Do voxel size and filter application on CBCT images improve the diagnosis of condylar morphological alterations? An ex vivo study.

BACKGROUND: There is no established protocol for the low doses of cone-beam computed tomography (CBCT) acquisition and filter application on the diagnosis of condylar morphological alterations. OBJECTIVES: The objective of the study was to evaluate the influence of voxel size and filter application on the diagnosis of condylar morphological alterations in CBCT using an ex vivo model. METHODS: CBCT scans of 36 temporomandibular joints were acquired using OP300 Maxio with voxel sizes of 0.085, 0.125 and 0.280 mm. Three radiologists evaluated the condyles in the CBCT volumes under three filter modes: no filter, '1x' sharpen filter and '2x' sharpen filter. The area under the ROC curve, sensitivity and specificity were calculated by comparing the evaluators' responses with the reference standard and compared among experimental groups using analysis of variance (ANOVA) (α = 5%). RESULTS: The area under the ROC curve, sensitivity and specificity were not affected by voxel size and filter application (p > .05). For osteophyte and flattening, there were more true-positive responses in smaller voxel size. For erosion, the increase of true- and false-positive responses occurred with a larger voxel size. Overall, there was a tendency to decrease true positives for osteophyte and erosion and increase false positives for flattening with the '2x' sharpen filter. CONCLUSIONS: The diagnosis of condylar morphological alterations assessed in this ex vivo analysis is not influenced by the voxel size and the application of the filters. However, attention is needed with the occurrence of false-positive diagnosis with a larger voxel size for erosion and '2x' sharpen filter for flattening.

Effect of metal artefact reduction level on the assessment of dental implant positioning by cone-beam computed tomography.

OBJECTIVES: This study evaluated the effect of metal artefact reduction (MAR) level and tube current on the assessment of dental implant positioning relative to the mandibular canal (MC) through cone-beam computed tomography (CBCT). METHODS: Titanium dental implants were placed in dried mandibles at 0.5-mm superior to the MC (group 1/n = 8) and 0.5-mm inside the MC with perforation of the cortex (group 2/n = 10). CBCT scans were obtained with different levels of MAR (off, medium, and high) and 2 tube currents (4 and 8 mA). Four examiners analysed the images and scored the contact between the implant and the MC using a 5-point scale. Sensitivity, specificity, area under receiver operating characteristic curve (ROC), and frequency of scores were calculated. Data were compared with analysis of variance 2-way and Tukey's test and scores with Chi-square test. RESULTS: Specificity and area under ROC curve decreased significantly when MAR level was high compared with MAR-medium and MAR-off. The frequency of score 3 (inconclusive) was the highest, and scores 1 and 5 (definitely no contact and definitely contact, respectively) were the lowest with MAR-high, regardless of the tube current. When MAR was off, there were higher frequencies of scores 1 and 5. CONCLUSIONS: The level of MAR influences the assessment of the relationship between the dental implant and the MC. MAR-high led to lower diagnostic accuracy compared with MAR-medium and off. ADVANCES IN KNOWLEDGE: This article shows that high level of MAR can interfere in the diagnostic of dental implant positioning relative to the MC, decreasing its accuracy.

Identification and classification of pulp calcifications in posterior teeth according to dental condition using digital panoramic radiography and cone beam CT.

OBJECTIVE: To compare digital panoramic radiography (DPR) and cone beam CT (CBCT) in the detection and classification of pulp calcifications in posterior teeth in relation to tooth condition and its location. METHODS: Two hundred and fifty patients with simultaneous DPR and CBCT scans were selected from a dental image bank. For each posterior tooth, its condition was registered (healthy, restored, or decayed). The presence of calcifications was assessed and classified according to location (coronal or radicular) and type (total obliteration, partial obliteration, narrowing, and no calcification). Chi-square and McNemar tests were used to compare DPR and CBCT results, with a significance level of 5%. DPR diagnostic values were calculated using CBCT as reference. RESULTS: Decayed and restored teeth showed a significantly (P < .001) higher prevalence of pulp calcifications than healthy teeth in both imaging exams. There was a significant discrepancy between the imaging modalities in the identification of calcifications (P < .001), especially for radicular calcifications of maxillary teeth (DPR = 55.2%; CBCT = 30.9%). In the case of coronal calcifications, there was a greater discrepancy between CBCT and DPR in the mandibular teeth (10.7%) than in the maxillary teeth (7.7%). Overall, DPR presents higher sensitivity (0.855) than specificity (0.483) for pulp calcifications detection. CONCLUSION: DPR considerably overestimates pulp calcifications in posterior teeth, as compared to CBCT. A higher prevalence of pulp calcifications is related to decayed and restored teeth.

Radiographic perception of anatomical structures and bony changes in oncologic patients under antiresorptive therapy.

PURPOSE: To assess radiographic presentation of anatomical structures, bony changes and soft tissue calcifications on panoramic radiographs of oncologic patients under high dose antiresorptive drug therapy (ART) before exposure to dental extraction. METHODS: Panoramic radiographs of 57 patients under ART, taken previously to tooth extraction, and 57 control patients were evaluated by two oral radiologists regarding bone pattern, anatomical structures visibility, estimation of cortical width, mandibular cortical index (MCI), and presence of soft tissue calcifications. Parameters were compared between ART and age- and gender-matched healthy control groups. Bone patterns were further assessed by regions with or without tooth extractions and according to uneventful healing or MRONJ development. All comparisons were made using chi-square test with significance level set at 5%. RESULTS: Mandible and posterior maxilla presented more sclerotic bone patterns in patients under ART, regardless of tooth extraction and MRONJ development status (p < 0.05). Heterogeneous bone pattern was identified in two regions that both were subsequently affected by MRONJ. Anatomical structure visibility and presence of soft tissue calcifications was not different among groups (p > 0.05). ART patients showed significantly more C0 (thickening) and C1 MCI (p < 0.05). CONCLUSION: Sclerotic bone pattern and thicker mandibular cortices may represent a consequence of ART rather than MRONJ specific findings. Prospective studies on larger patient samples radiographically followed-up during the ART treatment are advised, with specific attention to heterogenous trabecular bone pattern as a possible MRONJ predictor.

Local radiographic risk factors for MRONJ in osteoporotic patients undergoing tooth extraction.

OBJECTIVE: To identify local radiographic risk factors for Medication-Related Osteonecrosis of the Jaws (MRONJ) in osteoporotic patients treated with antiresorptive drugs (ARD) and undergoing tooth extraction. MATERIAL AND METHODS: Patients were included in this retrospective, longitudinal, case-control study, if having at least one administration of ARD, underwent tooth extraction(s), and had pre- and post-operative panoramic radiographs. Additionally, a matched control group was selected. Three calibrated, blinded, and independent observers assessed each tooth extraction site. Statistical analysis compared control against study group, and within the latter, sites MRONJ+ and MRONJ-. RESULTS: In total, 120 patients (99 females/21 males) with 354 tooth extractions were included, from which nine patients (7.5%) and eleven tooth extraction sites (3.1%) developed MRONJ. When comparing control with study group, the latter showed significantly more thickened lamina dura, persistence of the alveolar socket, heterogeneous bone patterns, and sequestrum formation. In the study group, MRONJ developed significantly more in males (19%, p = 0.049), smokers (25%, p = 0.008), in the mandible (82%, p = 0.027), when identifying a radiolucent or sclerotic trabecular pattern (p = 0.004) or when extracting teeth with furcation involvement (p < 0.001), root remnants (p = 0.017), or unrestored caries lesions (p = 0.005). CONCLUSIONS: Tooth extraction sites showing radiographic signs of chronic dental infection are prone to MRONJ.

Do cone-beam computed tomography low-dose protocols affect the evaluation of the temporomandibular joint?

BACKGROUND: There is no established acquisition protocol based on scientific evidence for the acquisition of cone-beam computed tomography (CBCT) exams to evaluate the temporomandibular joint (TMJ). OBJECTIVES: To evaluate the influence of acquisition protocols and jaw positioning on the diagnostic accuracy of TMJ condylar morphological alterations (CMA), dimension, position and excursion. METHODS: Thirty-six TMJs on 18 dry skulls were imaged using a CBCT unit (OP300 Maxio, Instrumentarium, Tuusula, Finland) at two exposure settings (4.5 and 6.3 mA), three voxel resolutions (0.085, 0.125 and 0.280 mm), three jaw positions (concentric, anteriorised and posteriorised) and three jaw excursions (normoexcursion, hyperexcursion and hypoexcursion). The macroscopic anatomy examination and high-resolution CBCT images were used as ground truth for CMA. Twenty-five TMJs had at least one CMA with 11 healthy TMJs serving as controls. Three experienced oral and maxillofacial radiologists evaluated the parasagittal images for the presence of CMA, position and excursion and measured dimensions. The area under the ROC curve, sensitivity and specificity were calculated. Weighted Kappa (α = 0.05) was used to determine intra- and interexaminer reliability and comparisons between dependent variables analysed by Analysis of Variance at an a prior level of significance of 0.05. RESULTS: The agreement of the evaluation of the position and excursion with the reference standard was high, independent of the protocol (range, 0.75-0.91). Various combinations of acquisition protocols and jaw position did not influence the CMA evaluation. Erosion was overdiagnosed in protocols with larger voxel sizes and the detection of osteophytes greater in images with smaller voxel sizes. The anteroposterior dimension was greater in the open jaw position (p < .05). CONCLUSION: CBCT protocols using reduced radiation exposure from the CBCT machine evaluated in this study can be used to assess condylar morphology, dimension, position and excursion, without compromising diagnostic performances for these parameters.

Automatic exposure compensation in intraoral digital radiography: effect on the gray values of dental tissues.

BACKGROUND: This study aimed to investigate the effect of automatic exposure compensation (AEC) of intraoral radiographic systems on the gray values of dental tissues in images acquired with or without high-density material in the exposed region using different exposure times and kilovoltages. The influence of the distance of the high-density material was also investigated. METHODS: Radiographs from the molar region of two mandibles were obtained using the RVG 6100 and the Express systems, operating at 60 and 70 kV and 0.06, 0.10, and 0.16 s. Subsequently, a titanium implant was inserted in the premolar's socket and other images were acquired. Using the ImageJ software, two regions of interest were determined on the enamel, coronary dentine, root dentine, and pulp of the first and second molars to obtain their gray values. RESULTS: In the RVG 6100, the implant did not affect the gray values (p > 0.05); the increase in kV decreased it in all tissues (p < 0.05), and the exposure time affected only the root dentine and pulp. In the Express, only enamel and coronary dentine values changed (p < 0.05), decreasing with the implant presence and/or with the increase in exposure factors. The distance of the implant did not affect the results (p > 0.05). CONCLUSIONS: AEC's performance varies between the radiographic systems. Its effect on the gray values depends not only on the presence or absence of high-density material but also on the kV and exposure time used.

Do anatomical variations of the mandibular canal pose an increased risk of inferior alveolar nerve injury after third molar removal?

OBJECTIVES: The present study aimed to assess whether anatomical variations of the mandibular canal are associated with neurosensory disturbances of the inferior alveolar nerve (IAN) following mandibular third molar removal. METHODS: Two observers compared the detection of third molar root-nerve relations and bifurcations of the mandibular canal on panoramic radiographs and CBCT images of 201 patients undergoing removal of 357 mandibular third molars. Potential neurosensory disturbances of the IAN were surveyed ten days after surgery. Fisher's Exact was performed to correlate presence of canal variations to postoperative neurosensory disturbances. Positive and negative predictive values (PPV, NPV) and likelihood ratios (LR + , LR-) were calculated. RESULTS: Thirteen patients reported postoperative altered sensation of the lower lip, with 2 of them having mandibular canal bifurcations on the ipsilateral side of the injury. Fisher's Exact showed that the studied mandibular canal variations were not related to postoperative neurosensory disturbances. CBCT was superior in visualization of anatomical variations of the mandibular canal. Prevalence of bifurcations was 14% on CBCT and 7% on panoramic radiographs. In both imaging modalities and for all parameters, PPVs were low (0.04 - 0.06) and NPVs were high (0.92 - 0.98), with LR ranging around 1. CONCLUSION: In the present study, the assessed mandibular canal variations had limited predictive value for IAN neurosensory disturbances following third molar removal. CLINICAL RELEVANCE: While a close relation between the third molar and the mandibular canal remains a high risk factor, mandibular canal variations did not pose an increased risk of postoperative IAN injury after third molar removal.

The impact of digital filters on the diagnosis of simulated root resorptions in digital radiographic systems.

OBJECTIVES: To evaluate the influence of digital filters of intraoral radiographic systems on the diagnosis of simulated internal and external root resorptions and image quality. MATERIALS AND METHODS: Internal root resorption (IRR) and external root resorption (ERR) were simulated in 34 teeth. For image acquisition, two radiographic systems were used: Digora Toto and VistaScan. All filters available in these systems were applied. Three observers scored the detection of root resorptions in a 5-point scale. The noise and the contrast-to-noise ratio (CNR) were calculated. The area under ROC curve, sensitivity, specificity, and accuracy were obtained. One-way ANOVA with Tukey's post hoc tests compared the diagnostic values, noise, and CNR between the filters (α = 0.05). RESULTS: For ERR, there were no significant differences in diagnostic values between the filters tested for both systems. For IRR, Original and Noise Reduction filters presented higher sensitivity than the Sharpen2 filter for images from Digora Toto, with no differences between the other groups. For VistaScan, there were no significant differences of diagnostic values between the groups studied. Noise values differed among the filters of both systems. The CNR of the filters differed only for the bone region for Digora Toto, while for VistaScan, both tooth and bone regions differed. CONCLUSIONS: Despite promoting changes in pixel intensities and affecting the noise level of the radiographic images, the digital filters of Digora Toto and VistaScan systems do not affect the diagnosis of internal or external root resorptions. CLINICAL RELEVANCE: Digital filters are common tools in digital radiographic systems and may be used by the professional without impairment in root resorptions diagnosis.

Imaging of the upper airway: which method is best for orthodontic assessment?

The objectives of the present study were to compare measurements of pharyngeal airway subregions on lateral cephalometric (LC) and cone beam computed tomographic (CBCT) images in relation to skeletal classes and discuss the advantages and disadvantages of these imaging formats for this type of assessment. The CBCT images were assessed via both multiplanar reconstruction (MPR) and 3-dimensional (3D) reconstruction. The LC and CBCT images from 107 patients were classified according to skeletal class: I, n = 35; II, n = 35; and III, n = 37. Linear measurements of the subdivisions of the upper airway were performed on the LC, MPR, and 3D images. In addition, area and volumetric measurements were performed on the MPR images. The relationships among imaging methods, skeletal class, and pharyngeal thirds were assessed by means of a 1-way analysis of variance (α = 0.05). No statistically significant differences in the linear, area, or volumetric measurements of the upper airway subregions were found among the skeletal classes (P > 0.05). For the linear measurements in the oropharynx and hypopharynx, greater values were observed for the LC images than for the MPR and 3D images (P ≤ 0.05). Based on the study findings, MPR images should be preferred for visualization of the pharyngeal airway subregions. However, LC imaging is preferable to 3D reconstruction.

A new model of classification of third molars development and its correlation with chronological age in a Brazilian subpopulation.

The present study correlated the mineralization of third molars to chronological age using a modified classification based on Demirjian's stages in a Brazilian subpopulation and compared with the original classification. A total of 1082 patients with age ranging from 6 to 26 years were included in the sample, with at least one third molar on panoramic radiographs. The third molars were classified according to the original Demirjian classification (8 stages) and a new model based on the Demirjian method, where the original stages were grouped into four stages: AB-enamel mineralization; CD-crown dentin mineralization; EFG-root formation; and H-complete development. Statistical analyses were performed by Kruskal-Wallis/Dunn tests (α = 0.05) and the multinomial logistic regression model. Data were analyzed according to percentiles for the probability of an individual being over 18 years old. The mean ages of the stages in both classifications did not present a significant difference between superior and inferior arches (p < 0.05). The differences in mean ages between all the stages of mineralization were statistically significant (p < 0.001) only for the 4-stage classification. Males attained root formation and complete formation earlier than females (p < 0.05) in the 4-stage classification. The modified classification system showed dependence between chronological age and mineralization stages of third molars, simplifying the age estimation process. At stage H, females present a 95.7% chance of being over 18, while for males, this probability is 89.6%. This modified classification system simplifies the dental age estimation process based on third molars and can be used as a reference for future studies.

Osteomyelitis, osteoradionecrosis, or medication-related osteonecrosis of the jaws? Can CBCT enhance radiographic diagnosis?

OBJECTIVE: To attempt defining differential radiographic diagnostic characteristics for osteonecrotic lesions using 2D as opposed to 3D images. MATERIALS AND METHODS: This was a cross-sectional study. Subjects presenting mandibular osteonecrotic lesions (osteomyelitis, osteoradionecrosis, and medication-related osteonecrosis of the jaws) were selected and compared to a group of age- and gender-matched controls, all having both cone-beam computed tomographic images (CBCT) and panoramic radiographs (PANO). Both imaging modalities (predictor variables) were evaluated by two radiologists that scored lesion presence, eight additional radiological features, and a composite severity index (outcome variables). For each pathologic condition, characteristic features were assessed in PANO and CBCT by the Wilcoxon signed-rank test. Regression tree analysis revealed the predictive value of PANO and CBCT (α = 5%). RESULTS: Overall, the predictive value of PANO reached 74%, while for CBCT it became 90%. Regarding the composite severity index, CBCT enabled to detect more subtle lesions. Also, CBCT imaging allowed showing more distinct radiographic diagnostic features as compared to PANO imaging, more specifically when distinguishing osteomyelitis from both other lesions. CONCLUSIONS: Cone-beam computed tomography enabled showing more differences in radiological features between distinct osteonecrosis disease entities. CBCT imaging might be a better contributor for the detection of early lesions and to monitor further pathological developments in the mandible.

Influence of the image file format of digital periapical radiographs on the diagnosis of external and internal root resorptions.

OBJECTIVES: To evaluate the influence of different image file formats of digital radiographic images on the diagnosis of external (ERR) and internal root resorption (IRR). MATERIALS AND METHODS: Thirty-four human teeth were selected. For ERR, 20 teeth were used (10 control and 10 with simulated ERR), and for IRR, 14 teeth were used (before and after IRR simulation). Digital periapical radiographs were acquired using the Digora Toto system and exported in four different image file formats: TIFF, BMP, PNG, and JPEG, totaling 192 radiographs. Five examiners evaluated the images using the JPEGView software and scored the detection of ERR or IRR on a 5-point scale. Sensitivity, specificity, accuracy, and the area under the ROC curve were obtained for the diagnosis of ERR and IRR in the different image file formats. Two-way ANOVA compared the diagnostic values between the file formats and the Kappa test assessed intra- and inter-examiner agreement. The significance level was set at 5% (α = 0.05). RESULTS: The mean values of intra-examiner agreement were substantial (0.740) for ERR and almost perfect (0.836) for IRR and, inter-examiner was fair (0.263) and moderate (0.421), respectively. No statistically significant differences were found among the different file formats for the diagnostic values of ERR and IRR. CONCLUSION: The file format of digital radiographs does not influence the diagnosis of ERR and IRR. CLINICAL RELEVANCE: Digital radiographic images may be susceptible to computational factors; however, they can be stored in multiple file formats without affecting the diagnosis of dental root resorptions.

Artefacts at different distances from titanium and zirconia implants in cone-beam computed tomography: effect of tube current and metal artefact reduction.

OBJECTIVES: To evaluate the effect of cone-beam computed tomography (CBCT) tube current (mA) on the magnitude of artefacts at different distances from titanium or zirconia implants, with and without activation of a proprietary metal artefact reduction (MAR). MATERIAL AND METHODS: Human mandibles were scanned on an OP300 Maxio CBCT unit (Instrumentarium, Tuusula, Finland) before and after the installation of dental implants, with four different tube currents (4 mA, 6.3 mA, 8 mA and 10 mA), with and without activation of proprietary MAR. The effect of mA on the standard deviation (SD) of gray values and contrast to noise ratio (CNR) were assessed in regions of interest located 1.5 cm, 2.5 cm, and 3.5 cm from implants. RESULTS: In the presence of titanium implants, a significant decrease in SD was found by increasing tube current from 4 mA to 6.3 mA or 8 mA. For zirconia implants, 8 mA yielded better results for all distances. MAR improved CNR in the presence of zirconia implants at all distances, whereas no differences were observed with the use of MAR for titanium implants. CONCLUSION: Increased tube current can improve overall image quality in the presence of implants, at all the distances tested. When a zirconia implant is present, such increase in mA should be higher in comparison to that for examinations with titanium implants. Activation of OP300 Maxio proprietary MAR improved image quality only among examinations with zirconia implants. CLINICAL RELEVANCE: Artefact-generating implants are common in the field of view of CBCT examinations. Optimal exposure parameters, such as tube current, ensure high image quality with lowest possible radiation exposure.

Effect of digital enhancement on the radiographic assessment of vertical root fractures in the presence of different intracanal materials: an in vitro study.

OBJECTIVES: To evaluate the effect of enhancement tools of intraoral digital radiographs on the assessment of vertical root fracture (VRF) and to quantify the resultant image noise. MATERIALS AND METHODS: Thirty single-rooted human teeth (15 control and 15 fractured) were each radiographed in four intracanal conditions: no filling, gutta-percha, metal post, and fiberglass post, totaling 120 original images. Two filters were applied to the original images-Sharpen filter (SF) and Edge Enhancement filter (EE), and brightness and contrast were adjusted in four combinations (B&C1 to 4), resulting in 840 images. Five oral radiologists analyzed the images for VRF detection. Pixel intensity was obtained in two regions from the radiographs. Diagnostic values were calculated and compared by two-way ANOVA, and the SD values of pixel intensity values were compared by one-way ANOVA (α = 0.05). RESULTS: There were no significant differences in accuracy for VRF detection between the experimental groups (p > 0.05). Teeth with metal post presented the lowest sensitivity (p < 0.05) for all experimental conditions, except for SF and EE (p > 0.05). B&C2, B&C3, and B&C4 had higher specificity than SF (p ≤ 0.05) for all intracanal conditions. Analysis of pixel intensity showed that all enhanced images presented statistically significant higher noise compared to those of the original images (p ≤ 0.05). CONCLUSION: Digital enhancement tools in digital radiography increase image noise; however, they can be used without compromising VRF detection. CLINICAL RELEVANCE: The use of digital enhancement does not impair the detection of VRF and, therefore, can be applied for this purpose according to the observer preference.

Artificial intelligence-driven novel tool for tooth detection and segmentation on panoramic radiographs.

OBJECTIVE: To evaluate the performance of a new artificial intelligence (AI)-driven tool for tooth detection and segmentation on panoramic radiographs. MATERIALS AND METHODS: In total, 153 radiographs were collected. A dentomaxillofacial radiologist labeled and segmented each tooth, serving as the ground truth. Class-agnostic crops with one tooth resulted in 3576 training teeth. The AI-driven tool combined two deep convolutional neural networks with expert refinement. Accuracy of the system to detect and segment teeth was the primary outcome, time analysis secondary. The Kruskal-Wallis test was used to evaluate differences of performance metrics among teeth groups and different devices and chi-square test to verify associations among the amount of corrections, presence of false positive and false negative, and crown and root parts of teeth with potential AI misinterpretations. RESULTS: The system achieved a sensitivity of 98.9% and a precision of 99.6% for tooth detection. For segmenting teeth, lower canines presented best results with the following values for intersection over union, precision, recall, F1-score, and Hausdorff distances: 95.3%, 96.9%, 98.3%, 97.5%, and 7.9, respectively. Although still above 90%, segmentation results for both upper and lower molars were somewhat lower. The method showed a clinically significant reduction of 67% of the time consumed for the manual. CONCLUSIONS: The AI tool yielded a highly accurate and fast performance for detecting and segmenting teeth, faster than the ground truth alone. CLINICAL SIGNIFICANCE: An innovative clinical AI-driven tool showed a faster and more accurate performance to detect and segment teeth on panoramic radiographs compared with manual segmentation.

Do the number of basis images and metal artifact reduction affect the production of artifacts near and far from zirconium dental implants in CBCT?

OBJECTIVES: This study aimed to evaluate the influence of the number of basis images and the metal artifact reduction (MAR) tool on the production of artifacts near and far from a zirconium implant in cone-beam computed tomography (CBCT). MATERIALS AND METHODS: CBCT scans of a mandible were acquired before and after insertion of an implant, using 450 and 720 basis images, with and without MAR activation. The mean and standard deviation (SD) of the gray values of the regions of interest (ROIs) located on the cortices adjacent to the implant and at different distances from it (in the soft tissue) were calculated. The mean of the gray values was used to calculate the absolute contrast difference (ACD) between the control and implant scans. RESULTS: In general, the number of basis images did not affect the SD and the ACD values of the buccal and lingual ROIs (p > 0.05). The implant increased the SD in the lingual cortical plate (p < 0.05). In this case, MAR activation decreased SD (p < 0.05). All ROIs located at different distances from the implant showed higher SD on scans acquired with 450 basis images (p < 0.05), regardless of MAR condition. CONCLUSIONS: A higher number of basis images reduces the magnitude of artifacts but does not influence the image quality in bone cortical plates. MAR improves the image in the areas most affected by artifacts. CLINICAL RELEVANCE: The number of basis images is known as a factor capable of influencing the image quality and radiation dose for the patient. Therefore, it is important to investigate its effect on the expression of artifacts in the CBCT images.

Early imaging signs of the use of antiresorptive medication and MRONJ: a systematic review.

OBJECTIVE: The main aim is to identify, by means of different imaging modalities, the early bone changes in patients "at risk" and in stage 0 MRONJ. MATERIALS AND METHODS: A search of the literature was performed on PubMed, Embase, Web of Science, and Cochrane Library databases, until June 9, 2020. No language or year restrictions were applied. Screening of the articles, data collection, and qualitative analysis was done. The Newcastle-Ottawa Scale (NOS) was used for observational studies, and the Systematic Review Centre for Laboratory Animal Experimentation's (SYRCLE) risk of bias tool for the animal studies. RESULTS: A total of 1188 articles were found, from which 47 were considered eligible, whereas 42 were suitable for the qualitative analysis. They correspond to 39 human studies and 8 animal studies. Radiographic findings such as bone sclerosis, osteolytic areas, thickening of lamina dura, persisting alveolar socket, periapical radiolucency, thicker mandibular cortex, widening of the periodontal ligament space, periodontal bone loss, and enhancement of the mandibular canal were identified as early bone changes due to antiresorptive therapy. All those findings were also reported later in Stage 0 patients. CONCLUSION: The main limitations of these results are the lack of prospective data and comparisons groups; therefore, careful interpretation should be made. It is a fact that radiographic findings are present in antiresorptive-treated patients, but the precise timepoint of occurrence, their relation to the posology, and potential risk to develop MRONJ are not clear. CLINICAL RELEVANCE: The importance of a baseline radiographic diagnosis for antiresorptive-treated patients.

Retrospective assessment of dental implant-related perforations of relevant anatomical structures and inadequate spacing between implants/teeth using cone-beam computed tomography.

OBJECTIVES: To assess the prevalence of dental implant-related perforations of relevant anatomical structures and inadequate spacing between the implant and the adjacent tooth or implant, and their association with anatomical location, implant dimension, thread exposure, and presence of graft, using cone beam computed tomography (CBCT). MATERIALS AND METHODS: CBCT scans of patients with implants were retrospectively assessed regarding the presence of implant-related perforation of adjacent anatomical structures, and inadequate mesial and distal spacing between the implant and the adjacent tooth/implant (i.e., < 1 mm or < 3 mm, respectively). Implants were classified according to anatomical location, dimensions, thread exposure, and the presence of graft (i.e., bone graft or bone substitutes). Prevalence of perforations and inadequate spacing was compared among the different implant classifications (Chi-squared test). Significance level was set at 5%. RESULTS: A total of 1109 implants were assessed, out of which 369 (33.3%) presented perforation of adjacent structures. Prevalence of perforations in the maxilla (43.5%) was higher than in the mandible (11.3%). Inadequate spacing was found in 18.2% of the mesial and distal measurements, which was more prevalent in the maxilla (p < 0.001). Implants perforating adjacent structures or placed with inadequate spacing presented higher prevalence of thread exposure (p < 0.001). No significant difference was found between the presence of perforations or inadequate spacing and presence of graft (p > 0.05). CONCLUSIONS: Implant-related perforations of relevant anatomical structures and inadequate spacing between the implant and the adjacent tooth/implant are relatively prevalent and more common in the maxilla. Both are associated with threads exposure. CLINICAL RELEVANCE: Information on dental implant-related perforations and inadequate spacing can assist dental surgeons in pre-surgical planning.

Is Panoramic Imaging Equivalent to Cone-Beam Computed Tomography for Classifying Impacted Lower Third Molars?

PURPOSE: Preoperative recognition of the relative position of the mandibular third molars may contribute to more reliable treatment planning, avoiding injuries and decreasing surgical and recovery times. The research questions for this study were as follows: 1) Is panoramic radiography (PR) equivalent to cone-beam computed tomography (CBCT) in determining the degree of mandibular third molar impaction? 2) For PR, is the external oblique ridge a more reliable reference to determine the degree of mandibular third molar impaction? MATERIALS AND METHODS: This retrospective case-series study assessed whether the imaging modalities (primary predictor variable) are equivalent in determining the degree of impaction of third molars (primary outcome variable) according to the parameters of the Pell and Gregory classification. Two oral and maxillofacial radiologists evaluated PR and CBCT images presenting at least 1 mandibular third molar. The degrees of impaction related to the ascending ramus and related to the external oblique ridge (secondary outcome variables) also were assessed. The agreement rates between PR and CBCT were presented, and the imaging modalities were compared by the McNemar-Bowker test (α = .05). RESULTS: A total of 173 patients were included (66 male and 107 female patients). Among these patients, 313 mandibular third molars were assessed. In relation to the occlusal plane, the agreement rate between PR and CBCT was 82.1% for Pell and Gregory class A, 90.5% for class B, and 65.6% for class C (P = .116). The overall agreement rate between the classifications in relation to the mandibular ramus on PR and CBCT ranged from 66.8% (considering the ascending ramus, P < .001) to 76.4% (considering the external oblique ridge, P < .001). CONCLUSIONS: PR performs similarly to CBCT in the classification of impaction in relation to the occlusal plane. However, PR shows a tendency to underestimate the space for accommodation of the third molar compared with CBCT. Furthermore, the external oblique ridge is not a reliable alternative landmark on PR.