Efficacy of digital intra-oral radiography in clinical dentistry

New Technique for Wedge Selection in Direct Class II Restorations: A Pilot Study

Background: Performing an appropriate Class II direct restoration is a great challenge. The correct selection of the matrix system and the elements used for its stabilization will have a great impact on the result. The aim of this study is to show a new digital method for a predictable selection of the wedge and compare it with the conventional method. Methods: Sixty patients were randomly divided into two groups. In Group 0, the wedge was selected intraoperatively by visual examination, while in Group 1 the wedge was selected preoperatively through the measurement of the cervical embrasure on the bite-wing radiography. The number of wedges used, modifications to them, and tissue damage were registered, along with the quality of the proximal contact and the marginal adaptation. Results: Student's t-test revealed a statistical difference between the number of wedges used, which was higher in Group 0 (p < 0.05). Pearson Chi-square test showed that tissue damage was statistically higher in Group 0 (p < 0.05), while there was no statistically significant difference between groups in wedge modifications (p > 0.05). Group 1 revealed a higher frequency of satisfactory proximal contact and marginal adaptation (p < 0.05). Conclusions: This new technique reduces wedges waste and tissue damage and provides an adequate interproximal anatomy.

Bibliometric Analysis of Context, Trends, and Contents of Digital Health Technology Used in Dental Health

Digital tools and apps are revolutionizing healthcare and provide creative answers to urgent problems. Through teamwork and the incorporation of digital technologies, dentistry has experienced a remarkable revolution. A large body of scholarly research backs up this trend. The context, trends, and content of digital health technology in oral and dental health are examined in our bibliometric analysis. Using targeted keywords and synonyms, an organized searching technique was used in the Scopus database, yielding 1942 articles that were extracted into a CSV file. To acquire insights into the content, trends, and context, visualization using VOSviewer 1.6.18 and a variety of analyses-including coauthorship, citation, cooccurrence of author keywords, bibliographic coupling, and cocitation-were executed. The analysis revealed that the USA and the UK contributed to a significant quantity of the literature, with newer contributions coming from nations like India. Cone Beam Computed Tomography, Dental Caries, and Artificial Intelligence were prominent keywords. It is important to note that BMC Oral Health was associated with a sizable number of the papers. This bibliometric analysis provides insightful information about the context, content, and trends of digital health in the field of oral and dental health. By implementing the right technology, policymakers can use this information to increase oral health, encourage dental literacy, and improve access to dental treatment. It is vital to take into account the wide variety of technologies and their classifications based on dental services and contextual variables.

Efficacy of a smartphone application as an aid to enhance the instruction of radiographic differential diagnosis of maxillofacial bony lesions

OBJECTIVES

The purpose of this study was to assess the efficacy of a smartphone application for instruction of radiographic differential diagnosis of maxillofacial bony lesions as an aid to enhance to traditional learning (lecture-based learning) for dental students.

METHODS

This quasi-experimental study evaluated 50 fifth-year dental students who were randomly divided into two groups. The two groups were matched in terms of grade point average to ensure their equal baseline knowledge level. The experimental group (n = 25) received instructions regarding differential diagnosis of maxillofacial bony lesions via a self-designed smartphone application, while the control group (n = 25) received lecture-based instruction of the same topic. The students participated in a written exam (10 questions) immediately and 2 months after the interventions. Each question had 3 differential diagnosis choices. The best answer choice was allocated a score of 0.5, while other answer choices were allocated a score of 0.25. Data were analyzed using repeated measures ANOVA, and Mann-Whitney U and Wilcoxon tests.

RESULTS

The mean score of the experimental group was significantly higher than that of the control group immediately after the intervention (p < 0.001) and also at 2 months (p < 0.001). The mixed effect linear model revealed that after controlling for the effect of age and sex, the mean score of the experimental group was still significantly higher than that of the control group immediately and at 2 months after the intervention (p < 0.001).

CONCLUSIONS

Smartphone-based mobile learning can effectively enhance the knowledge and practical skills of dental students in differential diagnosis of maxillofacial bony lesions as an aid to enhance to traditional learning.

Evaluation of the radiopacity of restorative materials with different structures and thicknesses using a digital radiography system

Purpose

The aim of this study was to evaluate the radiopacities of various types of restorative materials with different thicknesses compared with enamel, dentin, and aluminum.

Materials and Methods

Four bulk-fill resins, 2 hybrid ceramics, 2 micro-hybrid resin composites, 6 glass ionomer-based materials, 2 zinc phosphate cements, and an amalgam were used in the study. Twelve disk-shaped specimens were prepared from each of 17 restorative materials with thicknesses of 1 mm, 2 mm, and 4 mm (n=4). All the restorative material specimens with the same thickness, an aluminum (Al) step wedge, and enamel and dentin specimens were positioned on a phosphor storage plate and exposed using a dental X-ray unit. The mean gray values were measured on digital images and converted to equivalent Al thicknesses. Statistical analyses were performed using 2-way analysis of variance and the Bonferroni post hoc test (P<0.05).

Results

Radiopacity was significantly affected by both the thickness and the material type (P<0.05). GCP Glass Fill had the lowest radiopacity value for samples of 1 mm thickness, while Vita Enamic had the lowest radiopacity value for 2-mm-thick and 4-mm-thick samples. The materials with the highest radiopacity values after the amalgam were zinc phosphate cements.

Conclusion

Significant differences were observed in the radiopacities of restorative materials with different thicknesses. Radiopacity was affected by both the material type and thickness.

Evaluation of radiopacities of CAD/CAM restorative materials and resin cements by digital radiography

OBJECTIVE

This study aims to compare the radiopacities of computer-aided design/computer-aided manufacture (CAD/CAM) blocks and the adhesive cements used for their bonding.

MATERIALS AND METHODS

1 ± 0.2 mm thick specimens were obtained from six different CAD/CAM blocks (Incoris TZI, IPS e.max CAD, Vita Mark II, Cerasmart, Vita Enamic, and Vita Suprinity), four different adhesive resin cements (Panavia F2.0, Variolink Esthetic DC, RelyX Unicem Aplicap, G-CEM LinkAce), and a tooth. Radiographs of the specimens from each group, a tooth section, and an aluminum (Al) step-wedge were acquired. The radiopacity values of the materials were calculated as equivalents of Al thickness using the gray level values. The data were statistically analyzed using one-way ANOVA and Tukey HSD tests.

RESULTS

All the materials except Cerasmart and Vita Enamic had significantly higher radiopacity values than dentin (p < 0.05). Of the assessed blocks, the highest radiopacity value was observed in Incoris TZI, and the lowest radiopacity value was observed in Vita Enamic. Variolink Esthetic DC and RelyX Unicem Aplicap showed significantly higher radiopacity (p < 0.05) than the other adhesive cements, including enamel and dentin.

CONCLUSIONS

In this study, the majority of the CAD/CAM materials and all the adhesive resin cements were found to have sufficient radiopacity for prosthetic restorations according to the criteria set by the International Organization for Standardization (ISO).

CLINICAL RELEVANCE

From a clinical and biological point of view, materials should be chosen according to their radiopacity and other properties, such as biocompatibility and esthetics. If the selected restorative CAD/CAM blocks have a radiopacity value less than or equal to dentin, cements with higher radiopacity values are recommended to facilitate radiological diagnoses for periphery and interface of restorations.

Dental Diagnosis and Treatment Assessments: Between X-rays Radiography and Optical Coherence Tomography

A correct diagnosis in dental medicine is typically provided only after clinical and radiological evaluations. They are also required for treatment assessments. The aim of this study is to establish the boundaries from which a modern, although established, imaging technique, Optical Coherence Tomography (OCT), is more suitable than the common X-ray radiography to assess dental issues and treatments. The most common methods for daily-basis clinical imaging are utilized in this study for extracted teeth (but also for other dental samples and materials), i.e., panoramic, intraoral radiography, and three-dimensional (3D) cone beam computed tomography (CBCT). The advantages of using OCT as an imaging method in dentistry are discussed, with a focus on its superior image resolution. Drawbacks related to its limited penetration depth and Field-of-View (FOV) are pointed out. High-quality radiological investigations are performed, measurements are done, and data collected. The same teeth and samples are also imaged (mostly) with an in-house developed Swept Source (SS)-OCT system, Master-Slave enhanced. Some of the OCT investigations employed two other in-house developed OCT systems, Spectral Domain (SD) and Time Domain (TD). Dedicated toolbars from Romexis software (Planmeca, Helsinki, Finland) are used to perform measurements using both radiography and OCT. Clinical conclusions are drawn from the investigations. Upsides and downsides of the two medical imaging techniques are concluded for each type of considered diagnosis. For treatment assessments, it is concluded that OCT is more appropriate than radiography in all applications, except bone-related investigations and periodontitis that demand data from higher-penetration depths than possible with the current level of OCT technology.

Observer preference for a dedicated medical display vs a standard screen in the detection of dental radioanatomic features

OBJECTIVE

The aim of this study was to assess observers' preference for a dentomaxillofacial dedicated medical display (MD) vs a general-purpose standard screen (SS) for in vitro and in vivo observation of normal radioanatomic features.

STUDY DESIGN

The in vitro sample consisted of 2-dimensional (2-D) intraoral (n = 15), panoramic (n = 2), cephalometric (n = 2), and 3-dimensional (3-D) cone beam computed tomography (CBCT) (n = 9) data sets, acquired by utilizing commercially available skull and head-and-neck phantoms. The in vivo sample consisted of 80 radiographs (intraoral = 20; panoramic = 20; cephalometric = 20; and CBCT = 20). In vitro and in vivo data sets were both acquired by using Minray, Promax2-D, and Vistapano Ceph for 2-D images and Accuitomo, NewTom VGi evo, and Promax3-D for CBCT images. Five observers entered screen preferences when evaluating the appearance of radioanatomic structures on MD and SS.

RESULTS

Both in vitro and in vivo assessments showed good interobserver and excellent intraobserver agreement. In vitro data suggested a significant preference for MD over SS for viewing radioanatomic features on panoramic and CBCT images, whereas MD was significantly preferred for in vivo images of all imaging modalities (P < .001).

CONCLUSIONS

Overall, observers preferred MD over SS for both in vitro and in vivo observation of normal radioanatomic features irrespective of the imaging modality.

Evaluation of Radiopacity of Luting Cements Submitted to Different Aging Procedures

PURPOSE

To evaluate the radiopacity of luting cements submitted to different aging procedures.

MATERIALS AND METHODS

Twenty discs (1 × 4 mm) of each of the following cements were prepared: zinc phosphate, RelyX Luting 2, Variolink 2, AllCem, RelyX U200, Multilink, Panavia F2.0, and RelyX ARC. Then, they were randomly divided into two groups (n = 10/group), according to the aging procedure: thermal cycling group and water storage group. Before and after aging procedures, specimens were x-rayed with an aluminum step-wedge (11 steps, 1 mm thick each) and three dental slices (1 mm thick). The radiopacity was evaluated by means of optical density, which was measured using ImageJ software. The values were converted into millimeters of aluminum with a logistic regression calibration curve. The data were analyzed by one-way ANOVA and Tukey post-hoc test (α = 0.05).

RESULTS

In the thermal cycling group, RelyX Luting 2, RelyX U200, and Panavia F2.0 showed a statistically significant reduction in radiopacity (p < 0.05). In the water storage group, all cements showed a significant reduction in radiopacity (p < 0.05), and RelyX Luting 2 and Panavia F2.0 performed below the desired ISO 4049 standard.

CONCLUSIONS

The radiopacity of luting cements can decrease after aging, especially after 1-year water storage.

The Effects of Imaging Enhancement Tools in the Detection of Horizontal Root Fractures

INTRODUCTION

Detection of root fracture is challenging both clinically and radiographically. Root fractures occur in different planes with unpredictable presentations.

AIM

The aim of the study was to evaluate the diagnostic accuracy of selected digital image enhancement tools in the detection of horizontal Root Fracture (RF).

MATERIALS AND METHODS

Fifty three roots, of single and multi-rooted teeth, in eight dentate human cadaver mandibles were selected for this study. Following minimally traumatic extraction of the teeth, horizontal fractures were induced in 23 roots and remounted in the empty sockets of their respective human dry mandibles. The remaining teeth with no fractures were used as the control group. Twenty two periapical radiographs were obtained by using the paralleling technique and using Complementary Metal Oxide Semiconductor (CMOS). Image J software was used to enhance the original images with the Inversion (IN), Histogram-Equalization (EQ) and Polynomial (Poly) tools. A total of 88 periapical images (original and three enhanced images) were reviewed independently by three Oral and Maxillofacial Radiologists and two Endodontists. Receiver Operating Characteristic (ROC) curve analysis was used to evaluate the accuracy of fracture detection and the kappa statistic was used to assess agreement among reviewers.

RESULTS

The diagnostic accuracy for one of the observers was significantly different in detection of RF with only EQ enhancement tool. Sensitivity and specificity were not significantly different. Interobserver agreement showed no significant difference between imaging methods. Intra-observer agreement was high to moderate.

CONCLUSION

There was no significant difference between the different imaging modalities. No statistical difference for the agreement was found among or between the endodontists and radiologists in this study.

Radiopacity of Resin Cements Using Digital Radiography

STATEMENT OF PROBLEM

Monitoring performance of glass-ceramic based indirect restorations using radiographic imaging might be difficult due to their low radiopacity. Therefore, materials used for their cementation must possess adequate radiopacity.

PURPOSE

This study determined radiopacity of a group of resin-cements used for adhesive-cementation of glass-ceramic-based restorations using digital radiography.

METHODS

Two specimens were prepared from a group of resin cements (VariolinkII-opaque, VariolinkII-opaque (base), VariolinkII-Transparent, VariolinkII-Transparent (base), Nexus, RelyX Unicem, RelyX ultimate, Duolink, Monocem and Resinomer) and longitudinal sections of same thickness were obtained from molar and premolar. Specimens were assigned to two groups one had molar section with 10 specimens whereas other had premolar with remaining 10 specimens. Each group was placed on digital radiograph sensor (Schick CDR, size 2) together with aluminum step-wedge. Sensor was exposed to X-ray using standard technique. Two images were obtained for each group. Pixel measurements were made using NIH Image-J software. Mean pixel measurements were converted into aluminum thickness equivalents. Data were statistically-analyzed using one-way ANOVA and Tukey's tests.

RESULTS

ANOVA revealed significant difference in mean pixel values among cements (p < 0.001). VariolinkII-opaque showed highest mean aluminum equivalent (4.6 mm Al/1 mm) followed by VariolinkII-opaque-Base (4.5 mm Al/1 mm), VariolinkII-transparent (4.45 mm Al/1 mm), VariolinkII-transparent-Base (4.45 mm Al/1 mm), Nexus (2.95 mm Al/1 mm), Duolink (2.7 mm Al/1 mm), RelyX Unicem (2.2 mm Al/1 mm) and finally RelyX ultimate (2 mm Al/1 mm). All cements had mean radiopacity values higher than that of enamel whereas Monocem (1.25 mm Al/1 mm) and Resinomer (1.2 mm Al/1 mm) had means between those of enamel and dentin.

CONCLUSIONS

All tested resin-cements showed radiopacity values higher than that of dentin which is adequate for diagnostic purposes according to ISO recommendation.

CLINICAL SIGNIFICANCE

The use of resin cement with adequate radiopacity for adhesive cementation of glass-ceramic based restorations enables their radiographic monitoring. (J Esthet Restor Dent 29:215-221, 2017).

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

OBJECTIVES

Radiographic images suffer from varying amounts of noise. The most studied and discussed of these is random noise. However, recent research has shown that the projected anatomy contributes substantially to noise, especially when detecting low-contrast objects in the images. Our aim, therefore, was to evaluate the extent to which overprojected anatomical noise affects the detection of low-contrast objects in intra-oral images.

METHODS

Our study used four common sensor models. With each sensor, we took four series of images, three series with and one series without an anatomical phantom present. In each series, we exposed a low-contrast phantom at 18 different exposure times using a standardized method. 4 observers evaluated all 288 images.

RESULTS

The low-contrast characteristics differed substantially when imaging low contrast on a homogeneous background compared with imaging low contrast when an anatomical phantom was present. For three of the sensors, optimal exposure times for low-contrast imaging were found, while the fourth sensor displayed a completely different behaviour.

CONCLUSIONS

Calibrating the low-contrast properties of an imaging system using low-contrast objects on a homogeneous background is not recommended. On an anatomical background, low-contrast properties are completely different, and these will mimic the clinical situation much more closely, directing the operator how to best use the system. There is a clear demand for further research on this subject.

Evaluation of the Radiopacities of Bulk-fill RestorativesUsing Two Digital Radiography Systems

This study investigated the radiopacity values of bulk-fill restoratives by using two digital radiography systems. Nine bulk-fill restoratives and a conventional composite were used in the study. Six disc-shaped specimens were prepared from each of these materials, three each at thicknesses of 1 mm and 2 mm, and tooth slices with these same thicknesses were obtained. As a control, an aluminum step wedge varying in thickness from 0.5 to 10 mm in was used. Three specimens of each of the materials, together with the tooth slice and the aluminum step wedge, were placed over a complementary metal oxide semiconductor (CMOS) sensor and a storage photostimulable phosphor (PPS) plate system and exposed using a dental x-ray unit. The images were analyzed using a software program to measure the mean gray values (MGVs). Five measurements were obtained from each of the restorative materials, the enamel, the dentin, and the stepwedge. The MGVs were converted to the equivalent aluminum thicknesses. Three-way analysis of variance (ANOVA) was used to determine the significance of the differences among the groups. A Tukey test was applied for pairwise comparisons (p&lt;0.05). All composite-based restoratives were found to have greater radiopacities than enamel or dentin. Equia Fil had the lowest radiopacity value. Radiopacity increased as the thicknesses of the restorative material increased. The CMOS system showed significantly higher radiopacity values than the PSP system. In conclusion, all investigated bulk-fill restoratives passed the International Organization for Standardization and American National Standard Institute/American Dental Association requirements for radiopacity values when evaluated with the two digital radiography systems.

Stationary intraoral digital tomosynthesis using a carbon nanotube X-ray source array

OBJECTIVES

Intraoral dental tomosynthesis and closely related tuned-aperture CT (TACT) are low-dose three-dimensional (3D) imaging modalities that have shown improved detection of multiple dental diseases. Clinical interest in implementing these technologies waned owing to their time-consuming nature. Recently developed carbon nanotube (CNT) X-ray sources allow rapid multi-image acquisition without mechanical motion, making tomosynthesis a clinically viable technique. The objective of this investigation was to evaluate the feasibility of and produce high-quality images from a digital tomosynthesis system employing CNT X-ray technology.

METHODS

A test-bed stationary intraoral tomosynthesis unit was constructed using a CNT X-ray source array and a digital intraoral sensor. The source-to-image distance was modified to make the system comparable in image resolution to current two-dimensional intraoral radiography imaging systems. Anthropomorphic phantoms containing teeth with simulated and real caries lesions were imaged using a dose comparable to D-speed film dose with a rectangular collimation. Images were reconstructed and analysed.

RESULTS

Tomosynthesis images of the phantom and teeth specimen demonstrated perceived image quality equivalent or superior to standard digital images with the added benefit of 3D information. The ability to "scroll" through slices in a buccal-lingual direction significantly improved visualization of anatomical details. In addition, the subjective visibility of dental caries was increased.

CONCLUSIONS

Feasibility of the stationary intraoral tomosynthesis is demonstrated. The results show clinical promise and suitability for more robust observer and clinical studies.

Analysis of the reproducibility of the gray values and noise of a direct digital radiography system

The aim of this study was to evaluate the reproducibility of the gray values and noise of a direct digital radiography system (Visualix eHD) for various exposure times and analyzed regions. To obtain radiographic images in a standardized manner, the digital sensor of the system and a stepwedge were positioned in a phantom at a focus-film distance of 30 cm in a dental device at 70 kV, 7 mA and 2.2 mm filtration. Ten consecutive repetitions of X-ray imaging were performed at each exposure time (0.05, 0.07, 0.09 and 0.13 s). Gray values were analyzed using ImageJ software in five regions of interest (ROIs): alveolar bone (AB), soft tissue (ST) and three steps of the stepwedge (S1, S2 and S3). The results showed that both the variability of the gray values and the noise were statistically greater (p < 0.05) in the most radiolucent region (ST). Only the noise was affected by the exposure time. In conclusion, the reproducibility of the gray values and the noise of the Visualix eHD system can vary in specific areas with different radiolucency.

A method of determining the presence of blood in and on a dental needle after the administration of local anesthetic

BACKGROUND

In the study reported in this article, the authors aimed to demonstrate the presence of blood on the surface and in the lumen of two gauges of dental needles after administration of local anesthetic (LA) by using three LA-administering techniques normally used for the extraction of teeth.

METHODS

The authors obtained standardized photographs of 200 urine dipsticks after moistening the dipstick's chemical pads for blood with the first drop of liquid discharged from the needle lumen after LA administration. Using the histogram function of a software program, the authors analyzed differences in gray-scale values of the different blood parameters for the presence of blood. They used luminol spray to expose small quantities of blood on the surface of the needle after LA administration.

RESULTS

Blood was identified at 39 percent in the lumen and at 16 percent on the surface of the needles when analyzed after LA administration.

CONCLUSIONS

With the method used, it was possible to demonstrate and quantify the percentage of blood present in the lumen of needles (39 percent) after the administration of dental LA. Furthermore, the technique was adequately sensitive for demonstrating the quantity of blood in two needles of different diameters.

PRACTICAL IMPLICATIONS

By demonstrating the presence, as well as quantifying the percentage, of blood on two dental needles of different gauges after the administration of LA, dental health care workers can be motivated to report needlestick injuries and to follow the approved protocols recommended by their institutions.

A Subjective Assessment of Perceived Clarity of Indirect Digital Images and Processed Digital Images with Conventional Intra-oral Periapical Radiographs

OBJECTIVES

To compare and analyze the perceived clarity and diagnostic value of Conventional periapical Radiographs (CRs) with those of their Digitized Periapical Images (DIs) and Processed Digitized Periapical Images (PDIs) counterparts.

MATERIAL AND METHODS

Forty two intraoral periapical radiographs of patients with clinically suspected periapical pathosis were made to constitute the group of CRs. These were photographed by using a Canon Power Shot SD500 (7.1 Megapixel) digital camera and the unaltered images were transferred to a computer laptop, to form the group of DIs. Subsequently, the contrast and brightness of these images were modified to represent the group of PDIs. Two experienced oral radiologists independently evaluated 5 specific apical and periapical region parameters of all the 42 CRs, DIs and PDIs for perceived image quality and diagnostic value and graded them on a three point grading scale. Conventional radiographs served as the control. Data were analyzed by using paired t-test and Kappa analysis.

RESULTS

The clarity and diagnostic quality of the PDIs were statistically significant as compared to those of their conventional counterparts. In comparison, the DIs group fared badly, with deterioration of the image quality. The interobserver agreement was good and all the results were statistically significant.

CONCLUSION

Indirectly digitizing the radiographs by employing a digital camera and further digitally processing the images resulted in an improvement in their perceived clarity and they enhanced their diagnostic properties.

Study of the radio-opacity of base and liner dental materials using a digital radiography system

OBJECTIVES

This study investigated the radio-opacity of commercially available glass ionomer cements (GICs), flowable resin composites (FRCs) and calcium hydroxide cements (CHCs) and compared this with the radio-opacity of enamel, dentine and aluminium stepwedge. 16 GICs, 8 FRCs and 4 CHCs were analysed.

METHODS

Three sets of three samples were prepared: 1 mm, 2 mm and 3 mm thickness for GIC and FRC and 1 mm thickness for CHC. Specimens of enamel and dentine with the same thicknesses were obtained. As a control, an aluminium stepwedge was used. Radiographs were taken with a digital Kodak RVG 5000 (0.32 s, 30 cm). The images were analysed using the Image Tool(®) program (v. 2.00; The University of Texas Health Science Center, San Antonio, TV) to obtain the mean grey values.

RESULTS

Analysis of variance was used to investigate the significance of differences among the groups. For pairwise comparisons, the Tukey test was applied (p < 0.05). The GICs Ionomaster (Wilcos, Petrópolis, Brazil), Maxxion (FGM, Joinville, Brazil), Bioglass R (Biodinâmica, Ibiporã, Brazil), Bioglass F (Biodinâmica), Vidrion R (SS White, Rio de Janerio, Brazil) and Vidrion F (SS White), presented radio-opacity lower than that of dentine. All FRCs and CHCs studied showed radio-opacity higher than that of dentine. Vitro Fil (DFL, Rio de Janeiro, Brazil), Magic Glass (Vigodent, Rio de Janeiro, Brazil), Vitrebond (3M, Sumaré SP, Brazil), Riva Self Cure (SDI, Victoria, Australia), Riva Light Cure (SDI), Fill Magic (Vigodent), Opallis (FGM, Joinville, Brazil), Surefil SDR (Dentsply, Milford, DE), Tetric N (Ivoclar Vivadent, Schaan, Lichtenstein), Tetric (Ivoclar Vivadent), Hydro C (Dentsply, Petrópolis, Brazil), Hydcal (Technew, Madalena, Portugal) and Liner (Vigodent) showed radio-opacity similar to or greater than that of enamel for all thicknesses.

CONCLUSIONS

The increased thickness of the materials studied increases their radio-opacity. Some commercially available GICs used as a base and liner for restorations have a very low radio-opacity (Ionomaster, Maxxion, Bioglass R, Bioglass F, Vidrion R and Vidrion F).

Comparison of the delay in processing time and protective plastic cases in two phosphor plate systems

Objective. The purpose of this study was to analyze two phosphor plate systems (PSPs) (Dürr Dental, Digora Optime) according to their scanning delay and protective plastic case performances. Methods. Two PSPs using an aluminum step wedge were exposed. These plates were placed in three different protective plastic cases (manufacturers' original cases, black case, and white case) before obtaining the radiographs and were then processed immediately and 1, 5, 10, 30, 60, 120, 240, and 480 min after exposure. Mean gray values (MGVs) of the 3rd, 5th, 7th, and 9th steps of the wedges were compared using ANOVA. Results. Statistically significant differences were found between the two PSPs (P < 0.001). ANOVA revealed that the MGVs of four steps of the wedges were significantly different from each other for all scan delays (P < 0.001). MGVs increased with increasing scanning delay, except the group with Dürr plates in their original cases. Reduction in image quality began 5 min after exposure in the other Dürr plate groups. Conclusions. Within the limitations of the current study, it can be concluded that scanning delay causes a reduction in image quality, and using the manufacturer's original protective case will result in better performance of PSPs.

Film and digital periapical radiographs for the measurement of apical root shortening

Objectives: The aim of this study was to compare the accuracy and agreement of scanned film and digital periapical radiographs for the measurement of apical root shortening. Study design: Twenty-four film and digital [phosphor plate sensor (PPS)] periapical radiographs were taken using the long-cone paralleling technique for six extracted teeth before and after 1mm of apical root trimming. All teeth were mounted using a typodont and the radiographs were recorded using a film holder and polysiloxane occlusal index for each tooth to ensure standardization during the different radiographic exposures. The film radiographs were scanned and the tooth length measurements for the scanned film and digital (PPS) images were calculated using Image-J-Link 1.4 software (http://rebweb.nih.gov/ij/index.html) for the two groups. The accuracy and agreement among the tooth length measurements from each group and the true tooth length measurements were calculated using intra-class correlation (ICC) tests and Bland and Altman plots. Results: A high level of agreement was found between the true tooth length measurements and the scanned film measurements (ICC=0.979, limit of agreement 0.579 to -0.565) and the digital (PPS) radiograph measurements (ICC= 0.979, limit of agreement 0.596 to -0.763). Moreover, a high level of agreement was found between the scanned film and digital (PPS) radiographs for the measurement of tooth length ICC=0.991, limit of agreement 0.411-0.231. Conclusion: Film and digital (PPS) periapical radiographs are accurate methods for measuring apical root shortening with a high level of agreement.

Key words:Root shortening, measurement, periapical radiographs, film, digital.

Is there a role for the use of volumetric cone beam computed tomography in periodontics?

Volumetric computed cone beam tomography offers a number of significant advantages over conventional intraoral and extraoral panoramic radiography, as well as computed tomography. To date, periodontal diagnosis has relied heavily on the assessment of both intraoral radiographs and extraoral panoramic radiographs. With emerging technology in radiology there has been considerable interest in the role that volumetric cone beam computed tomography might play in periodontal diagnostics. This narrative reviews the current evidence and considers whether there is a role for volumetric cone beam computed tomography in periodontics.

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.

The usage of digital radiography and cone beam computed tomography among Turkish dentists

OBJECTIVES

The aim of this study was to determine the prevalence of the use of digital radiography and report how it was used by Turkish dentists.

METHODS

The survey was based on 383 dentists who were present at the sixteenth International Congress organized by the Turkish Dental Association. A questionnaire which consisted of 19 questions was given to the dentists who participated in the study. Data were assessed according to frequency distribution and the χ(2) test was used to determine the significance of differences between two independent groups.

RESULTS

376 questionnaires were analysed. The mean age of the dentists who participated in the study was 37.14 ± 9.6 years (range: 20-63 years). The distribution of the dentists according to the 7 regions of Turkey were: Marmara 58%, Aegean 13% and Mediterranean 10%, Central Anatolia 8%, Black Sea 7%, Southeastern Anatolia 3%, Eastern Anatolia 1%. 124 dentists (33%) said they did not work with digital radiography. 95 dentists indicated that they did not use digital radiography owing to cost (60%). 252 dentists (67%) said they used digital radiography. 40% of the participants noted that the repetition of periapical radiographs was due to digital radiography. 166 dentists (55.9%) and 79.1% academicians had knowledge about cone beam CT (CBCT).

CONCLUSION

Digital radiography users are increasing in Turkey and levels of knowledge of CBCT and awareness of radiation safety has also increased.

The effects of compression on the image quality of digital panoramic radiographs

Size reduction through compression is an important issue that needs to be investigated for possible effects on image quality. The aim of the present study was to evaluate the subjective image quality of digital panoramic radiographs which were lossless and lossy compressed for the visualization of various anatomical structures. Fifty-five digital panoramic radiographs in Tagged Image File Format (Tiff) were used in the study. Two types of lossy (Joint Photographic Experts Group (Jpeg)) and one type of lossless (Lempel-Ziv-Welch) compression were applied to the original radiographs. These radiographs were evaluated by two observers separately for the visibility of some anatomical structures with visual grading. Mean quality number for each radiograph was obtained. The differences between the mean quality numbers in each compression and original image mode were evaluated with Friedman test. Pair-wise comparisons revealed that there were statistically significant differences between all groups (p = 0.000) for all comparisons except for Jpeg_1 and Jpeg_2 groups. Kappa statistics was used to evaluate inter- and intra-observer agreements. Intra-observer agreements were ranging from 0.229 to 1.000 and inter-observer agreements were ranging from 0.154 to 1.000. The observers had better inter- and intra-observer agreements in highly compressed Jpeg_1 images. The anatomical structures evaluated in this study had better visibility in Tiff images than Jpeg images except for mandibular canal and mental foramen. While Jpeg compressed images offer high inter- and intra-observer agreements, the visibility of anatomical structures are better in Tiff images except for mandibular canal and mental foramen.

Radiodensity evaluation of dental impression materials in comparison to tooth structures

In the most recent decades, several developments have been made on impression materials' composition, but there are very few radiodensity studies in the literature. It is expected that an acceptable degree of radiodensity would enable the detection of small fragments left inside gingival sulcus or root canals.

Length of endodontic files measured in digital radiographs with and without noise-suppression filters: an ex-vivo study

OBJECTIVES

The aim of this study is to evaluate if theoretically possible edge shifts induced by noise-suppression filters potentially occur on objects found in digital radiographs. Most manufacturers carry out noise-suppression filtering of their images before they are displayed to the user. It is not usually possible for the user to disrupt the function of the filters. The use of these filters can lead to deletion of small image structures.

METHODS

K-files (ISO size 06, 08, 10 and 15) were placed in the root canals of 6 human teeth located in cadaver jaw segments. File tip positions were measured on original and filtered digital images by three observers. The file position was marked on each filtered image and compared with the unfiltered ones.

RESULTS

The 5 × 5 pixel-sized median and mean filters caused the largest underestimation of measured lengths between -7.87 pixels and -10.8 pixels (-306.93 μm and -421.2 μm). Maximum standard deviation for length differences was found for the calculated position ( = gold standard) and the original unfiltered images with 13.31 pixels. The standard deviation found for the 5 × 5 mean and median filter was 7.62 pixels and 8.68 pixels.

CONCLUSION

Different studies showed that noise-suppression filters can induce edge shifts in diagnostic radiographs. The high standard deviations found for length differences between the defined gold-standard and the original images indicate that theoretical edge shifts may not be clinically relevant for length measurements of endodontic files.

Effect of tube potential and image receptor on the detection of natural proximal caries in primary teeth

The aim of this study was to assess the detection of proximal caries in primary teeth at three different tube potentials using Ektaspeed films, storage phosphor plates (SPPs), and a charge-coupled device (CCD). Fifty-three extracted human primary molars with natural proximal caries were radiographed with three different imaging modalities--Digora Optime SPP system, RVGui CCD system, and Ektaspeed films--at 50-, 65-, and 70-kV tube potentials. Three observers scored the resultant images for the presence or absence of caries. The definitive diagnosis was determined by stereomicroscopic assessment. The diagnostic accuracy for each imaging modality was expressed as the area under the receiver operating characteristic curves (A(z)). Differences among the A(z) values were assessed using two-way ANOVA and t tests. Kappa was used to measure inter- and intra-observer agreement. Higher accuracy was found for SPPs compared to film and CCD images at all tube potentials. Accuracy was significantly different only at 50-kV tube setting in favor of SPPs (p < 0.05). Inter- and intra-observer agreement was high for all systems. A SPP system can be recommended for dental peadodontic clinics particularly with 50-kV tube potential for the diagnosis of proximal caries since further advantages include the elimination of chemical processing, image enhancement, and a better low-contrast detectability performance.

Relationship between radiation dose reduction and image quality change in photostimulable phosphor luminescence X-ray imaging systems

OBJECTIVES

The aim of the study was to clarify the change in image quality upon X-ray dose reduction and to re-analyse the possibility of X-ray dose reduction in photostimulable phosphor luminescence (PSPL) X-ray imaging systems. In addition, the study attempted to verify the usefulness of multiobjective frequency processing (MFP) and flexible noise control (FNC) for X-ray dose reduction.

METHODS

Three PSPL X-ray imaging systems were used in this study. Modulation transfer function (MTF), noise equivalent number of quanta (NEQ) and detective quantum efficiency (DQE) were evaluated to compare the basic physical performance of each system. Subjective visual evaluation of diagnostic ability for normal anatomical structures was performed. The NEQ, DQE and diagnostic ability were evaluated at base X-ray dose, and 1/3, 1/10 and 1/20 of the base X-ray dose.

RESULTS

The MTF of the systems did not differ significantly. The NEQ and DQE did not necessarily depend on the pixel size of the system. The images from all three systems had a higher diagnostic utility compared with conventional film images at the base and 1/3 X-ray doses. The subjective image quality was better at the base X-ray dose than at 1/3 of the base dose in all systems. The MFP and FNC-processed images had a higher diagnostic utility than the images without MFP and FNC.

CONCLUSIONS

The use of PSPL imaging systems may allow a reduction in the X-ray dose to one-third of that required for conventional film. It is suggested that MFP and FNC are useful for radiation dose reduction.

Work flow with digital intraoral radiography: a systematic review

OBJECTIVE

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Effectiveness of limited cone-beam computed tomography in the detection of horizontal root fracture

To compare the diagnostic accuracy of conventional film radiography, charge coupled device (CCD) and photostimulable phosphor plate (PSP) digital images and limited cone-beam computed tomography in detecting simulated horizontal root fracture. Root fractures were created in the horizontal plane in 18 teeth by a mechanical force and fragments were relocated. Another 18 intact teeth with no horizontal root fracture served as a control group. Thirty-six teeth were placed in the respective empty maxillary anterior sockets of a human dry skull in groups three by three. Intraoral radiographs were obtained in three different vertical views by utilizing Eastman Kodak E-speed film, CCD sensor, RVG 5.0 Trophy and a PSP sensor Digora, Optime. Cone beam CT images were taken with a unit (3D Accuitomo; J Morita MFG. Corp, Kyoto, Japan). Three dental radiologists separately examined the intraoral film, PSP, CCD and cone beam CT images for the presence of horizontal root fracture. Specificity and sensitivity for each radiographic technique were calculated. Kappa statistics was used for assessing the agreement between observers. Chi-square statistics was used to determine whether there were differences between the systems. Results were considered significant at P < 0.05. Cone beam CT images revealed significantly higher sensitivities (P < 0.05) than the intraoral systems between which no significant differences were found. Specificities did not show any statistically significant differences between any of the four systems. The kappa values for inter-observer agreement between observers (four pairs) ranged between 0.82-0.90 for the 3DX evaluations and between 0.63-0.71 for the different types of intraoral images. Limited cone beam CT, outperformed the two-dimensional intraoral, conventional as well as digital, radiographic methods in detecting simulated horizontal root fracture.

Comparison of digital with conventional radiography in detection of vertical root fractures in endodontically treated maxillary premolars: an ex vivo study

OBJECTIVE

The purpose of the present study was to compare the diagnostic ability of conventional intraoral film radiography and a charged-coupled device (CCD) sensor in detecting vertical root fractures (VRF) in endodontically treated single-rooted extracted human maxillary premolars.

STUDY DESIGN

The study consisted of 60 extracted single-rooted endodontically treated maxillary premolars: 30 with clinically confirmed VRF (experimental group) and 30 with no VRF (control group). An intraoral CCD sensor and conventional Kodak Insight Film were used. Two observers evaluated the digital and conventional radiographs twice with an interval of 4 weeks. Specificity and sensitivity for each radiographic technique were calculated and subjected to statistical analysis. Kappa values were calculated for intra- and interobserver agreement. Fisher's exact test was used to evaluate detection of VRF. The overall differences in sensitivity and specificity between radiographic techniques were evaluated by McNemar test.

RESULTS

The specificity of the digital system was significantly better (P = .016) for the second observer at the first reading. There were no significant differences in sensitivity and specificity for both observers between the 2 systems for other readings (P > .05).

CONCLUSIONS

No difference was found between the intraoral CCD sensor and conventional radiography in detecting vertical root fractures for single rooted maxillary premolars ex vivo.

In vitro analysis of the radiodensity of indirect composites and ceramic inlay systems and its influence on the detection of cement overhangs

The purpose of this study was to evaluate the radiodensity of indirect restorative systems and to determine its influence on detection of resin cement overhangs. Sixty sound molars with similar dimensions were selected, and MOD inlay preparations were made in a standardized fashion with 6 degrees taper of the walls. Restorations were made with a porcelain, Duceram LFC, and with three indirect composites, Solidex, Artglass, and Targis. Digital radiographic images were taken before and after cementation of the inlays (Digora system) and were analyzed on two regions, the cervical and the isthmus floor. Digital radiodensity measurements were performed on standardized points symmetrically distributed over each restoration and tooth structure. Cement overhangs were detected through visual analysis by three evaluators. Data were statistically analyzed utilizing ANOVA following Tukey's test (p < 0.05), showing that Solidex presented lower radiodensity than Duceram LFC, and both Artglass and Targis presented similar higher levels of radiodensity than the other groups. Radiodensity of cervical regions was always greater than for isthmus floor regions. Detection of the resin cement overhangs is easier observed on Solidex and Duceram LFC. Radiodensity is highly influenced by restorative material type and tooth regions. The detection of radiopaque resin cement overhangs is influenced by radiodensity of restorative materials.

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.

Effect of various digital processing algorithms on the measurement accuracy of endodontic file length

OBJECTIVE

The aim of this study was to compare the accuracy of endodontic file lengths after application of various image enhancement modalities.

STUDY DESIGN

Endodontic files of three different ISO sizes were inserted in 20 single-rooted extracted permanent mandibular premolar teeth and standardized images were obtained. Original digital images were then enhanced using five processing algorithms. Six evaluators measured the length of each file on each image. The measurements from each processing algorithm and each file size were compared using repeated measures ANOVA and Bonferroni tests (P = 0.05). Paired t test was performed to compare the measurements with the true lengths of the files (P = 0.05).

RESULTS

All of the processing algorithms provided significantly shorter measurements than the true length of each file size (P < 0.05). The threshold enhancement modality produced significantly higher mean error values (P < 0.05), while there was no significant difference among the other enhancement modalities (P > 0.05). Decrease in mean error value was observed with increasing file size (P < 0.05).

CONCLUSIONS

Invert, contrast/brightness and edge enhancement algorithms may be recommended for accurate file length measurements when utilizing storage phosphor plates.

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.

Lossy JPEG compression: easy to compress, hard to compare

OBJECTIVES

To review the literature on lossy compression in dental radiography and to discuss the importance and suitability of the methodology used for evaluation of image compression.

METHODS

A search of Medline (from 1966 to October 2004) was undertaken with the search expression "(Radiography, dental) and compression". Inclusion criterion was that the reference should be evaluating the effect of lossy image compression on diagnostic accuracy. For all included studies, information in relation to mode of image acquisition, image content, image compression, image display, and method of image evaluation was extracted.

RESULTS

12 out of 32 papers were included in the review. The design of these 12 studies was found to vary considerably. Parameters used to express the degree of information loss (DIL) were either or both compression ratio (CR) and compression level (CL). The highest acceptable CR reported in the studies ranged from 3.6% to 15.4%. Furthermore, different CR values were proposed even for the same diagnostic task, for example, for caries diagnosis CR ranged from 6.2% to 11.1%.

CONCLUSION

Lossy image compression can be used in clinical radiology if it does not conflict with national law. However, the acceptable DIL is difficult to express and standardize. CR is probably not suitable to express DIL, because it is image content dependent. CL is also probably not suitable to express DIL because of the lack of compression software standardization.

Ex vivo comparison of digital images with conventional radiographs for detection of simulated voids in root canal filling material

AIM

To compare the diagnostic potential of direct digital images with conventional radiographs for the detection of simulated root canal voids.

METHODOLOGY

The root canals of 80 extracted maxillary incisors with straight root canals were prepared and filled and the specimens divided into two groups: (i) a group of 40 teeth without voids; and, (ii) a group of 40 teeth with voids created in the root filling. Each root was imaged using the paralleling technique with a CCD-based digital system and F-speed film. Totally, there were 240 images: conventional radiographs (n = 80), digital images (n = 80) and digital zoomed images at 2x magnification (n = 80). These were interpreted for voids by a radiologist (without prior knowledge of the distribution of the voids). The reliability of the radiologist was confirmed using Cohen's Kappa Statistic, with the kappa value found to be >0.08. The sensitivity, specificity and predictive values were calculated. The differences in sensitivity and specificity between the imaging systems were then assessed using the Exact McNemar significance probability at the 95% significance level.

RESULTS

The sensitivities (95% CI) of conventional radiographs, digital images and zoomed images were 0.68 (0.57-0.78), 0.83 (0.74-0.91) and 0.80 (0.71-0.89), respectively. The specificities of the conventional radiographs, digital and zoomed images were 0.80 (0.71-0.89), 0.83 (0.74-0.91) and 0.83 (0.74-0.91), respectively. The positive predictive values (95% CI) were 0.77 (0.68-0.86), 0.83 (0.74-0.91) and 0.82 (0.74-0.90), respectively. The negative predictive values (95% CI) were 0.71 (0.61-0.81), 0.83 (0.74-0.91) and 0.80 (0.72-0.89), respectively. There were no significant differences between the sensitivity and specificity of digital images and conventional radiographs, and of digital images and zoomed images during the detection of voids in root fillings (P > 0.05).

CONCLUSIONS

Under the conditions of this laboratory study, the diagnostic performance of digital images and conventional radiographs, and between the digital images and digital zoomed images for simulated void detection in root fillings were not significantly different.

Radiodensity of base, liner and luting dental materials

The aim of this study was to determine the radiodensity of base, liner and luting dental materials and to compare them with human enamel and dentin. Four classes of materials were examined: conventional glass ionomers (CG)-Vitro Cem, Ketac Bond, Vidrion F, Vidrion C; resin-modified glass ionomers (RMGI)-Fuji II LC, Vitrebond; resinous cement (RC)-Rely-X ARC; and zinc phosphate cement (ZP)-Cimento LS. Five 2-mm-thick standard samples of each material and five 2-mm-thick enamel and dentin samples were produced. An aluminum step wedge served as control. Samples were positioned over a phosphor plate of Digora digital system, exposed to X-ray, and the radiodensity obtained in the software Digora for Windows 2.0. Data were submitted to Kruskal-Wallis and Dunnett multiple comparisons test (alpha=0.05). According to statistical analysis, the following sequence in degree of radiodensity could be seen among the groups: Cimento LS (ZP) > Vitro Cem (CG) = Fuji II LC (RMGI) = Rely-X ARC (RC) = Vitrebond (RMGI) > Ketac Bond (CG) > enamel = Vidrion F (CG) > Vidrion C (CG) = dentin. The presence of radiopaque fillers such as zinc, strontium, zirconium, barium, and lanthanium rather than material type seems to be the most important factor when analyzing material radiodensity. Almost all investigated materials presented an accepted radiodensity.