Canal length evaluation of curved canals by direct digital or conventional radiography

Comparison of the accuracy of conventional and digital radiography in root canal working length determination: An invitro study

Background. Digital radiography has widespread use in endodontics. Determining a correct working length is vital for a proper endodontic therapy. The aim of this study was to compare the accuracy of conventional and digital radiographic techniques for root canal working length determination.

Methods. After determining the real working lengths of 50 permanent maxillary central incisors (gold standard), the conventional (E- and F-speed films) and digital (CCD, PSP) images were obtained using the parallel technique. The mean registered working length of each modality was compared with the other and with the gold standard using one-way ANOVA at P<0.05.

Results. No significant difference was found between the recorded working length values using the conventional and digital radiographic techniques (P=0.828).

Conclusion. Within the limitations of this study, it was concluded that there was no difference between the measurement accuracy of CCD, PSP and conventional imaging techniques in root canal working length determination.

Influence of Root Canal Curvature on the Accuracy of Root ZX Electronic Foramen Locator: An In Vitro Study

Introduction:

The aim of this in vitro study was to evaluate the correlation between accuracy of Root ZX electronic foramen locator and root canal curvature.

Methods and Materials:

One hundred and ten extracted mandibular molars were selected. Access cavity was prepared and coronal enlargement of mesiobuccal canal was performed. A #10 Flexofile was inserted into the mesiobuccal canal, and a radiography was taken to measure the degree of curvature by Schneider's method. The actual working length (AWL) was defined by inserting the file until its tip could be observed at a place tangential to the major apical foramen and then 0.5 mm was subtracted from this measurement. For the electronic working length (EWL) measurement, the apical 3 or 4 mm of the root was embedded in alginate as the electrolyte material. The file was inserted into the root canal to the major foramen, until the APEX reading was shown on the electronic device and then pulled back until the visual display showed the 0.5-mm mark. The AWL was subtracted from the EWL to define the distance between the file tip and the point 0.5 mm coronal to the major apical foramen. Data were analyzed using the Pearson’s correlation coefficient.

Results:

The accuracy of Root ZX within ±0.1 mm and ±0.5 mm was 38.2% and 94.6%, respectively. There was no correlation between the distance from the EWL to the AWL and the degree of root canal curvature (r=0.097, P=0.317).

Conclusion:

Root canal curvature did not influence the accuracy of Root ZX foramen locator.

Digital radiography for determination of primary tooth length: in vivo and ex vivo studies

BACKGROUND

Methods for determining the root canal length of the primary tooth should yield accurate and reproducible results. In vitro studies show some limitations, which do not allow their findings to be directly transferred to a clinical situation.

AIM

To compare the accuracy of radiographic tooth length obtained from in vivo digital radiograph with that obtained from ex vivo digital radiograph.

METHOD

Direct digital radiographs of 20 upper primary incisors were performed in teeth (2/3 radicular resorption) that were radiographed by an intraoral sensor, according to the long-cone technique. Teeth were extracted, measured, and mounted in a resin block, and then radiographic template was used to standardise the sensor-target distance (30 cm). The apparent tooth length (APTL) was obtained from the computer screen by means of an electronic ruler accompanying the digital radiography software (CDR 2.0), whereas the actual tooth length (ACTL) was obtained by means of a digital calliper following extraction. Data were compared to the ACTL by variance analysis and Pearson's correlation test.

RESULTS

The values for APTL obtained from in vivo radiography were slightly underestimated, whereas those values obtained from ex vivo were slightly overestimated. No significance was observed (P ≤ 0.48) between APTL and ACTL.

CONCLUSION

The length of primary teeth estimated by in vivo and ex vivo comparisons using digital radiography was found to be similar to the actual tooth length.

Comparison of two methods of digital imaging technology for small diameter K-file length determination

OBJECTIVES

Obtaining the proper working length in endodontic treatment is essential. The aim of this study was to compare the working length (WL) assessment of small diameter K-files using the two different digital imaging methods.

METHODOLOGY

The samples for this in-vitro experimental study consisted of 40 extracted single-rooted premolars. After access cavity preparation, the ISO files no. 6, 8, and 10 stainless steel K-files were inserted in the canals in the three different lengths to evaluate the results in a blinded manner: At the level of apical foramen(actual)1 mm short of apical foramen2 mm short of apical foramen A digital caliper was used to measure the length of the files which was considered as the Gold Standard. Five observers (two oral and maxillofacial radiologists and three endodontists) observed the digital radiographs which were obtained using PSP and CCD digital imaging sensors. The collected data were analyzed by SPSS 17 and Repeated Measures Paired T-test.

RESULTS

In WL assessment of small diameter K-files, a significant statistical relationship was seen among the observers of two digital imaging techniques (P<0.001). However, no significant difference was observed between the two digital techniques in WL assessment of small diameter K-files (P<0.05).

CONCLUSION

PSP and CCD digital imaging techniques were similar in WL assessment of canals using no. 6, 8, and 10 K-files.

Direct digital radiography versus conventional radiography for estimation of canal length in curved canals

Purpose

The purpose of this study was to compare the conventional and digital radiography in the estimation of working length in mandibular molars.

Materials and Methods

Sixty molar teeth were selected and divided into three groups in the basis of canal curves (0-15°, 15-30°, >30°). After the placement of a 15 K-file, radiographs were taken with a conventional film (F-speed) and a digital sensor. Canal lengths were measured in these images by two observers. Statistical analysis was performed with repeated measures of ANOVA and paired sample t-test with 95% confidence.

Results

There was a high inter-observer agreement on the measurements of working length in conventional and digital radiographs. There was no significant difference between the mean values of measurements in conventional and digital radiography. Moreover, there was no significant difference between conventional and digital radiography with the actual values in the basis of canal curves.

Conclusion

The accuracy of conventional and digital radiography in the determination of the working length was in an acceptable range.

Better imaging: the advantages of digital radiography

BACKGROUND

Digital radiography has been available in dentistry for more than 25 years, but it has not replaced conventional film-based radiography completely. This could be because of the costs involved in replacing conventional radiographic equipment with a digital imaging system, or because implementing new technology in the dental practice requires a bit of courage. When the practitioner is fully aware of the new possibilities offered by digital radiography, he or she can make a more informed decision about adopting it. This article offers information about digital radiography, not just as a replacement of conventional radiography, but also as a concept offering benefits beyond those of conventional radiography.

OVERVIEW

Digital radiographs are composed of a set of numbers arranged as a grid of rows and columns. The dentist can perform mathematical operations on these numbers to create a new image in which certain characteristics are enhanced, thus making interpretation of the image easier. The dentist also can correct, to some extent, overexposed or underexposed images and can optimize contrast and brightness for specific diagnostic procedures, such as caries detection and bone level assessment. More advanced procedures are available as well, such as digital subtraction radiography and computer-aided recognition of image features.

CONCLUSIONS AND CLINICAL IMPLICATIONS

The author presents a selection of the advantages of digital radiography that are not achievable with conventional film-based radiography. Implementing digital radiography in the dental office requires additional training. However, once members of the dental team have gone through this initial phase, they have the benefits of several new diagnostic possibilities. With a digital system, information from radiographic images is collected more easily and in a more objective way, which will improve the performance of the diagnostic process.

New software: comparison between three software programs for root canal length measurement

OBJECTIVES

The purpose of this study was to design a software program to estimate the curved root canal working length by using curved line software and comparing its accuracy with Trophy and Cygnus software programs.

METHODS

120 simulated curved canals were divided into 12 groups based on the radius and the angle of the curvature. The true canal length was measured from the orifice to the terminus. Canals were filled with urographin and were imaged by a digital radiographic system. Canal length was measured with newly developed software that uses a curved line, as well as with Cygnus and Trophy software, both of which use a sequence of straight lines, and their accuracies were compared.

RESULTS

The proposed software was significantly more accurate than other software with respect to the gold standard (P < 0.001). However, the error was less than 0.5 mm in over 99% of the cases with all software with three clicks, and over 96% of the cases with six clicks in Trophy, which was not statistically significant (P = 0.99).

CONCLUSIONS

The studied software programs were not significantly different and their statistically significant difference compared with the gold standard is not clinically significant. The suggested software has to be studied more regarding its capabilities in the utilization of curved lines in measuring curved canals and calibration of the measurements.

Effect of ambient light and bit depth of digital radiograph on observer performance in determination of endodontic file positioning

OBJECTIVES

To examine the effects of the luminance and bit depth of digital image on observer performance for determination of endodontic file positioning.

STUDY DESIGN

Using extracted premolar teeth, no. 08 K-file was placed into the canal and positioned so that the tip was either flush or 1 mm short of the radiologic root apex. The samples were imaged with both conventional and digital radiographs at 8 and 12 bits. Eleven observers read the images under dark and bright condition, and receiver operating characteristics analysis was performed. Additionally, the interpreting time was measured.

RESULTS

The 12-bit images showed similar observer performance compared with conventional images, and better than the 8-bit images. The interpretation time for bright condition and 8-bit images was longer than for dark condition and 12-bit images.

CONCLUSION

Twelve-bit digital images were preferred to 8-bit for accurate determination of endodontic file position.

Digital and Advanced Imaging in Endodontics: A Review

This review provides an overview of digital radiography as it exists, including advanced imaging such as computed tomography (CT), cone beam volumetric imaging, and micro-CT as relevant to the practice of endodontics. An evidence-based approach to adoption of different imaging technologies is included to assist the practitioner with the selection process of imaging modalities. Commonly used imaging terminology is introduced, as well as the advantages and disadvantages of image processing. New image reconstruction techniques have been introduced that provide information three-dimensionally to the clinician for routine endodontic and surgical treatment planning. The age of three-dimensional imaging and image processing is here. Limitations and advantages of newly introduced imaging modalities are discussed briefly.

In vitro radiographic determination of distances from working length files to root ends comparing Kodak RVG 6000, Schick CDR, and Kodak insight film

Previous studies suggest that digital and film-based radiography are similar for endodontic measurements. This study compared the accuracy and acceptability of measured distances from the tips of size #10 and #15 files to molar root apices in cadaver jaw sections using the newly developed Kodak RVG 6000, and the Schick CDR digital systems to digitized Kodak film. Standardized images were taken of files placed 0.5 to 1.5 mm short of true radiographic lengths. Images were imported into Adobe PhotoShop 7.0, thereby blinding observers who measured distances from files to root apices and assessed images for clarity (acceptability). Repeated measures ANOVA and Tukey-Kramer post hoc tests demonstrated that Kodak RVG 6000 images with enhanced contrast produced significantly less measurement error than unenhanced contrast Schick CDR images (p < 0.05) and significantly higher acceptability ratings than all other systems (all p < 0.002). Among these conditions, the newly developed Kodak RVG 6000 system provided the best overall images.

A laboratory comparison of three imaging systems for image quality and radiation exposure characteristics

AIM

To measure and compare the relationships between image quality and X-ray exposure for three types of intraoral imaging system (conventional film, phosphor plate system and CCD-based system).

METHODOLOGY

Kodak 'Insight' F-speed film, Digora FMX (phosphor plate system) and Visualix USB (CCD system) were used to produce series of radiographic images of two tooth-bearing jaw specimens (maxillary molar and mandibular molar regions) at a range of X-ray exposures from 10 ms to 2000 ms (all at 6 mA and 60 kV). Digital images were viewed from a computer monitor and films viewed on a conventional light box. Five observers scored each image using a five-point subjective image quality scale (0-4).

RESULTS

Optimum image quality (4) was seen for conventional film. Neither digital system achieved this score at any exposure, achieving in both cases a maximum mean score of 3.1 (adequate visualization). The two digital systems, however, provided adequate visualization at substantially lower exposure times. Dose reduction over conventional film for maximum quality images with Visualix USB was 20%, but for Digora FMX it was 70%. All three systems gave acceptable (quality score of two or higher) images over a broad range of exposures.

CONCLUSIONS

In terms of subjective image quality, F-speed film performed better than the two digital systems, but this must be weighed against the ability of the two digital systems to give adequate image quality at lower radiation doses.

Filmless imaging

BACKGROUND

As use of digital radiography becomes more common, many dentists are wondering if and how they can replace conventional film-based imaging with a digital system. This article briefly describes the different technologies used for digital radiography in dentistry. The article provides general practitioners with a broad overview of the benefits and limitations of digital radiography to help them understand the role the technology can play in their practices.

OVERVIEW

The two technologies now available are solid-state systems and phosphor plate systems. Each has its strong points, and the choice of which to use depends on the type of dental practice. Image processing improves the diagnostic quality of the radiographic information. Advanced image-processing techniques, such as subtraction radiography, are available for specialized clinics.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Digital radiography no longer is an experimental modality. It is a reliable and versatile technology that expands the diagnostic and image-sharing possibilities of radiography in dentistry. Optimization of brightness and contrast, task-specific image processing and sensor-independent archiving are important advantages that digital radiography has over conventional film-based imaging.

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

OBJECTIVE

This study compared the accuracy of D- and F-speed intraoral radiographs and digital and enhanced digital radiographic images for endodontic file length determination.

STUDY DESIGN

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.

RESULTS

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.

Clarity and diagnostic quality of digitized conventional intraoral radiographs

OBJECTIVES

To compare digital images of conventional radiographs with the original radiographs for perceived clarity of endodontic files, periapical lesions and carious lesions, and to establish the diagnostic value of the digital images.

METHODS

Four groups of ten radiographs were used: standardized bitewings demonstrating carious lesions, periapical radiographs of apical lesions, periapical radiographs showing endodontic files of various sizes at working length, and standardized periapical radiographs with size 08 files at working length. Radiographs were photographed using an Olympus C 2500-L digital camera and a Nikon D1X digital camera and were scanned using a Nikon Supercoolscan 4000 ED film/slide scanner. The digital images were then transferred to a Toshiba Satellite 2210 laptop. Three general dental practitioners compared each conventional radiograph with the three matching digital images. Images were ranked for clarity and were assessed for diagnostic quality. Data were analysed using General Estimating Equations.

RESULTS

The clarity and diagnostic quality of the conventional radiographs were superior to the digital images produced by the three techniques (P < 0.001). No significant difference was found between the Nikon D1X and Camedia 2500-L cameras for clarity or diagnostic quality. The scanner was equivalent to the Camedia 2500-L camera for diagnostic quality, but was otherwise inferior to both cameras.

CONCLUSIONS

Digitizing conventional radiographs using current high-grade digital cameras or scanners does not produce images of diagnostic quality. Improved resolution of viewing monitors is necessary to fully harness the potential of digital technology.

Evaluation of endodontic files in digital radiographs before and after employing three image processing algorithms

OBJECTIVES

Two digital image processing algorithms, one aimed at correction for exponential attenuation and one at correction for visual response, have been developed. The aims of the present study were to test whether digital radiographs processed with these algorithms improve determination of the length of endodontic files and whether such processed radiographs are comparable with the radiographs processed with a default image processing method employed by one commercially available digital intraoral system.

METHODS

A dried human skull embedded in an acrylic compound was used for exposing radiographs of the upper and lower premolars and molars with endodontic files (Kerr files size 10 and size 15) positioned to the full length of the roots or 1.5 mm short of it. Radiographs were then processed in three sets. In one set, the radiographs were processed to compensate for exponential attenuation and the response of the human visual system. In the second, the radiographs were processed with the same compensation but with an additional shift in grey levels so that the output luminance in dentin at root tips corresponds to the mean of the luminance range of a computer monitor. In the third, the radiographs were processed with the default processing method in the Sidexis program. Ten viewers evaluated all radiographs. Receiver operating characteristic (ROC) curves were obtained and areas under the curves were calculated.

RESULTS

For file size 10, ROC curves for processed radiographs were higher than that for originals, while for file size 15, ROC curves for processed and original radiographs were close to each other. Significant differences were found between processed and original radiographs regarding areas under ROC curves for file size 10 but not between the differently processed radiographs. For file size 15, no significant differences were found.

CONCLUSION

Radiographs processed to correct for attenuation and visual response may improve determination of the length of thin endodontic files. Such processed radiographs are comparable with the radiographs processed with the default processing method in the Sidexis program.