Ravichandra.C 1, Nimeshika R 2, Smitha. R 3, Bhuvan Shome Venigalla 4, Shekar. K 5 ORIGINAL RESEARCH. ENDODONTOLOGY Volume: 27 Issue 2 December 2015

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1 ENDODONTOLOGY Volume: 27 Issue 2 December 2015 ORIGINAL RESEARCH The clinical accuracy of 2 electronic apex locators to determine working length in comparison with standard radiographic method in teeth with and without periapical lesions Ravichandra.C 1, Nimeshika R 2, Smitha. R 3, Bhuvan Shome Venigalla 4, Shekar. K 5 1,3,5 Reader, 2 PG student, 4 Professor and HOD, Sri Sai College of dental surgery, Vikarabad, Telangana. Corresponding Author: meetravichandra@gmail.com Abstract: Aim: The aim of this study was to evaluate the clinical efficacy of two apex locators i.e. Propex pixi and Root ZX in comparison with standard radiographic technique in cases with and without lesions. Methodology: A total of 40 patients scheduled for pulp space therapy with carious intact maxillary molars were taken into the study of which 20 cases with periapical lesions and 20 without periapical lesions were selected and the working length of palatal canal was determined using standard radiographic technique and two apex locators Propex pixi and Root ZX mini. Results: All the analysis was done using SPSS version 14. A p-value of <0.05 was considered statistically significant. Intragroup comparison was done using repeated measures ANOVA with post-hoc Bonferroni test and inter-group comparison was done using Independent sample t test. Conclusion: The results of the study concluded that in cases with lesions there was no much significance between the radiographic method and the apex locators whereas in cases without lesions radiographic method consistently showed a higher value when compared to the apex locators. Key words: Apex locators, Propex pixi, Root ZX, Periapical lesion, Working length, RVG INTRODUCTION Determination of the root canal length accurately from the coronal orifice to the apical foramen is critical in the endodontic management of the root canal space. Cementodentinal junction (CDJ) or minor constriction at the apical foramen is the landmark that anatomically and histologically determines where the pulp ends and the periodontal ligament begins. (1) The apical anatomy of root canals has been investigated by Kuttler, 1955; Ricucci, 1998; Green, 1956; Pineda, Kuttler, Dummer, et al., described the morphological variations of apical CD junctions in Many of these variations cannot be determined radiographically. Dummer et al. (1984) reported the mean apex to foramen distance in anterior teeth to be 0.36 mm whereas Kuttler (1955) measured the apex to foramen distances as 0.48 mm for a young group and 0.6 mm for an older group. Green(1956, 1960) reported the distance to be 0.3 mm in anterior teeth and 0.43 mm in posterior teeth. (2) Failure to accurately determine and maintain working length might either result in the length being too long leading to preparation through apical constriction, causing over preparation and overfilling or might also lead to shaping and cleaning short of the apical constriction, causing under filling. (3) There are 3 accepted methods for determination of the working length, which are radiographic method, Electronic method (EALs), and tactile sensation. Traditionally, measurements of working length have been made by using radiographs with a root canal file placed in the canal. However, it has been reported that it is difficult to determine the working length accurately with a 2-dimensional image. Moreover, the maintenance of the apical constriction is crucial for the instrumentation, and neither radiographic nor tactile methods can adequately determine this point. (4) The use of EALs for determining the root canal working length has become an indispensable part of endodontic treatment. More accurate EALs have evolved in recent years by improving the basic principles upon which the measurements are performed. In 19, Custer proposed the development of electronic devices to determine the working length. In 1942, Suzuki presented the first generation EAL using electrical resistance properties of the root canal to determine its working length whereas Sunada determined the electrical resistance value constantly at 6.5 ohms. This theory considered the electrical resistance between the oral tissues and the periodontal ligament to remain constant. (5) An example of the third-generation EAL is the Root ZX (J. Morita) which worked with a constant frequency principle. A fourth-generation EAL was created by Gordon and Chandler (2004), which worked with multiple frequencies. The first Endodontology, December 2015;27(2):

2 version of Root ZX EAL used the average measurements of two frequencies of 0.4kHz and 8kHz. Kobayashi and Suda (1994) (6) described this method as the EAL frequency ratio. The most recent version of Root ZX uses multiple frequencies and can be classified as a fourth-generation EAL. The fifth generation EAL also uses multiple frequencies, in addition to calculating the root mean square (RMS) values of the electric signals. The RMS represents the energy of the electric signals, and therefore, it is claimed to be less affected by electrical noises affecting other physical parameters such as amplitude or phase of electrical signal that are used by other EALs. An example of a fifthgeneration EAL is the Propex Pixi, a newer version of Propex (Dentsply Maillefer, Switzerland). Several in vivo studies have demonstrated the accuracy of different apex locators in determining the working length of root canals under various clinical conditions, such as in the presence of irrigants (Kobayashi & Suda 1994, Ozsezer et al. 2007) and pulp tissue (Shabahang et al. 1996, Ozsezer et al. 2007). Nevertheless, there are only a few in vivo studies reporting the performance of EALs in teeth with periapical lesions (Frank & Torabinejad 1993, Mayeda et al. 1993). The purpose of this in vivo study was to evaluate the accuracy of two apex locators in determining the working length of teeth with and without periapical lesions. (7) MATERIALS AND METHODS A total of 40 patients scheduled to undergo pulp space therapy of which 20 with periapical lesions and 20 without any periapical lesions were selected and working length was measured. Intact maxillary molars with carious lesions involving pulp and without any metallic restorations were included in the study. The patients were informed about routine endodontic procedures and an informed written consent in full accordance with ethical principles was obtained from each patient before the treatment was initiated. Patients with cardiac pacemakers, teeth with no apical patency or with the radiographic signs of resorption were excluded from the study. Under local anesthesia and isolation with rubber dam, caries was removed, standard access cavity was carried out using high-speed diamond round bur (Dentsply Maillefer, Ballaigues, Switzerland) under water coolant for each tooth and a straight-line access to the root canals was achieved using Endo Z / Howard Martin endo access bur. A small size flexi K file was used to explore the palatal canal followed by coronal enlargement using Gates Glidden drills(#1, #2, #3). The pulp tissue was then extirpated with #15 - #25 broaches and the canals were thoroughly irrigated with various irrigating solutions normal saline and 5.25% sodium hypochlorite solution. The working length in palatal was estimated using three methods. Recording of working length using Root ZX mini and Propex pixi: The working length was recorded with Root ZX using #15, #20 or# 25 file depending on the canal size. Root ZX was switched on, the contrary electrode was placed into the corner of the mouth and then the file holder was clipped on to the file. The file was then progressed until 00 appeared on the screen as per manufacturer s instructions. The silicone stop on the file was set to the reference point and the readings were recorded. Similar procedure was repeated for Propex pixi and the readings were measured as the file progressed to 00 on the screen.(fig 1 & fig 2) Working length recording using RVG: Paralleling technique was used for the measurement. An initial apical file was placed in palatal canal to the estimated length and working length radiograph was taken.the intraoral sensor was kept against the tooth and was exposed to radiation.the working length readings were recorded using standard radiographic technique,then tabulated and the values were subjected to statistical analysis. RESULTS Statistical analysis: All the analysis was done using SPSS version 14. A p-value of <0.05 was considered statistically significant. Intra-group comparison was done using repeated measures ANOVA with post-hoc Bonferroni test and inter-group comparison was done using Independent sample t test. A summary of results is given in table 1, table 2, chart 1, chart 2. In cases without lesions post hoc test showed that RVG showed a mean of with a significant difference of over the other two devices whereas in cases with lesions there was no much difference in the mean of the values among the three devices. According to Independent sample t test RVG showed significant higher working length value (19.40) in without lesions cases than with lesions(.00) cases whereas there was no significant difference in the mean working length values between Root ZX and Propex pixi in both with and without lesion cases. Endodontology, December 2015;27(2):

3 Table 1: Intragroup comparisons of mean values in cases with and without lesions Mean SD p-value Post-hoc test Without Lesions 1. RVG ; S 2. ROOTZX >2 3. PROPEX With Lesions 1. RVG ; NS - 2. ROOTZX PROPEX Table 2: Intergroup comparisons of mean values in cases with and without lesions Lesions without With p-value Mean SD Mean SD RVG ; Sig ROOTZX ; NS PROPEX ; NS 20 Chart 1: Chart 1: gives the comparison of mean values of the three devices in cases with and without lesions 20 Chart 2: Chart 2: gives the comparison of mean values of the three devices in cases with and without lesions Endodontology, December 2015;27(2):

4 APEXLOCATORS USED IN THE STUDY ROOT ZX MINI Fig. 1 PROPEX PIXI Fig. 2 Discussion Success and failure of endodontic treatment depends, among other parameters, on an accurate determination of the working length. Working length determination is made when the instrument tip is between the anatomic (major) and physiological (minor constriction) foramina, allowing the operator to decide which the right point basedon clinical experience is. The apical constriction or physiologic foramen is the point to which the cleaning and shaping and obturation should terminate. Traditionally, a radiographic evaluation has been the primary technique to determine the vertical limit of instrumentation, irrigation, and obturation in endodontic therapy Radiographs are useful for visualizing the existence of pathology, the amount of root to treat, and the direction of curvatures in the root canal system. However, radiography may lead to problems associated with the working length assessment as it is difficult to locate the apical constriction on a two-dimensional radiographic image. There are other limitations of radiography such as superposition of the apex on surrounding structures and insufficient resolution and magnification. (8) El Ayouti, et al., (2005) concluded that radiographic evaluation was not accurate enough and causes over-instrumentation, especially in 56% of premolars and 33%molars. (9) Radiographic assessment of small areas of resorption is difficult, particularly in cases where resorption occurs on buccal or lingual aspects of the root. This will often not be visible radiographically, resulting in an increased risk of over instrumentation and/or overfilling. (10) According to Mayeda et al., it is conceivable that in teeth with periapical lesions, no Endodontology, December 2015;27(2):

5 intact periodontal ligament may be maintained that is able to respond to the apex locator. (11) In this study the efficacy of the apex locators i.e. Root ZX and Propex pixi was checked in cases with and without lesions in comparision with the standard radiographic technique. Several laboratory and in vivo studies have assessed the accuracy of apex locators with various methodologies. However, there are limited in vivo studies evaluating the accuracy of apex locators. The literature review revealed that there are 8 in vivo studies using Root ZX and only 2 in vivo studies using Propex. (12) The Root ZX is a third generation EAL where no calibration is required and a microprocessor calculates the impedance quotient (Kobayashi & Suda 1994), processes the mathematical quotient and algorithm calculations required to give accurate readings (Gordon & Chandler) The change in electrical capacitance at the apical constriction is the basis for the operation of the Root ZX and its reported accuracy (Shabahang et al. 1996, Pagavino et al. 1998). Fan et al. encountered, in dry tubes that the accuracy of Root ZX was 75% to 91.7% within 0.5 mm and 100% within 1.0 mm. In tubes filled with electrolyte, the accuracy of the Root ZX decreased as tubule diameter increased. In turn in a study carried out by Plotino et al produced values to a precision of 97.37%. Lucena- Martin et al. reported that the Root ZX was accurate in 85% of the cases. (13) The multiple frequency processing technology, and use of RMS incorporated into the Propex Pixi is the basis for increasing the accuracy of the working length measurements, by reducing the electrical noises affecting other physical parameters like amplitude or phase of electrical signal that are used by other EALs. Hence it was used along with Root ZX as a bench mark in this study. Stainless-steel hand files were used in the present study. The file sizes were different in each root canal because of differences in root canal sizes. According to Herrera, the Root ZX EAL was more accurate if the diameter size of the file is less than a No. 60 (0.6 mm). (14) The largest apical file diameter used in the present study was 0.30 mm. Ebrahim et alreported that as the diameter of the root canal increased, (15) the electronically measured length with the smaller size files became shorter. Fan et al reported that when the tubules were dry or filled with less conductive electrolyte, (16) increase in tubule diameter did not influence the results. However, when the tubules were filled with strong electrolytes, the results of ProPex were negatively affected from the increase in tubule diameter. In the present study in patients with lesions there was no significant difference between the radiographic method and the two apex locators. This could be possibly because of the loss of apical constriction due to the presence of inflammatory apical root resorption, generally seen in cases of teeth with necrotic pulp and periapical lesions and cannot be identified radiographically. (17) In cases without lesions according to the results post hoc test showed that radiographic method showed significantly higher value when compared to the two apex locators. This can be explained by the fact that apex locators are capable of assessing the apical constriction more accurately than RVG which might be showing the anatomic apex. According to Hoer et al short measurements are not always inaccurate as the apical constriction sometimes may be found 3 mm short of the apex. () Conclusion Within the limitations of the study it can be concluded that in cases with lesions there is no much significance between the radiographic method and the apex locators whereas in cases without lesions radiographic method consistently showed a higher value when compared to the apex locators. Nevertheless for determining the accuracy of EAL s, a larger clinical sample with multiple parameters taken into consideration, would help choose appropriate EAL. References: 1. Grove C. Why canals should be filled to the dentinocemental junction. J Am Dent Assoc 1930; 17: Gordon MPJ, Chandler NP. Electronic apex locators. International Endodontic Journal 2004; 37: Ingle JI, Bakland LK. Endodontics. 5th ed. London: BC Decker Inc, 2002: Elayouti A, Weiger R, Lost C. Frequency of over instrumentation with an acceptable radiographic working length. J Endod 2001; 27: Sunada I. New method for measuring the length of the root canal. J Dent Res. 1962; 41: Kobayashi C, Suda H. New electronic canal measuring device based on the ratio method.j Endod. 1994; 20: Calıskan MK, Kaval ME & Tekin U. Clinical accuracy of two electronic apex locators in teeth with large periapical lesions. Int Endod J 2014; 47: Cox VS, Brown CE Jr, Bricker SL, Newton CW. Radiographic interpretation of endodontic file length. Oral Surg Oral Med Oral Pathol 1991; 72: Elayouti A, Kimionis I. Determining the apical terminus of root-end resected teeth using three modern apex locators: a comparative ex vivo study. Int Endod J. 2005; 38: Mente1 J, Seidel J. Electronic determination of root canal length in primary teeth with and without root resorption. Int Endod J. 2002; 35: Pommer O, Stamm O, Attin T. Influence of the Canal Contents on the Electrical Assisted Determination of the Length of Root Canals. J Endod 2002; 28: Ozsezer E, Inan U, Aydin U. In vivo evaluation of Pro- Pex electronic apex locator. J Endod 2007; 33: D Assuncao FL, de Albuquerque DS, Salazar-silva JR, de Queiroz Ferreira LC, Bezerra PM. The accuracy of Endodontology, December 2015;27(2):

6 root canal measurements using the Mini Apex Locator and Root ZX-II: an evaluation in vitro. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2007; 104: Herrera M, Abalos C, Planas AJ, Llamas R. Influence of apical constriction diameter on Root ZX apex locator precision. J Endod 2007; 33: Ebrahim AK, Yoshioka T, Kobayashi C, Suda H. The effects of file size, sodium hypochlorite and blood on the accuracy of Root ZX apex locator in enlarged root canals: an in vitro study. Aust Dent J 2006; 51: Fan W, Fan B, Gutmann JL, Bian Z, Fan MW. Evaluation of the accuracy of three apex locators using glass tubules. Int Endod J 2006; 39: Laux M, Abbott PV, Pajarola G, Nair PNR Apical inflammatory root resorption: a correlative radiographic and histological assessment. Int Endod J 2000;33: Hoer D, Attin T. The accuracy of electronic working length determination.int. Endod. J Feb; 37: Endodontology, December 2015;27(2):