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

Comparative Accuracy and Reliability of Three Electronic Apex Locators in Determining the Apical Constriction of Molar Canals: A Micro-CT Evaluation

Background: Determining the correct apical limit for root canal treatment is essential for its success. This study evaluates the accuracy of three electronic apex locators (EALs) in locating the apical constriction (AC) in molar canals. Methods: Forty extracted human mandibular molars were scanned using micro-CT, and endodontic access cavities were created. Teeth were mounted in alginate, and three EALs-Root ZX-mini, Root ZX-II, and Sirona integrated apex locator-were used to measure the canal working length in dry canals and with EDTA gel. Micro-CT scans were performed with files in place, and the distance from the AC was calculated. Measurements within 0.1-0.5 mm were categorized as 'close'. Those extending beyond towards the major foramen were categorized as 'beyond', otherwise they were classified as 'far'. Data analysis was conducted with a level of significance set at 5%. Results: Most readings for all EALs were in the 'close' category, with significant differences between devices (p < 0.0001). Root ZX-mini and Root ZX-II had 74.4% and 72.5% 'close' readings, respectively, versus 51% for Sirona integrated. Accuracy did not differ significantly between dry and EDTA-treated canals (p = 0.306). All EALs demonstrated excellent operator reliability (ICC 0.996-1.00). Conclusions: All EALs accurately determined AC, unaffected by lubricants. However, Root ZX-mini and Root ZX-II outperformed Sirona integrated. All EALs showed consistent reliability.

Clinicians' perspectives, inducements, preferences, and clinical experiences regarding the use of electronic apex locator and apex locator integrated engine-driven instrumentation: a cross-sectional study

BACKGROUND

This study aimed to investigate the perspectives, preferences, and clinical experiences regarding using electronic apex locator and apex locator integrated instrumentation of dentists and endodontists.

METHODS

A web-based questionnaire consisting of 3 parts and 23 closed-ended questions to achieve the objective of the study was carried out in ethical conditions between August and October 2023. The first part of survey included demographic information, while the second part was about evaluating electronic apex locator usage. In the last part, only participants' use of apex locator-integrated instrumentation was evaluated. Data were analyzed at a significance level of p < 0.05.

RESULTS

A total of 297 clinicians, including 59 endodontists and 34 endodontic residents/Ph.D. students participated in the questionnaire. Endodontists and endodontic residents/Ph.D. students perform statistically significantly more root canal treatments per week on average (p = 0.001). For the working length determination method (multiple option question), 78.5% of participants use an electronic apex locator and 39.7% apex locator-integrated engines. However, the preference rate for electronic apex determination technique was generally 95.6%, with the full rate confirmation of endodontists and endodontic residents/Ph.D. students (100%). A total of 21 endodontists out of 59 prefer apex locator integrated engine-driven instrumentation. Although many of these specialized clinicians use this technique, they stated that they measure electronic working length passively for confirmation of the working length before (90.5%) and after the preparation (66.7%).

CONCLUSIONS

Dentists, as well as endodontists, are skeptical about apex locator-integrated engine-driven instrumentation. Using this technique as a supporter rather than a primary way for preparation within safe limits may give safer results in terms of treatment outcomes.

Influence of different viewing conditions on the detection of fractured endodontic instruments using periapical radiographs at 3 projection angles

OBJECTIVES

The objective of this study was to assess the influence of ambient lighting levels and horizontal viewing angle (HVA) on the radiographic detection of fractured endodontic instruments in root canals in extracted human mandibular molars.

STUDY DESIGN

Thirty-two root canals were selected. Endodontic instrument fracture was induced in 24 canals, and all canals were endodontially treated. Periapical radiographs were obtained at orthoradial, mesioradial, and distoradial projection angles. Five oral radiologists examined the radiographs for detection of fractured endodontic instruments under 3 ambient lighting levels (high, 450 lux; medium, 28 lux; and low, 2.5 lux) and 3 HVAs (90°, 67.5°, and 45°). Area under the receiver operating characteristic curve (AUROC), accuracy, sensitivity, and specificity were calculated and compared by 2-way analysis of variance using Tukey post hoc tests (α = .05).

RESULTS

AUROC data indicated that ambient lighting (P = .739) and HVA (P = .238) did not significantly influence the detection of fractured endodontic instruments. Overall mean diagnostic values were 0.745, 0.57, 0.46, and 0.90 for AUROC, accuracy, sensitivity, and specificity, respectively.

CONCLUSIONS

The viewing conditions assessed in this study did not influence the radiographic detection of fractured endodontic instruments in root canals.

Effect of Orthodontic Brackets on the Accuracy of Apex Locators: A Pilot Study

The purpose of this study was to evaluate the effect of metal orthodontic brackets on the accuracy of electronic apex locator (EAL). The actual canal lengths (ACL) of 40 mandibular incisor teeth were determined. Then, the teeth were randomly divided into two groups (n = 20). Orthodontic metal brackets were applied in the first group, and no brackets, in the second group. The working length of each tooth was measured with an EAL under 3 test conditions according to the distance between the lip clip and sample tooth. Data were analyzed using one-way repeated measures analysis of variance and Tukey's post hoc tests (p = 0.05). In the bracketed samples, when the lip clip was located at 1 cm and 2 cm from the samples. The mean differences between the EAL measurements and ACLs were statistically higher than those when the samples were located 3 cm from the lip clip (p < 0.05). There were also statistically significant differences between EAL measurements and ACLs in the bracketed samples located 1 and 2 cm from the lip clip (p < 0.05). In the nonbracketed group, the differences between EAL measurements and ACLs were not statistically significant in the samples located 1, 2, and 3 cm from the lip clip (p > 0.05). Use of orthodontic metal brackets can negatively influence the accuracy of the electronic apex locator when the distance between the lip clip and bracket was short. A minimum of 3 cm distance should be kept between the lip clip and tooth in order to make consistent electronic measurements.

Ex Vivo Evaluation of the Accuracy of 3 Electronic Apex Locators in Different Environments: A Micro-Computed Tomography Study

Objective:

The aim of this study was to compare the accuracy of three electronic apex locators (EALs) (Propex Pixi, Mini Root ZX, Raypex 5) in determining working length (WL) under different environments (existence of blood-pulp/sodium hypochlorite in root canal space) using micro-computed tomography (micro-CT) measurements.

Methods:

Twenty-five single-rooted human teeth that were scheduled for extraction were selected for the study. Measurements were performed with the Propex Pixi, Mini Root ZX, Raypex 5 in vivo conditions in the presence of NaOCl irrigant solution or blood-pulp tissue. After that the teeth were extracted and scanned using micro-CT. The measurements of WL obtained with the different EALs in different environments were statistically compared. Significance was set at P<0.05.

Results:

There were no significant differences among the WL measurements performed with EALs or micro CT groups under different clinical enviroments. All EALs tested gave reliable results in respect to apical constriction.

Conclusion:

The accuracy of the tested EALs is not affected by pulp tissues and blood or NaOCl.

Effect of Resolution and Bit Depth on Inferior Alveolar Canal Visualization on Exported Mandibular Cone-Beam Computed Tomography Images

PURPOSE

Cone-beam computed tomography (CBCT) is commonly requested before dental implant treatment for the anatomic assessment of the inferior alveolar canal (IAC) to prevent its neurovascular content from being traumatized. CBCT images can be saved in different types of resolutions and bit depths; these parameters may significantly affect the diagnostic accuracy of images. This study aimed to assess the effect of resolution and bit depth on IAC visualization on exported mandibular CBCT images.

MATERIALS AND METHODS

Forty-one mandibular CBCT images of differing image resolutions and voxel sizes (0.16, 0.32, and 0.48 mm) and differing bit depths (12 and 15) were exported from a software program as a single file. Two observers evaluated the cross-sectional images in terms of IAC visibility using a 3-point scale (good, moderate, and poor). Disagreements were resolved by including a third observer, and the highest agreement was recorded.

RESULTS

Study interobserver agreement was acceptable (84.2%) for IAC observation. The percentage of IAC observation was from 84.1 to 100% with the 12- and 15-bit depths, with a constant image resolution of 0.16 and 0.32 mm, respectively. A significant difference (from 19.5 to 48.8%) was noted between the 2 bit depths in the percentage of good IAC visualization with a constant resolution of 0.48 mm. Reduction in the image resolution to 0.48 mm showed a significant difference (19.5 to 100%) between the 12- and 15-bit depths in good IAC visualization.

CONCLUSIONS

Exporting the mandibular CBCT images with 0.32 mm of resolution and a 12-bit depth will produce good and moderate radiographic IAC observation with the benefit of a smaller file size.

Is the digital radiographic detection of approximal caries lesions influenced by viewing conditions?

OBJECTIVES

The aim of this study was to assess the influence of different viewing conditions (combinations of computer display, horizontal viewing angle, and ambient lighting) on the detection of approximal caries lesions on digital radiographic images.

STUDY DESIGN

Forty posterior teeth were mounted in a plaster block and radiographed by using a CMOS sensor-based system. Three oral radiologists assessed the radiographic images under different conditions of computer display (iMac 5K 27", Barco MDRC-2124, and Dell P2314H), horizontal viewing angles (90 degrees, 67.5 degrees, and 45 degrees), and ambient lighting (low, medium, and high) and were asked to detect the presence of approximal caries lesions, which were confirmed by means of micro-computed tomography (micro-CT), using a 5-point scale. The area under the receiver operating characteristic curve, sensitivity, and specificity were calculated and compared by analysis of variance testing (α = 0.05). Intra- and interobserver agreements were assessed with the Kappa test.

RESULTS

Computer display, horizontal viewing angle, and ambient lighting did not significantly influence the diagnosis of approximal caries lesions. In general, moderate values of accuracy, low sensitivity, and high specificity were found for all viewing conditions.

CONCLUSIONS

The viewing conditions assessed in this study did not influence the detection of approximal caries lesions on digital radiographic images. Dental practitioners are encouraged to find their most comfortable viewing condition for this diagnostic task.

Influence of phosphor plate-based radiographic image specifications on fractal analysis of alveolar bone

OBJECTIVE

The aim of this study was to evaluate the influence of spatial resolution, bit depth, and enhancement filters on the fractal dimension (FD) of photostimulable phosphor (PSP) plate-based intraoral radiographic images of alveolar bone.

STUDY DESIGN

Periapical radiographs were obtained using PSP plates, which were scanned at 2 spatial resolutions: 1270 dpi and 2000 dpi. All images were subjected to 3 enhancement filters-Perio, Endo, and Fine-and exported in 8 and 16 bits. A region-of-interest was selected on alveolar bone and the FD value was calculated. The multiway analysis of variance test followed by the post hoc Tukey test compared the FD values between the different groups (α = 0.05).

RESULTS

No significant difference was observed in FD values between the 8- and 16-bit images. Except for the Perio filter, FD values were significantly higher for images at 1270 dpi. FD values were significantly higher for the Perio filter, followed by the Endo filter, and the Fine filter. The FD values of the Fine filter did not differ significantly from the original image.

CONCLUSIONS

Fractal analysis of alveolar bone obtained from PSP plate-based intraoral radiographic images is influenced by spatial resolution and some digital enhancement filters; therefore, for FD comparison purposes, images should have the same specifications.

Influence of interpretation conditions on the subjective differentiation of radiographic contrast of images obtained with a digital intraoral system

OBJECTIVES

The aim of this study was to evaluate interpretation conditions in the subjective in vitro assessment of dental tissue-equivalent radiographic contrast.

STUDY DESIGN

Radiographic images with the density of dental structures were randomized and arranged in 20 sequences with images juxtaposed and separated. Twelve observers interpreted the sequence among the most radiolucent and radiopaque images with 3 displays, 3 horizontal viewing angles, and 3 ambient light conditions. The evaluation time was recorded. The hit percentage was calculated for each evaluation. Three-way analysis of variance with Tukey's test was used to compare the conditions of interpretation. The intraclass correlation coefficient was used to assess agreement (α = 0.05).

RESULTS

No differences in hit percentages were found among the 3 displays or among the juxtaposed and separated images. Increased hit percentages were recorded for images assessed at 90° compared with 45° for all displays and in high ambient light vs intermediate and low light at 90°. Increased evaluation time was recorded for the consumer-grade display under high ambient light and for the separated images.

CONCLUSIONS

The subjective in vitro assessment of dental tissue-equivalent radiographic contrast is not influenced by computer display, which should be viewed at a horizontal viewing angle of 90° and under high ambient light. Longer evaluation times may be expected with consumer-grade displays.

Numerical Evaluation of Image Contrast for Thicker and Thinner Objects among Current Intraoral Digital Imaging Systems

The purpose is to evaluate the performance of current intraoral digital detectors in detail using a precise phantom and new method. Two aluminum step wedges in 0.5 mm steps were exposed by two photostimulable phosphor plate (PSP) systems—one with automatic exposure compensation (AEC) and the other without AEC—and a CCD sensor. Images were obtained with 3 doses at 60 kV. The effect of metallic material also was evaluated. The contrast-to-noise ratio (CNR) for thinner steps and the low contrast value (LCV) for thicker steps were obtained. The CCD system was the best under all conditions (P < 0.001), although the Gray value was sensitive to the dose, and the Gray value-dose relation varied greatly. The PSP system with AEC was superior to that without AEC for the LCV (P < 0.001) but was inferior to it regarding the CNR (P < 0.001). CNR and LCV in the PSP system without AEC were not affected by the metallic plate. Intraoral digital imaging systems should be chosen according to their diagnostic purpose. PSP system with AEC may be the best for detecting molar proximal caries, whereas the PSP system without AEC may be better for evaluating small bone regeneration in periodontal disease. The CCD system provided the best performance.

In vitro evaluation of Root ZX and Raypex 6 in teeth with different apical diameters

Background:

There is a growing interest about electronic apex locators for working length determination. There are several studies dealing with their performance in different conditions.

Aims:

The aim of this study is to evaluate the accuracy of Root ZX and Raypex 6 in teeth with different apical diameters.

Materials and Methods:

Actual working length (AWL) of 80 single rooted teeth were determined as 0.5 mm short of apical foramen. The teeth were divided into 4 groups (n = 20). First group (G 0) included teeth with mature apices. Root canals of the other groups (G 32, G 57 and G 72) were enlarged until apical sizes of 0.32, 0.57 and 0.72 mm were obtained. Samples were embedded in alginate and electronic measurements (EM) were performed.

Statistical analysis:

was achieved with Fisher exact test.

Results:

Both devices revealed a high rate of success in G 0 and G 32. Their accuracy decreased significantly in G 57 and G 72 groups (P < 0.05). Intra-group results of Root ZX and Raypex 6 were similar (P > 0.05).

Conclusions:

Root ZX and Raypex 6 are reliable in teeth with mature apices. At foramen diameters exceeding 0.57 mm, their accuracy is susceptible.

Quality assurance in digital dental imaging: a systematic review

OBJECTIVES

Doses induced by individual dental examinations are low. However, dental radiography accounts for nearly one third of the total number of radiological examinations in the European Union. Therefore, special attention is needed with regard to radiation protection. In order to lower patient doses, the staff performing dental examinations must have competence in imaging as well as in radiation protection issues. This paper presents a systematic review about the core competencies needed by the healthcare staff in performing digital dental radiological imaging quality assurance.

MATERIALS AND METHODS

The following databases were searched: Pubmed, Cinahl, Pro Quest and IEEXplore digital library. Also volumes of some dental imaging journals and doctoral theses of the Finnish universities educating dentists were searched. The search was performed using both MeSH terms and keywords using the option 'search all text'. The original keywords were: dental imaging, digital, x-ray, panoramic, quality, assurance, competence, competency, skills, knowledge, radiographer, radiologist technician, dentist, oral hygienist, radiation protection and their Finnish synonyms.

RESULTS

Core competencies needed by the healthcare staff performing digital dental radiological imaging quality assurance described in the selected studies were: management of dental imaging equipment, competence in image quality and factors associated with it, dose optimization and quality assurance.

CONCLUSIONS

In the future there will be higher doses in dental imaging due to increasing use of CBCT and digital imaging. The staff performing dental imaging must have competence in dental imaging quality assurance issues found in this review. They also have to practice ethical radiation safety culture in clinical practice.

Clinical efficacy of electronic apex locators: systematic review

INTRODUCTION

Apical constriction has been proposed as the most appropriate apical limit for the endodontic working length. Despite being the most used, some limitations are attributed to the radiographic method of working length determination. It lacks precision because it is based on the average position of the apical constriction. The electronic apex locators have been presented as an alternative to the odontometry performed by radiography. These devices detect the transition of the pulp to the periodontal tissue, which is anatomically very close to the apical constriction and may perform with improved accuracy.

METHODS

A systematic review was performed to compare the radiographic and electronic methods. Clinical studies that compared both methods were searched for on 7 electronic databases, a manual search was performed on the bibliography of articles collected on the electronic databases, and the authors were contacted to ask for references of more research not detected on the electronic and manual search.

RESULTS

Twenty-one articles were selected. The majority were comparative or evaluation studies, and very few clinical studies comparing both methods are available. Several methodological limitations are present on the collected articles and debated in this review.

CONCLUSIONS

Although the available scientific evidence base is short and at considerable risk of bias, it is still possible to conclude that the apical locator reduces the patient radiation exposure and also that the electronic method may perform better on the working length determination. At least one radiographic control should be performed to detect possible errors of the electronic devices.

Effect of pre-flaring and file size on the accuracy of two electronic apex locators

OBJECTIVE

This ex vivo study evaluated the effect of pre-flaring and file size on the accuracy of the Root ZX and Novapex electronic apex locators (EALs).

MATERIAL AND METHODS

The actual working length (WL) was set 1 mm short of the apical foramen in the palatal root canals of 24 extracted maxillary molars. The teeth were embedded in an alginate mold, and two examiners performed the electronic measurements using #10, #15, and #20 K-files. The files were inserted into the root canals until the "0.0" or "APEX" signals were observed on the LED or display screens for the Novapex and Root ZX, respectively, retracting to the 1.0 mark. The measurements were repeated after the preflaring using the S1 and SX Pro-Taper instruments. Two measurements were performed for each condition and the means were used. Intra-class correlation coefficients (ICCs) were calculated to verify the intra- and inter-examiner agreement. The mean differences between the WL and electronic length values were analyzed by the three-way ANOVA test (p<0.05).

RESULTS

ICCs were high (>0.8) and the results demonstrated a similar accuracy for both EALs (p>0.05). Statistically significant accurate measurements were verified in the pre-flared canals, except for the Novapex using a #20 K-file.

CONCLUSIONS

The tested EALs showed acceptable accuracy, whereas the pre-flaring procedure revealed a more significant effect than the used file size.

A new approach for locating the minor apical foramen using an artificial neural network

AIM

To develop a new approach for locating the minor apical foramen (AF) using feature-extracting procedures from radiographs and then processing data using an artificial neural network (ANN) as a decision-making system.

METHODOLOGY

Fifty straight single-rooted teeth were selected and placed in a socket within the alveolar bone of a dried skull. Access cavities were prepared and a file was place in the canals to determine the working length. A radiograph was taken to evaluate the location of the file in relation to the minor foramen and further checked after retrieving the tooth from the alveolar socket. The location of the file tip was categorized into: beyond the AF (long), within the root canal (short) and just at the minor AF (exact). Each radiograph was used to extract relevant features using K-means, Otsu method and Wavelet protocol. Thirty-six extracted features were used for training and the rest were used for evaluating the multi-layer Perceptron ANN model.

RESULTS

Analysis of the images from radiographs (test samples) by ANN showed that in 93% of the samples, the location of the AF had been determined correctly by false rejection and acceptation error methods.

CONCLUSION

Artificial neural networks can act as a second opinion to locate the AF on radiographs to enhance the accuracy of working length determination by radiography. In addition, ANN can function as a decision-making system in various similar clinical situations.

Effect of LCD monitor type and observer experience on diagnostic performance in soft-copy interpretations of the maxillary sinus on panoramic radiographs

Purpose

The aim of this study was to evaluate the effect of liquid crystal display (LCD) monitor type and observer experience on the diagnostic performance in soft-copy interpretations of maxillary sinus inflammatory lesions on panoramic radiographs.

Materials and Methods

Ninety maxillary sinuses on panoramic images were grouped into negative and positive groups according to the presence of inflammatory lesions, using CT for confirmation. Monochrome and color LCDs were used. Six observers participated and ROC analysis was performed to evaluate the diagnostic performance. The reading time, fatigue score, and inter-/intra-observer agreements were assessed.

Results

The interpretation of maxillary sinus inflammatory lesions was affected by the LCD monitor type used and by the experience of the observer. The reading time was not significantly different, however the fatigue score was significantly different between two LCD monitors. Inter-observer agreement was relatively good in experienced observers, while the intra-observer agreement for all observers was good with monochrome LCD but not with color LCD.

Conclusion

The less experienced observers showed lowered diagnostic ability with a general color LCD.

Work flow with digital intraoral radiography: a systematic review

OBJECTIVE

This systematic review evaluates the six most frequently emphasized advantages of working with digital radiography: less working time, lower radiation dose to the patient, fewer retakes and errors, wider dynamic range, easier access to patient information and easier image storage and communication. Moreover, some clinical aspects and possible disadvantages of digital imaging that were not foreseen at the beginning of the digital era, such as patient discomfort, damage to the receptor, degradation of the image, cross-contamination and viewing conditions, were assessed.

MATERIAL AND METHODS

The literature search used the PubMed database with no limits and was performed during June to August 2009. Search strategies are described in the text for each of the mentioned tasks. A hand search of task-specific journals supplemented the search strategies.

RESULTS

Time seems to be saved when switching from film to digital imaging in dental practice, a dose reduction may not be obtained, retakes and errors may be increased, the dynamic range may be wider with photostimulable storage phosphor (PSP) plates but not with sensors, the effect on patient information has not been well studied and storage and communication create new challenges with regard to handling large files and image compression. In addition, patient discomfort seems to be pronounced with sensors compared with PSP plates and film, the PSP plate may be scratched in clinical use and a two-layer barrier seems to be needed to prevent contamination of the receptor. The type of monitor may not be of major concern if the image is viewed in a room with subdued light.

CONCLUSIONS

Not all of the predicted advantages with digital compared to film-based radiography hold true in daily clinical work. Of particular interest is the relationship between number of images, retakes and the dose given to the patient.

The influence of tube potential on periodontal bone level measurements and subjective image quality using a digital photostimulable storage phosphor sensor

Objectives

The purpose of the present study was to determine the measurement accuracy and subjective image quality for periodontal disease diagnosis when using two X-ray tube voltages with a digital photostimulable storage phosphor sensor.

Material and Methods

A digital photostimulable storage phosphor (PSP) sensor (Vistascan) and a multipulse X-ray generator (Prostyle Intra) with two tube voltages were used in this study. The front, premolar and molar region of two adult human cadaver skulls jaws were imaged using the X-ray tube at 63 kV and 70 kV, both at 8 mA and decreasing exposure times (160 ms, 120 ms and 80 ms). A standardized exposure protocol containing waxed occlusal keys and an aiming device ensured proper and reproducible beam alignment. Three observers assessed the digital radiographs for 31 selected periodontal bone loss sites. Radiographic measurements were compared to physical measurements (Standard). Subjective ratings of lamina dura, crater defect and furcation involvement visibility, contrast perception and bone quality were also performed.

Results

Multiple regression equation of the variables kV and exposure time demonstrated no significant difference for the periodontal bone level measurements (P > 0.05). In 90.3% and 96.7% of the measurements for 70 kV and 63 kV respectively, deviation was within 1 mm. The subjective ratings produced similar findings in terms of image quality for both tube voltages and the three exposure times.

Conclusions

The results of the present study revealed that tube voltages of 63 kV and 70 kV provided similar accuracy and image quality for periodontal disease diagnosis.

Effect of bit depth and kVp of digital radiography for detection of subtle differences

OBJECTIVES

The purpose of this study is to investigate the effects of different bit depths and kilovoltage peak (kVp) values used in intraoral digital radiography on observer performance in detecting subtle radiographic density differences.

STUDY DESIGN

Using an intraoral CCD sensor set at 8- or 12-bit depth, kVp set at 60 or 70, and 14 different exposure times, digital radiographs were acquired of a specially designed aluminum step-wedge phantom with small holes of different depths in each step. Ten observers examined all images.

RESULTS

The observers counted more holes with the 12-bit images compared with the 8-bit images, particularly at 60 kVp. Significantly more holes were also counted with images taken at 70 kVp compared with those taken at 60 kVp.

CONCLUSION

Regarding the detection of subtle radiographic density differences, 12-bit images and 70 kVp were superior to 8-bit images and 60 kVp.