Effect of Mandible Phantom Inclination in the Axial Plane on Image Quality in the Presence of Implant Using Cone-Beam Computer Tomography.

Purpose To assess the effect of 30° phantom inclination on image quality in the presence of an implant using cone-beam computed tomography (CBCT). Materials and methods Three series of eight scans were taken and categorized by a range of 87-90 kVp and 7.1 mA, and 8 mA. For the first CBCT series, the phantom was placed on a flat plane. For the second series, the phantom was inclined at 30° in the axial plane. For the third series, inclined scans were re-oriented and included for statistics. In total, 24 scans were used for statistics. i.e., eight scans at three different planes (flat plane, inclined plane, and re-oriented inclined plane). All the images were analyzed for artifact and contrast-to-noise ratio (CNR) on ImageJ software. Results The inclination of the dry human mandible phantom by 30° reduces the artifact (p <0.05). However, the CNR was not affected by the phantom inclination. Conclusion The appropriate inclination of the head can significantly reduce the metal artifact in the presence of implants and thus improve the CBCT image quality for post-operative follow-up.

Assessing the Efficacy of Planmeca ProMax® 3D Cone-Beam CT Machine in the Detection of Root Fractures With Varied Metal Artifact Reduction Settings and Three Kilovoltage Peak Levels.

BACKGROUND: This study aims to examine the accuracy of cone-beam computed tomography (CBCT) machines in detecting root fracture when using different metal artifact reduction (MAR) settings at different kilovoltage peak (kVp) levels. METHODOLOGY: Sixty-six tooth roots were treated endodontically using a standardized technique. Of these, 33 roots were randomly selected to be fractured; the other 33 roots were intact and used as controls. The roots were placed randomly in prepared beef ribs to mimic the alveolar bone. Imaging was performed by Planmeca ProMax® 3D (Planmeca, Helsinki, Finland) using different MAR settings (no, low, mid, and high) at three different levels of kVp: 70, 80, and 90. Sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) were calculated. RESULTS: There was a significant difference in accuracy when using different MAR settings within the group of 70 kVp. Likewise, within the group of 90 kVp. There was no significant difference between different MAR settings at 80 kVp. Using low MAR/90 kVp had significantly higher accuracy relative to other MAR settings at 90 kVp; it also had the highest values of sensitivity, specificity, and AUC in the study. Using mid and high MAR at 70 kVp or 90 kVp decreased accuracy significantly. Mid MAR/90 kVp was the least effective setting in this study. CONCLUSIONS:  Using low MAR at 90 kVp significantly increased the accuracy within the group of 90 kVp. In contrast, mid MAR and high MAR in 70 and 90 kVp, respectively, decreased accuracy significantly.

Effect of a Motion Artifact Correction System on Cone-Beam Computed Tomography Image Characteristics.

OBJECTIVES: Determine the effect of the motion correction system on cone-beam computed tomography (CBCT) image quality parameters, artifacts, and contrast-to-noise ratio (CNR) using different motion settings. MATERIALS AND METHODS: A customized phantom insert array was prepared using SEDENTEX CT IQ Phantom (Leeds Test Objects, Yorkshire, England) stabilized over a rotating electric turntable. Thirty baseline CBCT scans were acquired with standardized technique factors on the ProMax 3D (Planmeca, Helsinki, Finland) machine using combinations of different motion settings, including no motion, three- and six-degree motion, and with and without the use of a motion correction system. The standardized images were exported to ImageJ software. Image quality parameters, artifacts, and CNR values were evaluated and compared among the different acquisition settings. RESULTS: The use of the motion correction system algorithm compared with the different motion settings showed a statistically significant difference for all the parameters (p<0.05) except for artifact values for six-degree motion (p<0.07). The effect of different motion settings on the parameters was not statistically significant. CONCLUSION: The use of a motion correction system, a proprietary algorithm-based system incorporated in the ProMax 3D CBCT unit, deteriorates the image quality characteristics evaluated in this in vitro study, namely artifact value and CNR. Its use in clinical settings might be limited to situations where patient motion is expected and appropriate head stabilization is not possible due to age or disease.

A comparison of panoramic radiographic findings in patients with familial adenomatous polyposis and the general population: a multicenter study.

OBJECTIVES: Familial adenomatous polyposis (FAP) is a hereditable disorder characterized by early and unremitting development of intestinal polyps and extraintestinal manifestations requiring multidisciplinary surveillance. Herein we describe a multicenter cross-sectional analysis of the dento-osseous radiographic findings of patients with FAP from North and South America. STUDY DESIGN: Groups I and II included individuals with FAP diagnosed by standard clinical criteria. Patients were paired with age- and sex-matched participants without FAP. Panoramic radiograph of both cohorts, including children and adults, were analyzed. RESULTS: Of 114 panoramic radiographs, 38 were from patients with FAP, composed of group I (n = 22) and group II (n = 16), and 76 were from matched control participants. Evaluators had excellent agreement on key findings (intraclass correlation coefficient = 0.89). The prevalence of osseous anomalies was higher in adults (75%) than in children (65.4%). Dental anomalies were also higher in children with FAP with a prevalence of 15.4%. CONCLUSIONS: We describe important and significant differences in the prevalence of dento-osseous anomalies in children compared with adult patients with FAP. These findings warrant careful consideration and may influence multidisciplinary management of the condition. Conversely, the presence of these abnormalities in pediatric dental patients even if not diagnosed with FAP should be borne in mind as possibly indicating de novo or unrecognized disease.

Wavelet Guided 3D Deep Model to improve Dental Microfracture Detection.

Epidemiological studies indicate that microfractures (cracks) are the third most common cause of tooth loss in industrialized countries. An undetected crack will continue to progress, often with significant pain, until the tooth is lost. Previous attempts to utilize cone beam computed tomography (CBCT) for detecting cracks in teeth had very limited success. We propose a model that detects cracked teeth in high resolution (hr) CBCT scans by combining signal enhancement with a deep CNNbased crack detection model. We perform experiments on a dataset of 45 ex-vivo human teeth with 31 cracked and 14 controls. We demonstrate that a model that combines classical wavelet-based features with a deep 3D CNN model can improve fractured tooth detection accuracy in both micro-Computed Tomography (ground truth) and hr-CBCT scans. The CNN model is trained to predict a probability map showing the most likely fractured regions. Based on this fracture probability map we detect the presence of fracture and are able to differentiate a fractured tooth from a control tooth. We compare these results to a 2D CNN-based approach and we show that our approach provides superior detection results. We also show that the proposed solution is able to outperform oral and maxillofacial radiologists in detecting fractures from the hr-CBCT scans. Early detection of cracks will lead to the design of more appropriate treatments and longer tooth retention.

Trends in oral and maxillofacial radiology career: A survey.

PURPOSE/OBJECTIVES: To understand the professional aspirations of oral and maxillofacial radiologists (OMRs) by exploring their career choices and their association with educational background, engagement in professional activities, professional values, and overall level of career satisfaction. METHODS: This prospective cross-sectional study surveyed board-certified OMRs in the United States and Canada from September to December 2019. A web-based questionnaire was created comprising 37 multiple-choice questions and an open-ended question focusing on their opinions regarding the profession's future. A thematic approach qualitatively explored open questions. RESULTS: Of the 86 OMRs, 68, 10, and eight were board certified in the United States, Canada, and both countries, respectively. Activities considered "rewarding" included teaching and mentoring (65%) and radiologic reporting (55%). The majority spent approximately 20-30 h/week writing radiographic reports and less than 10 h in research. On an average, OMRs produced 21.9 (SD 12.8) reports per day. Activities considered less rewarding included administrative work (11%) and productivity pressure in institutions. OMRs working in academia reported higher incomes (p < 0.05). Finally, the majority of the OMRs were pleased with their career choices (79%). CONCLUSIONS: There is an association between the contemporary OMRs' satisfaction feeling, teaching/mentoring, and the future challenges of participating in multidisciplinary teams. Overall, diverse career choices lead OMRs to be proud of their profession and significantly satisfied.

Assessment of the efficiency of a pre- versus post-acquisition metal artifact reduction algorithm in the presence of 3 different dental implant materials using multiple CBCT settings: An in vitro study.

PURPOSE: The aim of this study was to assess artifacts generated in cone-beam computed tomography (CBCT) of 3 types of dental implants using 3 metal artifact reduction (MAR) algorithm conditions (pre-acquisition MAR, postacquisition MAR, and no MAR), and 2 peak kilovoltage (kVp) settings. MATERIALS AND METHODS: Titanium-zirconium, titanium, and zirconium alloy implants were placed in a dry mandible. CBCT images were acquired using 84 and 90 kVp and at normal resolution for all 3 MAR conditions. The images were analyzed using ImageJ software (National Institutes of Health, Bethesda, MD) to calculate the intensity of artifacts for each combination of material and settings. A 3-factor analysis of variance model with up to 3-way interactions was used to determine whether there was a statistically significant difference in the mean intensity of artifacts associated with each factor. RESULTS: The analysis of all 3 MAR conditions showed that using no MAR resulted in substantially more severe artifacts than either of the 2 MAR algorithms for the 3 implant materials; however, there were no significant differences between pre- and post-acquisition MAR. The 90 kVp setting generated less intense artifacts on average than the 84 kVp setting. The titanium-zirconium alloy generated significantly less intense artifacts than zirconium. Titanium generated artifacts at an intermediate level relative to the other 2 implant materials, but was not statistically significantly different from either. CONCLUSION: This in vitro study suggests that artifacts can be minimized by using a titanium-zirconium alloy at the 90 kVp setting, with either MAR setting.

Trabecular and cortical mandibular bone investigation in familial adenomatous polyposis patients.

Mandibular cortical and trabecular bone abnormalities in patients with familial adenomatous polyposis (FAP) were evaluated using dental panoramic radiographs (DPR) radiomorphometric indices and fractal dimension (FD). Sixty DPRs from 15 FAP patients and 45 healthy controls were evaluated. FAP group was composed of 33.3% females and 66.6% males, agemean = 37.2 years (SD 15.79). The non-FAP group was paired by gender and sex. The parameters analyzed were: FD of the trabecular bone in four regions of interest (ROI), mandibular cortical index (MCI) and width (MCW). FD values were lower for the FAP group. Statistically significance differences were shown by ROI 2 and 3 anteriorly to the mental foramen bilaterally, p = 0.001, and p = 0.006. The ROI 1 and 4, at the mandibular angle trabeculae, indicated statistical significances on the right side (p = 0.036) and no differences on the left side (p = 0.091). There was no significant difference in MCI and MCW when the groups were compared, MCW (L) p = 0.247, and MCW (R) p = 0.070. Fractal values of FAP patients' mandibular trabecular bone were lower than healthy controls. The radiomorphometric indices MCI and MCW were not useful for analyzing the cortical bone pattern. Therefore, FD is a promising tool for detection of abnormal bone structure in DPRs and for supporting the appropriate referral of FAP patients.

Dental microfracture detection using wavelet features and machine learning.

Microfractures (cracks) are the third most common cause of tooth loss in industrialized countries. If they are not detected early, they continue to progress until the tooth is lost. Cone beam computed tomography (CBCT) has been used to detect microfractures, but has had very limited success. We propose an algorithm to detect cracked teeth that pairs high resolution (hr) CBCT scans with advanced image analysis and machine learning. First, microfractures were simulated in extracted human teeth (n=22). hr-CBCT and microCT scans of the fractured and control teeth (n=14) were obtained. Wavelet pyramid construction was used to generate a phase image of the Fourier transformed scan which were fed to a U-Net deep learning architecture that localizes the orientation and extent of the crack which yields slice-wise probability maps that indicate the presence of microfractures. We then examine the ratio of high-probability voxels to total tooth volume to determine the likelihood of cracks per tooth. In microCT and hr-CBCT scans, fractured teeth have higher numbers of such voxels compared to control teeth. The proposed analytical framework provides a novel way to quantify the structural breakdown of teeth, that was not possible before. Future work will expand our machine learning framework to 3D volumes, improve our feature extraction in hr-CBCT and clinically validate this model. Early detection of microfractures will lead to more appropriate treatment and longer tooth retention.

Intraoral Imaging in Dental Private Practice - A Rectangular Collimator Study.

OBJECTIVE: To gain a better understanding of the extent to which rectangular collimation is being used in private practice and the barriers to adoption by practitioners. METHODS: Licensed dentists in private practice were asked to answer a survey composed of 17 multiple-choice questions and 1 open-ended question regarding demographics, radiation safety, image receptor type, intraoral imaging techniques and use of rectangular collimation. RESULTS: Among all participants (n = 82), 86.6% used digital systems (n = 71) and 13.4% conventional film (n = 11). Most (74.0%, n = 60) were aware of the benefits of using rectangular collimation, with 5.5% reporting not knowing of the existence of this device (n = 3). Only 12.9% of the dentists reported using rectangular collimation routinely (n = 10). The youngest and oldest age groups had the lowest compliance rates, 5.6% and 0%, respectively. CONCLUSION: Although 74.0%, (n = 60) of private practitioners were aware of the benefits of using rectangular collimation to reduce radiation dose, only 12.2% (n = 10) used it routinely for intraoral imaging. Barriers to implementing rectangular collimation in private practice settings included challenges in training support staff and fear of an increase in the occurrence of technical errors that would result in re-exposure of patients.

Image-based Bone Density Classification Using Fractal Dimensions and Histological Analysis of Implant Recipient Site.

BACKGROUND: Success of dental implants is affected by the quality and density of the alveolar bone. These parameters are essential for implant stability and influence its load-bearing capacity. Their assessment is usually based on preoperative radiographs used as a tool prior to implant procedures. OBJECTIVE: The aim of the study was to compare the bone density of surgically harvested bone specimens at implant recipient sites in the maxillary and mandibular posterior region using histological analysis to the radiographic bone density using fractal dimension for reliability and determining an image based classification of bone density prior surgery. METHODS: Fifty implants were placed in the posterior region of male patients, (twenty five implants in the maxilla and twenty five in the mandible). The edentulous regions were presurgically assessed using Photo Stimulable Phosphor Plate (PSP) intra-oral radiographs and the fractal dimension box counting of region of interest was calculated at the implant recipient site. During surgery, bone core specimens were trephined, and bone densities and minerals parameters were evaluated based on histological analysis using SEM (Scanning Electron Microscopy), and atomic absorption spectrometry. RESULTS: Fractal dimensions (FD) values for the same region of interest (ROI) selected on the radiographs of bone blocks and edentulous sites were different but showed a proportional variation in molar and premolar region of the maxilla and mandible. Bone density results, calculated by the ratio of bone mass (BM) to the bone volume (BV) of the bone core specimen (D=M/V), increased in the mandibular bone blocks, and decreased in the maxilla specimens. Moreover, fractal dimension values of preoperative radiographs at implant recipient sites and bone density of trephined showed a statistically similar distribution. However, no significant difference was shown in the percentage of minerals contents and mass of calcium phosphate of each bone specimen between maxilla and mandible based on scanning electron microscopy analysis. Four types of bone densities were classified according to the distribution of FD values based on preoperative radiographs and on the densities of bone cores calculations. CONCLUSION: Radiographic estimation of bone quality calculated with fractal dimension could be a useful, non-invasive tool when using preoperative intra-oral radiographs to predict bone density at implant recipient sites with caution and limits concerning the kind of digital radiographs and size of region of interest, especially when these results were based with bone specimens harvested from implant site as an absolute reference.

Evaluation of artifacts generated by titanium, zirconium, and titanium-zirconium alloy dental implants on MRI, CT, and CBCT images: A phantom study.

OBJECTIVE: The aim of this study was to assess artifacts generated by zirconium, titanium, and titanium-zirconium alloy implants on magnetic resonance imaging(MRI), computed tomography(CT), and cone beam computed tomography(CBCT) and to correlate the findings to the dose-area product and exposure factors on CT and CBCT. STUDY DESIGN: Three phantoms were built by embedding zirconium, titanium, and titanium-zirconium implants in ultrasound gel. MRI, CT, and CBCT images were acquired by using multiple sequences and settings. For MRI, "artifact" was described as the length of signal void beyond the limits of the implant. For CT and CBCT, "artifact" was calculated by subtracting the gray level of the darkest pixel from the level of the lightest pixel. RESULTS: On MRI, zirconium implants had minor distortion artifacts, whereas titanium and titanium-zirconium implants created extensive artifacts (P < .05). On CT and CBCT, artifacts were less prominent with titanium and titanium-zirconium implants compared with zirconium (P < .05). Titanium grade 5 implants with 0.3 and 0.4 mm3 voxels produced the least severe artifacts. CONCLUSIONS: MRI images were less affected by artifacts from zirconium implants, whereas CT and CBCT images showed less severe artifacts from titanium and titanium-zirconium alloy implants. CT generated greater artifacts compared with CBCT. Larger CBCT voxel sizes reduced the dose-area product and the severity of artifacts.

MRI for Dental Applications.

Imaging of hard and soft tissue of the oral cavity is important for dentistry. However, medical computed tomography, cone beam computed tomography (CBCT), nor MRI enables soft and hard tissue imaging simultaneously. Some MRI sequences were shown to provide fast soft and hard tissue imaging of hydrogen, which increased the interest in dental MRI. Recently, MRI allowed direct visualization of cancellous bone, intraoral mucosa, and dental pulp despite that cortical bone and dental roots are indirectly visualized. MRI seems to be adequate for many indications that CBCT is currently used for: implant treatment and inflammatory diseases of the tooth.

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.

The effect of milliamperage, number of basis images, and export slice thickness on contrast-to-noise ratio and detection of mandibular canal on cone beam computed tomography scans: an in vitro study.

OBJECTIVES: The aim of this study was to evaluate the effect of milliamperage, number of basis images, and export slice thickness on contrast-to-noise ratio (CNR) and confidence in detecting mandibular canal. STUDY DESIGN: Two phantoms were used. Each phantom consisted of a dry mandible with an epoxy resin bone tissue substitute block and a water-equivalent block, submerged in water. Each mandible was scanned with a Morita 3D Accuitomo cone beam computed tomography (CBCT) machine (Morita, Kyoto, Japan). Scans were made with 180-degree and 360-degree rotations, at 4, 6, and 8 mA. Each scan was exported in Digital Imaging and Communications in Medicine (DICOM) format at slice thicknesses of 0.125 mm, 0.25 mm, 0.75 mm, and 1.0 mm, resulting in 24 image sets for each phantom. The CNR was calculated. Variables were analyzed using factorial analysis of variance. The scans were also evaluated by five observers who were asked to state their confidence in detecting the mandibular canal on a four-point confidence scale. RESULTS: Increasing the number of basis images, milliamperage, or export slice thickness significantly increased the CNR. Reducing the export slice thickness improved observers' confidence in detecting the mandibular canal. CONCLUSIONS: The CBCT acquisition settings should be carefully chosen, depending on specific diagnostic tasks. The lowest slice thickness equal to the voxel size should always be used for exporting CBCT data despite the higher noise.

Evaluation of a Mathematical Model for Digital Image Enhancement.

OBJECTIVE: The purpose of this study is to compare the detected number of holes on a stepwedge on images resulting from the application of the 5th degree polynomial model compared to the images resulting from the application of linear enhancement. Material and Methods : A 10-step aluminum step wedge with holes randomly drilled on each step was exposed with three different kVp and five exposure times per kVp on a Schick33(®) sensor. The images were enhanced by brightness/contrast adjustment, histogram equalization and with the 5th degree polynomial model and compared to the original non-enhanced images by six observers in two separate readings. Results : There was no significant difference between the readers and between the first and second reading. There was a significant three-factor interaction among Method, Exposure time, and kVp in detecting holes. The overall pattern was: "Poly" results in the highest counts, "Original" in the lowest counts, with "B/C" and "Equalized" intermediate. Conclusion : The 5th degree polynomial model showed more holes when compared to the other modalities.

Accuracy of digital periapical radiography and cone-beam computed tomography in detecting external root resorption.

PURPOSE: The purpose of this study was to evaluate and compare the efficacy of cone-beam computed tomography (CBCT) and digital intraoral radiography in diagnosing simulated small external root resorption cavities. MATERIALS AND METHODS: Cavities were drilled in 159 roots using a small spherical bur at different root levels and on all surfaces. The teeth were imaged both with intraoral digital radiography using image plates and with CBCT. Two sets of intraoral images were acquired per tooth: orthogonal (PA) which was the conventional periapical radiograph and mesioangulated (SET). Four readers were asked to rate their confidence level in detecting and locating the lesions. Receiver operating characteristic (ROC) analysis was performed to assess the accuracy of each modality in detecting the presence of lesions, the affected surface, and the affected level. Analysis of variation was used to compare the results and kappa analysis was used to evaluate interobserver agreement. RESULTS: A significant difference in the area under the ROC curves was found among the three modalities (P=0.0002), with CBCT (0.81) having a significantly higher value than PA (0.71) or SET (0.71). PA was slightly more accurate than SET, but the difference was not statistically significant. CBCT was also superior in locating the affected surface and level. CONCLUSION: CBCT has already proven its superiority in detecting multiple dental conditions, and this study shows it to likewise be superior in detecting and locating incipient external root resorption.

Detection of Class II caries on the iPad with Retina Display.

With the increasing use of digital radiography, the display parameters of the devices used to view radiographs have become important factors in caries detection. Interest in the use of tablet devices for this application has increased due to their availability, portability, and ease of use. However, to be effective in clinical situations, these portable devices must have displays that perform well under multiple lighting conditions and at different angles. The purpose of this study was to assess the utility of the iPad with Retina Display for the detection of Class II caries under common overhead lighting conditions. The device was used in both standing and angled positions by 5 reviewers, and their diagnoses of caries were compared to the diagnoses the same reviewers made using a thin-film transistor flat-panel display (TFT-FPD) in dim lighting conditions. Histological analysis was used as the gold standard to confirm the presence or absence of caries. In a standing position, the tablet device performed as well as the TFT-FPD. When used in the angled position, the tablet performed slightly worse than the TFT-FPD. The findings suggest that if the user can compensate for overhead glare, the tablet device may perform as well as a calibrated, upright display in a dimly lit room.