Direct digital radiography for the detection of periodontal bone lesions

ADGRU: Adaptive DenseNet with gated recurrent unit for automatic diagnosis of periodontal bone loss and stage periodontitis with tooth segmentation mechanism

BACKGROUND

Periodontics and gingivitis are two of the most widely prevalent illnesses that affect people nowadays. The sixth most common disease in the world is periodontitis, and detecting periodontal bone loss is essential in the earlier condition and is crucial for the development of the proper diagnosis. Early bone loss detection can be assisted by using computer-assisted radiography examination. Understanding disease progression helps to select the most effective treatment action.

OBJECTIVES

An effective deep model is suggested to detect periodontal bone loss at an earlier stage for preventing the progression of Periodontics bone loss.

METHODS

This work is intimated by collecting images from online resources. Further, the images gathered from the dataset are preceded by the tooth segmentation which is done using DenseUNet +  + . Further, the segmented images are given to the Adaptive DenseNet with Gated Recurrent Unit (AD-GRU) for detecting periodontal bone loss and this diagnosis is used for the periodontitis stage, where the ADGRU performance is augmented by optimizing the attributes using the Refined Red Kite Optimization Algorithm (RRKOA).

RESULTS

The offered approach attained an accuracy of 94.45% which is higher than the88.63%, 90.58%, 89.54%, and 92.96% attained by the LSTM, DenseNet, GRU, DenseNet-GRU.

DATA CONCLUSION

The findings of the simulation proved the designed framework outperformed the traditional model with high accuracy.

CLINICAL RELEVANCE

The developed effectual deep model-based periodontal bone loss and stage periodontitis diagnosis structure is used in healthcare applications.

Periodontal disease and emerging point-of-care technologies for its diagnosis

Periodontal disease (PD), a chronic inflammatory disorder that damages the tooth and its supporting components, is a common global oral health problem. Understanding the intricacies of these disorders, from gingivitis to severe PD, is critical for efficient treatment, diagnosis, and prevention in dental care. Periodontal biosensors and biomarkers are critical in improving oral health diagnostic skills. Clinicians may accomplish early identification, tailored therapy, and efficient tracking of periodontal diseases by using these technologies, ushering in a new age of accurate oral healthcare. Traditional periodontitis diagnostic methods frequently rely on physical probing and visual examinations, necessitating the development of point-of-care (POC) devices. As periodontal disorders necessitate more precise and rapid diagnosis, incorporating novel innovations in biosensors and biomarkers becomes increasingly crucial. These innovations improve our capacity to diagnose, monitor, and adapt periodontal therapies, bringing in the next phase of customized and effective dental healthcare. The review discusses the characteristics and stages of PD, clinical treatment techniques, prominent biomarkers and infection-associated factors that may be employed to determine PD, biomedical sensing, and POC appliances that have been created so far to diagnose stages of PD and its progression profile, as well as predicting future developments in this field.

Evaluation of simulated periodontal defects via various radiographic methods

OBJECTIVES

The aim of this study was to compare the diagnostic accuracy of conventional films and direct digital radiographs (DDR), in the determination of the depth and type of simulated periodontal intrabony defects.

MATERIALS AND METHODS

Three types of periodontal intrabony defects (one, two, and three walled) were artificially created in dry mandibles. Standard radiographic images were taken with Ultraspeed, Ektaspeed, Insight films, and DDR. The radiographic images were evaluated by three oral radiologists to identify the type and depth of these defects on the radiographs.

RESULTS

The average measured depth of the defects on the dry mandibles was 7.85 mm. The average depth of the type 1 defect on the radiographs was 7.19 mm, type 2 was 7.18 mm, and type 3 was 7.15 mm. The average depth of the defects via the Ultraspeed film was 7.15 mm, Ektaspeed film was 7.17 mm, Insight film was 7.19 mm, and DDR was 7.20 mm. Type 1, type 2, and type 3 defect depth measurements showed 8.9, 9.7, and 16.3% understated, respectively (p < 0.01). The accurate estimation rates of type 1, type 2, and type 3 defects were 93.8, 53, and 25.4%, respectively.

CONCLUSIONS

Both radiographic techniques have the same diagnostic value and display the minor destructive changes in the bone. As the number of osseous walls increases, it becomes difficult to determine the defect type and morphology. Further research is needed to monitor the intrabony defects, with less radiation exposure.

CLINICAL RELEVANCE

The accurate identification of defect type and depth depends on the number of walls, not the imaging methods.

Comparison of diagnostic accuracy of conventional intraoral periapical and direct digital radiographs in detecting interdental bone loss

BACKGROUND

Periodontitis is an inflammatory disease of the supporting tissues of the teeth caused by specific microorganisms, resulting in destruction of the periodontal ligament and alveolar bone. Progressive loss of alveolar bone is the salient feature of periodontal disease. Accurate detection of periodontal disease with the use of radiographs helps in diagnosis, treatment and prognosis.

AIMS

The present study aims to compare the efficacy of conventional intraoral periapical (IOPA) and direct digital radiographs (RVG) in detecting interdental alveolar bone loss using intrasurgical (IS) measurements as the gold standard.

MATERIALS AND METHODS

Thirty patients elected to undergo periodontal flap surgery with periodontitis computing to 60 interdental alveolar defects on mandibular first molars were considered. IOPA and RVG were captured using standardized techniques. Bone loss measurements in IOPA and RVG were compared to the IS measurements.

STATISTICAL ANALYSIS

Statistical analysis was carried out using student t test and ANOVA with the help of SPSS software and p-value <0.05 was considered as significant.

RESULTS

Both IOPA and RVG underestimated the bone loss measurements when compared to IS measurements which was statistically significant (p<0.0001). Bone loss measurements in RVG were closer to IS measurements than IOPA.

CONCLUSION

Both the radiographic techniques IOPA and RVG underestimated bone loss by 1.5-2.5 mm. RVG was superior to IOPA for the detection of interdental bone loss due to reduced time and radiation exposure to obtain the same diagnostic information.

Measurements of simulated periodontal bone defects in inverted digital image and film-based radiograph: an in vitro study

Purpose

This study was performed to compare the inverted digital images and film-based images of dry pig mandibles to measure the periodontal bone defect depth.

Materials and Methods

Forty 2-wall bone defects were made in the proximal region of the premolar in the dry pig mandibles. The digital and conventional radiographs were taken using a Schick sensor and Kodak F-speed intraoral film. Image manipulation (inversion) was performed using Adobe Photoshop 7.0 software. Four trained examiners made all of the radiographic measurements in millimeters a total of three times from the cementoenamel junction to the most apical extension of the bone loss with both types of images: inverted digital and film. The measurements were also made in dry mandibles using a periodontal probe and digital caliper. The Student's t-test was used to compare the depth measurements obtained from the two types of images and direct visual measurement in the dry mandibles. A significance level of 0.05 for a 95% confidence interval was used for each comparison.

Results

There was a significant difference between depth measurements in the inverted digital images and direct visual measurements (p>|t|=0.0039), with means of 6.29 mm (IC_95%:6.04-6.54) and 6.79 mm (IC_95%:6.45-7.11), respectively. There was a non-significant difference between the film-based radiographs and direct visual measurements (p>|t|=0.4950), with means of 6.64mm(IC_95%:6.40-6.89) and 6.79mm(IC_95%:6.45-7.11), respectively.

Conclusion

The periodontal bone defect measurements in the inverted digital images were inferior to film-based radiographs, underestimating the amount of bone loss.

Detection of vertical root fractures using digitally enhanced images: reverse-contrast and colorization

Root fracture diagnosis is a clinical difficulty that in most cases can only be detected through radiography. The objective of this study was to compare the diagnostic accuracy of two types of digitally enhanced images (reverse-contrast and colorization) with original digital radiographies in detecting experimental root fractures. Two hundred extracted single-rooted human teeth were endodontically instrumented and then divided in two groups, one control group and one test group, including fractured teeth. Vertical root fractures were experimentally made in the fractured group. The digital image of each tooth was taken, using the paralleling technique. There were three groups of images: (i) original, (ii) reverse contrast, and (iii) colorized. Three experienced dental specialists examined the images with no prior knowledge of the distribution of the root fractures. Two-way analysis of variance was used to assess the differences in accuracy, sensitivity, and specificity of each technique in detecting root fractures. Cohen's kappa coefficients were calculated to investigate the degree of interobserver agreement. The accuracy, sensitivity, and specificity of original images were 67.4%, 66.7%, and 68%, respectively; these amounts were 61.5%, 61%, and 65.5% in reverse contrast images and 66.4%, 70.7%, and 62% in colorized digital radiography. The original images had the best inter observer kappa coefficients (between 0.45 and 0.55). The results showed that the accuracy of original images is better than reverse contrast and colorized images. Use of reverse-contrast and colorization digital images in root fracture detection should be regarded as an adjunct to other diagnostic methods not as a highly critical diagnostic aid.

Effect of JPEG compression on the diagnostic accuracy of periapical images in the detection of root fracture

The ability of a periapical radiograph to exhibit the fracture depends on many factors including, but not limited to, the resolution of the image. The quality can be reduced by the image compression. The purpose of this study is to evaluate the effect of Joint Photographic Experts Group (JPEG) compressions on the diagnostic capability of periapical images in the detection of root fractures. Ten dry human mandibles containing 151 teeth were used in this study. Mandibles were radiographed with direct digital imaging sensor using the paralleling technique. Four observers detected root fracture on the images saved in one uncompressed and two compressed formats. Receiver operating characteristic (ROC) and anova analyses were performed to compare the performance of the three different systems and evaluate the effect of the compression on the accuracy of root fracture detection. Results did not show any statistically significant difference between the original, large images presented in tagged image file format (TIFF) and the two compressed images (JPEG medium file and JPEG small file images) in the detection of root fractures. The intra-rater comparison showed a significant consistency in the detection of the fracture. The compression reduced the file size considerably (from 1.77 MB to 453 and 95 Kb), but it did not affect the accuracy of root fracture detection. The file size reduction, on the other hand, is very beneficial for image electronic storage and mainly in teleradiology.

Comparison between inverted and unprocessed digitized radiographic imaging in periodontal bone loss measurements

The advances in digital imaging technology in dentistry have provided an alternative to film-based radiography and have given new options to detect periodontal bone loss. The purpose of this study was to compare inverted and unprocessed digitized radiographic imaging in periodontal bone loss measurements. Thirty-five film-based periapical radiographs of patients suffering from moderate to advanced untreated periodontal bone loss associated to lower premolar and molars was selected from the department files, with 40 bone loss areas. The film-based radiographs were digitized with a flatbed scanner with a transparency and radiograph adapter used for transilluminating the radiograph imaging. Digitization was performed at 600 dpi and in gray scale. The images were digitized using Image Tool software by applying image inversion, that is, transformation of radiopaque structures into radiolucent structures and vice-versa. The digital data were saved as JPEG files. The images were displayed on a 15-inch and 24-bit video monitor under reduced room lighting. One calibrated examiner performed all radiographic measurements, three times, from the cementoenamel junction to the most apical extension of the bone loss, in both types of image (inverted and unprocessed). Brightness and contrast were adjusted according to the examiner's individual demand. Intraclass correlation coefficient was used to compare the measurements from both types of images. The means of radiographic measurements, in mm, for inverted and unprocessed digitized imaging were 6.4485 and 6.3790, respectively. The intraclass correlation coefficient was significant (0.99) The inverted and unprocessed digitized radiographic images were reliable and there was no difference in the diagnostic accuracy between these images regarding periodontal bone loss measurements.

Comparison of simulated periodontal bone defect depth measured in digital radiographs in dedicated and non-dedicated software systems

OBJECTIVES

To compare simulated periodontal bone defect depth measured in digital radiographs with dedicated and non-dedicated software systems and to compare the depth measurements from each program with the measurements in dry mandibles.

METHODS

Forty periodontal bone defects were created at the proximal area of the first premolar in dry pig mandibles. Measurements of the defects were performed with a periodontal probe in the dry mandible. Periapical digital radiographs of the defects were recorded using the Schick sensor in a standardized exposure setting. All images were read using a Schick dedicated software system (CDR DICOM for Windows v.3.5), and three commonly available non-dedicated software systems (Vix Win 2000 v.1.2; Adobe Photoshop 7.0 and Image Tool 3.0). The defects were measured three times in each image and a consensus was reached among three examiners using the four software systems. The difference between the radiographic measurements was analysed using analysis of variance (ANOVA) and by comparing the measurements from each software system with the dry mandibles measurements using Student's t-test.

RESULTS

The mean values of the bone defects measured in the radiographs were 5.07 mm, 5.06 mm, 5.01 mm and 5.11 mm for CDR Digital Image and Communication in Medicine (DICOM) for Windows, Vix Win, Adobe Photoshop, and Image Tool, respectively, and 6.67 mm for the dry mandible. The means of the measurements performed in the four software systems were not significantly different, ANOVA (P = 0.958). A significant underestimation of defect depth was obtained when we compared the mean depths from each software system with the dry mandible measurements (t-test; P approximately equal to 0.000).

CONCLUSIONS

The periodontal bone defect measurements in dedicated and in three non-dedicated software systems were not significantly different, but they all underestimated the measurements when compared with the measurements obtained in the dry mandibles.

Detectability of experimental peri-implant cancellous bone lesions using conventional and direct digital radiography

BACKGROUND

The aim of this study was to compare the diagnostic performance obtained from direct digital radiographic images (in their original form and after applying a grey-scale inversion) and conventional film in the detection of artificial peri-implant cancellous bone lesions.

METHODS

Four titanium implants were placed into the cancellous bone of a dry mandible and increasingly larger bone defects were created in their approximal sites. Radiographs were taken using conventional film and a digital charge-coupled device sensor. Twelve observers estimated three series of images (conventional, digital original, digital inverse) on a 5-point confidence scale. Data were evaluated statistically by analysis of variance and the sensitivity, specificity and accuracy of the three imaging modalities were calculated.

RESULTS

Total mean observer confidence scores increased as the size of the defect also increased. No statistically significant differences were found among the three images for the absence of defect and the defect that corresponds to the smallest bur size. Significant differences were found for larger bur sizes between the conventional image and the two digital images and for the largest bur size between the digital inverse and the other two images. Specificity was high and sensitivity relatively low.

CONCLUSIONS

Peri-implant bone lesions must exceed a certain size to be confidently detected but the lesion absence is detected equally well with all three imaging modalities.

Accuracy of direct digital radiography in the study of the root canal type

OBJECTIVES

To determine the accuracy of direct digital radiography (DDR) in the study of the root canal type. A sub aim was to assess intraexaminer and interexaminer agreement for this feature using DDR system.

METHODS

100 recently extracted permanent maxillary first premolars from Chinese population were used. Standardized periapical DDR images were taken from a buccolingual and mesiodistal direction. Then the specimens were accessed, injected with dye, demineralized, dehydrated and finally were cleared. The DDR images were evaluated based on the root canal type by two independent trained post-graduate students (examiner A and B) twice at an interval of 2 weeks. The cleared teeth were examined under 5 x magnification using a dental operating microscope by another experienced endodontist, and the data of root canal type were collected.

RESULTS

The Kappa values for the agreement between the examiner A and the clearing technique were 0.3793 and 0.329, between the examiner B and the clearing technique were 0.2481 and 0.2184. While the Kappa values between the two observations of each examiner were 0.7704 and 0.7725, between the two examiners they were 0.537 and 0.4793, respectively.

CONCLUSIONS

The intraexaminer agreement was good, and the interexaminer agreement was moderate, but the agreement between either DDR examiner and the clearing technique was poor, indicating the limited value of DDR alone when studying root canal type.

Comparison of the diagnostic potential of direct digital and conventional intraoral radiography in the evaluation of peri-implant conditions

The aims of this study were to examine whether viewers agreed on details seen in direct (real time) digital and conventional film radiographs of implants, and whether there were differences in agreement between the systems. Intra-oral radiographs of implants were exposed both as direct digital and conventional film radiographs. Fifty pairs of radiographs with similar projection and exposure were selected, showing 59 implants. Ten viewers assessed the radiographs separately and noted eight different details. The viewers showed very high agreement in their assessments of radiographs of each technique separately, and there were no statistically significant differences. However, there was a tendency to stronger agreement in the direct digital radiographs in four assessed points out of eight. The patients' experience of having radiographs exposed with the two methods was also studied by questionnaire. The patients' opinions on the two techniques did not differ statistically. This study shows that digital radiography has at least equal diagnostic yield compared to film radiography.

Comparison of complementary metal oxide semiconductor and charge-coupled device intraoral X-ray detectors using subjective image quality

OBJECTIVE

To compare the subjective image quality of the newer generation Schick CDR detector employing complementary metal oxide semiconductor (CMOS) technology with images using the earlier generation charge-coupled device (CCD) Schick CDR detector.

METHODS

All radiographic images were made using the same formalin-fixed adult cadaver maxilla with surrounding natural soft tissues in place. The X-ray generator used was a Villa Sistemi Medicali Diamatic srl AP/Explor X operated at 70 kVp and 8 mA. The source-to-detector distance was set at 38 cm and an optical bench was used to ensure reproducible beam geometry. A range of exposures was applied for both detectors. A panel of nine dentists independently observed and evaluated images made at each exposure. For both detectors, the three images ranked highest were randomized for re-evaluation in panels of six images. Each image was repeated randomly a total of 10 times. Features chosen as observation points were: (1) proximal dental caries; (2) gingival soft tissues; (3) cortical bone; (4) root canal space; (5) root apices; (6) periodontal ligament space; and (7) endodontic instrument tip clarity. Comparisons were made by use of odds ratio analysis applying a 95% confidence level. Interrater and intrarater reliabilities were computed to assess consistency in observer ratings.

RESULTS

The CMOS sensor was rated as outperforming its CCD predecessor for depiction of cortical bone and root apices; the CCD detector was only rated superior for depiction of root canal space. No significant difference was found between the two detectors in perceived depiction of proximal dental caries, gingival soft tissues, periodontal ligament space or endodontic instruments. Combining rating scores from each of the tasks, CMOS and CCD detectors had a similar proportion of image ratings of excellent, acceptable and poor.

CONCLUSIONS

Regarding subjective image quality, the Schick CMOS and CCD detectors were perceived to produce radiographic images of similar overall quality.

Influence of displayed image size on radiographic detection of approximal caries

OBJECTIVES

To evaluate the validity of approximal caries detection on digital bitewing radiographs displayed at different image sizes on either a cathode ray tube (CRT) monitor or a thin film transistor (TFT) monitor.

METHODS

Five observers assessed digital radiographs of a charge-coupled device (CCD)-based sensor system (Sidexis) of 160 unrestored premolars and molars for approximal caries using a six category caries rating scale. Images were displayed at ratios of 1:1, 1:2 and 1:7 on a CRT monitor (Nokia 446 XS) and a TFT display (Panasonic LC 50S). Histological assessments of serial sections were used as the validation standard. Diagnostic accuracy was expressed as area under the receiver operating characteristic (ROC) curve (AUC) and was calculated at two levels of caries penetration: presence of caries (I) and presence of a lesion in the dentine (II). The influence of the factors "monitor type", "image size" and "validation threshold" were analysed with repeated measures analysis of variance.

RESULTS

The ROC curve areas for approximal caries detection at both histological penetration levels were not influenced by the type of monitor display, whereas image size had a significant impact (P<0.01). AUCs for image size 1:7 (I, 0.62; II, 0.65) were smaller compared with ratios of 1:1 and 1:2 (P<0.01). No differences were observed between image size ratios 1:1 (I, 0.69; II, 0.74) and 1:2 (I, 0.68; II, 0.73).

CONCLUSIONS

In this study, the type of monitor did not influence approximal caries detection on digital radiographs. Image sizes with a display ratio of 1:1 and 1:2 resulted in better diagnostic validity than those with a ratio of 1:7.

Root fracture detection on digital images: effect of the zoom function

To assess the accuracy of root fracture detection at various levels of image magnification.

METHODS

Extracted single-rooted human teeth (100 non-fractured and 101 fractured) were mounted singly in wax blocks and a charge-coupled device (CCD)-based digital Sidexis imaging system was used to take images using the paralleling technique. Image sizes 1 : 1, 2 : 1, and 1 : 2 were prepared for each tooth. All 603 images were examined randomly and interpreted by an experienced radiologist unaware of which images were of fractured roots. The degree of agreement between image interpretation and the actual condition was estimated using a kappa statistic. A modified goodness-of-fit chi2-test was used to assess the significance of the difference between the three image sizes. The sensitivity, specificity, predictive value, and likelihood ratio were used to evaluate the accuracy of root fracture detection at each level of magnification. The degree of agreement between pairs of viewing conditions was also calculated using a kappa statistic.

RESULTS

There was substantial agreement between image interpretation and the actual condition for both the 1 : 1 and 1 : 2 image sizes but only moderate agreement for the 2 : 1 size. The kappa values (and 95% CIs) were 0.65 (0.51-0.79), 0.63 (0.49-0.77), and 0.58 (0.44-0.72), respectively. The differences were not statistically significant (P-value = 0.79). The sensitivity (95% CI) of the image magnification ranged between 79.0% (70.0-87.5%) and 81.0% (72.2-87.5%). The 1 : 1 image size gave the highest specificity of 86.1% (95% CI: 78.1-91.6%). The positive predictive values (95% CI) of the 1 : 1, 1 : 2, and 2 : 1 images sizes were 84.9% (76.3-90.8%), 81.8% (73.1-88.2%), and 77.9% (69.0-84.8%), respectively. The negative predictive values (95% CI) were 80.6% (72.1-86.9%), 81.4% (73.8-88.9%), and 80.4% (71.4-87.1%) for the 1 : 1, 1 : 2, and 2 : 1 image sizes, respectively. The likelihood ratios of the positive test (95% CI) were 5.70 (3.47-9.36), 4.55 (3.00-6.98), and 3.56 (2.45-5,16) for the 1 : 1, 1 : 2, and 2 : 1 image sizes, respectively. The likelihood ratios of the negative test (95% CI) were 0.24 (0.17-0.36), 0.23 (0.15-0.35), and 0.25 (0.16-0.37) for the 1 : 1, 1 : 2, and 2 : 1 image sizes, respectively. The reliability between pairs of viewing conditions was substantial. The kappa statistics (95% CI) was 0.80 (0.72-0.88), 0.73 (0.64-0.83), and 0.77 (0.68-0.86), respectively.

CONCLUSION

In this in vitro study, the three digital magnifications used did not affect the detection of root fractures.

In vitro comparison of root-canal measurements with conventional and digital radiology

AIM

The present study compared the efficacy of digital and conventional radiology for root-canal length measurement.

METHODOLOGY

Seventy extracted teeth with pre-served roots were used. Root-canal length measurements were completed with K-Flexofiles (numbers 08, 10 and 15) with conventional and digital radiography using two systems (radiovisiography and photostimulate storage phosphor). All films and sensors were exposed at projections of 0 degrees and 20 degrees to the mesial. The images obtained were evaluated with and without magnification, and analysed using the Cohen's kappa test. The accuracy of the three systems to determine the root-canal length were evaluated by measuring the distance from the tip of the file to the apex.

RESULTS

Most of the values corresponding with the apex occurred with conventional radiology. The digital systems yielded negative values that improved with a size 15 file. The agreement between the two digital systems was the best with size 15 file using 0 degrees projection (66.7%).

CONCLUSIONS

Conventional radiology remains the technique of choice in determining the root-canal length; the digital techniques yielded good results for size 15 file.

A comparative evaluation of the diagnostic efficacy of film and digital sensors for detection of simulated periapical lesions

OBJECTIVE

The purpose of this study was to evaluate the diagnostic efficacy of Ektaspeed Plus film (EPF), a charge-coupled device (CCD), and photostimulable phosphor (PSP)-based digital images for detection of simulated periapical lesions.

STUDY DESIGN

Lesions were simulated in the periapical areas of 24 human mandibular sections invested in acrylic using burs of sizes #1, 2, 4, and 6 and imaged using EPF, CCD, and PSP sensors. Percent correct response scores, sensitivity, and specificity values were computed for all variables. Repeated-measures analysis of variance and post hoc testing were performed to determine the effects of imaging modality, observer, and lesion sizes with respect to lesion detection.

RESULTS

EPF displayed the highest sensitivity and specificity, followed by PSP and CCD images (P <.001). Percent correct score was the highest for 3 of 4 observers when EPF was used. Analysis of variance revealed significance (P <.001) with respect to all variables. Observers with experience in digital image-viewing performed better than those without such experience (P <.001). Intraobserver agreement was fair (kappa = 0.5).

CONCLUSIONS

EPF outperformed CCD and PSP images when observers could manipulate image characteristics.

Advances in dental imaging

The number of dental radiographs taken in the UK has steadily increased over the past 20 years--recently estimating around 18 million taken in the general dental services alone, and dental radiographs now account for nearly 25% of all medical radiographic exposures. Radiographs remain our most useful diagnostic aid. Their strength is in demonstrating hard tissue pathology, which makes radiographs particularly effective in the maxillofacial region. Although well accepted in this capacity, there remain a number of limitations and drawbacks to conventional radiographs which recent developments have begun to overcome. There have been improvements in the scope and capabilities of dental imaging equipment. There has also been a continuing effort to reduce radiation-induced harm by limiting our exposure to it. This has been possible both through the introduction of new methods and protocols for reducing individual radiation exposures and by the creation of guidelines for selecting radiographs more effectively and thereby reducing the total number of radiographs taken.

Influence of developer exhaustion on accuracy of quantitative digital subtraction radiography: an in vitro study

OBJECTIVE

The aim of the study was to evaluate the influence of developer exhaustion on accuracy of quantitative digital subtraction radiography.

STUDY DESIGN

Six objects, each incorporating a section of dry human mandible, were radiographed with 4 exposure times. Baseline films were processed in fresh solutions, whereas follow-up films were processed in fresh and in increasingly exhausted solutions (ie, 1, 2, and 3 weeks old). Bone loss and bone gain were computer simulated in 17 regions of interest on baseline radiographs. Area and volume of changes in mineralization were measured in subtracted images, obtained by subtraction of baseline from their corresponding follow-up radiographs. Friedman's 2-way analysis of variance by ranks and Wilcoxon signed-rank test were used for statistical analysis.

RESULTS

Because of exhausted developer, bone loss was relatively underestimated from 6.6% to 16.5% (P <.05), whereas bone gain was relatively overestimated from 9.7% to 16.7% (P <.05).

CONCLUSIONS

This in vitro study demonstrates that films for quantitative digital subtraction radiography should be processed in fresh developer or error might be introduced.

Radiographic and digital imaging in periodontal practice

This review defines terms such as accuracy, validity, and reliability, which are used to describe the quality of methods for taking x-rays and for analyzing digital images. Values for these parameters are described for techniques of taking standardized x-rays such as ear-rod fixation and fixation by use of teeth with a dental impression. In addition, values are given for linear measurements on digitized images and for quantitative image subtraction. Differences are addressed between quantitative subtraction with a reference ramp and relative subtraction using the computer-assisted densitometric image analysis (CADIA) system. The relationship between radiographic bone height and clinical attachment level is also discussed. Finally, present and future use in the periodontal office of linear radiographic measurements on digital images and digital subtraction is discussed.

Potential for fraudulent use of digital radiography

BACKGROUND

Digital radiographic images can be manipulated using personal computers. To test the potential for fraudulent use, the authors altered a series of dental radiographs, printed them to simulate duplicated films and submitted them for authorization of proposed treatment.

MATERIALS AND METHODS

The authors obtained periapical radiographs of teeth that contained small restorations or were unrestored from the files of three dental patients at a private dental practice. The authors used a flatbed scanner to digitize and import the radiographs into a computer. Then they added dental caries, large restorations, fractures and periapical pathosis to the radiographs. The authors proposed to the insurance companies that the teeth in question be restored using expensive treatment, such as root-canal therapy and full-coverage crowns.

RESULTS

In each case, the insurance companies authorized the proposed treatment based on the appearance of the teeth on the radiographs. The altered images illustrated an apparent need for dental treatment that was not required and that could have led to payment for treatment that was not actually performed.

CONCLUSIONS

This study illustrates the potential for the fraudulent use of manipulated digital radiographic images.

CLINICAL IMPLICATIONS

Dentistry should be aware of the implications of the potential for such abuse and should develop measures both to prevent it from occurring and to facilitate its detection.

Radiographic study of the maxillary canine tooth of four mesaticephalic cats

The radiopaque and radiolucent anatomical structures that are superimposed over the root of the maxillary canine tooth in mesaticephalic cats were identified on digital radiographs made at various angles. The vomer bone, the nasal bone, the palatine fissure, and the infraorbital foramen were not superimposed over the root of the canine tooth in the range of angles examined. Superimposition with the palatine sulcus (which is rarely visible clinically because of silhouetting of the soft tissues) only occurred at extreme horizontal (cross-sectional arc) angles. The second premolar tooth was superimposed at a cross-sectional angle of 80 degrees and 90 degrees. The structures of concern in the interpretation of radiographs of the maxillary canine tooth in mesaticephalic cats are the conchal crest, the line of conjunction between the vertical body of the maxilla and its palatine process, the incisivomaxillary canal (which is rarely visible on radiographic images), and the lachrymal canal. Because of their anatomical vicinity, the radiographic position of these structures relative to the maxillary canine tooth can only be minimally changed. It was not possible to identify an "ideal" angle to radiograph the maxillary canine tooth in these four mesaticephalic cats. However, an acceptable compromise between minimal distortion of the image and satisfactory visualization of the root was obtained with the radiographic beam (rostro-caudal rotation) angled at 80 degrees and the skull (rotation in cross-sectional arc) angled at 70 degrees.

Assessment of image quality in dental radiography, part 2: optimum exposure conditions for detection of small mass changes in 6 intraoral radiography systems

OBJECTIVE

The purpose of this study was to compare 2 film systems and several digital intraoral systems with regard to visual image quality through use of a test phantom developed for this purpose.

STUDY DESIGN

The detectors used for digital imaging were as follows: Computed Dental Radiography (CDR), Digora, Dixel, and Sens-A-Ray without scintillator layer. Two types of digital images were prepared for the observer performance test: one with original gray scales and another with contrast enhancement. Images with and without enhancement from the 4 systems were displayed to 7 observers. The change in the average number of perceptible holes was plotted against exposure, and modified perceptibility curves were created and compared with curves for the film systems. The exposure level at which the maximum number of holes was perceived was defined to be optimum. The optimum exposure levels were determined for each digital system and compared with that of the film systems. At the optimum exposure, the average maximum numbers of perceptible holes in each digital system with and without contrast enhancement were compared with the maximum numbers for the film systems. The minimum exposure levels were determined to be those at which the number of perceptible holes exceeded the number for film, and the possibility of exposure reduction was evaluated.

RESULTS

All digital systems except the Digora system showed lower optimum exposures than E-speed film. In all digital images without enhancement, however, the maximum number of perceptible holes was significantly lower than that for the film systems at that exposure. With contrast enhancement, all digital systems except the Sens-A-Ray system showed visibility superior to that of the film systems. With the CDR, Digora, and Dixel systems, exposures could be further reduced by a considerable amount, with greater retention of information than was associated with film.

CONCLUSIONS

Our results strongly suggest that digital systems, if properly used, can exceed film systems in the detection of small mass changes.

Assessment of image quality in dental radiography, part 1: phantom validity

OBJECTIVE

The purpose of this study was to describe and validate an image-quality phantom to be used in dental radiography for comparison of film and digitally acquired images.

STUDY DESIGN

An aluminum block of 12 steps, with 7 holes in each step, was covered by acrylic blocks. This phantom was radiographed with Kodak Ultra-speed and Ektaspeed Plus films at 70, 65, and 60 kVp with the whole exposure range available. All together, 50 dental films were randomly sequenced and presented to 7 observers. The average number of perceptible holes from all steps was plotted against exposure for each tube voltage and film type, generating a modified perceptibility curve. The tentative optimum exposure level was determined from perceptibility curves in each experimental condition and compared with that determined by means of the standard aluminum stepwedge and the preset time of the x-ray machine. The density range of this phantom at the optimum exposure was compared with that of clinical dental radiographs. Validity of the phantom was evaluated according to the optimum exposure level from the modified perceptibility curves and the overall density range. Finally, the average maximum numbers of perceptible holes at the tentative optimum exposure level were compared for each tube voltage and film type. The statistical test used was a 2-way factorial analysis of variance.

RESULTS

The exposure at the perceptibility curve peak approximated that obtained by means of the standard aluminum step-wedge and the time preset by the manufacturer. The overall density range at the perceptibility curve peak covered the clinical density range for each tube voltage and film type. There were no statistically significant differences between film types or among tube voltages.

CONCLUSIONS

The x-ray attenuation range for this phantom seemed to approximate clinical conditions. In addition, differences in image quality could be quantitatively evaluated by means of the number of the holes seen in the phantom.

Film and digital radiography for detection of simulated root resorption cavities

OBJECTIVES

The purpose of this study was to evaluate observers' ability to detect simulated root resorption cavities in conventional radiographs and digital radiographs from a charge-coupled device system and a storage phosphor system and to determine whether the detectability was influenced by resorption size and exposure.

STUDY DESIGN

In teeth from dry mandibular jaw specimens, resorptive defects 1.2 mm in diameter and two different depths (0.6 and 0.9 mm) were prepared in the buccal root surface. Each tooth was radiographed at a number of different exposure settings. Observers were asked to rate their confidence that a resorption was or was not present using a five-graded confidence scale. Receiver operating characteristic analysis was used to evaluate the results.

RESULTS AND CONCLUSION

Given optimal exposures, all systems reached what might be considered clinically acceptable Az values (> 0.75). The storage phosphor system reached this value at considerably lower exposures than those required for both the film and charge-coupled device systems. There was a tendency to better detect the deeper lesions and to identify them at lower exposures.

Interpretation of periapical lesions comparing conventional, direct digital, and telephonically transmitted radiographic images

The purpose of this study was to evaluate direct digital radiography (DDR) and telephonically transmitted images versus conventional radiography in the interpretation of artificial periapical bone lesions. Five teeth were chosen from four cadaver jaw specimens. Three types of DDR images were evaluated: DDR stored images, DDR transmitted images, and DDR reversed images. A total of 150 DDR computer monitor images and 56 D-speed film images were evaluated by three endodontists and one endodontic graduate student. The Wilcoxon signed-ranks test was used for statistical analyses of the results. DDR reversed images were statistically inferior to DDR stored images, DDR transmitted images, and conventional radiography images (p < 0.0001). There were no statistically significant differences between DDR stored images, DDR transmitted images, and conventional film images in the ability of the evaluator to identify artificial periapical bone lesions (p > 0.05).

Direct digital radiography for the detection of periapical bone lesions: a clinical study

The aim was to compare the observer performance of direct digital radiography, with and without image processing, with that of conventional radiography, for the detection of periapical bone lesions. For 50 patients, a conventional periapical radiograph using E-speed film was taken. Then, a direct digital image of the same area was made. The images presenting the periapical bone tissue of 59 roots were assessed by seven observers using a 5-point confidence scale. The digital images were first presented as original images, with default contrast and brightness set by the computer system. Following this, the observers were allowed to use the processing facilities for greyscale treatment. The results for original and processed direct digital images and for conventional radiographs were compared by Receiver Operating Characteristic (ROC) analysis. The area under the ROC curve, calculated as P(A) value, was 0.88 for conventional film, 0.82 for original digital images and 0.78 for processed images. Corresponding Az values were slightly higher, 0.89, 0.84 and 0.81. Statistically significant differences between ROC areas calculated as P(A) values for the methods were found. Comparison between Az values showed no significant differences between conventional radiographs and original digital images, whereas the difference between Az values for original and processed digital images was still significant. It was concluded that conventional film radiography performed slightly better for the detection of periapical bone lesions than direct digital radiography and that image processing did not improve the observer performance.

Evaluation of a digital radiography to estimate working length

The working lengths obtained with different methods in single-rooted teeth were compared. An endodontic rule in millimeters and calipers was used as a direct method of measurement (on endodontic files). As indirect methods, measurements were taken from conventional x-rays with calipers and with a digital radiological measurement system. No statistically significant differences were obtained between the direct and indirect methods. Three vertical angulations were taken for the indirect methods (0 degree, 15 degrees, and 30 degrees). No significant differences were found between results for the two indirect methods versus the standard method except for the 30 degrees angulation, which resulted in an impression of a shortened image of about 1.5 mm when using the indirect methods (significance level: alpha = 0.05).

Marginal bone level buccal to mandibular molars in digital radiographs from charge-coupled device and storage phosphor systems. An in vitro study

The aim of this in vitro study was to compare bone loss measurements in the furcation area of mandibular molars in digital radiographs from a CCD-(Sens-A-Ray) and a storage phosphor (Digora) system, 10 1st and 7 2nd mandibular molars, with intact lingual but reduced buccal bone with furcation involvements, were used. Radiographs were first taken with lead markers at the most apical part of the buccal bone and at the cemento-enamel junction. These radiographs were used to establish a radiographically true distance between the CEJ and the buccal bone level. The lead marker at the CEJ served as a reference point for the observers' subsequent estimates of the extent of bone removed, which were made in radiographs without lead markers at the bone level. 1 exposure (400 ms) for the CCD- and 5 (160 ms, 200 ms, 250 ms, 320 ms, 400 ms) for the storage phosphor system were used. Measurements were made in unprocessed (original) and processed images (contrast enhanced and/or high pass filtered). The results showed underestimation of bone loss, but smaller than previously reported for film radiographs. No significant difference was found between the 2 systems when compared at the same exposure. Nor were any significant differences found between unprocessed and processed images or between storage phosphor images from different exposures. We conclude that digital radiographs are comparable to film based radiographs for measurement of buccal bone loss but that lower exposures can be used, especially with the storage phosphor system.

Efficacy of digital intra-oral radiography in clinical dentistry

OBJECTIVES

This article emphasizes the comparison of intra-oral digital imaging to film-based imaging. Additional possibilities of digital imaging that may contribute to system efficacy are discussed as well.

STUDY SELECTION

The main subjects for research in digital imaging are image quality, image acquisition, diagnostic quality, image manipulation, automated analysis, and application software.

DATA SOURCES

Representative articles on these subjects from the international literature are used for this review. Indirect digital imaging still requires film processing, sophisticated film digitizers, and time to digitize film. Although it is not an efficient method for the dental practice, digitization can be very useful for quantitative analysis of radiographs. Direct digital imaging is more efficient than indirect digital imaging. The main advantages are (semi) real time imaging, low X-ray dose requirements, and no need for chemical processing. In spite of a more limited resolution of the images, direct imaging may perform as accurately as film-based imaging. Direct image plate systems can well be used, for instance, for full-mouth series. The main application of direct sensor systems appears to be endodontology and implantology. In summary, direct digital imaging may be as efficient as film-based imaging in clinical dentistry. The computer provides for many additional options in digital imaging, such as the digital storage, compression, and exchange of radiographic information. Image manipulation (e.g. image enhancement, subtraction radiography and image reconstruction) and automated analysis may benefit radiodiagnosis.

CONCLUSION

It can be concluded that digital imaging certainly has great potential, especially with respect to improvement of diagnostic quality and automated image analysis.

Detection of small differences in mass using a direct digital dental X-ray system

OBJECTIVES

To evaluate experimentally how in direct digital radiography heterogenous detector response may influence the depiction of small mass differences.

METHODS

A step wedge of a bone-simulating resin was imaged at 70 kVp using RadioVisioGraphy ZHR 32000. Exposure time and step wedge position on the detector varied. The pixel values of the stored images of the step wedge were converted to luminance values of the displayed images.

RESULTS

The relationship between pixel and luminance values was non-linear. The difference in luminance between adjacent steps varied with position of step wedge. Regardless of position, there was an increase in difference of luminance between steps with increasing exposure. A greater relative change in luminance was consequently seen in the thinner parts of the step wedge. The failure to perceive individual steps of the wedge in its thicker parts was related to insufficient relative change in luminance between steps.

CONCLUSIONS

The heterogeneous response of the detector resulted in a varying ability to depict small mass changes over the detector area.

Criteria for the assessment of intrinsic performances of digital radiographic intraoral sensors

RATIONALE AND OBJECTIVES

In sensor-based dental digital radiographic imaging systems, it should be possible to assess the intrinsic performance of the sensor by means of objective criteria, independent of the related electronic hardware and image-treatment software.

METHODS

Six criteria are presented and discussed for the objective assessment and quantification of the intrinsic performance of intraoral sensors for dental digital radiography, independent of the characteristics of the subsequent image-treatment software. The criteria are signal-to-noise ratio, blooming, sensitivity, spatial uniformity, modulation transfer function, and geometric deformations. These criteria have been used to evaluate the Visualix sensor.

RESULTS

For each criterion, a series of numerical data are presented as graphs.

CONCLUSION

A method is proposed for objective assessment of radiographic sensors that makes it possible to compare sensors with each other and with conventional radiographs. The criteria proposed also increase understanding of digital diagnostic images and improve their clinical use.

Diagnostic accuracy of direct digital dental radiography for the detection of periapical bone lesions: overall comparison between conventional and direct digital radiography

OBJECTIVES

The diagnostic accuracy of direct digital radiography for the detection of small, experimentally made, periapical lesions was compared with that of E speed film. The high- and low-contrast resolutions of the imaging systems were also compared.

STUDY DESIGN

The high-contrast resolution was evaluated with a line pair plate. The low-contrast resolution was determined with a contrast-detail plexiglass phantom. To evaluate the diagnostic accuracy, the periapical region of dry human mandibles was examined. Receiver operating characteristic based on the readings of seven observers were generated.

RESULTS

The high-contrast resolution of the digital system was inferior, but the low-contrast resolution was comparable to that of E-speed film. For diagnostic accuracy no significant difference was seen between the areas under the receiver operating characteristic curves.

CONCLUSIONS

The quality of the direct digital images is comparable to that of E-speed film for the detection of periapical bone lesions.

Dose reduction of two digital sensor systems measuring file lengths

OBJECTIVE

The aim of this study was to determine the effect of dose reduction on the image quality of two sensor systems with automatic greyscale adjustment.

STUDY DESIGN

Two digital sensor systems, Sidexis (Siemens, Bensheim, Germany) and Digora (Soredex, Helsinki, Finland), were tested. The image quality of the systems was determined by comparing lengths of endodontic files (025, 020, 015, and 010 files) and a premolar root in the digital images with lengths on conventional radiographic films. For the experiments the exposure was changed to 100%, 50%, 25%, 12.5%, 6.25%, and 3.125% of that for Ektaspeed films.

RESULTS

The lengths of 025 and 020 files and the premolar root in the digital images were comparable with the lengths on films even if the exposure was reduced to 6% of that used for Ektaspeed films. The lengths of 015 files reduced as the exposure was reduced. The lengths of 010 files were significantly shorter than the lengths on films.

CONCLUSIONS

With the systems tested, a dose reduction of approximately 95% compared with Ektaspeed films is possible to determine the lengths of a premolar root and 025 and 020 files. For thinner objects a dose reduction is questionable.

Interpretation of chemically created lesions using direct digital imaging

This study compared conventional radiography to digital imaging in detecting chemically created lesions. Six human cadaver jaw specimens were used. A 70% perchloric acid solution was used to create lesions on the buccal cortical plate of each specimen. Digital imaging and conventional images were created after progressing time increments; each increment represented a more advanced lesion. The images were randomly evaluated by five evaluators. This study concluded: (i) when no lesion existed, there was no significant difference in digital imaging or conventional radiography in early detection; (ii) at 12 and 24 h, digital imaging demonstrated lesions significantly earlier than conventional radiography (p = 0.0001); (iii) no difference could be found between imaging techniques at 36 h and thereafter; and (iv) there were no significant differences in the various RadioVisioGraphy enhancement settings used at any of the time points examined.

Digital radiographic images will benefit endodontic services

Future assurances for endodontic services and assessments of traumatized teeth will depend in part on significant improvements to the quality of dental radiographs. Whereas digital images offer many potential sensor, display and archival advantages over film-based radiographs, the marginal image improvements from intraoral sensors primarily benefit patient education. Precisely digitized conventional radiographs are more likely to yield quantum image resolution improvements, although neither dentists nor patients will benefit until cost-effective digitizing systems have been developed for the dental office.

Effect of image magnification of digitized bitewing radiographs on approximal caries detection: an in vitro study

OBJECTIVE

To evaluate whether or not image magnification of digitized bitewing radiographs had an effect on approximal caries detection.

METHODS

Twenty general dental practitioners (GDPs) rated a total of 140 digital images (28 approximal surfaces at five different magnifications, x3, x6, x12, x18 and x30) for caries on a 5-point confidence scale. The observations were compared with the state of the approximal surfaces on visual inspection. For each GDP the average response rate was calculated. Paired t-tests were used to compare the diagnostic response at the five different image magnifications.

RESULTS

The mean response rates obtained at x18 and x30 magnifications were significantly inferior to those at the three smaller magnifications (p < 0.007).

CONCLUSION

Digital image magnification has a significant influence on observer performance in the detection of approximal caries, with an upper limit beyond which diagnostic accuracy may be reduced. Further research is needed to determine limits for various different diagnostic tasks so as to give GDPs guidelines on the appropriate magnifications to use.

Future trends in dental radiology

Direct digital dental radiographic systems offer the potential to radically change the way dentists diagnose and treat dental pathoses. They offer instantaneous availability of radiographs, markedly lower patient radiation exposure, and the elimination of developing chemicals and developing equipment. The storage of dental radiographs as digital data permits their transmittal over phone lines facilitating phone consultations and may someday allow expedited authorization of treatment plans by dental insurance companies. With the use of digital subtraction radiology the dental practitioner will be able to diagnose periodontal disease progression and dental caries progression long before current techniques can detect a change. With tuned aperture computed tomography, the owner of a filmless digital system can make tomographic radiographs that allow the visualization of slices through areas of interest without having to buy additional hardware. Computer-aided diagnosis will facilitate the detection of proximal dental caries and osteoporosis, and may someday allow automated tracing of cephalometric radiographs.