Comparative Analysis of the Reproduction Accuracy of Main Methods for Finding the Mandible Position in the Centric Relation Using Digital Research Method. Comparison between Analog-to-Digital and Digital Methods: A Preliminary Report.

Purpose: To compare the aspect of the reproduction accuracy in studied methods of determination of the (CR) of jaws using the digital research methods. The methods used were bilateral manipulation by P.E. Dawson, frontal deprogrammer, leaf gauge, and intraoral device for recording of Gothic arch angle. Methods: To determine the reproduction accuracy of the centric relation of jaws, we examined 5 patients with intact dentition in a prosthetic dentistry clinic (first class in Angle's system). For each method, 20 registrations of the centric jaw relation were carried out by one operator. The breaks between definitions were 30 minutes. A total of 400 CR recording operations were carried out (400 records of CR). In order to study the reproducibility of CR determination methods, 200 recorded mandible positions were analyzed by means of an analog-to-digital method (a macro kit Canon 650D, Canon 60 mm macro IS USM f2.8, Canon macro ring MR-14 EX and the computer program Adobe Photoshop) to assess the first occlusal contact obtained in the CR of jaws, while the other 200 were analyzed by means of a digital method (the computer program Avantis for 3D modeling, Prime as a laboratory 3D scanner (DOF), and Trios as an intraoral scanner (3Shape)) to assess the spatial position of the mandible in the CR. Statistical analysis was carried out using STATISTICA-10. In all statistical analysis procedures, the critical significance level p was assumed to be 0.05. Results: In the study of the data by means of the computer program Avanti 3D, the reproducibility of the mandible position in the CR reached 0.119 ± 0.012 mm for frontal deprogrammer, 0.225 ± 0.028, p ≤ 0.05 for bilateral manipulation by Dawson P.E., 0.207 ± 0.02, p ≤ 0.05 for leaf gauge, and 0.120 ± 0,013, p ≤ 0.05 using an intraoral device for recording the Gothic arch angle. The analog-to-digital method showed an identical tendency for reproduction of the mandible position. Conclusions: The digital analysis we made using the Avantis 3D program showed, with high confidence, that the maximum reproducibility of the CR position was reached by using our own design frontal deprogrammer and the device for recording Gothic arch angle.

A comparative study on image quality of two digital intraoral sensors.

OBJECTIVES: The aims of this study were to evaluate the subjective image quality and reliability of two digital sensors. In addition, the image quality of the two sensors evaluated by specialists and general dentists were compared. METHODS: 30 intraoral bitewings from five patients were included in the study, 15 were exposed with a Dixi sensor (CCD-based) and 15 with a ProSensor (CMOS-based) using modified parallel technique. Three radiologists and three general dentists evaluated the images in pair. A five-point scale was used to register the image quality. Visual grading characteristics (VGC) analysis was performed to compare the image quality and the observer agreement was assessed in terms of intra class correlation co-efficient. RESULTS: No statistically significant difference was found on image quality between the sensors. The average scores of the observer agreement were moderate with an average of 0.66 and an interval of 0.30 to 0.87, suggesting that there was a large variation on preference of image quality. However, there was a statistically significant difference in terms of the area under the VGC- curves between the specialist group and the general dentist group ( p = 0.043), in which the specialist group tended to favor the ProSensor. CONCLUSIONS: Subjective image quality of the two intraoral sensors were comparable when evaluated by both general and oral radiologists. However, the radiologists seemed to prefer the ProSensor to the Dixi as compared to general dentists. Inter- observer conformance showed a large variation on the preference of the image quality.

Evaluation of the effect of storage time and disinfectant solutions on the dimensional accuracy of impression materials with digital radiography.

BACKGROUND: The dimensional accuracy of impression materials has been evaluated for a long time, but thus far, digital radiography has not been used for this purpose. The dimensional accuracy of impression materials is very important for the final adaptation of dental prostheses. OBJECTIVES: The objective of this study was to evaluate the effects of different disinfectant solutions and storage times on the dimensional stability of different impression materials by means of digital radiography. MATERIAL AND METHODS: Polyether (PE), hydrocolloid (IH), condensation silicone (CS), and addition silicone (AS) materials were used for preparing impressions, taken from an acrylic master model with 2 vertical and 2 horizontal reference points. Water (W), sodium hypochlorite (SH) and a disinfectant solution without aldehyde (Z) were applied on the impressions. Half of the impressions were poured over immediately and half of them - 1 day after. Digital radiography was used to determine the dimensional accuracy of the impression materials. The data was analyzed with a variance analysis and Tukey's multiple comparison test. RESULTS: While PE showed the smallest dimensional changes, IH showed the greatest in all lines. Applying SH and pouring 1 day after caused the greatest dimensional changes in all impression materials. CONCLUSIONS: Different disinfectant solutions and storage times had a different effect on the impressions, but the dimensional changes were clinically acceptable.

Dentists' use of digital radiographic techniques: Part II - extraoral radiography: a questionnaire study of Swedish dentists.

OBJECTIVE: The present study aims to gain knowledge about the dentist's use and choice of digital extraoral imaging methods, panoramic radiography and cone beam computed tomography (CBCT). MATERIALS AND METHODS: A questionnaire sent to 2481 dentists within the Swedish Dental Society contained questions about the panoramic technique and CBCT technique used, education, clinic size and type of service. The response rate was 53%. RESULTS: The study showed that 61% of the Swedish dentists had access to panoramic techniques and that 84% used a direct digital sensor, while 6% used storage phosphor plate techniques. Around 8% of the Swedish dentists had access to CBCT. It was also observed that group practices had two times higher odds of having panoramic equipment compared with solo practices. Approximately 40% of the dentists had undergone postgraduate education in oral radiology during the last 5 years. Dental nurses and dental hygienists exposed 92% of the panoramic radiographs and 75% of the CBCTs. Thirty per cent of those clinics with access to a panoramic unit exposed >30 panoramic radiographs per month and 56% of the clinics having access to CBCT did more than 75 examinations per year. CONCLUSIONS: Today 61% of Swedish dentists have access to panoramic radiography and 8% have access to CBCT. There is a greater likelihood of having access if the dentist works in the public dental health service or in a group practice and if the dentist has undergone any postgraduate course in oral radiology.

Dentists' use of digital radiographic techniques: Part I - intraoral X-ray: a questionnaire study of Swedish dentists.

OBJECTIVE: The present study aims to gain knowledge about the dentist's use and choice of digital intraoral imaging methods. MATERIALS AND METHODS: A questionnaire sent to 2481 dentists within the Swedish Dental Society contained questions about the type of X-ray technique used, problems experienced with digital radiography, and reasons for choosing digital technology, and about indications, clinic size and type of service. Response rate was 53%. RESULTS: Ninety-eight percent of the dentists had made the transition to digital radiography; only 2% used film technique, and solid-state detector (SSD) was the most used digital technique. More years in service decreases the likelihood of applying individual indications for performing a full mouth examination. More retakes were done with SSDs compared to storage phosphor plates. Reasons for choosing digital techniques were that work was easier and communication with the patients improved. However, dentists also experienced problems with digital techniques, such as exposure and projection errors and inadequate image quality. The Swedish Radiation Safety Authority states that all radiological examinations should be justified, something not always followed. CONCLUSIONS: This study showed that 98% of the respondents, Swedish dentists within the Swedish Dental Society, used digital techniques, and the most used was the solid-state technique.

Standard Health Level Seven for Odontological Digital Imaging.

BACKGROUND: A guide for the implementation of dental digital imaging reports was developed and validated through the International Standard of Health Informatics-Health Level Seven (HL7), achieving interoperability with an electronic system that keeps dental records. INTRODUCTION: Digital imaging benefits patients, who can view previous close-ups of dental examinations; providers, because of greater efficiency in managing information; and insurers, because of improved accessibility, patient monitoring, and more efficient cost management. Finally, imaging is beneficial for the dentist who can be more agile in the diagnosis and treatment of patients using this tool. MATERIALS AND METHODS: The guide was developed under the parameters of an HL7 standard. It was necessary to create a group of dentists and three experts in information and communication technologies from different institutions. DISCUSSION: Diagnostic images scanned with conventional radiology or from a radiovisiograph can be converted to Digital Imaging and Communications in Medicine (DICOM) format, while also retaining patient information. The guide shows how the information of the health record of the patient and the information of the dental image could be standardized in a Clinical Dental Record document using international informatics standard like HL7-V3-CDA document (dental document Level 2). Since it is an informatics standardized document, it could be sent, stored, or displayed using different devices-personal computers or mobile devices-independent of the platform used. CONCLUSIONS: Interoperability using dental images and dental record systems reduces adverse events, increases security for the patient, and makes more efficient use of resources. This article makes a contribution to the field of telemedicine in dental informatics. In addition to that, the results could be a reference for projects of electronic medical records when the dental documents are part of them.

The effect of anatomical noise on perception of low contrast in intra-oral radiographs: an in vitro study.

OBJECTIVES: Radiographic images suffer from varying amounts of noise. The most studied and discussed of these is random noise. However, recent research has shown that the projected anatomy contributes substantially to noise, especially when detecting low-contrast objects in the images. Our aim, therefore, was to evaluate the extent to which overprojected anatomical noise affects the detection of low-contrast objects in intra-oral images. METHODS: Our study used four common sensor models. With each sensor, we took four series of images, three series with and one series without an anatomical phantom present. In each series, we exposed a low-contrast phantom at 18 different exposure times using a standardized method. 4 observers evaluated all 288 images. RESULTS: The low-contrast characteristics differed substantially when imaging low contrast on a homogeneous background compared with imaging low contrast when an anatomical phantom was present. For three of the sensors, optimal exposure times for low-contrast imaging were found, while the fourth sensor displayed a completely different behaviour. CONCLUSIONS: Calibrating the low-contrast properties of an imaging system using low-contrast objects on a homogeneous background is not recommended. On an anatomical background, low-contrast properties are completely different, and these will mimic the clinical situation much more closely, directing the operator how to best use the system. There is a clear demand for further research on this subject.

Are children's dental panoramic tomographs and lateral cephalometric radiographs sufficiently optimized?

OBJECTIVES: Children are especially vulnerable to harmful effects of ionizing radiation. Cutting down the dimensions of the X-ray beam is the most effective way to reduce the patient dose. We evaluated the appropriateness of field-size in the most frequent radiographs, dental panoramic tomographs (DPTs) and lateral cephalometric radiographs (LCRs) among 7- to 12-year-olds. MATERIALS AND METHODS: The image field-size of 241 DPTs and 118 LCRs was analysed. The image field was considered appropriate when it did not include anatomic structures beyond the area of clinical interest. The image field was compared with factors such as the age of the patient, the radiographic equipment used and the programme selected. Moreover, we assessed the use of thyroid shield in LCR. RESULTS: The field-size was too large in 70% of the DPTs horizontally and in 96% vertically. None of the DPTs were segmented. Every LCR showed appropriate limitation anteriorly, but the image field was too large in 54% posteriorly, in 86% superiorly, and in 76% inferiorly. A thyroid shield had been used in only 71% of cases. CONCLUSION: Most DPTs and LCRs had been performed sub-optimally. An abundancy of DPTs had been taken using an adult programme, and the field-size had not been sufficiently adjusted in LCRs, possibly for technical reasons. To facilitate adherence to radiological best practice the equipment used for DPTs and LCRs should facilitate the adjustment of field-size in both the vertical and horizontal planes. In addition, those involved in taking radiographs should maintain their skills through regular update courses.

DOSE REFERENCE LEVELS IN SPANISH INTRAORAL DENTAL RADIOLOGY: STABILISATION OF THE INCORPORATION OF DIGITAL SYSTEMS IN DENTAL CLINICAL PRACTICES.

A total of 34 044 official quality assurance reports in dental radiodiagnostic surgery from 16 regions of Spain, compiled from 2002 to 2014, were studied in order to determine the progress of diagnostic reference levels (DRLs) for obtaining diagnostic images under normal conditions for clinical practice in Spanish dental clinics. A DRL of 2.8 mGy was set in 2014, which represents a 41.7 % decrease compared with that of 2002 (4.8 mGy). Over the same time period, the mean dose fell by 55.2 %. However, over the last 3 y, the stabilisation of the mean dose administered to patients has been observed with only a 6.7 % reduction in DRLs, which corresponds to the stabilisation of dental radiodiagnostic surgery on replacing the use of radiographic film with digital imaging systems.

Optimization of exposure in panoramic radiography while maintaining image quality using adaptive filtering.

Objective The purpose of the present study was to investigate the potential of using advanced external adaptive image processing for maintaining image quality while reducing exposure in dental panoramic storage phosphor plate (SPP) radiography. Materials and methods Thirty-seven SPP radiographs of a skull phantom were acquired using a Scanora panoramic X-ray machine with various tube load, tube voltage, SPP sensitivity and filtration settings. The radiographs were processed using General Operator Processor (GOP) technology. Fifteen dentists, all within the dental radiology field, compared the structural image quality of each radiograph with a reference image on a 5-point rating scale in a visual grading characteristics (VGC) study. The reference image was acquired with the acquisition parameters commonly used in daily operation (70 kVp, 150 mAs and sensitivity class 200) and processed using the standard process parameters supplied by the modality vendor. Results All GOP-processed images with similar (or higher) dose as the reference image resulted in higher image quality than the reference. All GOP-processed images with similar image quality as the reference image were acquired at a lower dose than the reference. This indicates that the external image processing improved the image quality compared with the standard processing. Regarding acquisition parameters, no strong dependency of the image quality on the radiation quality was seen and the image quality was mainly affected by the dose. Conclusions The present study indicates that advanced external adaptive image processing may be beneficial in panoramic radiography for increasing the image quality of SPP radiographs or for reducing the exposure while maintaining image quality.

In vitro evaluation of proximal carious lesions using digital radiographic systems.

The study aimed to compare the sensitivity and specificity of digital radiographic systems for the diagnosis of proximal carious lesions. Extracted human teeth (3 canines, 3 premolars, and 3 molars) were submitted to one of three types of proximal lesions (demineralized area, cavity affecting the enamel alone, and cavity affecting enamel and dentin). Bitewing radiographs were obtained from each system (Sirona, Kodak, and Schick) and evaluated by 12 raters (4 dental students, 4 radiology specialists, and 4 dentists). The chi-squared test was used to determine the frequency of correct diagnoses among the different systems, raters, teeth, and types of lesion. Sensitivity and specificity regarding demineralized areas were calculated for each system. The frequencies of correct diagnoses were found: Schick (70.8%), Kodak (63.9%), Sirona (59.0%), specialists (69.4%), students (62.5%), dentists (61.8%), premolars (70.1%), canines (65.3%), and molars (58.3%). No significant differences were found among the different systems, raters, or teeth (P > 0.05). Sensitivity and specificity were 0.64 and 0.47 (Schick), 0.56 and 0.50 (Sirona), and 0.48 and 0.58 (Kodak). The most correct diagnoses were achieved using the Schick digital system on premolars and evaluated by specialists in radiology. The systems demonstrated low sensitivity and specificity for the diagnosis of demineralized areas.

Digital panoramic radiography for diagnosis of the temporomandibular joint: CBCT as the gold standard.

Three-dimensional imaging modalities have been reported to be more accurate than panoramic radiographs (PR) for the assessment of bone components of the temporomandibular joint (TMJ). No exact prior information is available that demonstrates which specific limitations occur in terms of TMJ diagnosis when using PR for this purpose. This study aimed to assess the clinical validity of digital panoramic radiography (DPR) when diagnosing morphological disorders of the TMJ using cone-beam computed tomography (CBCT) images as the gold standard. A sample composed of TMJ images (N = 848), including 212 DPR and 212 CBCT images obtained from the same patient, was used to assess any morphological changes in the TMJ. Four appraisers diagnosed all of the DPR images, whereas the CBCT images were used to establish the gold standard. The reliability of each appraiser's response pattern was analyzed using the Kappa test (κ), and diagnostic tests were performed to assess each appraiser's performance using a significance level setting of 5% (α = 0.05). Reliability of each appraiser's response pattern compared to the gold standard ranged from a slight-to-moderate agreement (0.18 ≤ κ ≤ 0.45); and among the different appraisers, the response pattern showed a fair agreement (0.22 ≤ κ ≤ 0.39). Diagnostic tests showed a wide range among the different possible morphological changes diagnosed. DPR does not have validity when diagnosing morphological changes in the TMJ; it underestimates the radiological findings with higher prevalence, and thus, it cannot be used effectively as a diagnostic tool for bone components within this region.

DICOM part 14: GSDF-calibrated medical grade monitor vs a DICOM part 14: GSDF-calibrated "commercial off-the-shelf" (COTS) monitor for viewing 8-bit dental images.

OBJECTIVES: To investigate whether there is any difference in the presented image quality between a medical grade monitor and a "commercial off-the- shelf" (COTS) monitor when displaying an 8-bit dental image. METHODS: The digital imaging and communications in medicine (DICOM) part 14: greyscale standard display function (GSDF) was verified for both monitors. A visual grading characteristics (VGC) curve was constructed to measure the difference in image quality between the two monitors by comparing radiological structures displayed on each monitor with a DICOM part 14: GSDF-calibrated laptop monitor as reference. RESULTS: All of the monitors conformed to within the American Association of Physicists in Medicine Task Group 18 10% tolerance levels for the assessment of the DICOM part 14: GSDF. There was no difference in the preferred perceived visual sensation for the displayed image between the two tested monitors with the area under the VGC curve = 0.53 and 95% confidence interval = 0.47-0.59. CONCLUSIONS: A DICOM part 14: GSDF COTS monitor is capable of displaying an image quality that is equally preferred to a DICOM part 14: GSDF medical grade monitor for an 8-bit image file.

Comparison of methods for acceptance and constancy testing in dental cone-beam computed tomography.

PURPOSE: The aim of this work was to implement, validate, and compare two procedures for routine image quality (IQ) assurance in dental cone-beam computed tomography (CBCT): 1. the German standard DIN 6868 - 161 introduced in 2013 and 2. the established standard IEC 61,223 - 3-5 for clinical CT x-ray equipment referenced as "DIN" and "IEC" below. MATERIALS AND METHODS: The approximated in-plane modulation transfer function (MTF), the contrast-to-noise indicator (CNI), and the uniformity indicator (UI*) were determined in accordance with DIN. Image noise, the uniformity index (UI), the contrast-to-noise ratio (CNR), and the 3 D MTF were measured according to IEC 61,223 - 3-5 using a previously proposed quality assurance (QA) framework. For this, a modular phantom was used. All experiments were performed on a clinical dental CBCT unit. The severity of image artefacts was measured at different z-positions. A dedicated computer program was implemented to allow for automated QA procedure. RESULTS: The position and orientation of the phantoms were detected automatically in all of the measurements providing a reproducible placement of the evaluation regions and volumes. 50 % and 10 % in-plane MTF values of the approximated and the exact MTF calculation procedure were in agreement to within 5 %. With increasing axial distance from the isocentre, UI* and CNI dropped by 30 % and 19 %, respectively. Conventional IQ parameters showed higher sensitivity to image artefacts; i. e., UI and CNR were reduced by about 197 % and 37 %. CONCLUSION: The implemented automated QA routines are compatible with both the DIN and the IEC approach and offer reliable and quantitative tracking of imaging performance in dental CBCT for clinical practice. However, there is no equivalence between the DIN and the IEC metrics. In addition, direct measurements of physical IQ parameters such as image contrast and noise, uniformity, and axial resolution are not supported by the new concept according to DIN. KEY POINTS: The new DIN 6868 - 161 is not equivalent to the established IEC 61 223 - 3-5. Noise, uniformity, and contrast are well-suited to assess image artefacts. The implemented automated quality assurance program fits clinical routine.

Guide to Digital Radiographic Imaging.

This is a resource for clinicians who are considering purchasing a digital imaging system or those already using one who want to optimize its use. It covers selected topics in digital imaging fundamentals, detector technology, image processing and quality assurance. Through a critical appraisal of the strengths and limitations of digital imaging components, the goal of this guide is to contribute to the appropriate use of these systems to maximize the health benefit for patients.

Digital panoramic radiography for diagnosis of the temporomandibular joint: CBCT as the gold standard

Three-dimensional imaging modalities have been reported to be more accurate than panoramic radiographs (PR) for the assessment of bone components of the temporomandibular joint (TMJ). No exact prior information is available that demonstrates which specific limitations occur in terms of TMJ diagnosis when using PR for this purpose. This study aimed to assess the clinical validity of digital panoramic radiography (DPR) when diagnosing morphological disorders of the TMJ using cone-beam computed tomography (CBCT) images as the gold standard. A sample composed of TMJ images (N = 848), including 212 DPR and 212 CBCT images obtained from the same patient, was used to assess any morphological changes in the TMJ. Four appraisers diagnosed all of the DPR images, whereas the CBCT images were used to establish the gold standard. The reliability of each appraiser’s response pattern was analyzed using the Kappa test (κ), and diagnostic tests were performed to assess each appraiser’s performance using a significance level setting of 5% (α = 0.05). Reliability of each appraiser’s response pattern compared to the gold standard ranged from a slight-to-moderate agreement (0.18 ≤ κ ≤ 0.45); and among the different appraisers, the response pattern showed a fair agreement (0.22 ≤ κ ≤ 0.39). Diagnostic tests showed a wide range among the different possible morphological changes diagnosed. DPR does not have validity when diagnosing morphological changes in the TMJ; it underestimates the radiological findings with higher prevalence, and thus, it cannot be used effectively as a diagnostic tool for bone components within this region.

Quality assurance tests for digital radiography in general dental practice.

UNLABELLED: Quality assurance (QA) is essential in dental radiography. Digital radiography is becoming more common in dentistry, so it is important that appropriate QA tests are carried out on the digital equipment, including the viewing monitor. The aim of this article is to outline the tests that can be carried out in dental practice. CLINICAL RELEVANCE: Quality assurance for digital equipment is important to ensure consistently high quality images are produced.

Radiographic observers' ability to recognize patient movement during cone beam CT.

OBJECTIVES: To assess radiographic observers' ability to recognize patient movement during cone beam CT and to decide early termination of the examination. METHODS: 100 patients were video-recorded during cone beam CT examination. Patients' videos were cropped twice: fitting the active 20-s examination time or the initial non-radiation 3 s of the examination. x- and y-coordinates of pre-defined points marked on the patient's face were used to define the reference standard for movement in the 20-s videos. A sample of 40 non-moving and 20 moving patients was selected. Eight observers scored the videos. The 3-s videos were scored: 0, the patient did not move; 1, the patient moved and the examination should be terminated. The 20-s videos were scored: 0, the patient did not move; 1, the patient moved. Re-assessment of 15% of the videos provided intra-observer reproducibility. The 20-s videos were compared with the reference standard providing sensitivity and specificity values (movement/non-movement recognition). The scores of the 3-s videos were compared with the scores of the 20-s videos. RESULTS: Intra- and interobserver reproducibility ranged from substantial to almost perfect for both videos. The 20-s videos allowed patient movement recognition with a high specificity and a medium to high sensitivity. The 3-s videos allowed early termination of the examination with a small number of incorrect positive scores. The majority of the patients scored as moving in the 20-s videos were detected in the 3-s videos. CONCLUSIONS: By observing video recordings, trained observers are able to recognize patient movement during cone beam CT examination with high specificity and to decide an early termination of the examination.

Comparison of landmark identification and linear and angular measurements in conventional and digital cephalometry.

The purpose was to compare the reliability of landmark identification and linear and angular measurements in conventional versus digital cephalometry. Using 50 cephalometric radiographs, four orthodontic residents identified 19 cephalometric landmarks followed by 18 linear and angular measurements of the same radiographs. The values of 18 measurements were compared to quantify the measurement difference and interobserver errors between these two methods. Multivariate analysis of variance showed that the "cephalometric radiograph" and "landmark" variation had greater influence than that of "method" (landmark identification on original radiograph/on digital). A statistically significant difference for interobserver errors between the two methods was noted only for 5 out of 19 cephalometric landmarks. The most accurately identified landmark in conventional and digitized method was Sella (S), followed by Nasion (N). Landmarks requiring further scrutiny in digital images were Porion (P) Articulare, ANS, UM, and LM. The advantages of digital cephalometry were also substantiated.

Printed radiographs--is what you see what you get?

UNLABELLED: Digital dental radiography allows for exchange of images between primary and secondary care. However, it is common practice for radiographs to be printed out and attached to referrals.This study investigates the loss of diagnostic information of printed radiographs compared to the on-screen digital image.The best quality was achieved with images printed onto radiographic film or onto photographic paper with an inkjet printer. Laser and inkjet printer output onto 80 gsm office paper resulted in a loss of diagnostic information. Wherever possible, radiographs should be transmitted digitally between clinicians to maintain image integrity. CLINICAL RELEVANCE: This paper illustrates the potential pitfalls of printing radiographs to be sent with referrals.