• Restorative Dentistry and Endodontics
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• v.37 no.2
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• pp.68-73
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• 2012

Objectives: The purpose of this study was to assess the accuracy of Root ZX (J. Morita Corp.) according to the location of major foramen and open apex. Materials and Methods: 81 mandibular premolars with mature apices were selected. After access preparation, 27 teeth were instrumented to simulate open apices. 54 teeth were classified according to location of major foramen under surgical microscope (${\times}16$). The file was fixed at the location of apical constriction by Root ZX using glass ionomer cement .The apical 4 mm of the apex was exposed and photo was taken and the distance from file tip to the major foramen was measured by calibrating metal ruler on graph paper. The results were statistically analyzed using ANOVA and Scheffe test at p < 0.05 level. Results: Mean distance from file tip to major foramen was 0.308 mm in Tip foramen group (I), 0.519 mm in Lateral foramen group (II) and 0.932 mm in open apex group (III). Root ZX located apical constriction accurately within ${\pm}0.5mm$ in group I of 85.71%, in group II of 59.09%, and in group III of 33.33%. There was a statistically significant difference between group I and III (p < 0.05). Conclusion: Root ZX located apical constriction accurately regardless of location of major foramen. However, Root ZX couldn't find it in open apex. Clinicians have to use a combination of methods to determine an appropriate working length at open apex. It may be more successful than relying on just electronic apex locator.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.2
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• pp.139-145
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• 2012

The purpose of this study was to evaluate the accuracy of Root ZX and Sybron Mini in determining the working length using 2.5% Sodium Hypochlorite, 2% Chlorhexidine gel and saline. Donnelly's gelatin technique was used for measuring twenty extracted human teeth. Electronic working length was measured at the display 0.5 and 0.0 level of each electronic apex locator using a digital caliper to the nearest 0.01 mm. Each measurement was repeated for each different irrigants. Accuracy of Sybron Mini was not significantly different from the Root ZX in the three different irrigants, and there was no significant difference in the accuracy of electronic apex locators among the irrigants when used as recommended by manufacturer (measuring electronic working length at 0.0 level of Sybron Mini and at 0.5 level of Root ZX).

• Journal of Biomedical Engineering Research
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• v.19 no.6
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• pp.595-602
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• 1998

Among the apex locators, the frequency dependent type is more accurate and convenient to use than others, But the accuracy of the apex locator is still influenced by the presence of various electrolytes used in root canal treatments. In this study, we have developed a frequency dependent electronic apex locator minimizing the influence of the electrolytes on the measurement of root canal lengths. It was also confirmed that two frequencies of 500Hz and 100kHz are optimal for the measuring impedance compare with commercial product used(400Hz and 8kHz)a and there were no differences in accuracy among the three different types of the waveforms; sinusoidal, triangular, and rectangular waves(p>0.05). Impedance ratio of the two different frequencies represents the position of the file in root canal, and the voltage difference of two signals represents the status of the fluid in the root canal. As a result of compensation using the voltage differences, the errors were decreased on the average from +0.54mm to +0.18mm in $H_2O_2$ solution (p<0.01), and from -0.33mm to -0.01mm in NaOCl solution(p<0.01). The accuracies based on ${\pm}$0.5mm, in $H_2O_2$ and NaOCl solutions were improved with the automatic compensation from 71.1% and 91.1% to 82.2% and 100% respectively.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.3 no.2
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• pp.97-100
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• 2007

In patients with cerebral palsy, dental treatments, which require absolute patient's corporation, have many difficulties because of muscle spacity, involuntary muscle movements and spasm. Especially in endodontic treatments which very meticulous instrumentation is needed, these muscle discordances may lead to unexpected accidents such as tissue damage while filing, over-instrumentation and swallowing instruments. Also, taking radiographs for measuring canal length is often hindered by walking and movement disorders. This paper is to present a clinical case of one-visit root canal treatment using electrical apex locator under general anesthesia in a cerebral palsy patient.

• Restorative Dentistry and Endodontics
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• v.21 no.1
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• pp.150-160
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• 1996

The present study was to evaluate the accuracy of the frequency dependent type apex locator, Root-ZX. The subjects included 505 root canals of 238 teeth treated by the Department of Conservative Dentistry, and 22 human premolars which were schduled to be extracted for the orthodontic reasons. The results were as follows ; 1. The working lengths determined by Root-ZX were compared with radiographic readings. Of the total 505 root canals, 66 % showed coincidence within ${\pm}0.5mm$ and the average readings of Root-ZX were $0.13mm{\pm}1.05$ longer than those of radiographic readings. 2. The length difference between the file tip determined by Root-ZX and the apical constriction in extracted teeth were measured. Of the total 24 root canals, 70.8 % showed coincidence within ${\pm}0.5mm$ and the average readings of Root-ZX were $0.12mm{\pm}0.50$beyond the apical constriction. 3. The vitality of the teeth did not show any statistical difference(p>0.05) in the accuracy of the Root-ZX readings. The presence of the periapical lesions, however, significantly lowered the percentage of ${\pm}0.5mm$ accuracy in Root-ZX measurements.(p<0.05). In the presence of periapical lesions, the percentage within ${\pm}0.5mm$ was significantly lower.

• Restorative Dentistry and Endodontics
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• v.40 no.1
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• pp.44-49
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• 2015

Objectives: This study compared the ability of several techniques to remove calcium hydroxide (CH) from the root canal and determined the influence of CH residues on the accuracy of the electronic apex locator. Materials and Methods: Root canals of 90 human maxillary lateral incisors with confirmed true working length (TWL) were prepared and filled with CH. The teeth were randomly assigned to one of the experimental groups according to the CH removal technique (n = 14): 0.9% saline; 0.9% saline + master apical file (MAF); 17% ethylenediamine tetraacetic acid (EDTA); 17% EDTA + MAF; 5.25% sodium hypochlorite (NaOCl); 5.25% NaOCl + MAF. Six teeth were used as negative control. After CH removal, the electronic working length was measured using Root-ZX (Morita Corp.) and compared with TWL to evaluate Root-ZX accuracy. All specimens were sectioned longitudinally, and the area of remaining CH (CH) and total canal area were measured using imaging software. Results: The EDTA + MAF and NaOCl + MAF groups showed better CH removal than other groups (p < 0.05). Root-ZX reliability to prevent overestimated working length to be > 85% within a tolerance of ${\pm}1.0mm$ (p < 0.05). There was strong negative correlation between amount of CH residues and EAL accuracy (r = -0.800 for ${\pm}0.5mm$; r = -0.940 for ${\pm}1.0mm$). Conclusions: The mechanical instrumentation improves the CH removal of irrigation solutions although none of the techniques removed the dressing completely. Residues of CH medication in root canals affected the accuracy of Root-ZX adversely.

• Restorative Dentistry and Endodontics
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• v.31 no.5
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• pp.371-377
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• 2006

The purposes of this study were to assess the accuracy of measurements in pre-enlarged canals with small instruments and to compare the accuracies, in enlarged canal, with small size instruments and instruments that match the actual canal diameter using Root ZX, Bingo1020, SmarPex, and e-Magic Finder. Ten extracted teeth were embedded in an alginate model made for testing apex locators. A size 10 file was placed into the root canal until the tip of the file reached the plane of the major diameter of the foramen under a dental operating microscope at the 25 x magnification. The measurement was done with digital caliper and defined as actual length. Electronic length measurement with a size 10 file in pre-enlarged canal was done by reading the index indicating Apex of each device to gain a definite value After completion of canal enlargement to a size 45 file, each difference between actual length and electric measurement value with a size 10 and 40 files in enlarged canal was recorded as L10 and L40. The one-way ANOVA and Scheffe's multiple range tests were computed for analyze the differences among the four apex locators in the same group. The Student's t-test between L10 and L40 of each locator was done. The accuracies of electronic measurements were significantly different among the 4 devices. The file size made no difference on the accuracy of electronic measurement in enlarged canal with same device. The e-Magic Finder was the most accurate device among the 4 apex locators used in this study.

• Restorative Dentistry and Endodontics
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• v.40 no.2
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• pp.113-122
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• 2015

Objectives: The aim of this paper was evaluating the ratios of electrical impedance measurements reported in previous studies through a correlation analysis in order to explicit it as the contributing factor to the accuracy of electronic apex locator (EAL). Materials and Methods: The literature regarding electrical property measurements of EALs was screened using Medline and Embase. All data acquired were plotted to identify correlations between impedance and log-scaled frequency. The accuracy of the impedance ratio method used to detect the apical constriction (APC) in most EALs was evaluated using linear ramp function fitting. Changes of impedance ratios for various frequencies were evaluated for a variety of file positions. Results: Among the ten papers selected in the search process, the first-order equations between log-scaled frequency and impedance were in the negative direction. When the model for the ratios was assumed to be a linear ramp function, the ratio values decreased if the file went deeper and the average ratio values of the left and right horizontal zones were significantly different in 8 out of 9 studies. The APC was located within the interval of linear relation between the left and right horizontal zones of the linear ramp model. Conclusions: Using the ratio method, the APC was located within a linear interval. Therefore, using the impedance ratio between electrical impedance measurements at different frequencies was a robust method for detection of the APC.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.316-317
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• 1997

For successful endodontic therapy, complete and accurate biochemical and chemical preparations will allow accurate root canal. Hence the accurate determination of root length is very important for the highest rates of success in endodontic therapy. Among the apex locators, frequency dependent type has higher accuracy and more advantages than others. In this paper, we proposed better frequencies for the method of measuring root canal length by the ratio of two different impedances. It was found that 500Hz and 10kHz is better selection than other frequencies used in the commercial products.

• Restorative Dentistry and Endodontics
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• v.33 no.1
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• pp.20-27
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• 2008

The purpose of this study was to evaluate the consistency of two electronic apex locators in vitro model. Materials consisted of fifty two extracted premolars and two electronic apex locators; Root ZX (J. Morita, Osaka, Japan) and E-Magic Finder Deluxe (S-Denti. Cheonan, Korea). After access preparation, the teeth were embedded in a saline-mixed alginate model. Canal lengths of each tooth were measured at "0.5" and "Apex" mark of the apex locators, respectively so that each tooth had two measurements from 0.5 and Apex points. The file was fixed at final measurement using a glass ionomer cement. The apical 4 mm from the apex was exposed to measure the distance from the file tip to the major apical foramen of each tooth. Average distances and standard deviations were used to evaluate the consistency. Results showed that all measurements of both Root ZX and E-Magic Finder located the major foramen the range of ${\pm}0.5\;mm$ level. Both apex locators showed better consistency at Apex mark than at 0.5 mark. The average distance of file tip-major foramen was - 0.18 mm at 0.5 mark and - 0.07 mm at Apex mark in Root ZX, - 0.25 mm at 0.5 mark and - 0.02 mm at Apex mark in E-Magic Finder. Standard deviation was 0.21 at 0.5 mark and 0.12 at Apex mark in Root ZX, 0.12 at 0.5 mark and 0.09 at Apex mark in E-Magic Finder.