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A clinical evaluation of the Endocater—An electronic apex locator
0099-2399/91/1706-0271/$03.00/0 JOURNAL OF ENDODONTICS Copyright 9 1991 by The American Association of Endodontists
Printed in U.S.A.
VOL. 17, NO. 6, JUNE 1991
A Clinical Evaluation of the Endocater--An Electronic Apex Locator Michael E. Keller, DDS, MSD, Cecil E. Brown, Jr., DDS, MS, and Carl W. Newton, DDS, MSD
Currently, the most popular method for determining proper root canal length depends a great deal on radiographic interpretation. However, there are inherent problems associated with using radiographs, including image distortions, radiographic interpretation of the clinician, and interference of anatomical structures. Radiation hygiene is also a consideration. These factors have stimulated the development of electronic instruments which reportedly can locate the position of the apical constriction. Sunada (5) reported in 1962 that a constant electronic resistance existed between the periodontal ligament and oral mucosa. Since Sunada reported his findings, a variety of apex locators have been marketed which determine the position of the apical constriction by measuring this resistance value. Numerous studies (6-8) have been done to determine the accuracy of various electronic apex locators based on this theory. Many studies (9, 10) have reported over 80% accuracy. Other studies (11, 12) have cast doubt on the reported accuracy. Recently, an electronic apex locator, the Endocater (13) has been introduced by the Hygenic Corp. Unlike previous units that measured the change in electrical resistance, the Endocater's circuitry is based on the electrical phenomenon that under certain conditions impedance (resistance) is greatest at the narrowest point of the canal. That point, which in the case of the tooth is considered to be the cementodentinal junction, can then be located electronically. A plastic coated probe is used to determine these conditions. Two studies (14, 15) have found the device to be accurate in locating the apical constriction. This investigation was designed to determine the ability of the Endocater to locate the position of the apical constriction in mature adult teeth, and to compare the clinical applicability of the device with radiographic interpretation of file length adjustments.
The purpose of this study was to evaluate the accuracy of an electronic apex Iocator, the Endocater, in determining the location of the apical constriction or cementodentinal junction (CDJ). Measurements made by the Endocater were also compared with the adjustments recommended by an experienced endodontist. A total of 69 teeth with 99 canals from nine patients were evaluated. The results indicated that the evaluator was 95.8% and the Endocater 67.7% accurate in positioning the probe within __.1.000 mm from the CDJ. Thirty-three canals or 34.4% appeared to be clinically acceptable radiographically and no adjustments were deemed necessary by the evaluator. There was a significant difference (p < 0.003) between the evaluator's ability to adjust the electronically generated file length radiograph to acceptable clinical standards and the Endocater's ability to determine the location of the CDJ. A total of 59 canals (59.6%) of the electronically determined working lengths were beyond the CDJ (n = 99). In 27 canals, the tip of the probe was greater than 1 mm beyond the constriction. Without radiographs to confirm working lengths, many canals in this study would have been overinstrumerited. Future research with electronic apex Iocators is needed before accepting the technique as a substitution for radiographic working length determination.
One important factor in successful endodontic treatment is the correct determination of the length of root canal. In order to achieve an effective biomechanical preparation and obturation of the canal system, it is necessary for this measurement to be as accurate as possible. Research has shown (1, 2) that overinstrumentation induces an inflammatory reaction in the periapical tissue which results in a less predictable healing response. Investigators (3, 4) agree that the cementodentinal junction is the ideal place to terminate instrumentation and obturation.
MATERIALS AND METHODS Patients selected for the study were undergoing treatment at the Indiana University School of Dentistry for the removal of teeth. Only patients that had noncontributory medical histories and those without cardiac pacemakers were included in the study. Necessary consent forms were developed under the guidelines established by the Indiana University School of Dentistry Human Subjects Committee.
271
272
Keller et al.
The Endocater (Hygenic Corp., Akron, OH) was used in the study to electronically measure root canal length. A total of 69 teeth with 99 canals from nine patients were evaluated. Thirty anterior teeth and 39 posterior teeth were involved. A preoperative periapical radiograph was taken of each tooth using a parallel cone technique and a standardized processing procedure. After administering profound local anesthesia and applying rubber dam isolation, an endodontic access opening was made into the pulp chamber of each tooth using high speed and water coolant spray. Canals were located and, when possible, the pulpal tissue was removed by broaching. The canals were irrigated with sterile water. No attempt was made to dry the canals. Because multiple teeth were involved with each patient, electric vitality testing was not performed on each tooth. However, the clinical appearance of the pulpal contents were recorded at the time of access as to whether or not hemorrhage was present. If hemorrhage was present, the tooth was considered to be vital. The Endocater was calibrated according to the manufacturer's instructions. A #10 coated probe (Hygenic Corp.) either 25 mm or 31 mm was selected based on the estimated preoperative radiographic working length. A return electrode of the Endocater was held firm by the patient and the #10 coated probe was attached to the lead clip of the unit. The probe was then inserted into the canal until the unit indicated that the apical constriction had been reached. This was demonstrated by the analogue meter needle of the Endocater centering in the vertical position. In 28 canals the probes bound in the coronal to mid-root areas and could not be advanced further apically without stripping the insulative coating. When the probes bound, vertical centering of the meter needle was not achieved. The probes were marked, removed, examined for stripping of the plastic coating and the depth of apical penetration was recorded. These canals were sequentially filed in small increments with a #I0 K file and then a new probe was inserted into each canal. According to Hygenic, by alternating the fileprobe-file action, the location of the apical constriction could be determined in calcified canals. When the Endocater indicated that the apical constriction had been reached, Concise (3M Co., St. Paul, MN), an autopolymerizing composite resin, was injected into the access opening with the probe held carefully in position. Upon completion of the composite curing, the probe handle was sectioned and removed. The positive lead of the Endocater probe clip was used to confirm the correct reading of the unit by touching the sectioned probe shaft and ensuring that the meter needle returned to the vertical position. The rubber dam was then removed and a final periapical radiograph was taken. The teeth were immediately extracted and placed in 2.5% sodium hypochlorite solution for 48 h to remove all soft tissue and then placed into saline for storage. Those teeth in which the probe extended beyond the apical foramen were examined microscopically with the Nikon measuring microscope (Nikon Inc., Tokyo, Japan) at x5 magnification to determine if the insulative coating was intact. All specimens were carefully ground with a #1157 bur at high speed until the anatomical outline of the root canal and probe was visible under a thin layer of dentin. With the use of x5 magnification loupes and a #11 scalpel blade, the remaining tooth structure was meticulously removed to expose the probe, apical constriction, and apical foramen (Fig. 1.).
Journal of Endodontics
Measurements were made to 0.001 mm on the 99 sectioned root canals using the Nikon measuring microscope with digital readout capable of measuring in the X, Y, and Z coordinates. The Nikon microscope under x 10 magnification was used to determine the distance of the probe tip from the established position of the cementodentinal junction in each canal. An independent evaluator viewed the postoperative electronically generated file length radiographs and was asked to state what adjustments, if any, should be made in order to place the file lengths from 0.5 to 1.0 mm short of the radiographic apex. Radiographic viewing was done using the Wolf ]ntensi-Spot viewlight (Quint Sectograph Corp., Los Angeles,
FIG 1. Problem place, exposed for viewing by careful removal of tooth structure.
TABLE 1. Evaluator's adjustments to the electronically determined radiographic working lengths No. of
Appeared Radiographically
Add or Subtract (mm)
No adjustments Short Short Short Short
0 +0.5 +1.0 +1.5 +1.5
Total
33 7 6 2 1 16
Long Long Long Long
Total
16 15 5 1_!1 47
Canals
% or Total Canals
Total
34.4 7.3 6,2 2,1 1.0 16.7
Total
16.7 15.6 5.2 11.5 48,7
-0.5 -1.0 -1.5 -1.5
Evaluation of Endocater
Vol. 17, No. 6, June 1991
CA). The evaluator did not use any measuring devices to assist him in making length measurements. A t test for correlated items was performed on the direct measurements from the Endocater and the corresponding adjusted values from the evaluator. The mean, standard deviation, separate variances t test, and the p value were used.
in
L O N G
RESULTS The evaluator was unable to make a judgment of the working length on three radiographs. Two of those cases were 5.421 and 6.113 mm beyond the cementodentinal junction (CDJ) and could not be judged without a measuring device. The other case was discarded because of radiographic distortion. The working length adjustments made by the evaluator from the radiographs of the electronically determined postoperative working lengths are shown in Table 1. Data indicate that 33 canals or 34.4% of the electronically generated file lengths appeared to be clinically acceptable to the evaluator. Sixteen canals or 16.7% of the cases appeared to be short and 47 canals or 48.7% appeared to be long. The t test for correlated items of the 96 cases showed the ability of the evaluator to determine the location of the apical constriction versus the Endocater was highly significant at p < 0.003. Figure 2 shows the frequency distribution of 0.5-mm intervals for the evaluator and the Endocater with relationship to the location of the apical constriction. The highest number of cases, 42, was in the -0.0- to -0.5-mm range, short of the constriction, for the evaluator. For the Endocater, the highest number of cases, 23, was in the 0- to +0.5-ram range beyond the constriction. Data showed that the Endocater was 51.5% accurate in placing the probe within 4-0.5 mm from the apical constriction. The evaluator was 80.2% accurate in adjusting the radiographic image of the probe to within _+0.5 mm of the apical constriction (Table 2). DISCUSSION The Endocater was able to determine the exact location of the CDJ in 15 canals (15.2%) (Fig. 2). Hemorrhage was present in 89 of the canals in the study, and nonvital pulps were recorded in 10 canals. This suggested that pulp vitality made no significant difference (p = 0.7) in the ability of the Endocater to determine the location of the apical constriction. The independent evaluator was asked to view the radiographs of the electronically determined file lengths and make adjustments, if any, to achieve a clinically acceptable working length measurement within 0.5 to 1.0 mm short of the radiographic apex. The evaluator was 95.8% and the Endocater was 67.7% accurate at positioning the probe within 1.000 mm from the apical constriction (Table 2). A total of 59 canals (59.6%) of the electronically determined working lengths was beyond the cementodentinal junction. In comparison, 31 canals or 32.3% of the cases adjusted by the evaluator were beyond the cementodentinal junction. Without radiographs to confirm working lengths, many canals in this study would have been overinstrumented. Safeguards were implemented in the study in an attempt to avoid experimental error. A new, calibrated Endocater unit was used and manufacturer's instructions were followed
S H O R T
273
Rpngr Millim~t~,r ~ 6 O-S.5 5.5-60 5,0-5.5 4.5-5.0 40-45 35-40 30-35 2.5-30 2.0-Z 5 1.5-20 1,0-15 0.5-1.0 0-0.5 0 (-)05-0 (-)10.05 ( )1.5-10 ( )20-1.5 (-)2520 (-)30-25 (-)3.5-30 (-)4035 (-)4.5-40 ( )5.0-4.5 ( )5.5-5.0 (-)6055 (-)65-60 n
5
20
10
25
30
35
40
45
FIG 2. Frequency distribution of Endocater and evaluator measurement relationship to CDJ.
TABLE 2. Comparison of the parameters of the study
mm from CDJ (apical constriction)
0 0.250 0.500 1.000 2.000
Endocater (n = 99)
Evaluator (n = 96)
No. of Cases
%
No. of Cases
%
15 27 51 67 90
15 27.3 51.5 67.7 90.1
14 57 77 92 96
14.6 59.4 80.2 95.8 100
closely. Verification of the patient grasping the holding rod was repeatedly checked, and the plastic coating on the probe was observed frequently to check the integrity of the sheath. Even with these precautions, microscopic analysis revealed that the plastic coating had been stripped in six cases in which the probes extended beyond the cementodentinal junction. Fouad (16) also found in his study that the Endocater #10 probes could only be used in 60% of the canals because of their inability to reach the working length in uninstrumented canals. McDonald and Hovland (15) reported an accuracy of 93.4% and +0.5 mm from the apical constriction with the Endocater. However, 17.1% of the canals were eliminated because the # 10 probes bound in the coronal portion of the canals. Dr. Keller is assistant professor of endodontics, Indiana School of Dentistry, Indianapolis, IN. Dr. Brown is associate professor and director of graduate endodontics, Indiana University School of Dentistry. Dr. Newton is professor and chairman, Department of Endodontics, Indiana University School of Dentistry. Address requests for reprints to Dr. Cecil E. Brown, Jr., Department of Endodontics, IndianaUniversitySchool of Dentisty, 1121 West MichiganStreet, Indianapolis, IN 46202.
References 1. Bhaskar SN, Rappaport HM. Histologic evaluation of endodontic procedures in dogs. Oral Surg 1971;31:526-35.
274
Keller et al.
Journal of Endodontics
2. Seltzer S, Soltanoff W, Smith J. Biological aspects of endodontics. Part V. Periapical tissue reactions to root canal instrumentation beyond the apex and root canal fillings short of and beyond the apex. Oral Surg 1973;36:72537. 3. Kuttler Y. Microscopic investigation of root apices. J Am Dent Assoc 1955;50:544-52. 4. Kuttler Y. A precision and biologic root canal filling technic. J Am Dent Assoc 1958;56:38-49. 5. Sunada I. New method for measuring the length of the root canal. J Dent Res 1962;41:375-87. 6. O'Neill LJ. A clinical evaluation of electronic root canal measurement. Oral Surg 1974;38:469-73. 7. Berman LH, Fleischman SB. Evaluation of the accuracy of the NeosonoD electronic apex Iocator. J Endodon 1984;10:164-7. 8. Abbott PV. Clinical evaluation of an electronic root canal measuring device. Aust Dent J 1987;32:17-21.
9. Blank LW, Tenca JI, Pelleu GB. Reliability of electronic measuring devices in endodontic therapy. J Endodon 1975;1:141-5. 10. Trope KM, Rabie G, Tronstad L. Accuracy of an electronic apex Iocator under controlled clinical conditions. Endod Dent Traumatol 1985;1:142-5. 11. Chunn CB, Zardiackas LD, Menke RA. In vivo root canal determination using the Forameter. J Endodon 1981 ;7:515-20. 12. Tidmarsh BG, Sherson W, Stalker NL Establishing endodontic working length: a comparison of radiographic and electronic methods. N Z Dent J 1985;81:93-6. 13. Hasegawa K, lizuka H, Takei M, Goto N, Nihei M, Ohashi M. A new method and apparatus for measuring root canal length. J Nihon Univ Sch Dent 1986;28:117-28. 14. Czonstkowsky M, Grassi M, EI-Tagouri H, Holstein F. An in vivo assessment of new endodontic apex Iocator. [Abstract]. J Endodon 1988;14:198.
The Way It Was Contemporary Endodontics in 1880? Could it be that contemporary practices in the diagnosis and management of pulpal-periradicular problems differ little from those practiced over a century ago? A cursory review of nineteenth century dental literature reveals many interesting and surprisingly contemporary approaches to the management of tooth problems. For example, Truman W. Brophy (Chicago Med J Exam 1880~41~,582) provides us with a most accurate accounting of his management of a patient who exhibited an extraoral "fistula." In performing his evaluation he used heat on the teeth to test for responsiveness; he traced the tract to the bone adjacent to the tooth in question; and he ultimately verified his diagnosis with a "test cavity." "Examining the face carefullyl I found that a probe passed into the fistula, and came in contact with denuded bone...With a small round file heated, I ascertained by applying it to the gold fillings., that the left canine tooth was, unlike the other, devoid of sensation...I verified my diagnosis by drilling through the palatal surface of the nonsensitive canine tooth, when I found, as I had anticipated, the pulp canal filled with sero-pus." With the correct diagnosis in hand, Dr. Brophy proceeded to perform surgical endodontictreatment complete with root-end obturation and seal of the apical filling material. I can only hope that he also spent some time in proper canal cleaning and shaping. "...Having thus demonstrated that the diagnosis was correct...I made an incision through the mucous membrane, down upon the apex of the affected tooth...With an engine drill I cut away the exposed portion of the root, and the carious bone surrounding it, then filled the canal with gutta percha, and smoothed it off carefully at the apex." Is it possible that we have not progressed as far as we believe with both our diagnostic procedures and clinical techniques? James L. Gutmann
Printed in U.S.A.
VOL. 17, NO. 6, JUNE 1991
A Clinical Evaluation of the Endocater--An Electronic Apex Locator Michael E. Keller, DDS, MSD, Cecil E. Brown, Jr., DDS, MS, and Carl W. Newton, DDS, MSD
Currently, the most popular method for determining proper root canal length depends a great deal on radiographic interpretation. However, there are inherent problems associated with using radiographs, including image distortions, radiographic interpretation of the clinician, and interference of anatomical structures. Radiation hygiene is also a consideration. These factors have stimulated the development of electronic instruments which reportedly can locate the position of the apical constriction. Sunada (5) reported in 1962 that a constant electronic resistance existed between the periodontal ligament and oral mucosa. Since Sunada reported his findings, a variety of apex locators have been marketed which determine the position of the apical constriction by measuring this resistance value. Numerous studies (6-8) have been done to determine the accuracy of various electronic apex locators based on this theory. Many studies (9, 10) have reported over 80% accuracy. Other studies (11, 12) have cast doubt on the reported accuracy. Recently, an electronic apex locator, the Endocater (13) has been introduced by the Hygenic Corp. Unlike previous units that measured the change in electrical resistance, the Endocater's circuitry is based on the electrical phenomenon that under certain conditions impedance (resistance) is greatest at the narrowest point of the canal. That point, which in the case of the tooth is considered to be the cementodentinal junction, can then be located electronically. A plastic coated probe is used to determine these conditions. Two studies (14, 15) have found the device to be accurate in locating the apical constriction. This investigation was designed to determine the ability of the Endocater to locate the position of the apical constriction in mature adult teeth, and to compare the clinical applicability of the device with radiographic interpretation of file length adjustments.
The purpose of this study was to evaluate the accuracy of an electronic apex Iocator, the Endocater, in determining the location of the apical constriction or cementodentinal junction (CDJ). Measurements made by the Endocater were also compared with the adjustments recommended by an experienced endodontist. A total of 69 teeth with 99 canals from nine patients were evaluated. The results indicated that the evaluator was 95.8% and the Endocater 67.7% accurate in positioning the probe within __.1.000 mm from the CDJ. Thirty-three canals or 34.4% appeared to be clinically acceptable radiographically and no adjustments were deemed necessary by the evaluator. There was a significant difference (p < 0.003) between the evaluator's ability to adjust the electronically generated file length radiograph to acceptable clinical standards and the Endocater's ability to determine the location of the CDJ. A total of 59 canals (59.6%) of the electronically determined working lengths were beyond the CDJ (n = 99). In 27 canals, the tip of the probe was greater than 1 mm beyond the constriction. Without radiographs to confirm working lengths, many canals in this study would have been overinstrumerited. Future research with electronic apex Iocators is needed before accepting the technique as a substitution for radiographic working length determination.
One important factor in successful endodontic treatment is the correct determination of the length of root canal. In order to achieve an effective biomechanical preparation and obturation of the canal system, it is necessary for this measurement to be as accurate as possible. Research has shown (1, 2) that overinstrumentation induces an inflammatory reaction in the periapical tissue which results in a less predictable healing response. Investigators (3, 4) agree that the cementodentinal junction is the ideal place to terminate instrumentation and obturation.
MATERIALS AND METHODS Patients selected for the study were undergoing treatment at the Indiana University School of Dentistry for the removal of teeth. Only patients that had noncontributory medical histories and those without cardiac pacemakers were included in the study. Necessary consent forms were developed under the guidelines established by the Indiana University School of Dentistry Human Subjects Committee.
271
272
Keller et al.
The Endocater (Hygenic Corp., Akron, OH) was used in the study to electronically measure root canal length. A total of 69 teeth with 99 canals from nine patients were evaluated. Thirty anterior teeth and 39 posterior teeth were involved. A preoperative periapical radiograph was taken of each tooth using a parallel cone technique and a standardized processing procedure. After administering profound local anesthesia and applying rubber dam isolation, an endodontic access opening was made into the pulp chamber of each tooth using high speed and water coolant spray. Canals were located and, when possible, the pulpal tissue was removed by broaching. The canals were irrigated with sterile water. No attempt was made to dry the canals. Because multiple teeth were involved with each patient, electric vitality testing was not performed on each tooth. However, the clinical appearance of the pulpal contents were recorded at the time of access as to whether or not hemorrhage was present. If hemorrhage was present, the tooth was considered to be vital. The Endocater was calibrated according to the manufacturer's instructions. A #10 coated probe (Hygenic Corp.) either 25 mm or 31 mm was selected based on the estimated preoperative radiographic working length. A return electrode of the Endocater was held firm by the patient and the #10 coated probe was attached to the lead clip of the unit. The probe was then inserted into the canal until the unit indicated that the apical constriction had been reached. This was demonstrated by the analogue meter needle of the Endocater centering in the vertical position. In 28 canals the probes bound in the coronal to mid-root areas and could not be advanced further apically without stripping the insulative coating. When the probes bound, vertical centering of the meter needle was not achieved. The probes were marked, removed, examined for stripping of the plastic coating and the depth of apical penetration was recorded. These canals were sequentially filed in small increments with a #I0 K file and then a new probe was inserted into each canal. According to Hygenic, by alternating the fileprobe-file action, the location of the apical constriction could be determined in calcified canals. When the Endocater indicated that the apical constriction had been reached, Concise (3M Co., St. Paul, MN), an autopolymerizing composite resin, was injected into the access opening with the probe held carefully in position. Upon completion of the composite curing, the probe handle was sectioned and removed. The positive lead of the Endocater probe clip was used to confirm the correct reading of the unit by touching the sectioned probe shaft and ensuring that the meter needle returned to the vertical position. The rubber dam was then removed and a final periapical radiograph was taken. The teeth were immediately extracted and placed in 2.5% sodium hypochlorite solution for 48 h to remove all soft tissue and then placed into saline for storage. Those teeth in which the probe extended beyond the apical foramen were examined microscopically with the Nikon measuring microscope (Nikon Inc., Tokyo, Japan) at x5 magnification to determine if the insulative coating was intact. All specimens were carefully ground with a #1157 bur at high speed until the anatomical outline of the root canal and probe was visible under a thin layer of dentin. With the use of x5 magnification loupes and a #11 scalpel blade, the remaining tooth structure was meticulously removed to expose the probe, apical constriction, and apical foramen (Fig. 1.).
Journal of Endodontics
Measurements were made to 0.001 mm on the 99 sectioned root canals using the Nikon measuring microscope with digital readout capable of measuring in the X, Y, and Z coordinates. The Nikon microscope under x 10 magnification was used to determine the distance of the probe tip from the established position of the cementodentinal junction in each canal. An independent evaluator viewed the postoperative electronically generated file length radiographs and was asked to state what adjustments, if any, should be made in order to place the file lengths from 0.5 to 1.0 mm short of the radiographic apex. Radiographic viewing was done using the Wolf ]ntensi-Spot viewlight (Quint Sectograph Corp., Los Angeles,
FIG 1. Problem place, exposed for viewing by careful removal of tooth structure.
TABLE 1. Evaluator's adjustments to the electronically determined radiographic working lengths No. of
Appeared Radiographically
Add or Subtract (mm)
No adjustments Short Short Short Short
0 +0.5 +1.0 +1.5 +1.5
Total
33 7 6 2 1 16
Long Long Long Long
Total
16 15 5 1_!1 47
Canals
% or Total Canals
Total
34.4 7.3 6,2 2,1 1.0 16.7
Total
16.7 15.6 5.2 11.5 48,7
-0.5 -1.0 -1.5 -1.5
Evaluation of Endocater
Vol. 17, No. 6, June 1991
CA). The evaluator did not use any measuring devices to assist him in making length measurements. A t test for correlated items was performed on the direct measurements from the Endocater and the corresponding adjusted values from the evaluator. The mean, standard deviation, separate variances t test, and the p value were used.
in
L O N G
RESULTS The evaluator was unable to make a judgment of the working length on three radiographs. Two of those cases were 5.421 and 6.113 mm beyond the cementodentinal junction (CDJ) and could not be judged without a measuring device. The other case was discarded because of radiographic distortion. The working length adjustments made by the evaluator from the radiographs of the electronically determined postoperative working lengths are shown in Table 1. Data indicate that 33 canals or 34.4% of the electronically generated file lengths appeared to be clinically acceptable to the evaluator. Sixteen canals or 16.7% of the cases appeared to be short and 47 canals or 48.7% appeared to be long. The t test for correlated items of the 96 cases showed the ability of the evaluator to determine the location of the apical constriction versus the Endocater was highly significant at p < 0.003. Figure 2 shows the frequency distribution of 0.5-mm intervals for the evaluator and the Endocater with relationship to the location of the apical constriction. The highest number of cases, 42, was in the -0.0- to -0.5-mm range, short of the constriction, for the evaluator. For the Endocater, the highest number of cases, 23, was in the 0- to +0.5-ram range beyond the constriction. Data showed that the Endocater was 51.5% accurate in placing the probe within 4-0.5 mm from the apical constriction. The evaluator was 80.2% accurate in adjusting the radiographic image of the probe to within _+0.5 mm of the apical constriction (Table 2). DISCUSSION The Endocater was able to determine the exact location of the CDJ in 15 canals (15.2%) (Fig. 2). Hemorrhage was present in 89 of the canals in the study, and nonvital pulps were recorded in 10 canals. This suggested that pulp vitality made no significant difference (p = 0.7) in the ability of the Endocater to determine the location of the apical constriction. The independent evaluator was asked to view the radiographs of the electronically determined file lengths and make adjustments, if any, to achieve a clinically acceptable working length measurement within 0.5 to 1.0 mm short of the radiographic apex. The evaluator was 95.8% and the Endocater was 67.7% accurate at positioning the probe within 1.000 mm from the apical constriction (Table 2). A total of 59 canals (59.6%) of the electronically determined working lengths was beyond the cementodentinal junction. In comparison, 31 canals or 32.3% of the cases adjusted by the evaluator were beyond the cementodentinal junction. Without radiographs to confirm working lengths, many canals in this study would have been overinstrumented. Safeguards were implemented in the study in an attempt to avoid experimental error. A new, calibrated Endocater unit was used and manufacturer's instructions were followed
S H O R T
273
Rpngr Millim~t~,r ~ 6 O-S.5 5.5-60 5,0-5.5 4.5-5.0 40-45 35-40 30-35 2.5-30 2.0-Z 5 1.5-20 1,0-15 0.5-1.0 0-0.5 0 (-)05-0 (-)10.05 ( )1.5-10 ( )20-1.5 (-)2520 (-)30-25 (-)3.5-30 (-)4035 (-)4.5-40 ( )5.0-4.5 ( )5.5-5.0 (-)6055 (-)65-60 n
5
20
10
25
30
35
40
45
FIG 2. Frequency distribution of Endocater and evaluator measurement relationship to CDJ.
TABLE 2. Comparison of the parameters of the study
mm from CDJ (apical constriction)
0 0.250 0.500 1.000 2.000
Endocater (n = 99)
Evaluator (n = 96)
No. of Cases
%
No. of Cases
%
15 27 51 67 90
15 27.3 51.5 67.7 90.1
14 57 77 92 96
14.6 59.4 80.2 95.8 100
closely. Verification of the patient grasping the holding rod was repeatedly checked, and the plastic coating on the probe was observed frequently to check the integrity of the sheath. Even with these precautions, microscopic analysis revealed that the plastic coating had been stripped in six cases in which the probes extended beyond the cementodentinal junction. Fouad (16) also found in his study that the Endocater #10 probes could only be used in 60% of the canals because of their inability to reach the working length in uninstrumented canals. McDonald and Hovland (15) reported an accuracy of 93.4% and +0.5 mm from the apical constriction with the Endocater. However, 17.1% of the canals were eliminated because the # 10 probes bound in the coronal portion of the canals. Dr. Keller is assistant professor of endodontics, Indiana School of Dentistry, Indianapolis, IN. Dr. Brown is associate professor and director of graduate endodontics, Indiana University School of Dentistry. Dr. Newton is professor and chairman, Department of Endodontics, Indiana University School of Dentistry. Address requests for reprints to Dr. Cecil E. Brown, Jr., Department of Endodontics, IndianaUniversitySchool of Dentisty, 1121 West MichiganStreet, Indianapolis, IN 46202.
References 1. Bhaskar SN, Rappaport HM. Histologic evaluation of endodontic procedures in dogs. Oral Surg 1971;31:526-35.
274
Keller et al.
Journal of Endodontics
2. Seltzer S, Soltanoff W, Smith J. Biological aspects of endodontics. Part V. Periapical tissue reactions to root canal instrumentation beyond the apex and root canal fillings short of and beyond the apex. Oral Surg 1973;36:72537. 3. Kuttler Y. Microscopic investigation of root apices. J Am Dent Assoc 1955;50:544-52. 4. Kuttler Y. A precision and biologic root canal filling technic. J Am Dent Assoc 1958;56:38-49. 5. Sunada I. New method for measuring the length of the root canal. J Dent Res 1962;41:375-87. 6. O'Neill LJ. A clinical evaluation of electronic root canal measurement. Oral Surg 1974;38:469-73. 7. Berman LH, Fleischman SB. Evaluation of the accuracy of the NeosonoD electronic apex Iocator. J Endodon 1984;10:164-7. 8. Abbott PV. Clinical evaluation of an electronic root canal measuring device. Aust Dent J 1987;32:17-21.
9. Blank LW, Tenca JI, Pelleu GB. Reliability of electronic measuring devices in endodontic therapy. J Endodon 1975;1:141-5. 10. Trope KM, Rabie G, Tronstad L. Accuracy of an electronic apex Iocator under controlled clinical conditions. Endod Dent Traumatol 1985;1:142-5. 11. Chunn CB, Zardiackas LD, Menke RA. In vivo root canal determination using the Forameter. J Endodon 1981 ;7:515-20. 12. Tidmarsh BG, Sherson W, Stalker NL Establishing endodontic working length: a comparison of radiographic and electronic methods. N Z Dent J 1985;81:93-6. 13. Hasegawa K, lizuka H, Takei M, Goto N, Nihei M, Ohashi M. A new method and apparatus for measuring root canal length. J Nihon Univ Sch Dent 1986;28:117-28. 14. Czonstkowsky M, Grassi M, EI-Tagouri H, Holstein F. An in vivo assessment of new endodontic apex Iocator. [Abstract]. J Endodon 1988;14:198.
The Way It Was Contemporary Endodontics in 1880? Could it be that contemporary practices in the diagnosis and management of pulpal-periradicular problems differ little from those practiced over a century ago? A cursory review of nineteenth century dental literature reveals many interesting and surprisingly contemporary approaches to the management of tooth problems. For example, Truman W. Brophy (Chicago Med J Exam 1880~41~,582) provides us with a most accurate accounting of his management of a patient who exhibited an extraoral "fistula." In performing his evaluation he used heat on the teeth to test for responsiveness; he traced the tract to the bone adjacent to the tooth in question; and he ultimately verified his diagnosis with a "test cavity." "Examining the face carefullyl I found that a probe passed into the fistula, and came in contact with denuded bone...With a small round file heated, I ascertained by applying it to the gold fillings., that the left canine tooth was, unlike the other, devoid of sensation...I verified my diagnosis by drilling through the palatal surface of the nonsensitive canine tooth, when I found, as I had anticipated, the pulp canal filled with sero-pus." With the correct diagnosis in hand, Dr. Brophy proceeded to perform surgical endodontictreatment complete with root-end obturation and seal of the apical filling material. I can only hope that he also spent some time in proper canal cleaning and shaping. "...Having thus demonstrated that the diagnosis was correct...I made an incision through the mucous membrane, down upon the apex of the affected tooth...With an engine drill I cut away the exposed portion of the root, and the carious bone surrounding it, then filled the canal with gutta percha, and smoothed it off carefully at the apex." Is it possible that we have not progressed as far as we believe with both our diagnostic procedures and clinical techniques? James L. Gutmann