Endodontic File Length Research Articles

The Effect of Different Image Processing Techniques on the Measurement Accuracy of Endodontics File Length.

Different software capabilities have been used in digital systems to increase the diagnostic quality of radiographic projections. Considering the availability of different enhancement techniques, it is necessary to determine the suitability of each technique for various diagnostic cases. There is controversy between studies over the effect of different digital enhancement techniques on the accuracy of file length measurements in endodontics. The present in vitro study aimed to determine the effect of the software capabilities on the diagnostic accuracy to determine endodontic file lengths in photostimulable phosphor (PSP) radiographs. In the present in vitro study, standard access cavities were prepared in 44 extracted human single-rooted permanent teeth. An endodontic file was placed in each root canal. PSP sensors were used for digital imaging using the parallel technique. All the images were reviewed on a same monitor; once normally with no software enhancement and once using software manipulations including pseudo-color, sharpness, emboss, and edge enhancement. The distance from the file tip to the rubber stop was measured on the images by an electronic ruler. Significantly, all of the image enhancement techniques presented shorter measurements comparing to the actual length. The results revealed the significant accuracy of the measured error in the pseudo-color enhancement technique compared to other techniques. The results revealed significant differences between the initial measurements (the gold standard) and those made on the manipulated radiographs. In all cases, the measurements were significantly lower than the real values. Therefore, none of these digital enhancement techniques can increase the accuracy of file length measurements significantly. However, manipulation with the pseudo-color option resulted in fewer errors compared to other options and the normal images. Hence, for precise measurements of the endodontic file lengths, pseudo-color processing algorithm can be suggested when using PSP sensors.

The Cyclic Fatigue Resistance of Different Lengths of CM Gold Wire and CM Blue Wire NiTi Alloy Endodontic Rotary Files: An In Vitro Study

Background: The objective of the present study was to measure and compare how the length of CM Gold Wire and CM Blue Wire NiTi alloy endodontic rotary files impacts their resistance to cyclic fatigue. Methods: A total of 40 sterile endodontic rotary files were chosen and allocated to the following study groups: (A) 25.06 CM Gold wire NiTi alloy endodontic rotary files, 31 mm in length (n = 10); (B) 25.06 CM Gold wire NiTi alloy endodontic rotary files, 25 mm in length (n = 10); (C) 25.06 CM Gold wire NiTi alloy endodontic rotary files, 21 mm in length (n = 10); and (D) 25.06 CM Blue wire NiTi alloy endodontic rotary files, 17 mm in length (n = 10). A specialized device was designed using artificial root canal systems made from stainless steel for the dynamic cyclic fatigue tests, with an apical diameter of 250 µm, curvature angle of 60°, radius of curvature of 5 mm, lengths of 31, 25, 21, and 17 mm, and a 6% taper. An individual operator determined failure of the endodontic rotary instrument through direct observation and the tests were filmed so as to precisely measure the exact time to failure. The results were analyzed using ANOVA and Weibull statistical analysis. Results: The results found statistically significant differences across all study groups (p < 0.05). Conclusions: Rotary file length is inversely proportional to the cyclic fatigue resistance of the 25.06 CM Gold wire NiTi alloy at 31 mm, 25 mm, and 21 mm in length and of the 25.06 CM Blue wire NiTi alloy 17 mm length endodontic rotary files, with a greater length contributing to lower resistance to cyclic fatigue.

Comparison of vibration characteristics of file systems for root canal shaping according to file length.

ObjectivesNo studies have yet assessed vibration characteristics according to endodontic file length. Accordingly, the objective of the present study was to examine the vibration characteristics according to nickel-titanium file length and to compare these characteristics between different file systems.Materials and MethodsA total of 45 root canal models were divided into 3 experimental groups (n = 15 each) based on the file system used (ProTaper Gold [PTG], ProTaper Next, or WaveOne Gold [WOG]). Each experimental group was further divided into 3 subgroups according to file length (21, 25, or 31 mm). An electric motor (X-SMART PLUS) was used in the experiment. For each file system, vibrations generated when using a size 25 file were measured and used to calculate the average vibration acceleration. The differences in vibrations were analyzed using 1-way analysis of variance and the Scheffé post hoc test with a confidence interval of 95%.ResultsIn the PTG file system, significantly lower vibration acceleration was observed when using a 21-mm file than when using a 31-mm file. In the WOG file system, significantly stronger vibration acceleration was observed when using a 31-mm file than when using 21- or 25-mm files. Regardless of the file length, the WOG group exhibited significantly stronger vibration acceleration than the other 2 experimental groups.ConclusionsIn clinical practice, choosing a file with the shortest length possible could help reduce vibrations. Additionally, consideration should be given to vibrations that could be generated when using WOG files with reciprocating motion.

Effect of different levels of sharpness processing filter on the measurement accuracy of endodontic file length

Introduction: The present study was undertaken to evaluate the effect of different levels of sharpness processing filter on the accuracy of endodontic file length determination using digital periapical radiography. Materials and Methods: Forty human single-rooted permanent teeth were selected and International Organization for Standardization (ISO) #08 K-files were inserted into the root canals of the teeth. The file lengths were measured with a digital caliper as the gold standard. Digital periapical images were obtained using a phosphor storage plate as a detector. Three levels of sharpness tool of Scanora software program version 5.1 was used to produce enhanced images: Sharpen 1 (mild level), Sharpen 2 (moderate level), and Sharpen 3 (high level). Two radiologists and two endodontists measured file lengths on the original and enhanced images. The measurements were compared using repeated measures ANOVA and Bonferroni tests (α = 0.05). Results: There were no significant differences between the measurement accuracy of original images and that of the Sharpen 1 and Sharpen 2 enhanced images ( P > 0.05). However, significant differences were found between the measurement accuracy of original and that of the Sharpen 3 enhanced images ( P P > 0.05). Conclusion: The application of mild and moderate levels of sharpness processing filter did not influence the accuracy of endodontic file length determination. However, high-level sharpness processing filter is not recommended due to its unfavorable effects on measurement accuracy.

Effect of Contrast Inversion Enhancement on the Accuracy of Endodontic File Length Determination in Digital Radiography.

The aim of this ex vivo study was to evaluate the accuracy of endodontic file length measurement on digital periapical radiographs after application of contrast inversion digital enhancement. Forty single-rooted single-canal mature permanent human teeth with canals measuring 20-24 mm in length were used in this study. ISO #08 K-files were placed in the root canals of the teeth. The file lengths were measured with a digital caliper as the gold standard. Standard periapical digital images were obtained with the Digora storage phosphor plates and Digora Optime scanner as the original images. The contrast inversion option of Scanora software program version 5.1 was used to produce enhanced images. Three radiologists and three endodontists measured file lengths on the original and enhanced images. The measurements were compared using repeated measures ANOVA and Bonferroni tests (α=0.05). There were significant differences between the measurement accuracy of the original and enhanced images (p<0.05). The enhanced images exhibited longer measurements compared to the original images. However, the two sets of digital radiographs provided significantly longer measurements compared to the gold standard (p<0.05). The contrast inversion tool of Scanora software program decreases measurement accuracy of the length of small endodontic files on digital periapical radiographs. It is suggested that contrast inversion should not be used in determining the lengths of small endodontic files.

In vitro comparison of three different image receptors for determining the length of endodontic files

Background/purposeThe aim of this study was to evaluate the accuracy of endodontic file length measurements of E-speed radiographs, Digora storage phosphor plates, and Schick charge-coupled device sensors, with a secondary aim of assessing the influence of image enhancement on the measurement accuracy. Materials and methodsForty-seven extracted mandibular first premolar teeth were selected. ISO size 8, 10, and 15 files were inserted into each canal, and the files were fixed when the tip was seen at the apical foramen. The teeth were mounted in acrylic blocks and exposed using E-speed films, Digora storage phosphor plates, and Schick charge-coupled device sensors. Two radiologists and two endodontists measured the length of each file between the file stopper and tip on each image. Measurements were carried out on original and magnified images as well as on revealer images for Schick CDR. The actual lengths of the files were measured using a calipers to the nearest 0.01 mm and served as the “true length”. Repeated measures analysis of difference and Tukey honestly significant difference tests were used to analyze the data (P < 0.05). ResultsE-speed films were superior to digital systems for the measurement accuracy of the size 08 file (P < 0.05). Revealer images gave equivalent results with E-speed films for the measurement of the size 10 file (P > 0.05). The most accurate results were obtained with the size 15 file regardless of the image receptor (P > 0.05). ConclusionSize 15 or larger files should be used for endodontic working length determinations. Revealer images gave equivalent results with E-speed films and may be utilized for determining the file length of size 10 files.

Effect of digital noise reduction on the accuracy of endodontic file length determination

PurposeThe aim of the present study was to evaluate the measurement accuracy of endodontic file length on periapical digital radiography after application of noise reduction digital enhancement.Materials and MethodsThirty-five human single-rooted permanent teeth with canals measuring 20-24 mm in length were selected. ISO #08 endodontic files were placed in the root canals of the teeth. The file lengths were measured with a digital caliper as the standard value. Standard periapical digital images were obtained using the Digora digital radiographic system and a dental X-ray unit. In order to produce the enhanced images, the noise reduction option was applied. Two blinded radiologists measured the file lengths on the original and enhanced images. The measurements were compared by repeated measures ANOVA and the Bonferroni test (α=0.05).ResultsBoth the original and enhanced digital images provided significantly longer measurements compared with the standard value (P<0.05). There were no significant differences between the measurement accuracy of the original and enhanced images (P>0.05).ConclusionNoise reduction digital enhancement did not influence the measurement accuracy of the length of the thin endodontic files on the digital periapical radiographs despite the fact that noise reduction could result in the elimination of fine details of the images.

Effect of Combined Digital Imaging Parameters on Endodontic File Measurements

IntroductionThis study assessed the effect of the combination of a dedicated endodontic filter, spatial resolution, and contrast resolution on the determination of endodontic file lengths. MethodsForty extracted single-rooted teeth were x-rayed with K-files (ISO size 10 and 15) in the root canals. Images were acquired using the VistaScan system (Dürr Dental, Beitigheim-Bissingen, Germany) under different combining parameters of spatial resolution (10 and 25 line pairs per millimeter [lp/mm]) and contrast resolution (8- and 16-bit depths). Subsequently, a dedicated endodontic filter was applied on the 16-bit images, creating 2 additional parameters. Six observers measured the length of the endodontic files in the root canals using the software that accompanies the system. The mean values of the actual file lengths and the measurements of the radiographic images were submitted to 1-way analysis of variance and the Tukey test at a level of significance of 5%. The intraobserver reproducibility was assessed by the intraclass correlation coefficient. ResultsAll combined image parameters showed excellent intraobserver agreement with intraclass correlation coefficient means higher than 0.98. The imaging parameter of 25 lp/mm and 16 bit associated with the use of the endodontic filter did not differ significantly from the actual file lengths when both file sizes were analyzed together or separately (P > .05). When the size 15 file was evaluated separately, only 8-bit images differed significantly from the actual file lengths (P ≤ .05). ConclusionsThe combination of an endodontic filter with high spatial resolution and high contrast resolution is recommended for the determination of file lengths when using storage phosphor plates.

Differential Scanning Calorimetric (DSC) Analysis of Rotary Nickel-Titanium (NiTi) Endodontic File (RNEF)

To determine the variation of Af along the axial length of rotary nickel-titanium endodontic files (RNEF). Three commercial brands of 4% taper RNEF: GTX (#20, 25 mm, Dentsply Tulsa Dental Specialties, Tulsa, OK, USA), K3 (#25, 25 mm) and TF (Twisted File #25, 27 mm) (Sybron Kerr, Orange, CA, USA) were cut into segments at 4 mm increment from the working tip. Regional specimens were measured for differential heat-flow over thermal cycling, generally with continuous heating or cooling (5 °C/min) and 5 min hold at set temperatures (start, finish temperatures): GTX: −55, 90 °C; K3: −55, 45 °C; TF: −55, 60 °C; using differential scanning calorimeter. This experiment demonstrated regional differences in Af along the axial length of GTX and K3 files. Similar variation was not obvious in the TF samples. A contributory effect of regional difference in strain-hardening due to grinding and machining during manufacturing is proposed.

Length of endodontic files measured in digital radiographs with and without noise-suppression filters: an ex-vivo study.

The aim of this study is to evaluate if theoretically possible edge shifts induced by noise-suppression filters potentially occur on objects found in digital radiographs. Most manufacturers carry out noise-suppression filtering of their images before they are displayed to the user. It is not usually possible for the user to disrupt the function of the filters. The use of these filters can lead to deletion of small image structures. K-files (ISO size 06, 08, 10 and 15) were placed in the root canals of 6 human teeth located in cadaver jaw segments. File tip positions were measured on original and filtered digital images by three observers. The file position was marked on each filtered image and compared with the unfiltered ones. The 5 × 5 pixel-sized median and mean filters caused the largest underestimation of measured lengths between -7.87 pixels and -10.8 pixels (-306.93 μm and -421.2 μm). Maximum standard deviation for length differences was found for the calculated position ( = gold standard) and the original unfiltered images with 13.31 pixels. The standard deviation found for the 5 × 5 mean and median filter was 7.62 pixels and 8.68 pixels. Different studies showed that noise-suppression filters can induce edge shifts in diagnostic radiographs. The high standard deviations found for length differences between the defined gold-standard and the original images indicate that theoretical edge shifts may not be clinically relevant for length measurements of endodontic files.

Efficacy of several digital radiographic imaging systems for laboratory determination of endodontic file length

To compare the efficacy of different digital radiographic imaging systems for determining the length of endodontic files. K-type endodontic files were introduced into the canals of 40 extracted human permanent single-rooted teeth and fixed in place at random lengths. The teeth were radiographed using Digora Optime, CygnusRay MPS and CDR Wireless digital imaging systems. Six observers measured every file length in all the images and repeated this procedure in 50% of the image samples, and assigned a score to the level of difficulty found. Analysis of variance for differences between digital systems and Tukey's test were performed. The level of intraobserver agreement was measured by intraclass correlation. The assigned scores were evaluated by Kruskal-Wallis and Dunn's tests. The CDR Wireless values did not differ significantly from the actual lengths and the CygnusRay MPS values. The Digora Optime system was significantly different from the others and overestimated the values (P ≤ 0.05). The Digora Optime was significantly easier to use for taking measurements and the CygnusRay MPS the most difficult (P ≤ 0.05). All digital radiographic imaging systems showed excellent agreement with the Intraclass Correlation Coefficient >0.95. The three digital radiographic imaging systems were precise. The CDR Wireless system was significantly more accurate in determining endodontic file lengths, and similarly to Digora Optime, was considered the least difficult to use when assessing endodontic file lengths.

Study of endodontic working length of Korean posterior teeth

Objectives: The aim of this study was to investigate average working lengths of Korean posterior teeth and evaluate validity of endodontic file length. Materials and Methods: The endodontic working length of the posterior teeth of 670 Korean patients were measured than each mean value and standard deviation were investigated than the frequency deviation and standard deviation per each length were calculated. Results: Among the canals of premolar, 66.5% of canal length was marked under 20 mm by endodontic working length and 95.4% could be measured under 22 mm and Among the canals of molars, 95.5% of canal length was marked under 20 mm endodontic working length . Conclusions: With the result of measurement of endodontic working length of premolars of Korean, it sug- gested that 23 mm endodontic file is more proper than the 21 mm and 25 mm file on the market.

Effect of various digital processing algorithms on the measurement accuracy of endodontic file length

The aim of this study was to compare the accuracy of endodontic file lengths after application of various image enhancement modalities. Endodontic files of three different ISO sizes were inserted in 20 single-rooted extracted permanent mandibular premolar teeth and standardized images were obtained. Original digital images were then enhanced using five processing algorithms. Six evaluators measured the length of each file on each image. The measurements from each processing algorithm and each file size were compared using repeated measures ANOVA and Bonferroni tests (P = 0.05). Paired t test was performed to compare the measurements with the true lengths of the files (P = 0.05). All of the processing algorithms provided significantly shorter measurements than the true length of each file size (P < 0.05). The threshold enhancement modality produced significantly higher mean error values (P < 0.05), while there was no significant difference among the other enhancement modalities (P > 0.05). Decrease in mean error value was observed with increasing file size (P < 0.05). Invert, contrast/brightness and edge enhancement algorithms may be recommended for accurate file length measurements when utilizing storage phosphor plates.

Accuracy of film-based, digital, and enhanced digital images for endodontic length determination

This study compared the accuracy of D- and F-speed intraoral radiographs and digital and enhanced digital radiographic images for endodontic file length determination. Size 15 K-files were bonded in 51 canals of 34 human cadaver teeth. The distance from file tip to root apex was measured on D- and F-speed film and on unenhanced and enhanced digital images. The quality of the images was rated by the observers. Overlying cadaver bone and root structure were subsequently removed to expose the file tip for actual measurement to the apex. The distance measured on each image was compared with the actual measurement. ANOVA, Kruskal-Wallis, sign test, and Pearson correlation statistical analyses were applied. There were no significant differences in measurement accuracy among the 4 image types (P < or = .05). Subjective ratings showed a preference for the quality of enhanced digital images. Conclusion All 4 image types were similar in accuracy of file measurement. The image quality of enhanced digital images was subjectively superior to the others.

A resource guide for practice development through technology

A resource guide for practice development through technology

Measurement of Endodontic File Lengths: Calibrated Versus Uncalibrated Digital Images

This in vitro study compared the accuracy of file length measurements made on calibrated and uncalibrated direct digital images. Endodontic files of known lengths and ISO sizes were used in 10 single-rooted, relatively straight teeth within cadaver specimens. The crowns of the teeth were ground flat and an orthodontic wire of known length was secured to the coronal surface. This wire was placed mesiodistally and perpendicular to the root and served as the reference point for the file measurement and as a calibration reference length. A #20 file was hand-measured to a length that reached the apical third of each tooth. It was inserted and a radiographic image was secured. The instrument was remeasured three additional times at different lengths on the same tooth and reinserted before each image acquisition. Thus 40 digital images were acquired using a GE X-ray unit and a Schick Computed Dental Radiography (CDR) #2 sensor. These images were placed in random order, and an independent, blinded investigator determined the file lengths using on-screen calibrated and uncalibrated measurement of the CDR image with a straight-line and multiple-line measuring technique. The experimental measurements were compared with each other and with the known clinical measurements. A two-way analysis of variance indicated that there was a statistically significant difference showing that the calibrated measurements were more accurate than the uncalibrated measurements (p = 0.0001), and there was no significant difference between the straight-line and multiple-line measuring techniques (p = 0.14).

Measurement of Endodontic File Lengths: A Density Profile Plot Analysis

The purpose of this study was to evaluate measurements of endodontic files of known length and diameter using a density profile plot analysis of digital images. Ten single-rooted teeth with relatively straight roots in cadaver specimens were used. The crowns of the teeth were removed and a rectangular orthodontic wire, 5.13 mm in length, was placed horizontally on the occlusal surface to serve as a calibration reference point. The #8, #10, #15, and #20 FlexOFiles were measured to the nearest 0.5 mm and then placed to four working lengths that terminated within the apical third of each root. A GE X-ray unit and a Schick CDR #2 sensor were used to digitally acquire 160 images. The digital images were placed in random order and an independent, blinded investigator determined the file length using a density profile plot analysis. The measurements generated by the histogram analysis (experimental) were compared with the original clinical measurements. The paired t test, intraclass correlation coefficient, and the Bradley-Blackwood test were used to assess reliability. The results revealed that the means of the experimental measurements of all file sizes were within 0.5 mm of the known lengths and were always shorter than the known lengths. Also, the larger the file size the less deviation from the known lengths: #20, -0.16 mm (p = 0.0001); #15, -0.21 mm (p = 0.0001); #10, -0.34 mm (p = 0.0001); and #8, -0.45 mm (p = 0.0001). This study demonstrated that the density profile plot analysis might be a useful adjunct for the measurement of endodontic file lengths on a digital image.

Comparison of Digital Dental X-ray Systems with Self-Developing Film and Manual Processing for Endodontic File Length Determination

Human skulls were sectioned into 15 sextants. Teeth were then removed and 45 canals were instrumented to their apical foramina. Endodontic files were glued in place at random distances from the apical foramina. Image geometry was maintained by a custom mounting jig. Images were captured with self-developing film, manually processed D-speed film, and a digital radiographic system (Dexis). Digital images were read on a conventional color monitor (cathode ray tube) and a laptop screen (active-matrix liquid crystal display). Fifteen dentists measured the distance from the file tip to the apical foramen of the tooth. Results showed that the measurement error was significantly less for the digital images than for the film-based images. It is likely that these statistical differences may not be of great clinical significance because the digital images could be measured in increments < 0.25 mm.

The effects of developer age on diagnostic accuracy: a study using assessment of endodontic file length

The effects of developer age on diagnostic accuracy: a study using assessment of endodontic file length

OR 14 Measurement of endodontic file lengths: a density profile plot analysis of digital images

OR 14 Measurement of endodontic file lengths: a density profile plot analysis of digital images