Electronic Apex Locators: An Evidence-Based Study

Transcription

1 Electronic Apex Locators: An Evidence-Based Study M. Dagenais, S. Hooper, B. Kong, S. Prusky, J. Yip, and H. Zohoor A b s t r a c t The purpose of this evidence-based review of the literature was to determine the accuracy of the electronic apex locator (EAL) in locating the apical constriction of human, permanent teeth for endodontic treatment in vivo. This study acquired evidence and information from 3 main sources: a search of several electronic bibliographic databases, a review of references from relevant studies for additional potentially relevant articles, and from discussions with an endodontic resident. A total of 28 articles were reviewed, of which 10 relevant articles remained. These articles were critically appraised using a diagnostic test checklist and were considered to provide strong evidence as they achieved scores ranging from six to nine out of a possible ten points on the checklist. EAL sensitivity ranged from 34.4% to 93.4%, with a median of 82.3%. Overall, the evidence shows EALs are highly sensitive devices in permanent teeth that should be used in conjunction with radiographs to accurately determine the working length during endodontic therapy. Key Words: endodontics, apical constriction, root apex, working length, apex locator A constriction, is essential for successful endodontic ccurate determination of root canal length, or working length, as measured to the apical treatment. 1 The apical constriction, when viewed under histological cross-sectioning, is the narrowest part of the root canal, and preparation to this mark is thought to result in optimal healing conditions. 2 Among clinicians, it is generally accepted that working length extends from the coronal portion of the root canal to the apical constriction. Various anatomic studies have determined the apical constriction to fall 0.5 to 1.0 mm from the apical opening of the tooth, or major foramen. 3, 4 This measurement is necessary to ensure complete removal of all pulp tissue and necrotic material from within the root canal, but also to prevent extrusion of filling material into surrounding bone which can behave as a physiological irritant. 2 Clinically, working length can be established by tactile sensation, radiography, or more recently, through the use of electronic apex locator (EAL) devices. Anatomical variations in the size and location of the apical constriction result in tactile sensation being largely unreliable in assessing working length. Furthermore, the apical constriction can be sclerosed or resorbed in certain cases, making it near impossible for the operator to use tactile sensation alone. Consequently, tactile sensation, even in the best of circumstances, is only useful when performed by experienced clinicians. 5 Radiographs have traditionally been the most common method for determining working length. The reliability of radiographs is compromised because they provide a two-dimensional image of a threedimensional subject, are technique sensitive, and subject to observer interpretation. 6 Also, large tori, dense maxillary bone, or the zygoma, can often superimpose on the image of the root apices, resulting in interpretive error. 7 Furthermore, since the apical

2 Table 1 Brand name EALs by generational status 5 1 st Generation 2 nd Generation 3 rd Generation 4 th Generation Dentometer Endodontic Meter Endodontic Meter S II Endo Radar Root Canal Meter Dentometer Digipex I, II & III Endo Analyzer Endocater Exact-A-Pex Forameter Formatron IV Sono-Explorer Sono-Explorer Mk III Apex Finder AFA Endex Neosono Ultima EZ Root ZX Apex Locator Bingo 1020/Ray-Pex 4 Elements Diagnostic Unit constriction is not visible on radiographs, common practice involves using anatomical averages to estimate this landmark by determining working length to be 1-2 mm short of the anatomical apex. In addition, patients are often apprehensive towards taking radiographs due to radiation concerns. Due to these shortcomings, electronic methods for root length determination have been developed. Custer first introduced the concept in 1916, which was later revisited by Suzuki in 1942 when he observed that a consistent electrical resistance between an instrument in a root canal and an electrode on the oral mucous membrane could be used for measuring canal length. 8,9 Since that discovery, several generations of EALs have been developed to refine their accuracy. The first generation of EALs were largely resistance based and were found to both over and underestimate working length when compared to radiographs. 5 Second generation EALs rely on impedance measurements to measure the location within a canal. These devices often have difficulty taking accurate measurements in wet canals, and require insulative sheaths over the probe to protect them from conductive fluids. Third generational devices are largely frequency-based and use multiple frequencies to determine the distance from the end of the canal. Certain third generational devices use a ratio algorithm between two electrical currents and are designed to make accurate readings regardless of fluid electrolytes being present within the canal. Recently, fourth generation devices have arrived in the market that claim to use differing frequencies to further reduce errors. Table 1 summarizes the various brand names available in the market by generation. 5 This systematic literature review was performed to assess the accuracy, or more specifically the sensitivity, of EALs for the determination of working length for endodontic treatment. Methods The following strategy was used to identify and select articles to evaluate the sensitivity of EALs. Search strategy Two methods of searching for relevant literature on the accuracy of apex locators were employed in order to systematically identify potential articles for this review paper. A search of the following electronic databases was performed: Ovid MEDLINE(R) (1966 to present), Ovid MEDLINE(R) In-Process & Other Non- Indexed Citations, AMED (1985 to present),

3 CINAHL(1982 to present), Cochrane DSR, ACP Journal Club, DARE, CCTR, CLCMR, CLHTA, CLEED, EMBASE(1980 to present), HAPI(1975 to present), and HealthSTAR. The following keywords were used in the primary search: working length or apical foramen or canal length or actual length or electronic length or CDJ or cementodentinal junction or apex locator. A second search of the same databases was then conducted using the following keywords: endodontics or root canal therapy or root canal treatment or endoontology or endodontic therapy or endodontic treatment. These two individual searches were then combined and duplicates were removed. Finally, the results were limited to those published in English, and those available locally through the University of Toronto library system. Using this primary strategy, 262 articles were found. The secondary search strategy utilized was a search of the reference sections from the relevant review articles. This method produced 15 additional articles that were found to be potentially relevant. As a result, a total of 277 articles were identified for the title stage reading. A defined set of inclusion criteria for selecting the best evidence was formulated prior to the literature search. mnemonic PICO : Population The criteria are listed below and have the human, permanent teeth Intervention in vivo test of electronic apex locator Control Outcome histological sectioning of the tooth with some form of magnified measurement of file position relative to the apical constriction sensitivity based on file location with respect to a defined interval around the apical constriction All 277 articles, returned by the searches, were evaluated at the title stage by a consensus of all 6 researchers in an open-forum style setting, using PICO. A total of 114 articles were rejected, leaving 163 articles to evaluate at the abstract stage. For this stage, the 163 abstracts were subdivided into three separate groups, with group read independently by two researchers and assessed according to PICO. The pairs of researchers then reconvened and compared their decisions on each article. An article was only considered for the full text stage if both researchers agreed on its relevance. An average of 90% agreement was reached on across all articles for this stage. This process resulted in 135 articles being rejected, leaving 28 to be evaluated at the full text stage. The full text stage took place in two parts. First, all 28 articles were again separated into three groups and read independently by two researchers and evaluated for relevance to the proposed question and satisfaction of the inclusion criteria. This process produced ten articles that were deemed relevant. The 18 rejected articles and the reasons for their exclusion are listed in Table 3. The ten selected articles were re-read, summarized, critically appraised, and then scored using a Checklist for Assessing a Diagnostic or Predictive Test by Leake that was modified to be better suited to electronic apex locators (Table 2). 10 The level of evidence provided by each study was also categorized as either good, fair, or poor, based on the combined critical appraisal notes of all researchers who read the article. All ten studies were controlled clinical trials, and all scored between six and nine out of a possible ten

4 points on the checklist. As all articles scored relatively well on the checklist, and satisfied the initial PICO criteria, it was decided that all would be kept in order to maximize the body of evidence available for this review. The evidence table is presented as Table 4. Results The results from the ten studies included in this review, are presented in the evidence table (See Table 4). The gold standard for all of the studies was a histological section of each tooth canal. Sectioning of the tooth provided an unobstructed view of the file tip in relation to the apical constriction and allowed direct measurement of this distance. Prior to sectioning, the file was fixed in the canal in one of two ways. Two studies used a removable type of fixing with either a rubber stopper or composite resin pattern. This allowed the use of two different EALs on the same canal. 11,12 The remaining studies used a permanent fixing method, with cementation of the file in the canal. 1,13-19 Six out of ten studies rechecked the 1,11,13, position of the file following fixation. This served to minimize any inaccuracies that may have occurred as a result of mobility of the file during the fixation procedure. All studies were performed in vivo on adult permanent teeth. Sample sizes varied from 20 to 79 teeth. 11,14 teeth. 11,19 Two studies used only single rooted One study solely used posterior teeth with multiple canals, while the majority of the studies used both single-rooted and multi-rooted teeth in their samples. 12,14-16 Half of the studies compared the sensitivity of two different electronic apex locators to 1, the gold standard. The remaining five examined Table 2 Checklist for assessing a diagnostic or predictive test 1. Was the study ethical? 2. Is the test clearly described? 3. Was the test measured against a biological gold standard? 4. Was tooth vitality considered? 5. Were a range of tooth types examined? 6. Was accuracy reported within a range of ± 0.5 mm of the apical constriction? 7. Is the effect of moving the cutoff reported? 8. Does the study compare the test results to the current standard (radiographs)? 9. Is the test likely to be acceptable to patients? 10. Was the loss of sample less than 20%? the sensitivity of a single electronic apex locator compared to the histological gold standard Two levels of accuracy are defined in the literature. A distance of 1.0 mm from the apical constriction is regarded as clinically acceptable. 13 clinical tolerance of However, the 0.5 mm to the apical constriction is regarded as being superior. 11 The 0.5 mm threshold was applied in each study used for this review. definitions Three studies included data for both Variations in sensitivity of EALs were observed across studies. Sensitivity at the 0.5 mm threshold ranged from a low of 34.4%, to a high of 93.4%. 1,18 When the distance from the apical constriction was increased to also increased. 1, mm, the sensitivity The range of sensitivity varied depending on the particular generation of EAL used in the study. For first generation EALs, the sensitivity range was %, however this was based upon only a single study. 12 For second generation EALs, the sensitivity range was % and for third generation EALs, the sensitivity range was %. 1,11-19 Fourth generations EALs exhibited 1, 11, 13 sensitivity ranging from %. Overall, the Root ZX, a third generation EAL, provided the greatest

5 sensitivity in working length determination with a range of % within 0.5 mm of the apical 1, 11, 13, 15 constriction. The Endo-Analyzer, a fourth generation EAL, was found to be the worst performer at 34.4%. 1 All of the studies included pre-operatory radiographs as a part of their method. However, only two studies actually compared the results obtained by the EAL with those obtained by the radiographic technique. 14,16 Hoer and Attin found a sensitivity of 81% for EALs in the target interval between the apical constriction to the major foramen, whereas only 71% of the working lengths calculated by radiograph were within this interval. 14 The apical constriction was identified exactly in 57% of electronically determined working lengths and 43% of radiographic determined working lengths; however this difference was not significant. In the study conducted by Keller & Brown, the measurements made by an EAL were compared against an experienced endodontist, who estimated working length after viewing postoperative, electronically generated, radiographs with files placed within the canals. 16 The results indicated that the evaluator was 80.2%, and the EAL, 51.5% accurate in positioning the probe within 0.5 mm from the apical constriction. Additional Variables Two studies looked specifically at the sensitivity of EALs in vital and necrotic canals. 15, 19 Both found no statistical difference in the ability of the EAL to determine the apical constriction in vital canals or necrotic canals. The study by Pallares and Faus examined the difference in sensitivity between wet and dry canals and found no significant difference. 12 Two additional studies determined that root resorption lowered the sensitivity of working length determination, though 1, 18 statistical calculations were not carried out. Discussion This systematic review shows good evidence that EALs are highly sensitive devices that provide valuable information during endodontic therapy. The sensitivity of EALs across all studies was found to range from 34.4 to 93.4%, with a median of 83%. EAL devices measure the constant resistance or impedance value between the patient s oral mucosa and the periodontal ligament. In vital teeth, the reading is maximized in the area of the apical constriction, as it is the site where the pulpal tissue meets the periodontal ligament. 19 In necrotic teeth, it is possible that the apical periodontal ligament and/or the apical constriction itself may have been obliterated due to the disease process. Therefore, it is reasonable to infer that inaccuracies may exist when EALs are used in necrotic cases. Pulp vitality was considered by several studies and there was no significant difference found in sensitivity between vital and necrotic canals. 11, 14, 15, 17, 19 However, no studies explicitly noted the presence or absence of apical pathology including loss of the periodontal ligament or obliteration of constriction. Currently, radiographs are the standard method for working length determination. To determine working length by radiograph, 1 mm is subtracted from the radiographic apex where the main root canal is thought

6 to exit onto the root surface at the apical foramen. 14 However, as discussed previously, radiographs have several shortcomings, especially those related to its two-dimensional nature that may be overcome by using an EAL. Examples of such situations include buccal or lingual root dilacerations and root resorption. Nevertheless, EALs are not an absolute substitute for radiographs, which provide valuable information regarding crown to root angulations and canal curvatures, which are not shown by EAL devices. The reviewed studies had strong designs and gave reliable data. Key factors considered in study design strength are: File cementation prior to extraction Devices were used according to manufacturer s recommendations Use of histological section as the gold standard Measurements were made to the nearest , mm. There are currently 4 different generational types of EALs, and many companies producing differing branded devices. Evidence compiled in this review shows good overall consistency between both generation type and brand. However, 2 brands were markedly less sensitive than the rest. The Endo Analyzer provided a sensitivity level of 34.4%. 1 The authors suggested that the low sensitivity may be due to the severe root resorption in 12 of the sample teeth. The Justy II reported 51% sensitivity. 14 This number underestimates its accuracy because the cut-off for this study was measured directly against the apical constriction, instead of comparing against an interval from the constriction, as done with all other studies. As a result, certain measurements were less than ± 0.5 mm from the constriction, but were deemed a negative result by the authors, since an interval approach was not used. Even with stringent selection criteria, there were several limitations in the research papers chosen for this systematic review. Due to the stringent conditions placed on article selection, 10 studies remained, and thus, few EAL evaluations were available. There are many brands available in the marketplace which require evaluation so that comparisons can be made between differing brands. 5 Furthermore, limited sample size, as low as 20 canals, decreased the power of the results for certain studies. 11 Variations in sample selection, such as tooth type and tooth morphology, were rarely considered or even mentioned. Only studies with permanent teeth were chosen for this review due to lack of studies evaluating EALs on primary teeth. Variation in tooth morphology such as accessory canals, large apical constriction or foramen diameters, and root resorption, could all affect the accuracy of EALs. 1,20 The impact of these variations requires a more thorough investigation. A fundamental problem in endodontic practice arises when root canals contain conducting substances such as water, blood, pus, or sodium hypochlorite. Only one study examined the difference in sensitivity between wet and dry canals, and found no significant difference. Due to the low sample size, and thus power, of the single study, we do not feel comfortable making an evidence based conclusion on the sensitivity of EALs with regard to this variable. 12 For future research, we recommend developing a standardized testing procedure to reduce inter-study

7 variation and promote direct comparison of different brands of EALs, including those already in use and more novel products. Suggestions for a standardized procedure include the following: Establish larger sample sizes. Increasing the number and types of teeth will give externally valid and reliable statistical data Test teeth with varying anatomy to determine the effect of these variables Tooth vitality should be recorded and statistical analysis performed on the differences in sensitivity, should any exist Files should be placed using the rubber stopper or removable composite pattern to record working length when files are to be removed. Files to remain in the canal during extraction should be fixed using composite resin and rechecked to ensure that the file has not shifted during fixing Measurements should be made from the apical constriction to the file tip All measurements should be recorded to 0.01 mm using calibrated instruments and some form of magnification Histological section should be used as the gold standard Future studies should also be conducted to test the sensitivity of EALs when used in conjunction with radiographs, as is the current practice. Conclusion Electronic apex locators are highly sensitive devices that can be used to accurately determine the location of the apical constriction within a narrow interval in both vital and necrotic permanent teeth. Although the use of EALs can reduce radiographic exposure for the patient, as the operator may need fewer radiographs to correctly determine the working length, it is important to note that EALs are not an absolute substitute for radiographs and should be used as an adjunct. Further research is required to determine the sensitivity of these devices in various clinical situations, such as teeth with root resorption, wet or irrigated canals and complex pulpal morphology. Development of a standard procedure for testing EALs would allow direct and reliable comparison of the many different brands of locators across a number of studies. This would eventually provide a body of evidence to determine the most accurate brand or brands of apex locators and would allow for straightforward comparison of new brands as they are released onto the market. Acknowledgements: The authors thank Dr. A. Azarpazhooh for his guidance throughout the production of this manuscript. References 1. Welk AR, Baumgartner JC, Marshall JG. An in vivo comparison of two frequency-based electronic apex locators. Journal of Endodontics 2003; 29(8): Ricucci D, and Langeland K. Apical limit of root canal instrumentation and obturation, part 2. International Endodontic Journal 1998; 31: Kuttler Y. Microscopic investigation of root apexes. Journal of the American Dental Association 1955; 50: Green D. A stereomicroscopic study of 700 root apices of maxillary and mandibular anterior teeth. Oral Surgery, Oral Medicine, Oral Pathology 1960; 13: Gordon MPJ and Chandler NP. Electronic apex locators. International Endodontic Journal 2004; 37: Cox VS, Brown CE Jr., Bricker SL, Newton CW. Radiographic interpretation of endodontic file length. Oral Surgery, Oral Medicine, Oral Pathology 1991; 72: Tamse A, Kaffee I, Fishel D. Zygomatic arch interference with correct radiographic diagnosis in maxillary molar endodontic. Oral Surgery, Oral Medicine, Oral Pathology 1980; 50: Custer LW. Exact methods of locating the apical foramen. J Natl Dent Assoc 1916; 5: Suzuki K. Experimental study on iontophoresis. Japanese Journal of Stomatology 1942; 16: Leake JL, Department of Biological and Diagnostic Sciences, Faculty of Dentistry, University of Toronto. Unpublished document. Course notes DENT 300Y Checklist originally adapted from Fletcher RH, Fletcher SW, Wagner EH. Clinical epidemiology. The essentials. 3rd ed. Baltimore: Williams and Wilkins, 1996; and Sackett DL, Richardson WS, Rosenberg W, Haynes RB. Evidencebased medicine: how to practice and teach. EBM. 2 nd ed. New York: Churchill Livingstone, 1997.

8 11. Wrbas KT, Ziegler AA, Altenburger MJ, Schirrmeister JF. In vivo comparison of working length determination with two electronic apex locators. International Endodontic Journal 2006; 40: Pallares A, and Faus V. An in vivo comparative study of two apex locators. Journal of Endodontics 1994; 20(12): Tselnik M, Baumgartner JC, Marshall, JG. An evaluation of Root ZX and Elements diagnostic apex locators. Journal of Endodontics 2005; 31: Hoer D and Attin T. The accuracy of electronic working length determination. International Endodontic Journal 2004; 37: Dunlap CA, Remeikis NA, BeGole EA, Rauschenberger CR. An in vivo evaluation of an electronic apex locator that uses the ratio method in vital and necrotic canals. Journal of Endodontics 1998; 25: Keller ME, Brown CE, Newton CW. A Clinical Evaluation of the Endocarter- An Electronic Apex Locator. Journal of Endodontics 1991; 17(6): Ricard O, Roux D, Bourdeau L, Woda A. Clinical Evaluation of the Accuracy of the Evident RCM Mark II Apex Locator. Journal of Endodontics 1991; 17: McDonald, NJ and Hovland EJ. An Evaluation of the Apex Locator Endocater. Journal of Endodontics 1990; 16: Mayeda DL, Simon JH, Aimar DF, Finley K. In vivo measurement accuracy in vital and necrotic canals with Endex apex locator. Journal of Endodontics 1993; 19(11): Stein TJ, Corcoran JF, Zillich RM. Influence of the major and minor foramen diameters on apical electronic probe measurements. Journal of Endodontics 1990; 16(11):520-2.

9 Table 3 List of articles excluded and reasons for exclusion Article 1) Rambo et al ) Shanmugaraj et al., ) Vahid, et al., 2006 Reason for Exclusion This study did not discuss the accuracy of the electronic apex locator Gold standard was not histology (not apparent from abstract) Full text not available through U of T Libraries 4) Smadi, L., ) Kielbassa et al., 2003 Research was conducted in Jordan and paper was poorly translated into English, making results difficult to interpret. Histological sectioning was not the gold standard used in the study. Study was performed on primary teeth. 6) Mente et al., 2002 Researchers used primary teeth, and conducted the study in vitro, violating two of our inclusion principles. 7) Nam et al., 2002 Study focused mainly on the effects of electrolytes in the canal. 8) Vladimirov, Filipov & Vangelov, 2001 Gold standard was not histology (not apparent from abstract) 9) Fouad & Reid, ) Kim et al., ) Arora & Gulabivala, ) Frank & Torabinejad, ) Stein, Corcoran & Zillich, ) Kaufman et al., 1989 Gold standard was not histology (not apparent from abstract) Biomedical engineering paper geared towards developing a frequencydependent-type apex locator to determine which frequencies provide the greatest accuracy. Study did not analyze any commercially available devices, and operated largely in vitro. Gold standard was not histology (not apparent from abstract) Study measured accuracy of Endex device in vivo, but failed to outline how working length was determined. Since neither histological cross-sectioning, nor any other method, was outlined under materials and methodology, the study's results could not be validated. Outcome measured was not applicable to question Gold standard was not histology (not apparent from abstract) 15) Tidmarsh, Sherson & Stalker, 1985 Gold standard was not histology (not apparent from abstract) 16) Berman & Fleischman, 1984 Gold standard was not histology (not apparent from abstract) 17) Negm M., 1982 Article did not examine accuracy of electronic apex locators. 18) Chunn et al., 1981 No mention of age of patients, types of teeth, or condition of teeth. Small sample size. Studied the Forameter, which is an outdated EAL. Arora, R., Gulabivala, K. An in vivo evaluation of the ENDEX and RCM Mark II electronic apex locators in root canals with different contents. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 1995; 79(4): Berman LH. Fleischman SB. Evaluation of the accuracy of the Neosono-D electronic apex locator. Journal of Endodontics, 1984; 10(4): Chunn CB. Zardiackas LD. Menke RA. In vivo root canal length determination using the Forameter. Journal of Endodontics 1981; 7(11): Fouad, A., Reid, L. Effect of Using Electronic Apex Locators on Selected Endodontic Treatment Parameters. Journal of Endodontics, 2000; 26(6): Frank, A., Torabinejad, M. An in vivo evaluation of Endex electronic apex locator. Journal of Endodontics, 1993; 19(4):

10 Kaufman AY. Szajkis S. Niv N. The efficiency and reliability of the Dentometer for detecting root canal length. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 1989; 67(5): Vladimirov, S., Filipov, I., Vangelov, L. Electrometric determination of the working length of root canals by means of Apex locator. Folia Med (Plovdiv), 2001; 43(1-2):42-5. Kielbassa, A., Muller, U., Munz, I., Monting, J. Clinical evaluation of the measuring accuracy of Root ZX in primary teeth. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology & Endodontics, 2003; 95(1): Kim, D., Nam, K., Lee, S. Development of a frequencydependent-type apex locator with automatic compensation. Crit Rev Biomed Eng., 2000; 28(3-4): Mente, J., Seidel, J., Buchalla, W., Koch, M. Electronic determination of root canal length in primary teeth with and without root resorption, International Endodontic Journal, 2002; 35(5): Nam, K., Kim, S., Lee, S., Kim, Y., Kim, N., Kim, D. Root canal length measurement in teeth with electrolyte compensation. Medical and Biological Engineering and Computing, 2002; 40(2): Negm, M. An instrument for measuring root canal length and apex location. A rapid technique. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 1982; 53(4): Rambo, M., Gamba, H., Ratzke, A., Schneider, F., Maia, J., Ramos, C. In Vivo Determination of the Frequency Response of the Tooth Root Canal Impedance versus Distance from the Apical Foramen. Engineering in Medicine and Biology Science. 29 th International Conference of the IEEE 2007; , Smadi, L. Comparison between two methods of working length determination and its effect on radiographic extent of root canal filling: a clinical study. BMC Oral Health, 2006; 6(4) Shanmugaraj M, Nivedha R, Mathan R, Balagopal S. Evaluation of working length determination methods: An in vivo / ex vivo study. Indian J Dent Res. 2007; 18: Stein TJ, Corcoran JF, Zillich RM. Influence of the major and minor foramen diameters on apical electronic probe measurements. Journal of Endodontics, 1990; 16: Tidmarsh BG, Sherson W, Stalker N. Establishing endodontic working length: a comparison of radiographic and electronic methods. New Zealand Dental Journal, 1985; 81, Vahid, A., Bahraminia, A., Kahrazi, F. Evaluation of two electronic apex locator of 4th generation, Raypex4 and Apit7, in canal; length determination. Journal of Dentistry of Tehran Univeristy of Medical Sciences, 2006; 18(4): 1-7.

11 Table 4 Studies Examining the Sensitivity of Electronic Apex Locators Article Sample Apex Locator (s) Tested Tselnik et al., 2005 n= 40 teeth with 40 canals Age: not mentioned Tooth type: incisors, canines and premolars Vitality: not stated Setting: University/Dental school Root ZX (third generation, two frequency) and Elements Diagnostic Apex locator (fourth generation, 5 frequency) Adjunct Tests Gold Standard Definition of a true positive measurement Radiographs were taken in buccolingual and mesiodistal planes, but were not used in any calculations. Histological section. Photographed at x15 and x30 magnification. Slides of each specimen were projected onto a screen at x600 and x1200 original magnification for measurement. The study reported ±0.5 mm, ±0.75 mm, and ±1 mm. from the apical constriction. As well, the study reported mean distances and noted files positioned between major and minor foramen. Outcome, Results and Loss of Sample Root ZX: Mean = 0.410mm beyond constriction ±0.5= 75% sensitivity ±0.75= 83.3% sensitivity ±1.0= 88.9% sensitivity Elements: Mean = 0.346mm beyond constriction ±0.5= 75% sensitivity ±0.75= 88.9% sensitivity ±1.0= 91.7% sensitivity There was no statistically significant difference between the sensitivity of the two electronic apex locators in locating the minor diameter. Conclusions, critical appraisal, checklist score and level of evidence to support test Authors Conclusions: In locating the minor constriction the Root ZX was accurate 75% of the time to +/- 0.5 mm, 83.3% of the time +/ mm, and 88.9% of the time +/- 1.0 mm. The Elements diagnostic was accurate 75% of the time to +/- 0.5 mm, 88.9% +/ mm, and 91.7% of the time +/- 1.0mm. Tested each locator in the same tooth requiring removal of the file and calculation of distance from apex. Did not consider tooth vitality. Rechecked file position after Checklist score: 9/10 Level of Evidence: Good Hoer & Attin, 2004 n= 79 teeth with 93 canals Age: years old, 27 women, 15 men Tooth type: various Vitality: 59 vital, 20 necrotic Setting: Not stated Endy 5000 & Justy II (both third generation, two frequency type) Radiographic measurement of apex length, minus 1mm, to determine radiographic working length. Histological section with diamond bur in straight hand-piece, with remaining dentine removed with a probe under 16x magnification. Both being right at apical constriction and between apical constriction and major foramen were considered true positives and reported separately. Loss of Sample: 4 teeth lost during preparation Justy II was 51% and Endy 5000 was 64.3% accurate in finding constriction exactly. Justy II was 82.4% and Endy % accurate in finding area between minor and major foramen. Loss of Sample: None Authors Conclusions: Under clinical conditions, [the two apex locators] were able to identify apical constriction to major foramen with high degree of success. Did not recheck position of file after No statistical analysis of vital vs. necrotic. Checklist Score: 9/10 Level of Evidence: Good Welk et al., 2003 n= 35 canals in 35 teeth Age: Seven healthy adults ages 37 to 82 Tooth type: incisors, canines and premolars Vitality: Not stated Setting: University/Dental School Root ZX (third generation, two frequency) and Endo Analyzer 8005 (fourth generation, 5 frequency) Pre-op radiograph taken but not used in calculations All teeth were viewed under dissecting microscope. Apical 4mm of tooth was shaved using carbide bur until file could be seen through dentin. Last layer of dentin removed with #15 scalpel. Two investigators (blinded to which EAL was used) marked the distance of the file position to the minor diameter. ± 0.5mm Root ZX sensitivity = 90.7% Endo Analyzer sensitivity = 34.4% The mean distance between the electronic apex locator working length and minor diameter was 1.03mm for the Endo Analyzer and 0.19mm for the Root ZX. Endo Analyzer found to be significantly beyond apical constriction compared to Root ZX (p <0.0001) Loss of Sample: 2 teeth fractured during extraction, 1 fractured during exposure of the apical constriction. Both were omitted. Authors Conclusions: The use of EALs is a reliable method for determining root canal length. The Root ZX was able to predictably locate the minor diameter (+/- 0.5 mm) (90.7% accuracy) more frequently than the Apex Finder AFA Model 8005 (34.4% accuracy). Further clinical studies should be performed to evaluate EALs under different clinical conditions, such as the presence of apical resorption or blunderbuss canals. Single rooted teeth only. No mention of vitality status of teeth. Rechecked file position after Checklist Score: 9/10 Level of Evidence: Good

12 Dunlap et al., 1998 n= 35 canals in 29 teeth Age: adults Tooth type: various Vitality: 18 vital canals, 17 necrotic canals Setting: University Root ZX (third generation, two frequency) Radiographs taken pre-op and after extraction but not used in any calculations. Histological section by diamond disc and scalpel blade with 12x magnification microscope measurement ±0.5mm and ±0.75mm 82.3% sensitivity within 0.5mm of the apical constriction 94.1% sensitivity within 0.75 mm of apical constriction No significant difference between necrotic and vital canals (p>0.05) Loss of Sample: One specimen from vital group was excluded due to fracture during specimen preparation Authors Conclusions: The Root ZX was 82.3% accurate to within 0.5mm of the apical constriction. There was no statistical difference between the ability of the Root ZX to determine the apical constriction in vital canals versus necrotic canals. Various types of teeth examined Both necrotic and vital cases are compared. File position not rechecked after Checklist score: 9/10 Level of evidence: Good Wrbas et al., 2007 Keller & Brown, 1991 n= 20 canals in 20 teeth Age: adult Tooth type: all single canal Vitality: 7 vital and 13 necrotic Setting: University/ Dental school n= 69 teeth with 99 canals Age: 9 adult patients Tooth type: 30 anterior, 39 posterior Vitality: not stated Setting: Dental school Root ZX (third generation, two frequency) and Raypex locator (fourth generation, two frequency) Both locators tested on same teeth. Endocater (second generation, single frequency impedance type) Pre-op radiograph taken but not used in calculations. Endodontist evaluation of radiographs compared to EAL accuracy. Histological section of apical 4mm by finishing bur and scalpel with 36x magnification microscope measurement. Used removable stopper type fixing with composite. Histological section by #1157 bur, with 5x magnification loupes and #11 scalpel blade for final removal of dentin. ±0.5mm ±0.5mm Root ZX sensitivity = 75% Raypex sensitivity = 80% Loss of Sample: None Endocater sensitivity = 51.5% Endodontist evaluator was 80.2% accurate. Loss of Sample: None Authors Conclusions: The use of EALs is a reliable method for determining working length. The differences between the two EALs were not statistically significant. Single rooted teeth only. Somewhat small sample size. No report of accuracy differences between vital and necrotic canals. Rechecked file position after file cured in removable composite pattern. Checklist: 8/10 Level of evidence: Good Authors Conclusions: Future research with electronic apex locators is needed before accepting as a substitution for radiographic working length determination. Many teeth taken from very few patients Insulative coating stripping was issue in 6 cases Endodontist omitted 3 radiographs because of distortion Rechecked position of file after Ricard et al n= 37 teeth (72 before loss) Age: years old Tooth type: 22 anterior, 15 posterior Vitality: 24 vital, 11 necrotic Setting: Dental school RCM Mark II (second generation single frequency, impedence type) Pre-op radiograph taken but not used in calculations Histological section using diamond bur when necessary under binocular microscope. Apical foramen ±0.5mm RCM Mark II sensitivity = 86.5% No significant difference between sensitivity in vital and necrotic pulps. Loss of Sample: Study lost 35 teeth because of fracture, crack in the root or breaking of the composite seal. Checklist Score: 8/10 Level of Evidence: Fair Authors Conclusions: The reliability of the RCM device could be considered acceptable Rechecked position after cementation - file moved in 7/37 cases. Large number of sample lost after extraction. (about 50%) Checklist Score: 7/10 Level of Evidence: Fair

13 McDonald & Hovland, 1990 n= 47 teeth with 67 canals Age: Adult Tooth type: Anterior and posterior teeth Vitality: not stated Setting: Dental school Endocator electronic apex locator (second generation, single frequency impedance type) Preoperative radiograph taken but not used in any calculations. Tooth sectioned buccolingually using #701 tungsten carbide bur until root canal visible. Under 10x magnification remaining tooth structure removed with Soflex discs until probe visible through thin layer of dentin. Remaining tooth structure was removed with #15 scalpel and stereomicroscope to expose probe. ±0.5mm Endocater sensitivity = 93.4% Results had a mean distance of 0.11 mm short of apical constriction In underdeveloped teeth where apical constriction has not formed (under 17 years of age) the Endocater was unable to determine working length with any degree of accuracy Loss of Sample: The Endocater probe was bound in 13 canals in 8 teeth and these were eliminated from the study. 4 additional teeth were lost during processing. Authors Conclusions: Endocator proved highly accurate in locating the apical constriction, the use of the unit requires and understanding of the principles upon which it operates. A lack of understanding results in difficulty in operating and interpreting its findings. Lost 17 sample canals large loss Radiographs taken but not used in calculations. Did not examine vitality status of teeth. Rechecked file position after Checklist score: 7/10 Level of Evidence: Fair Pallares & Faus, 1994 n= 116 canals in 24 teeth Age: adults Tooth type: maxillary and mandibular molars Vitality: not stated Setting: Not stated Odontometer (first generation, resistance locator) Endocater (second generation, single frequency impedance type) Pre-op radiograph taken but not used in calculations Histological section of the apical 4mm of root by diamond disc with microscope measurement Used removable stopper type fixing with composite. ±0.5mm Wet canals: Odontometer sensitivity = 79.3% Endocater sensitivity = 88.7% Cleaned and dried canals: Odontometer sensitivity = 84.8% Endocater sensitivity = 89.6% Loss of Sample: None Authors Conclusions: Unlike the Endocater, the Odontometer measurements vary considerably depending on whether the canals have been dried or not. The Endocater with covered probes exhibited greater accuracy than the Odontometer, although a high percentage of acceptable measurements were obtained with both devices. Pulp vitality was not determined in this study and only molars were used. The investigators chose to use both instruments within the same canal, ensuring the conditions are the same for the two EALs. Error with the Endocater may be attributable to the insulating cover being lost. Did not recheck file position after fixing. Mayeda et al., 1993 n= 33 canals in 33 teeth Age: not stated Tooth type: all single canal Vitality: 17 vital, 16 necrotic Setting: Not stated Endex apex locator ( third generation, two frequency) Radiographs were taken before and after the Endex apex locator was used. However, no comparison was made between the results obtained by the EAL vs. radiographic determination of working length. The roots were encased in clear orthodontic acrylic resin to aid in handling. The acrylic and the root were cut, first using a bur to remove the acrylic, then Soflex discs to trim the root. Once the file could be seen, the root bulk was removed while tracking the file as it moved apically. There was no clear definition of true positives provided. All measurements were made from the apical foramen, rather than the constriction. Vital: -0.71mm to 0.50 mm with a mean of mm Necrotic: -0.86mm to 0.43 mm with a mean of mm. (*Negative values denote distance short of apical foramen, while positive values denote distance past apical foramen) No significant difference between the means of the vital and necrotic cases. Loss of Sample: None Checklist: 6/10 Level of Evidence: Fair Authors Conclusion: There were no statistical differences in measurements between vital and necrotic canals. Measurements made and reported from apical foramen and not constriction. Only single rooted teeth were used. Pre-op radiographs taken to aid in placement of Endex file. Did not recheck file position after Checklist: 6/10 Level of Evidence: Poor