Optimization of orofacial cleft imaging protocols using device-specific low-dose cone-beam computed tomography.

OBJECTIVE: The aim of this study was to present optimized device-specific low-dose cone-beam computed tomography (CBCT) protocols with sufficient image quality for pre-surgical diagnostics and three-dimensional (3D) modelling of cleft defects. METHODS: Six paediatric skulls were acquired, and an artificial bony cleft was created. A high-resolution CBCT scan acted as a reference standard (Accuitomo 170, Morita, Kyoto, Japan) for comparing eight low-dose protocols of Newtom VGi-evo (QR Verona, Cefla, Verona, Italy), which included Eco and Regular protocols with different field of views (FOVs). Delineation of lamina dura, cementoenamel junction (CEJ), trabecular bone and bony bridge were assessed. A 3D model of the defect was also evaluated. RESULT: The dose area product of low-dose protocols ranged from 31 to 254 mGy*cm2. Despite the dose difference of up to eight times between applied protocols, trabecular bone and CEJ exhibited appropriate image quality in all scans. However, Regular small FOV protocols (5 × 5 and 8 × 5 cm2), for both lamina dura and bony bridge, demonstrated a significant improvement in image quality compared to Eco FOV counterparts. Based on 3D defect analysis, no significant difference existed between low-dose protocols and the reference standard. CONCLUSION: The findings highlight the possibility of achieving a considerable reduction (up to eight times) in the radiation dose using low-dose CBCT protocols while maintaining sufficient image quality for assessing anatomical structures and 3D modelling in cleft cases.

Key insights into antiresorptive drug use and osteonecrosis in osteoporotic patients undergoing tooth extractions: A clinical and CBCT assessment.

This study investigates the effects of antiresorptive drugs and risk factors for medication-related osteonecrosis of the jaws in osteoporotic patients undergoing tooth extraction. Among the findings, antiresorptive-treated patients had thicker lamina dura and longer healing times. Additionally, corticosteroid intake and multi-rooted teeth carried a higher osteonecrosis risk. Bone sequestrum indicated osteonecrosis. PURPOSE: To describe the effects of antiresorptive drugs (ARD) in the maxilla and mandible and risk factors for medication-related osteonecrosis of the jaws (MRONJ) in osteoporotic patients undergoing tooth extractions using clinical data and cone beam computed tomography (CBCT). METHODS: This retrospective cohort study collected clinical and CBCT data from 176 patients. The study group (n = 78; 224 extractions) received ARD treatment, underwent tooth extraction, and had a pre-operative CBCT. Additionally, age-, sex-, and tooth-matched controls were selected (n = 98; 227 extractions). Radiographic examinations were performed independently by three calibrated examiners. Statistical analysis included Chi-square, Fisher's exact, Mann-Whitney U, and t-tests to contrast clinical and radiographic data between study and control, MRONJ + and MRONJ - , and bisphosphonate and denosumab patients/sites. Significance was set at p ≤ 0.05. RESULTS: From the study group, 4 patients (5%) and 5 sites (2%) developed MRONJ after tooth extraction. ARD-treated patients exhibited significantly more thickening of the lamina dura and a longer average mucosal healing time (4.4 weeks) than controls (2.6 weeks). In the study group, MRONJ risk significantly increased with corticosteroid intake and in multi-rooted teeth. No significant differences between bisphosphonates and denosumab use were seen in the tomographic features (p > 0.05). Lastly, bone sequestrum was exclusively observed in osteoporotic patients, who exhibited post-operative exposed bone or histological evidence of osteonecrosis. CONCLUSION: Osteoporotic patients under ARD may exhibit thickening of the lamina dura and prolonged post-operative healing. Among these patients, multi-rooted teeth are at higher risk for MRONJ than single-rooted teeth. Sequester formation is a radiographic indicator of osteonecrosis.

Association between maxillary sinus floor perforation by dental implants and mucosal thickening: A cone-beam computed tomography study.

OBJECTIVE: To investigate the association of perforation of the maxillary sinus floor by dental implants with mucosal thickening and to describe its characteristics in perforated cases. STUDY DESIGN: One-hundred and twenty-nine maxillary sinuses of 93 patients presenting 202 dental implants in the maxillary posterior region were retrospectively assessed in cone-beam computed tomography scans and classified according to maxillary sinus perforation, bone graft, mucosal thickening, and mucosal appearance. Logistic regression determined the chance of mucosal thickening in perforated maxillary sinuses. The chi-square test compared categorical variables between maxillary sinus perforated or not by implants and maxillary sinus with or without mucosal thickening. The significance level assumed was 5 % (α = 0.05). RESULTS: There was perforation of 60 maxillary sinuses floor (46.5 %) by 74 dental implants. The chance of mucosal thickening was higher when the implant tip was trespassing on the maxillary sinus floor (p < 0.001). There was a significant association between maxillary sinus mucosal thickening and perforation by a dental implant with the tip trespassing the maxillary sinus floor (p < 0.05). CONCLUSION: Maxillary sinus mucosal thickening is associated with sinus floor perforation by dental implants and does not depend on the number of implants perforating it. CLINICAL RELEVANCE: There is an association between dental implants' perforation of the maxillary sinus floor and the thickening of the maxillary sinus. In those cases, the appearance of the mucosa thickening may be irregular, local, or total opacification of the sinus cavity.

Three-dimensional clinical assessment for MRONJ risk in oncologic patients following tooth extractions.

OBJECTIVES: To identify clinical and local radiographic predictors for medication-related osteonecrosis of the jaws (MRONJ) by the assessment of pre-operative CBCT images of oncologic patients treated with anti-resorptive drugs (ARDs) undergoing tooth extractions. METHODS: This retrospective, longitudinal, case-control study included clinical and imaging data of 97 patients, divided into study and control group. Patients in the study group (n = 47; 87 tooth extractions) had received at least one dose of ARD, undergone tooth extraction(s), and had a pre-operative CBCT. An age-, gender-, and tooth extraction-matched control group (n = 50; 106 tooth extractions) was selected. Three calibrated, blinded, and independent examiners evaluated each tooth extraction site. Statistical analysis used χ2/Fisher's exact/Mann-Whitney U test to contrast control and study group, ARD type used, and sites with or without MRONJ development. p-value ≤ 0.05 was considered significant. RESULTS: From the study group, 15 patients (32%) and 33 sites (38%) developed MRONJ after tooth extraction. When controls were compared to study sites, the latter showed significantly more thickening of the lamina dura, widened periodontal ligament space, osteosclerosis, osteolysis, and sequestrum formation. In the study group, MRONJ risk significantly increased in patients who had multiple tooth extractions, were smokers, and had shorter drug holidays. Periosteal reaction and sequestrum formation may indicate latent MRONJ lesions. Additionally, patients given bisphosphonates showed considerably more osteosclerosis than those given denosumab. CONCLUSIONS: Periosteal reaction and sequestrum formation are suspected to be pre-clinical MRONJ lesions. Furthermore, ARD induced bony changes and radiographic variations between ARD types were seen.

Influence of binarization methods on the fractal dimension of alveolar bone using digital radiographs.

OBJECTIVE: The aim of this study was to evaluate the influence of binarization methods (BnMs) on the fractal dimension (FD) of the alveolar bone in digital radiographic images. STUDY DESIGN: Five identical periapical radiographs were obtained from each of 20 anatomic regions. Using ImageJ/Fiji software, a standardized region of interest was positioned in the trabecular bone of all radiographs, 14 BnMs were independently applied, and FD was calculated. The Friedman test and Dunn post hoc tests were used to evaluate the influence of BnMs on FD (α = 0.05). The intraclass correlation coefficient (ICC) was used to assess correlation among BnMs. RESULTS: No significant differences were observed in the threshold value between the BnMs. No significant differences in FD were observed among 9 BnMs (Default, Huang, Iso Data, Li, Mean, Min Error[I], Moments, Otsu, and Shanbhag). These methods presented significantly higher FDs than those from 3 other BnMs (Max Entropy, Renyi Entropy, and Yen), which did not significantly differ from each other. The Triangle method significantly differed from all BnMs, and the Percentile method produced significantly higher FDs than Huang, IsoData, Li, Moments, Otsu, and Shanbhag. Most BnMs presented good or excellent correlation (ICC ≥ 0.76). CONCLUSIONS: Binarization methods influence FD of the alveolar bone from digital periapical radiographs; thus, this technical aspect is relevant for comparison purposes and should be standardized. For comparison of published FD research, the Default method is recommended.

Automated segmentation of the mandibular canal and its anterior loop by deep learning.

Accurate mandibular canal (MC) detection is crucial to avoid nerve injury during surgical procedures. Moreover, the anatomic complexity of the interforaminal region requires a precise delineation of anatomical variations such as the anterior loop (AL). Therefore, CBCT-based presurgical planning is recommended, even though anatomical variations and lack of MC cortication make canal delineation challenging. To overcome these limitations, artificial intelligence (AI) may aid presurgical MC delineation. In the present study, we aim to train and validate an AI-driven tool capable of performing accurate segmentation of the MC even in the presence of anatomical variation such as AL. Results achieved high accuracy metrics, with 0.997 of global accuracy for both MC with and without AL. The anterior and middle sections of the MC, where most surgical interventions are performed, presented the most accurate segmentation compared to the posterior section. The AI-driven tool provided accurate segmentation of the mandibular canal, even in the presence of anatomical variation such as an anterior loop. Thus, the presently validated dedicated AI tool may aid clinicians in automating the segmentation of neurovascular canals and their anatomical variations. It may significantly contribute to presurgical planning for dental implant placement, especially in the interforaminal region.

Automatic exposure compensation of digital radiographic technologies does not affect alveolar bone-level measurement.

OBJECTIVE: To evaluate whether the automatic exposure compensation in the presence of high-density materials can affect the measurement of alveolar bone level. METHODS: Thirty regions of seven dry skulls and six mandibles were radiographed with and without a high-density material, using two digital radiographic technologies: photostimulable phosphor plate (PSP, Digora Optime) and sensor (CMOS, Digora Toto), totaling 120 images. The distances from the cement-enamel junction to the alveolar bone crest were measured using cone-beam computed tomography (CBCT) images to represent the reference standard. The same measurements of alveolar bone level and the average of the pixel values of the image were evaluated on the radiographs. Paired t test compared the average pixel values and alveolar bone-level measurements between images with and without high-density material. One-way analysis of variance compared the difference between radiographic and CBCT measurements (α = 0.05). RESULTS: The high-density material reduced the pixel values in PSP (p = 0.002) and CMOS (p < 0.001) technologies, demonstrating the AEC functioning in both technologies. There was no difference in bone-level measurements between the images without and with the high-density material for both technologies (p ≥ 0.091), or between the tomographic and radiographic measurements (p ≥ 0.319). CONCLUSION: In the presence of high-density material, the automatic exposure compensation reduces the average pixel values of the images (i.e., images get darker), but does not influence the radiographic measurements of alveolar bone level.

Three-dimensional maxillary virtual patient creation by convolutional neural network-based segmentation on cone-beam computed tomography images.

OBJECTIVE: To qualitatively and quantitatively assess integrated segmentation of three convolutional neural network (CNN) models for the creation of a maxillary virtual patient (MVP) from cone-beam computed tomography (CBCT) images. MATERIALS AND METHODS: A dataset of 40 CBCT scans acquired with different scanning parameters was selected. Three previously validated individual CNN models were integrated to achieve a combined segmentation of maxillary complex, maxillary sinuses, and upper dentition. Two experts performed a qualitative assessment, scoring-integrated segmentations from 0 to 10 based on the number of required refinements. Furthermore, experts executed refinements, allowing performance comparison between integrated automated segmentation (AS) and refined segmentation (RS) models. Inter-observer consistency of the refinements and the time needed to create a full-resolution automatic segmentation were calculated. RESULTS: From the dataset, 85% scored 7-10, and 15% were within 3-6. The average time required for automated segmentation was 1.7 min. Performance metrics indicated an excellent overlap between automatic and refined segmentation with a dice similarity coefficient (DSC) of 99.3%. High inter-observer consistency of refinements was observed, with a 95% Hausdorff distance (HD) of 0.045 mm. CONCLUSION: The integrated CNN models proved to be fast, accurate, and consistent along with a strong interobserver consistency in creating the MVP. CLINICAL RELEVANCE: The automated segmentation of these structures simultaneously could act as a valuable tool in clinical orthodontics, implant rehabilitation, and any oral or maxillofacial surgical procedures, where visualization of MVP and its relationship with surrounding structures is a necessity for reaching an accurate diagnosis and patient-specific treatment planning.

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.

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.

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.

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.

Influence of Metal Post in Adjacent Teeth in the Detection of Vertical Root Fracture Using Cone-beam Computed Tomography with Different Acquisition Parameters.

INTRODUCTION: The aim of the present study was to evaluate the detection of vertical root fracture (VRF) in the presence of adjacent teeth restored with a metal post and the influence of acquisition parameters (tube current and metal artifact reduction [MAR] algorithm) on this diagnostic task. METHODS: Cone-beam computed tomographic images of 10 single-rooted teeth were acquired before and after the simulation of VRF. The acquisitions were set up to simulate different conditions regarding the presence of adjacent teeth restored with a metal post (control, 1 adjacent tooth, and both adjacent teeth), different tube currents (4, 8, and 10 mA), and the use of MAR (without MAR and with MAR). Images were assessed by 5 oral and maxillofacial radiologists using a 5-point scale for the presence of VRF. Diagnostic values were calculated and compared by 2-way analysis of variance (significance level of 5%). RESULTS: The area under the receiver operating characteristic curve (Az) values for VRF detection were affected by the presence of adjacent teeth and the variation of milliamperes. For 4 mA, when both restored teeth were present, Az values were significantly lower than the control group (P ≤ .05). In the presence of both restored teeth, 8 mA presented significantly higher Az values compared with 4 mA (P ≤ .05). CONCLUSIONS: The presence of both adjacent teeth restored with a metal post impairs VRF detection; however, an increase in tube current up to 8 mA may aid in this diagnostic task. Moreover, the MAR tool does not seem to be efficient in those cases.

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.

Effect of micro-computed tomography reconstruction protocols on bone fractal dimension analysis.

OBJECTIVES: To evaluate the influence of the level of three micro-CT reconstruction tools: beam-hardening correction (BHC), smoothing filter (SF), and ring artefact correction (RAC) on the fractal dimension (FD) analysis of trabecular bone. METHODS: Five Wistar rats' maxillae were individually scanned in a SkyScan 1174 micro-CT device, under the following settings: 50 kV, 800 µA, 10.2 µm voxel size, 0.5 mm Al filter, rotation step 0.5°, two frames average, 180° rotation and scan time of 35 min. The raw images were reconstructed under the standard protocol (SP) recommended by the manufacturer, a protocol without any artefact correction tools (P0) and 35 additional protocols with different combinations of SF, RAC and BHC levels. The same volume of interest was established in all reconstructions for each maxilla and the FD was calculated using the Kolmogorov (box counting) method. One-way ANOVA with Dunnet's post-hoc test was used to compare the FD of each reconstruction protocol (P0-P35) with the SP (α = 5%). Multiple linear regression verified the dependency of reconstruction tools in FD. RESULTS: Overall, FD values are not dependent on RAC (p = 0.965), but increased significantly when the level of BHC and SF increased (p < 0.001). FD values from protocols with BHC at 45% combined with SF of 2, and BHC at 30% combined with SF of 4 or 6 had no statistical difference compared to SP. CONCLUSIONS: BHC and SF tools affect the FD values of micro-CT images of the trabecular bone. Therefore, these reconstruction parameters should be standardized when the FD is analyzed.

Influence of phosphor plate-based radiographic image specifications on fractal analysis of alveolar bone.

OBJECTIVE: The aim of this study was to evaluate the influence of spatial resolution, bit depth, and enhancement filters on the fractal dimension (FD) of photostimulable phosphor (PSP) plate-based intraoral radiographic images of alveolar bone. STUDY DESIGN: Periapical radiographs were obtained using PSP plates, which were scanned at 2 spatial resolutions: 1270 dpi and 2000 dpi. All images were subjected to 3 enhancement filters-Perio, Endo, and Fine-and exported in 8 and 16 bits. A region-of-interest was selected on alveolar bone and the FD value was calculated. The multiway analysis of variance test followed by the post hoc Tukey test compared the FD values between the different groups (α = 0.05). RESULTS: No significant difference was observed in FD values between the 8- and 16-bit images. Except for the Perio filter, FD values were significantly higher for images at 1270 dpi. FD values were significantly higher for the Perio filter, followed by the Endo filter, and the Fine filter. The FD values of the Fine filter did not differ significantly from the original image. CONCLUSIONS: Fractal analysis of alveolar bone obtained from PSP plate-based intraoral radiographic images is influenced by spatial resolution and some digital enhancement filters; therefore, for FD comparison purposes, images should have the same specifications.