6. BRIEF RESUME OF THE INTENDED WORK:
6.1 NEED OF THE STUDY :
Accurate determination of root canal length is a prerequisite for successful endodontic therapy. The ideal terminus of a root canal preparation is the minor apical foramen, which may coincide or not with the cementodentinal junction (CDJ).1 It is nearly impossible to radiographically identify the minor apical foramen, and the distance between the minor apical foramen and the radiographic apex (major foramen) is highly variable. The development of modern electronic apex locators has helped make non-radiographic measurement of root canal length more accurate and reliable.2 To use these devices, a coronal glide path is established, then a manual file is introduced into the root and stopped at the level dictated by the device. This distance, called working length, is carefully measured by means of a rubber stop placed on the file and transferred to a sequence of instruments to be used for preparation. More recently, devices have been introduced that integrate an electronic apex locator with an endodontic handpiece for canal preparation. These apex locator– controlled handpieces eliminate the need to maintain working length with multiple files by stopping the rotation of the nickel-titanium (NiTi) files as the point estimated to be the end of the root canal is reached.
A variety of apex locators are now available in the market. Each manufacturer claims one or the other advantage and superiority of his product over another. Apex locators incorporated with endomotor and pulp tester also offers many advantages, but the accuracy of the apex locator should be assessed individually to evaluate its efficiency. In the current study, an in vitro model will be used to test the efficacy of five different apex locators – Root Zx, i – Root s, Endo Master, Triauto Zx and Elements apex locator.
6.2 REVIEW OF LITERATURE
Pratten D.H, McDonald N.J. (1996)3 compared the ability of radiographic and electronic methods to determine the location of the apical constriction. The author conducted an experiment in cadaver teeth, which were then extracted and histologically examined to determine the ideal termination point. The authors concluded that using the apex locator for determination of termination point is more reliable than the radiographic method.
Jenkins J.A, Walker W.A, Schindler W.G, Flores C.M (2001)4 evaluated the accuracy of Root ZX in vitro in the presence of a variety of endodontic irrigants. There was virtually no difference in the length determination with the several irrigants used. These results strongly support the concept that the Root ZX is a useful, versatile and accurate device for the determination of root canal lengths over a wide range of irrigants commonly used in the practice of endodontics.
Kaufman A, Keila S, Yoshpe M (2002)5 tested an in vitro model for the accuracy of Bingo l020 apex locator, Root ZX, and radiographic method for working length determination. The investigators concluded that both apex locators were reliable to use and they were better than the radiographic method to measure working length.
Grimberg F, Banegas G, Chiacchio L, Zmener O (2002)6 assessed the clinical performance of a cordless hand piece with a built in apex locator. The Tri auto ZX designed for root canal preparation with nickel titanium files was compared with the radiographic method and confirmed with an SEM study. The investigators concluded that it is reliable, useful and protected from over instrumentation.
Vatkar N.A, Sathe S, Hegde V (2008)7 conducted an invitro study to evaluate the efficacy of five different apex locators - Dentaport ZX, Root ZX, Raypex 5, Propex and E-Magic Finder. The study concluded that Root ZX and E-Magic Finder were the most precise, followed by Dentaport ZX, Raypex 5 and Propex.
Barthelemy et al (2009)8 conducted an in vitro study to evaluate the accuracy of three newly developed electronic apex locater-controlled handpiece devices (Dentaport ZX, Endomaster, XSmart Dual), both in manual mode and motor-driven mode. The authors concluded that although the motor-driven mode of these devices appeared to be clinically safe, measurements obtained in manual and motor-driven operating modes are not equivalent.
6.3 OBJECTIVE OF THE STUDY:
To evaluate the efficacy of five different electronic apex locators in locating the minor diameter.
The study also aims to assess the accuracy of apex locators incorporated with endomotor and pulp tester.
7. MATERIALS AND METHODS :
7.1 SOURCE OF DATA
Thirty extracted, single-rooted, maxillary central incisors with mature apices.
7.2 METHOD OF COLLECTION OF DATA :
Freshly extracted single rooted maxillary central incisors will be collected from the Department of Oral and Maxillofacial Surgery, Rajarajeshwari Dental College and Hospital, Bangalore.
INCLUSION CRITERIA :
Single rooted teeth (Maxillary central incisors).
Completed root formation.
EXCLUSION CRITERIA :
Roots with caries.
Roots with fracture line.
Roots with open apex.
Tooth with root tip fracture.
STUDY METHOD :
Preparation of samples-
Thirty freshly extracted single rooted maxillary central incisors will be collected from the outpatient clinic of Department of Oral and Maxillofacial Surgery. The teeth will be soaked in 2.5% sodium hypochlorite for 24 hours to dissolve any tissue on the root surface, and then stored in sterile 0.9% saline until used. Soft tissue and calculus will be removed from the root surfaces with an ultrasonic scaler (EMS Piezon® Master 400, CH-1260 Nyon, Switzerland).
Standard access preparation will be carried out using a high-speed diamond round or fissure point (Mani, Tochigi, Japan) under water coolant. The incisal or occlusal edges will be ground to create a flat surface to simplify length measurements.
Working model for electronic working length determination-
Three plastic rectangular boxes, 15 cm x 3 cm x 4 cm in dimension will be used for preparing this model. Ten teeth among the selected samples will be glued to a plastic frame. Alginate will be poured into the box, and the frame with the teeth will be embedded into the alginate. In order to reproduce the clinical conditions involved in the electronic measurement of root canal length, the labial clip of the apex locator will be fixed to the edge of the plastic box and immersed in alginate. All the measurements will be made within 2 hours of the model being prepared.
Electronic working length measurement-
Five apex locators will be used for this study – Root Zx (J. Morita Corp., Tokyo, Japan), i – Root s (S-Denti, Seoul, Korea), Elements Apex locator (Sybron Endo, Glendora, CA, USA), Endo Master (EMS, Nyon, Switzerland) and Triauto Zx Apex locator (J. Morita Corp., Tokyo, Japan). Each tooth among the thirty samples will be subjected to electronic working length measurement using all the five apex locators.
Measurement of actual working length-
The actual canal length will be determined by introducing a size 10 or 15 K-file (Mani, Tochigi, Japan) into the canal until the tip of the file becomes visible at the apical foramen under microscope (Seiler, St.Louis, Missouri, USA). The silicon stop will then be carefully adjusted to the reference level and the distance between the base of the silicon stop and the file tip will be measured using a vernier caliper and recorded to the nearest 0.01 mm. The actual working length will be established by subtracting 0.5 mm from this measured length.
The data will be analysed by ANOVA and Chi-square test.
7.3 DOES STUDY REQUIRE INVESTIGATION OR INTERVENTION TO BE CONDUCTED ON PATIENT OR ANIMALS? IF SO EXPLAIN BRIEFLY :
7.4 HAS ETHICAL CLEARANCE BEEN OBTAINED FROM YOUR INSTITUTION IN CASE OF 7.3?
8. LIST OF REFERENCES:
Ricucci D, Langeland K. Apical limit of root canal instrumentation and obturation. Part 2. A histological study. Int Endod J 1998; 31:394-409.
Nekoofar MH, Ghandi MM, Hayes SJ, Dummer PM. The fundamental operating principles of electronic root canal length measurement devices. Int Endod J 2006; 39:595-609.
Pratten D.H, McDonald N.J. Comparison of radiographic and electronic working lengths. J Endodon 1996; 22(4):173-176.
Jenkins J.A, Walker W.A, Schindler W.G, Flores C.M. An in vitro evaluation of the accuracy of the root ZX in the presence of various irrigants. J Endodon 2001; 27(3):209-211.
Kaufman A.Y, Keila S, Yoshpe M. Accuracy of a new apex locator: an in vitro study. Int Endod J 2002; 35:186-192.
Grimberg F, Banegas G, Chiacchio L, Zmener O. In vivo determination of root canal length: a preliminary report using the Tri Auto ZX apex-locating hand piece. Int Endod J 2002; 35:590-593.
Vatkar N.A, Sathe S, Hegde V. In Vitro Evaluation of the Efficacy of Five Apex Locators. Endodontology 2008; 20(2):36-42.
Barthelemy J, Gregor L, Krejci I, Wataha J, Bouillaguet S. Accuracy of electronic apex locater-controlled handpieces. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 107:437-441.