Compensation of differences in density of radiographs by densitometry.

Radiographs were made of a dried human mandible with variations in kilovolt peak, exposure time, soft-tissue thickness substitutes, and developing time. The densitometric measurements of the image of dental and bony structures were transformed into millimeters of aluminum equivalents by means of densitometric measurements on the penetrometer. Variations in kilovolt peak, exposure time, soft-tissue thickness substitutes, and developing time do not affect the densitometric measurements after transformation, except when radiographs are very dark.     

Spatial resolution requirements for digitizing dental radiographs

A study was performed to determine the appropriate spatial resolution for digitizing and transmitting dental radiographs with the KODAK EKTASCAN, a computer-based digital enhancement and transmission system. Periapical, bitewing, and panoramic radiographs were digitized in three formats representing varying spatial resolution parameters. Eight viewers used a 5-point rating scale to evaluate the detectability of periapical pathosis on the periapical images, of proximal surface caries on the bitewing images, and of various bony abnormalities on the panoramic images. Receiver operating characteristic curves were generated, and the results of the periapical, bitewing and panoramic experiments were presented as trapezoidal and maximum likelihood receiver operating characteristic curve areas. The results of this study indicate that digital images of dental radiographs provide adequate diagnostic accuracy for evaluating the presence of periapical pathosis, proximal surface caries, and specified bony abnormalities. The digitization parameters established for the KODAK EKTASCAN provide a guide for digitizing dental radiographs on other commercially available digital image-processing systems.     

The effect of a bioresorbable matrix barrier in endodontic surgery on the rate of periapical healing: an in vivo study

The purpose of this prospective clinical study was to assess the rate of healing of periapical bony defects created at the time of endodontic periapical surgery by measuring the densitometric ratio change in periapical osseous tissues, after periapical endodontic surgery was performed, by using or not using Guidor bioresorbable membrane material. Periapical surgeries were performed on 25 patients where nonsurgical root canal therapy had failed and a periapical lesion was present. For inclusion in the study, the osseous defect to be analyzed had to be confined to the apical area, with bone covering the entire root surface coronally, and an intact lingual cortical plate had to be present. A series of radiographs at the 3-, 6-, and 12-month recalls were compared with the radiograph taken immediately after surgery by using digital imaging and a densitometric ratio that gave a numerical estimation of osseous healing. Using repeated-measure ANOVA, it was shown that there was no statistical difference between the rate of healing in those cases where a Guidor resorbable membrane was used and those cases where no membrane was used. The results suggest that placement of a guided tissue membrane over the bony opening created during an endodontic periapical surgical procedure has no beneficial effect on the rate of healing and the added expense to the patient would not be warranted in these cases.     

Interpretation of artificial and in vivo periapical bone lesions comparing conventional viewing versus a video conferencing system

The purpose of this study was to compare the interpretation of conventional radiographs transmitted by a video teleconferencing system to conventional viewbox interpretation for both artificial and in vivo periapical bone lesions. A total of 30 radiographic images were used in this study: 20 radiographic images of artificial lesions and 10 radiographs from actual patients. Two endodontists evaluated the 30 images by giving a "yes" or "no" response when determining whether a periapical lesion was present on the radiograph. The study was conducted in two sessions, separated by a 6-wk interval to minimize evaluator recall. Results of the study revealed no statistical difference between the ability of the evaluator to identify periapical bone lesions using conventional radiographs on a viewbox and his ability to interpret the same images transmitted on a monitor screen.     

Digital subtraction radiography for detecting cortical and cancellous bone changes in the periapical region

Previous studies have found that bony lesions cannot be visualized on conventional radiographs unless there is cortical plate involvement. The aim of this project was to compare the sensitivity of digital subtraction to conventional radiography for detecting periapical changes in cortical and cancellous bone. Using a long source-to-object X-ray technique and E-speed film, serial radiographs of a dry skull mandible were obtained. Two bone lesions per radiograph were simulated using #1 to 8 round burs. Conventional and digitally subtracted images were evaluated for lesion presence by a board of reviewers. The results demonstrated greater sensitivity scores for digitally subtracted images in identifying cortical and cancellous bone changes. The lower limit of detection was less for digitally subtracted images in cortical and cancellous bone as well.     

Diagnosing periapical bone lesions on radiographs by means of texture analysis.

Trabecular pattern, the radiographic projection of trabecular bone, is a repeated structure that appears in a dental radiograph. Texture analysis, the computer image analysis of repeated patterns, is a technique that can be used to automate the diagnosis of periapical lesions with the detection of the absence of the texture that corresponds to the trabecular bone. The purpose of this study was to determine whether it is feasible to use texture analysis to identify the presence of the trabecular pattern in radiographs and to detect a periapical bone lesion based on a local absence of this pattern. Thirty-two mandibular periapical films, 16 with and 16 without periapical lesions, were used in this study. Texture analysis was carried out on the digital images of these radiographs. In the 16 films with lesions, they were all correctly identified, and no lesions were found in the 16 films without lesions. This result is based on the a prior knowledge of the user about the localization of the disease. Locating periapical regions without user interaction is a goal for future research.     

Liquid crystal displays for the evaluation of dental

We assessed whether dental x-ray images observed on a liquid crystal display (LCD) could be applied to diagnosis. A 13-inch TFT (thin film transistor) display was utilized in this study. Fifty x-ray films of radiographically diagnosed periapical lesions and fifty normal films were digitized at 300 DPI. These sample images were randomized and evaluated by five observers who compared them with the original films using a continuously distributed confidence rating method. The data were analyzed with a Receiver Operating Characteristics (ROC) analysis. The CRT images were evaluated in the similar way. The results showed no statistically significant differences between the original dental x-ray films, images on the TFT display and the CRT regarding the diagnosis of periapical lesions. We conclude that a TFT-type liquid display provides sufficient detail for the diagnostic observation of dental radiographs. Thus, such displays may be useful for dental clinics.     

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

Abstract 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 A_z 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 A_z values showed no significant differences between conventional radiographs and original digital images, whereas the difference between A_z 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 the pathophysiology of odontogenic maxillary sinusitis using bone scintigraphy

The inflammatory changes in the maxillary sinus mucosa and wall (mucosal and bony lesions) were evaluated to identify the pathophysiology of odontogenic maxillary sinusitis. Out of 80 patients who underwent CT, 32 patients were examined using single photon emission computerized tomography (SPECT) bone scintigraphy (bone SPECT) with 99mTc-hydroxymethylene-diphosphonate. Mucosal and bony lesions were evaluated morphologically on both images. SPECT data were used to assess the bone activity by calculating the count ratios of the causative alveolar process over the cervical vertebrae. The relationships with clinical symptoms, mucosal changes around the maxillary ostium (ostial lesions), and radiolucencies around the causal teeth (periapical lesions) were assessed. Bone SPECT showing the causal site was valuable for aiding a definitive diagnosis. Mucosal lesions tended to exceed bony lesions horizontally and vertically. Bony lesions tended to extend posteriorly and then anteriorly. The vertical extent of mucosal lesions and the horizontal and vertical extent of bony lesions were correlated with the presence of facial symptoms, ostial lesions, and periapical lesions. Bone activity was significantly correlated with the horizontal and vertical extent of mucosal lesions, horizontal extent of bony lesions, and presence of infraorbital symptoms, ostial lesions, and periapical lesions. Bone activity caused by alveolitis affects the pathophysiology of this disease.     

Subtraction radiography for the diagnosis of periapical bone lesions

Abstract Subtraction and conventional radiography were evaluated for the diagnostic potential to assess periapical bone lesions. The periapical region of dry human mandibles was radio-graphically examined, subjectively evaluated and measured by ¹²⁵I absorptiometry before and after the creation of bone defects. Both conventional radiographs and subtraction images made from the conventional radiographs after digitization were interpreted by 10 dentists. Receiver operating characteristic (ROC) analysis technique was used to compare the two techniques. There was a higher diagnostic accuracy using subtraction technique. For a lesion depth corresponding to < 2 mm of compact bone, there was a clear difference between the techniques, but for deeper lesions the conventional technique gained force. The subtraction technique was significantly superior for lesions confined to cancellous bone. The statistical difference in the diagnostic utility of subtraction compared with conventional technique was found to be less for lesions of the cortical bone. Therefore, the conclusion is that subtraction radiography improves the detection of small lesions in the periapical bone area.     

Healing assessment of osseous defects of periapical lesions associated with failed endodontically treated teeth with use of freeze-dried bone allograft

Freeze-dried bone allograft (FDBA) has been used extensively in periodontal surgery and in the treatment of pocket osseous defects resulting from inflammatory periodontal disease. No other endodontic investigation has used this type of graft material in the treatment of bony resorptive defects of the periapical lesions associated with failed endodontic therapy. Therefore this study was conducted with the use of FDBA, to assess healing ability of osseous defects after removal of periapical lesions associated with failed endodontically treated teeth. In all patients periapical lesions were surgically removed with retrograde amalgam seal and the graft material was then carefully packed without pressure into the bony defect. The lesions were fixed in 10% neutral buffered formalin and prepared for histologic examination. Long-term recall demonstrated bone regeneration and good tolerance of allograft material by the periapical tissues. The periapical lesions were either periapical granulomas or apical periodontal cysts. We conclude that FDBA is a biocompatible material of osteogenic potential and can be used effectively in treating osseous defects of periapical lesions associated with failed endodontically treated teeth.     

The potential applications of cone beam computed tomography in the management of endodontic problems

AIM: To provide core information on cone beam computed tomography (CBCT) technology and its potential applications in endodontic practice. SUMMARY: CBCT has been specifically designed to produce undistorted three-dimensional information of the maxillofacial skeleton as well as three-dimensional images of the teeth and their surrounding tissues. This is usually achieved with a substantially lower effective dose compared with conventional medical computed tomography (CT). Periapical disease may be detected sooner using CBCT compared with periapical views, and the true size, extent, nature and position of periapical and resorptive lesions can be assessed. Root fractures, root canal anatomy and the true nature of the alveolar bone topography around teeth may be assessed. CBCT scans are desirable to assess posterior teeth prior to periapical surgery, as the thickness of the cortical and cancellous bone can be accurately determined as can the inclination of roots in relation to the surrounding jaw. The relationship of anatomical structures such as the maxillary sinus and inferior dental nerve to the root apices may also be clearly visualized. KEY LEARNING POINTS: CBCT has a low effective dose in the same order of magnitude as conventional dental radiographs. CBCT has numerous potential applications in the management of endodontic problems.     

Densitometric analysis of lower molar interradicular areas in superposable radiographs

Superposable radiographs of lower molar areas were obtained by means of a specially designed film holder and a gnathostat maintained in a constant position with respect to long-cone radiological equipement. A quantitative evaluation of the bone mass in the interradicular area was obtained by scanning the area under a photodensitometer. A photodensitometric scan of the image of an aluminium wedge adapted to each radiograph was also performed. This allowed the transformation, with the aid of a computer, of the photodensitometric recording of bone into a tracing of mm of aluminium equivalents. The reproducibility and precision of the method were verified by comparing magnifications of repeated radiographs, by photodensitometric readings of radiographs developed in different batches and by repeated quantitative readings of the same film. The method allowed one, for instance, to follow quantitatively the healing of a radiographically visible periapical lesion. It was also used to evaluate quantitatively, in the interradicular area, bone changes which could not be seen with the marked eye.     

Clinical efficacy of dental radiography in the detection of dental caries and periodontal diseases

This article reports the ability of dental radiographs to correctly detect evidence of dental caries and periodontal disease (sensitivity) and to correctly establish the absence of these diseases (specificity). The analysis used a unique data set that was collected as part of the Veterans Administration Dental Longitudinal Study in Boston. Periapical, panoramic, and posterior bitewing radiographs were independently compared with a consensus radiographic standard of all three radiographs read simultaneously. Findings showed that the sensitivities of all three radiographs to detect dental caries were lower than expected, at approximately 60%, whereas the sensitivities to detect evidence of periodontal disease averaged approximately 85%. Panoramic radiographs were substantially less sensitive for detecting dental caries than periapical and posterior bitewing radiographs, but no difference between these modalities was observed in the analysis of sensitivity to periodontal disease. The proportion of false-negative and false-positive readings from dental radiographs was substantial and requires further investigation.     

Assessment of alveolar bone loss with high resolution computed tomography

In this in vitro study we compared high resolution computed tomography (HR-CT) with dental radiographs regarding the interpretation of horizontal and vertical alveolar bone loss. After removal of the soft tissue and metallic restorations of 20 dentate upper and lower jaw segments 40 infra-alveolar bony defects of different dimensions were experimentally produced. The specimens were examined radiographically with standardized dental radiographs and 1.0 mm thick contiguous axial CT-scans. On the specimens, radiographs and CT-scans the bone loss was measured between the cemento-enamel junction and the adjacent alveolar bone level of 472 mesial and distal tooth surfaces; the identification, classification and vertical depth of the infra-alveolar bony defects were also compared. An average underestimation of 0.6 mm of horizontal alveolar bone loss in the dental radiographs and an overestimation of 0.2 mm in CT-scanning was shown. No significant differences between the imaging accuracy of horizontal alveolar bone loss between dental radiographs and CT-scanning could be evaluated. In the dental radiographs 24 (60%) of the infra-alveolar bony defects could be identified and the vertical depth was underestimated by a mean of 2.2 mm. In comparison, all 40 (100%) infra-alveolar defects could be identified in the CT-scans and the vertical depth was underestimated by an average of 0.2 mm. The HR-CT-technique offers a three-dimensional interpretation of the alveolar morpholoy without overlying structures. This permits a high identification rate and classification of infra-alveolar bone loss according to the number of surrounding bone walls into one-, two or three-walled bony pockets.     

Detectability of artificial marginal bone lesions as a function of lesion depth

Subtraction of serially obtained standardized radiographs of the marginal periodontal bone offers possibilities for an increased detectability of small bony changes compared to conventional radiography. In this study, the depth of artificially induced bone lesions in the alveolar crest was assessed by means of 125I absorptiometry. The results served as reference values when a series of radiographs containing lesions of various depths was interpreted by 10 examiners. Both conventional radiographs and subtraction images made from the conventional radiographs after digitization were interpreted. The ROC-curve technique was used to evaluate the two techniques. A close to perfect accuracy was found at a lesion depth corresponding to 0.49 mm of compact bone using the subtraction technique. A similar degree of accuracy was not reached for the conventional technique until the lesions were approximately 3 times deeper.     

In vitro calibration and validation of a digital subtraction radiography system using scanned images

OBJECTIVES: To calibrate and validate a digital subtraction radiography system using scanned images for quantification of alveolar bone changes by means of computer-assisted densitometric image analysis (CADIA) in vitro. MATERIALS AND METHODS: Noise levels were determined using 10 standardized periapical radiographs of the same lower molar region in a human dry skull. For validation of the system, radiographs were taken before and after bovine bone particles in measures with increments of 2 mg weighing from 2 to 20 mg were added into each socket of three dry skulls. Radiographs were developed and scanned into a computer with a flatbed scanner. After digitization, the images were subjected to alignment, normalization and subtraction. Appropriate regions of interest (ROIs) were selected and their CADIA values were calculated for the determination of noise levels, and correlations between the CADIA values and the actual bone mass were performed. RESULTS: When the threshold value was 7, the percentage of pixels deviating from the set threshold value was small (0-11.3%). There were statistically significant correlations between the actual bone mass and the CADIA value for anterior sockets (p<0.001, r2=0.89) and posterior sockets (p<0.001, r2=0.9). For pooled data of both anterior and posterior sockets, the correlation was also statistically significant (p<0.001, r2=0.88). CONCLUSIONS: A high and statistically significant correlation between the actual bone mass and CADIA value was obtained, which suggests that the system could be suitable for the detection of small alveolar bone changes.     

Periapical lesion development in rats inhibited by dexamethasone

Bone resorption is one of the hallmarks of inflammatory periapical lesions and is mediated by cytokines. Recent insights into the immunobiology of these lesions indicate that pharmacological modulation of their bone resorbing activity may be possible. Periapical lesions were induced in rats by occlusal exposure of the pulps of their lower first molars. The size of the resulting lesions was followed-up and evaluated by image analysis of their radiographs. The lesions increased with time, and the average area of their radiographic images reached 2.18 (+/- 0.33) mm2 by day 21. Systemic dexamethasone treatment (0.5 mg/kg, every third day) inhibited the growth of the periapical lesions, which reached an average area of 1.63 (+/- 0.30) (p < 0.01). These results support the hypothesis that bone resorption in periapical inflammatory lesions may be pharmacologically down regulated.     

A comparison of phosphor-plate digital images with conventional radiographs for the perceived clarity of fine endodontic files and periapical lesions

OBJECTIVE: We sought to compare digital images with radiographs for the perceived clarity of small endodontic file tips at 2 different working lengths, as well as for the visualization of periapical bone lesions. STUDY DESIGN: Standardized conventional radiographic and phosphor-plate digital images were taken of 20 extracted permanent mandibular molars with 06 K-files placed in the distal root canal either 2 mm short or flush with the apical foramen. Similar images were obtained from mandibles with teeth that demonstrated large (n = 10) or small (n = 10) periapical lesions. Four evaluators ranked the clarity of the digital image with that of the radiograph. Results were analyzed by using the 2-sided sign test, ordinal logistic regression, and the kappa test. RESULTS: The perceived clarity of an endodontic file tip, at any position, and of a small or large periapical lesion was significantly (P < .01) less on all digital images compared with conventional films. CONCLUSION: Evaluator ratings indicated that the perceived clarity of fine endodontic files and periapical lesions was significantly less with phosphor-plate digital images than with conventional radiographs.