of the three new generation instruments had a clinically acceptable result at the tolerance of } 0.5 mm. If the instruments are used according to the manufacturer's instructions, experience is not necessary to use electronic root canal measurement devices. The pre-flaring in the crown-down technique, which is being used frequently in recent years, makes it easier to reach the apical foramen and has not affected the accuracy in any of the instruments. Thus, we advise the use of this technique in endodontic operations. References 1. Sjogren U, Hagglund B, Sundqvist G, Wing K (1990) Factors affecting the long-term result of endodontic treatment. J Endod 16, Kuttler Y (1955) Microscopic investigation of root apexes. J Am Dent Assoc 50, Dummer PMH, McGuinn JH, Rees DG (1984) The position and topography of the apical canal constriction and apical foramen. Int Endod J 17, Fouad AF, Rivera EM, Kreell KV (1993) Accuracy of the Endex with variations in canal irrigants and foramen size. J Endod 19, Shabahang S, Goon WWY, Gluskin AH (1996) An in vivo evaluation of Root ZX electronic apex locator. J Endod 22, De Moor RJG, Hammer GMG, Martens LC, De B oerer, JG (1999) Accuracy of four electronic apex locators: an in vitro evaluation. Endod Dent Traumatol 15, Stabholz A, Rotstein I, Torabinejad M (1995) Effect of preflaring on tactile detection of the apical constriction. J Endod 21, Reddy SA, Hicks ML (1998) Apical extrusion of debris using two hand and two rotary instrumentation techniques. J Endod 24,

5 95 9. Ibarrola JL, Chapman BL, Howard JH, Knowles KI, Ludlow MO (1999) Effect of preflaring on Root ZX apex locators. J Endod 25, Katz A, Mass E, Kaufman AY (1996) Electronic apex locator: a useful tool for root canal treatment in the primary dentition. J Dent Child 63, Tinaz AC, Sevimli LS, Gorgul G, Turkoz EG (2002) The effects of sodium hypochloride concentrations on the accuracy of an apex locating device. J Endod 28,