Image quality of two solid-state and three photostimulable phosphor plate digital panoramic systems, and treatment planning of mandibular third molar removal

Preliminary evaluation of dual imaging plate intraoral radiography

PURPOSE

This study evaluated the contrast-to-noise ratio (CNR), spatial resolution, and subjective quality of dual imaging plates (DIP) intraoral radiography.

METHODS

The DIP and conventional single IP (CSIP) methods both used YCR DT-1 imaging plates (Yoshida Co.). The DIP, comprising a front IP (FIP) and back IP (BIP), was constructed. DIP images were synthesized from the FIP and BIP images. An aluminum step phantom was used to measure the CNR. A line pair gauge was used to measure the spatial imaging resolution. A phantom comprising a porcine mandible embedded in acrylic resin was used for subjective evaluation.

RESULTS

The CNR of the DIP image was 32% higher than that of the FIP image. The spatial resolution achieved using the FIP, DIP, and CSIP was highly comparable except above 4 line pairs/mm, where that of the CSIP was highest. In subjective evaluation, the noise in the DIP images was significantly lower than in those obtained using the FIP and CSIP.

CONCLUSION

The CNR of the DIP was higher than that of the FIP. The decrease in spatial resolution of the DIP was limited. The subjective image quality of the DIP was higher than that of the FIP.

Reject Rates of Radiographic Images in Dentomaxillofacial Radiology: A Literature Review

This report surveyed the image reject rates of intra-oral, extra-oral, and cone-beam computed tomography (CBCT) imaging in the academic literature. PubMed, Web of Science, and Scopus databases were queried in mid-April 2021. Manual screening of the reference lists of the identified publications was performed to identify papers missed from the database search. All publications returned by the searches were initially included. Exclusion criteria included irrelevance, no reporting of reject rate, no access to the article, and not original article. The total number of images and the number of rejects were recorded for each type of radiographic images. Factors and commonest errors associated with the rejects were recorded. Twenty-six original articles were identified and reviewed. The average reject rate was 11.25% for bitewings, 16.38% for periapicals, 4.10% for panoramics, 6.08% for lateral cephalography, and 2.77% for CBCT. Positioning error and patient movement were two common reasons for the rejects. The average reject rates computed from data pooled across studies should form the reference values for quality assurance programs to follow. Future reject analysis studies should report more radiographic parameters such as type of collimation for intra-oral radiography and patient posture for CBCT.

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

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

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

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

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

The effects of image acquisition control of digital X-ray system on radiodensity quantification

Objectives

Aluminum step wedge (ASW) equivalent radiodensity (eRD) has been used to quantify restorative material's radiodensity. The aim of this study was to evaluate the effects of image acquisition control (IAC) of a digital X-ray system on the radiodensity quantification under different exposure time settings.

Materials and Methods

Three 1-mm thick restorative material samples with various opacities were prepared. Samples were radiographed alongside an ASW using one of three digital radiographic modes (linear mapping (L), nonlinear mapping (N), and nonlinear mapping and automatic exposure control activated (E)) under 3 exposure time settings (underexposure, normal-exposure, and overexposure). The ASW eRD of restorative materials, attenuation coefficients and contrasts of ASW, and the correlation coefficient of linear relationship between logarithms of gray-scale value and thicknesses of ASW were compared under 9 conditions.

Results

The ASW eRD measurements of restorative materials by three digital radiographic modes were statistically different (p = 0.049) but clinically similar. The relationship between logarithms of background corrected grey scale value and thickness of ASW was highly linear but attenuation coefficients and contrasts varied significantly among 3 radiographic modes. Varying exposure times did not affect ASW eRD significantly.

Conclusions

Even though different digital radiographic modes induced large variation on attenuation of coefficient and contrast of ASW, E mode improved diagnostic quality of the image significantly under the under-exposure condition by improving contrasts, while maintaining ASW eRDs of restorative materials similar. Under the condition of this study, underexposure time may be acceptable clinically with digital X-ray system using automatic gain control that reduces radiation exposure for patient.

Image quality assessment in panoramic dental radiography: a comparative study between conventional and digital systems

This study is designed to compare and evaluate the diagnostic image quality of dental panoramic radiography between conventional and digital systems. Fifty-four panoramic images were collected and divided into three groups consisting of conventional, digital with and without post processing image. Each image was printed out and scored subjectively by two experienced dentists who were blinded to the exposure parameters and system protocols. The evaluation covers of anatomical coverage and structures, density and image contrast. The overall image quality score revealed that digital panoramic with post-processing scored the highest of 3.45±0.19, followed by digital panoramic system without post-processing and conventional panoramic system with corresponding scores of 3.33±0.33 and 2.06±0.40. In conclusion, images produced by digital panoramic system are better in diagnostic image quality than that from conventional panoramic system. Digital post-processing visualization can improve diagnostic quality significantly in terms of radiographic density and contrast.

Accuracy of scanography using storage phosphor plate systems and film for assessment of mandibular third molars

OBJECTIVES

The aim of this study was to compare the diagnostic accuracy of two digital photostimulable storage phosphor (PSP) systems and film for assessment of mandibular third molars before surgery.

METHODS

110 patients were referred to have both their mandibular third molars removed. Each patient underwent a radiographic examination with scanography using either Digora (Soredex, Helsinki, Finland) and film or VistaScan (Dürr Dental, Beitigheim-Bissingen, Germany) and film in a randomized paired design. Two observers examined the following variables on the scanograms: bone coverage, angulation of the tooth in the bone, number of roots, root morphology and the relationship to the mandibular canal. In 75 of the pairs (Digora/film pair = 38 and Vista/film pair = 37) both third molars were eventually removed. During and after surgery the same variables were assessed, which served as reference standard for the radiographic assessments. The Wilcoxon signed-rank test tested differences in accuracy (radiographic compared with surgical findings) between Digora/film and between Vista/film.

RESULTS

There was no statistically significant difference between the diagnostic accuracy of film and either of the two digital receptors for assessment of mandibular third molars before surgery (P > 0.05), although Digora obtained a higher accuracy than film.

CONCLUSIONS

Scanography is a valuable method for examination of mandibular third molars before removal and the PSP digital receptors in this study were equal to film for this purpose.

Perception of anatomical structures in digitally filtered and conventional panoramic radiographs: a clinical evaluation

OBJECTIVES

The aims of the study were to compare subjective image quality of clinical images obtained with a storage phosphor plate (SPP)-based digital and conventional film-based panoramic system for the visualization of various anatomical structures and to evaluate the effect of various processing algorithms on image interpretation.

METHODS

Panoramic radiographs were taken in 42 patients both with film and with a SPP system. SPP images were treated with shadow, sharpen, negative, greyscale sigma and greyscale exponential filters. Four observers subjectively evaluated films and unfiltered and filtered SPP images for the visibility of anatomical structures with various radiodensities as well as for overall image quality on a three-point rating scale. The statistical methods used were Kruskal-Wallis, odds ratio analysis and Cohen's kappa.

RESULTS

No statistically significant difference was found between film and unfiltered digital images except for low-contrast structures (P > 0.05). Film images were preferred for the visibility of low-contrast structures (P < 0.05). Best overall image quality was obtained with sharpened images (P < 0.05) followed by films and unfiltered digital images. Among all filtered images, sharpened ones received the highest ratings for the visibility of all anatomical structures (P < 0.05). The intra- and interobserver agreement ranged between moderate and substantial and between fair and moderate, respectively.

CONCLUSIONS

Film and unfiltered SPP-based panoramic images performed equally well in terms of overall quality; however, films were best for the perception of low-contrast structures. The sharpening filter may be recommended for enhancing SPP panoramic images to improve the visual perception of most of the anatomical structures as well as overall quality.

Development of a new dental panoramic radiographic system based on a tomosynthesis method

The objective of this study was to develop a new practical method to reconstruct a high-quality panoramic image in which radiographers would be free from the onerous task of correctly locating the patient's jaws within the image layer of the panoramic unit. In addition, dentists would be able to freely select any panoramic plane to be reconstructed after the acquisition of the raw scan data. A high-speed data acquisition device was used with a CdTe (cadmium telluride) semiconductor detector and a sophisticated digital signal-processing technique based on tomosynthesis was developed. The system processes many vertical strip images acquired with the detector and generates a high-resolution and high-contrast image. To apply the tomosynthesis technique to the acquired strip images correctly, the actual movement of the panoramic unit was measured, including the X-ray tube and detector, in a scan using a calibration phantom and the authors generated a shift amount table needed for the shift-and-add tomosynthesis operation. The results of the experiments with a PanoACT-1000 panoramic unit, which was a PC-1000 panoramic unit fitted with a high frame rate semiconductor detector SCAN-300FPC, demonstrated the capability of a tomosynthesis technique which, when applied to the strip images of a dry skull phantom, could change the location and inclination of an imaging plane. This system allowed the extraction of an optimum-quality panoramic image regardless of irregularities in patient positioning. Moreover, the authors could freely reconstruct a fine image of an arbitrary plane with different parameters from those used in the original data acquisition to study fine anatomical details in specific locations.

Comparison between digital panoramic radiography and cone-beam computed tomography for the identification of the mandibular canal as part of presurgical dental implant assessment

PURPOSE

A variety of imaging modalities (eg, panoramic radiography, tomography, or computed tomography [CT]) were compared for their efficiency in the identification of the mandibular canal. The recently introduced cone-beam computed tomography (CBCT) seems to be a promising imaging modality which also reduces patient exposure considerably, compared with ordinary CT. The literature includes no studies comparing its performance in such delicate tasks as mandibular-canal identification with other traditionally used imaging modalities. The goal of this study was to compare CBCT reformatted panoramic images and digital panoramic images for the identification of the mandibular canal as part of preimplant assessment.

MATERIALS AND METHODS

Panoramic images, generated by 3 different imaging modalities used for general maxillofacial diagnosis and preimplant assessment, were compared: CBCT reformatted panoramic images (I-CAT; Imaging Sciences, Hatfield, PA), direct (charge-coupled device-based) panoramic radiographs (DIMAX; Planmeca, Helsinki, Finland), and digital panoramic radiographs based on a storage phosphor system (DENOPTIX; Gendex, Chicago, IL). We used 3 independent groups of images (40 in each group) from patients examined by one of the above imaging modalities over a period of 6 months. In total, 68 randomly selected mandibular canals (out of a possible 80) per imaging modality were evaluated. Four experienced raters evaluated the images of each modality in 3 sessions under standardized conditions for clarity in the visualization of the mandibular canal in 3 locations, using a 4-point scale.

RESULTS

The CBCT reformatted panoramic images outperformed the digital panoramic images in the identification of the mandibular canal.

CONCLUSIONS

Due to the fact that the CBCT images were reformatted slices of the maxilla and mandible, they were free of magnification, superimposition of neighboring structures, and other problems inherent to panoramic radiology. This may result in very clear images that better depict the mandibular canal.

Comparison of diagnostic accuracy of film and digital tomograms for assessment of morphological changes in the TMJ

OBJECTIVE

To compare diagnostic accuracy of tomograms obtained with film and three digital image receptor modalities for detection of morphological changes in the temporomandibular joint (TMJ).

METHODS

Lateral and frontal cross-sectional tomograms of 158 TMJs in 80 dry human skulls were obtained with four X-ray receptors: one conventional film (Agfa-Gevaert), two photostimulable phosphor (PSP) plates: VistaScan and Digora PCT and one charge-coupled device (CCD): ProMax. The film and the PSP plate tomograms were exposed in a Cranex Tome X-ray unit and the CCD tomograms in the ProMax X-ray unit. The tomograms were examined by three observers for the presence of morphological changes in the condyle, the mandibular fossa and the articular tubercle. Naked-eye inspection of the articular surfaces of the TMJs performed by the same three observers served as the gold standard for the true presence of morphological changes.

RESULTS

For examination of TMJ changes using lateral and frontal tomograms in combination and lateral tomograms separately, the ProMax modality obtained a significant lower diagnostic accuracy than the other three modalities, between which no significant differences were found. For morphological changes localized to the condyle in which the highest number of changes were present according to the gold standard, the same result was found.

CONCLUSION

The ProMax modality was significantly less accurate than the film, VistaScan and Digora PCT modalities for the detection of overall TMJ morphological bone changes as well as condylar bone changes.

Filmless imaging

BACKGROUND

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

OVERVIEW

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

CONCLUSIONS AND CLINICAL IMPLICATIONS

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

Accuracy of digital panoramic images displayed on monitor, glossy paper, and film for assessment of mandibular third molars

OBJECTIVE

The aim of this study was to compare the accuracy of 3 modalities of digital panoramic radiographs-monitor-displayed images and printed copies on glossy paper and on blue transparent film-for assessment of position and morphology of mandibular third molars.

STUDY DESIGN

164 third molars were recorded with one of 2 digital panoramic systems (Digora and Orthophos Plus) and assessed by 4 observers on 3 radiographic modalities: monitor display, glossy paper, and transparent film. The assessments were compared with surgeons' findings at the time of the operation ("gold standard").

RESULTS

Overall, the observer variation was larger than the variation between methods. A detailed paired analysis revealed some differences between the modalities for some diagnostic categories, but these were few and inconsistent.

CONCLUSION

Printed images from the Kodak 1200 ink-jet printer on glossy paper and blue transparent film may be as accurate as the original monitor-displayed digital panoramic images from the Digora and Orthophos Plus systems for assessment of position and morphology of mandibular third molars.

Mandibular third molar removal: Risk indicators for extended operation time, postoperative pain, and complications

OBJECTIVES

The aim of this study was to identify risk indicators for extended operation time and postoperative complications after removal of mandibular third molars.

STUDY DESIGN

There were 388 molars included in the study. The teeth were removed using the buccal approach under local anesthesia. Four hours postoperatively the patient recorded his or her pain perception on a visual analogue scale (VAS). After surgery a surgeon recorded parameters regarding the tooth and if the mandibular nerve had been visible during the operation. One week postoperatively the postoperative pain and complications were recorded. Logistic regression models were made to identify risk indicators for extended operation time, postoperative pain, and complications.

RESULTS

Females were at higher risk for postoperative pain and dry socket than males. Older patients were at higher risk for extended operation time than younger patients. Radiographically fully impacted molars increased the risk of postoperative general infection. If the nerve was visible during surgery there was a higher risk of a high VAS score, postoperative pain, and general infection than if the nerve had not been visible.

CONCLUSION

Several indicators were found to increase the risk of postoperative complications, but a visible alveolar inferior nerve during the operation was repeatedly found to be the highest single risk indicator.

Accuracy of digital and film panoramic radiographs for assessment of position and morphology of mandibular third molars and prevalence of dental anomalies and pathologies

OBJECTIVES

To compare the accuracy of digital and film panoramic radiographs for determining (1) the position and morphology of mandibular third molars before surgical removal and (2) the prevalence of dental anomalies and pathologies.

METHODS

Three hundred and eighty-eight third mandibular molars were available for examination. Position and morphology of third molars observed on film radiographs and on digital panoramic images from five systems (DenOptix, DigiDent, Digora, Dimax2 and Orthophos Plus) were recorded by two observers and were compared with surgeons' findings at the time of the operation (gold standard). One observer further recorded the prevalence of dental anomalies and pathologies on both imaging modalities.

RESULTS

Few differences were found between the digital and film-based panoramic systems in the assessment of accuracy of position and morphology of mandibular third molars. The prevalence of dental anomalies and pathologies determined with the two modalities was roughly similar.

CONCLUSION

The five digital panoramic systems evaluated in this study were equally as useful for third molar treatment planning and diagnosis of dental anomalies and pathologies as conventional film-based panoramic radiographs.