Electronic Length Measurement Research Articles

Kök Uçları Farklı Açılarda Rezeke Edilmiş Dişlerin Cerrahi Olmayan Yeniden Tedavilerinde 3 Elektronik Apeks Bulucunun Doğruluğu: In-Vitro Çalışma

Aim: The accuracy of three electronic apex locators (EALs) during retreatment of root-end resected teeth with different resection bevel angles were evaluated in the present study. Materials and Methods: Forty mandibular premolar teeth were divided into two groups regarding resection bevel angle after root canal filling. In the first group, the apical 3 mm of each specimen was resected at a 0-degree bevel angle using a diamond bur. The resection bevel angle was approximately 45-degree in the second group. Electronic length measurements were obtained with a size 15 K-file advanced apically in dissolved gutta percha using Dentaport ZX, Propex Pixi, and Apit 15. The filling materials were then completely removed from the root canals, and the actual lengths up to the resection region were determined. The actual length was subtracted from the electronic length measurements for each specimen. Measurements were analyzed statistically using independent sample t-test, repeated-measures analysis of variance, and Bonferroni tests. The level of statistical significance was defined as P<0.05. Results: In the 45-degree group, a significant difference was found between Propex Pixi and Apit 15. Measurements at 0- and 45-degree resection bevel angles were not statistically different from each other in any EAL groups. Conclusions: The resection bevel angle did not affect the accuracy of the tested EALs. More accurate measurements were obtained with the Propex Pixi at a 45-degree resection bevel angle compared with the Apit 15.

Accuracy of Different Apex Locaters. (A Comparative in Vitro Study)

Aims: The objective of this in vitro study was to compare the accuracy of the Root-ZX II, Root ZX Mini,i Pex II, Kerr apex ID , Root PI and YD2 electronic apex locators (EALs) in locating the apical foramen.Materials and Methods: Fifty extracted human teeth with mature apices were used. Access cavities wereprepared. In order to make sure that we have an accurate working length of 21 mm the crown was sectionedwith diamond disc (control). The teeth were then embedded in an alginate model to simulate the periodontiumafter that the Canals were irrigated with 2.5% sodium hypochlorite. The actual length and electronic lengthmeasurements were made on each specimen separately by apex locator devices with an aid of a K-type file.Results: Statistical results showed no significant difference between the 6 devices although concerninglocating the apical foramen, Root-ZXII , Root ZX Mini, were accurate 96% of the time to ±0.5mm, where asI pex II and Kerr apex ID were accurate 94% of the time to 0.5 mm from the apical foramen, 44% ±0.5mmfor the Root PI and 44% ±0.5mm for the yD2. Conclusions: All the apex locators were able to determinedthe position of the apical foramen but consequently the Root-ZX II, Root ZX Mini, i Pex II, Kerr apex IDwere more accurate than Root PI and YD2 apex locators.

OPERATIONAL EXPERIENCE OF GNSS RECEIVERS WITH CHIP SCALE ATOMIC CLOCKS FOR BASELINE MEASUREMENTS

Currently, one of the topical issues of improving GLONASS system is modernization of its uniformity measurement equipment, including RF measurement equipment and electronic length measurement equipment. To this end, at the Spatial Reference Proving Ground of theSiberian State University of Geosystems and Technologies (SSUGT), the authors of this article carried out a successful experiment to measure a short GNSS baseline by receivers equipped with Chip Scale Atomic Clocks (CSACs) with instability of 10−11 showed that the mean deviation between the slant distance (D) measured using GNSS receivers connected to CSACs and their certified value varied in the range of 0.1–2.5 mm, with the average value of 0.9 mm. The mean deviation obtained using GNSS geodetic receivers not connected to CSAC and their certified value made up 9.4 mm. The obtained experimental results suggest that substitution of quartz frequency generators with temperature compensation used in geodetic GNSS receivers for Chip Scale Atomic Clocks in any metrological or verification kit increases accuracy and reliability of short baselines measurements results, which highly perspective in view of development of techniques for creating reference baselines with a reproduction error of unit length of about 1 mm per 1 km. The above-mentioned experiment opens up new horizons for the use of Chip Scale Atomic Clocks in such fields of science as metrological support of geodetic equipment, geodesy, etc.

Evaluation of the accuracy of nine electronic apex locators by using Micro-CT.

To determine the accuracy of locating the apical constriction using apex locators. Extracted teeth were micro-CT scanned preoperatively to localize the apical constriction. Electronic length measurements of 91 root canals were made using nine electronic apex locators (EAL) connected to a mounting model. Distances from the major foramen were recorded at each scale bar of the EALs, and a file was fixed in the canal at a position indicated by each EAL to be the apical constriction. A second micro-CT scan was conducted, and distances from the file tip to constriction and major foramen were calculated for each EAL. The accuracy of EALs was determined with a tolerance of 0.1, 0.25, 0.5 and 1mm, and the 95% confidence interval was used to compare the EALs. A rank analysis was performed in which measurements beyond the major foramen were considered as inaccurate. Regardless of the type of teeth, there was no significant difference in the accuracy of determining the apical constriction and major foramen between the nine EALs within a tolerance of ±0.5mm and 1mm, but there was a significant difference for the tolerances of ±0.1 and 0.25mm. The highest ranks close to the constriction (98% and 94%) and to the major foramen (86% and 73%) were observed in Dentaport ZX and Elements Diagnostic Unit, respectively. Overestimation of working length beyond the major foramen was observed in all EALs (5% to 71%) when the scale for the major foramen, as recommended by the manufacturers, was used. However, when the scale for the constriction was used, only 3% of the measurements were beyond the major foramen. Electronic apex locators were able to determine the apical constriction. Using EALs to determine the major foramen led to overestimation of the working length. Therefore, it may be recommended to use the EAL scale of the constriction.

Comparison of accuracy of two electronic apex locators in the presence of various irrigants: An in vitro study

Aim:This study was designed to compare the accuracy of Root ZX and SybronEndo Mini, electronic apex locators (EALs), in the presence of various irrigants.Materials and Methods:Sixty extracted, single-rooted human teeth were decoronated and the root canals coronally flared. The actual length (AL) was assessed visually and teeth mounted in the gelatin model. The electronic length (EL) measurements were recorded with both EALs in the presence of 0.9% saline; 1% sodium hypochlorite (NaOCl); 2% chlorhexidine digluconate (CHX), and 17% EDTA solution, at “0.5” reading on display. The differences between the EL and AL were compared.Results:The accuracy of EL measurement of Root ZX and Sybron Mini within±0.5 mm of AL was consistently high in the presence of NaOCl and found to be least with EDTA.Conclusion:EL measurements were shorter with 1% NaOCl, whereas longer with 2% CHX for both the devices. Sybron Mini was more accurate with 1% NaOCl and 2% CHX than Root ZX.

The fundamental operating principles of electronic root canal length measurement devices

It is generally accepted that root canal treatment procedures should be confined within the root canal system. To achieve this objective the canal terminus must be detected accurately during canal preparation and precise control of working length during the process must be maintained. Several techniques have been used for determining the apical canal terminus including electronic methods. However, the fundamental electronic operating principles and classification of the electronic devices used in this method are often unknown and a matter of controversy. The basic assumption with all electronic length measuring devices is that human tissues have certain characteristics that can be modelled by a combination of electrical components. Therefore, by measuring the electrical properties of the model, such as resistance and impedance, it should be possible to detect the canal terminus. The root canal system is surrounded by dentine and cementum that are insulators to electrical current. At the minor apical foramen, however, there is a small hole in which conductive materials within the canal space (tissue, fluid) are electrically connected to the periodontal ligament that is itself a conductor of electric current. Thus, dentine, along with tissue and fluid inside the canal, forms a resistor, the value of which depends on their dimensions, and their inherent resistivity. When an endodontic file penetrates inside the canal and approaches the minor apical foramen, the resistance between the endodontic file and the foramen decreases, because the effective length of the resistive material (dentine, tissue, fluid) decreases. As well as resistive properties, the structure of the tooth root has capacitive characteristics. Therefore, various electronic methods have been developed that use a variety of other principles to detect the canal terminus. Whilst the simplest devices measure resistance, other devices measure impedance using either high frequency, two frequencies, or multiple frequencies. In addition, some systems use low frequency oscillation and/or a voltage gradient method to detect the canal terminus. The aim of this review was to clarify the fundamental operating principles of the different types of electronic systems that claim to measure canal length.

In vitrocomparison of measurement accuracy in pre-enlarged and enlarged canals with four apex locators

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. [J Kor Acad Cons Dent 31 (5) :371-377, 2006]

Electronic length measurement using small and large files in enlarged canals.

Electronic apex locators are frequently used attached to a small size endodontic file; however, the effect on the measurement of the relative diameters of the file and the root canal has not been clarified. In this study, the length of enlarged canals was measured using small size files and files matching the canal diameter to observe a possible discrepancy. The accuracy of electronic length control during canal preparation with rotary files was also assessed. The root canals in 21 extracted, single rooted teeth were accessed, and their actual length (AL) established by passing a size 10 file just through the minor apical foramen. The teeth were then embedded in an alginate mold. The initial canal length (IL) was measured with the Root ZX apex locator by negotiating a size 10 file to the apical constriction. The canal was enlarged to size 60 with rotary files while the length was continuously controlled with the apex locator. Then, the final length measurements were obtained with a size 10 file and a size 60 file (FL-10 and FL-60, respectively). The average values of IL, FL-10 and FL-60 were calculated and compared using Repeated Measures Analysis of Variance followed by Tukey's Studentized Range test (P < 0.05). Using composite resin, the size 60 files were secured at the FL-60 length, the teeth were removed from the alginate mold, stained with Picroformal DI Buoin stain and the position of the file tip was observed histomorphometrically after the apical 4 mm of the canal was exposed by grinding the buccal aspect of the root. The IL was 0.45 mm shorter than AL (P < 0.05). The differences between FL-10, FL-60 and IL were not statistically significant. Histomorphometrically, the apical constriction was absent in all the teeth, but the file tips were confined within the root. This study concluded that the Root ZX indicated the location of an apical constriction even when the anatomic constriction was eliminated. In the enlarged canals, length measurements obtained with small and large size files were comparable.

OR 30 Electronic length measurement using small and large files in Enlarged Canals: HQ Nguyen*, RC Komorowski, AY Kaufman, S Friedman. Universities of Toronto, Canada and Tel-Aviv, Israel

OR 30 Electronic length measurement using small and large files in Enlarged Canals: HQ Nguyen*, RC Komorowski, AY Kaufman, S Friedman. Universities of Toronto, Canada and Tel-Aviv, Israel

REDUCTION OF ELECTRONIC LENGTH MEASUREMENTS

The following is a review of the method of correcting electronic length measurements for slope, height above sea level, and curvature of electric waves.

CANADIAN SHORAN EFFORT, 1949–1953

The application, in Oanada, of shoran electronic length measurement to surveying and mapping may be regarded as having been initiated in 1947, when experimental work by Federal Government bureaus was conducted in the vicinity of Ottawa over several long lines between stations of the first-order triangulation. During the succeeding two winters this work was continued, and the results indicated shoran as suitable for establishing position, in Canada's vast northland, quickly and with greater accuracy than by means of astronomic methods. It was realized that trilateration might fail in securing the necessary accuracy because of the many factors involved. Since no information was available, or even existed, from the experience of other survey organizations as to the error in position which might be generated in a comparatively long arc, the first work planned was for a 1100-mile axial-length arc between geodetic bases. This arc, situated in Manitoba and Saskatchewan, was measured in 1949 and 1950. The result indicated that shoran, with careful supervision of all details, could produce results of accuracy superior to astronomic positioning, which is the only reasonable and speedy alternative method of control for mapping at the present stage of development of the northern areas.

CANADIAN SHORAN EFFORT, 1949–1953

The application, in Oanada, of shoran electronic length measurement to surveying and mapping may be regarded as having been initiated in 1947, when experimental work by Federal Government bureaus was conducted in the vicinity of Ottawa over several long lines between stations of the first-order triangulation. During the succeeding two winters this work was continued, and the results indicated shoran as suitable for establishing position, in Canada's vast northland, quickly and with greater accuracy than by means of astronomic methods. It was realized that trilateration might fail in securing the necessary accuracy because of the many factors involved. Since no information was available, or even existed, from the experience of other survey organizations as to the error in position which might be generated in a comparatively long arc, the first work planned was for a 1100-mile axial-length arc between geodetic bases. This arc, situated in Manitoba and Saskatchewan, was measured in 1949 and 1950. The result indicated that shoran, with careful supervision of all details, could produce results of accuracy superior to astronomic positioning, which is the only reasonable and speedy alternative method of control for mapping at the present stage of development of the northern areas.