Synthetic CT (sCT) generated from CBCT has proven effective in artifact reduction and CT number correction, facilitating precise radiation dose calculation. However, the quality of different regions in sCT images is severely imbalanced, with soft tissue region exhibiting notably inferior quality compared to others. To address this imbalance, we proposed a Multi-Task Attention Network (MuTA-Net) based on VGG-16, specifically focusing the enhancement of image quality in soft tissue region of sCT. First, we introduced a multi-task learning strategy that divides the sCT generation task into three sub-tasks: global image generation, soft tissue region generation and bone region segmentation. This approach ensured the quality of overall sCT image while enhancing the network's focus on feature extraction and generation for soft tissues region. The result of bone region segmentation task guided the fusion of sub-tasks results. Then, we designed an attention module to further optimize feature extraction capabilities of the network. Finally, by employing a results fusion module, the results of three sub-tasks were integrated, generating a high-quality sCT image. Experimental results on head and neck CBCT demonstrated that the sCT images generated by the proposed MuTA-Net exhibited a 12.52% reduction in mean absolute error in soft tissue region, compared to the best performance among the three comparative methods, including ResNet, U-Net, and U-Net++. It can be seen that MuTA-Net is suitable for high-quality sCT image generation and has potential application value in the field of CBCT guided adaptive radiation therapy.
Cone-Beam Computed Tomography/methods* ; Humans ; Image Processing, Computer-Assisted/methods* ; Artifacts ; Algorithms ; Bone and Bones/diagnostic imaging* ; Neural Networks, Computer

This paper aims to propose a noninvasive radiotherapy patient positioning system based on structured light surface imaging, and evaluate its clinical feasibility. First, structured light sensors were used to obtain the panoramic point clouds during radiotherapy positioning in real time. The fusion of different point clouds and coordinate transformation were realized based on optical calibration and pose estimation, and the body surface was segmented referring to the preset region of interest (ROI). Then, the global-local registration of cross-source point cloud was achieved based on algorithms such as random sample consensus (RANSAC) and iterative closest point (ICP), to calculate 6 degrees of freedom (DoF) positioning deviation and provide guidance for the correction of couch shifts. The evaluation of the system was carried out based on a rigid adult phantom and volunteers' body, which included positioning error, correlation analysis, and receiver operating characteristic (ROC) analysis. Using Cone Beam CT (CBCT) as the gold standard, the maximum translation and rotation errors of this system were (1.5 ± 0.9) mm along Vrt direction (chest) and (0.7 ± 0.3) ° along Pitch direction (head and neck). The Pearson correlation coefficient between results of system outputs and CBCT verification distributed in an interval of [0.80, 0.84]. Results of ROC analysis showed that the translational and rotational AUC values were 0.82 and 0.85, respectively. In the 4D freedom accuracy test on the human body of volunteers, the maximum translation and rotation errors were (2.6 ± 1.1) mm (Vrt direction, chest and abdomen) and (0.8 ± 0.4)° (Rtn direction, chest and abdomen) respectively. In summary, the positioning system based on structured light body surface imaging proposed in this article can ensure positioning accuracy without surface markers and additional doses, and is feasible for clinical application.
Humans ; Patient Positioning/methods* ; Phantoms, Imaging ; Cone-Beam Computed Tomography ; Algorithms ; Radiotherapy, Image-Guided/methods* ; Radiotherapy Planning, Computer-Assisted/methods*

Cone-beam computed tomography (CBCT) is widely used in dentistry, surgery, radiotherapy and other medical fields. However, repeated CBCT scans expose patients to additional radiation doses, increasing the risk of secondary malignant tumors. Low-dose CBCT image reconstruction technology, which employs advanced algorithms to reduce radiation dose while enhancing image quality, has emerged as a focal point of recent research. This review systematically examined deep learning-based methods for low-dose CBCT reconstruction. It compared different network architectures in terms of noise reduction, artifact removal, detail preservation, and computational efficiency, covering three approaches: image-domain, projection-domain, and dual-domain techniques. The review also explored how emerging technologies like multimodal fusion and self-supervised learning could enhance these methods. By summarizing the strengths and weaknesses of current approaches, this work provides insights to optimize low-dose CBCT algorithms and support their clinical adoption.
Cone-Beam Computed Tomography/methods* ; Deep Learning ; Humans ; Algorithms ; Image Processing, Computer-Assisted/methods* ; Radiation Dosage ; Artifacts

This study aims to develop a fully automated method for tooth segmentation and root canal measurement based on cone beam computed tomography (CBCT) images, providing objective, efficient, and accurate measurement results to guide and assist clinicians in root canal diagnosis grading, instrument selection, and preoperative planning. The method utilized Attention U-Net to recognize tooth descriptors, cropped regions of interest (ROIs) based on the center of mass of these descriptors, and applied an integrated deep learning method for segmentation. The segmentation results were mapped back to the original coordinates and position-corrected, followed by automatic measurement and visualization of root canal lengths and angles. The results indicated that the Dice coefficient for segmentation was 96.42%, the Jaccard coefficient was 93.11%, the Hausdorff Distance was 2.07 mm, and the average surface distance was 0.23 mm, all of which surpassed existing methods. The relative error of the root canal working length measurement was 3.15% (< 5%), the curvature angle error was 2.85 °, and the correct classification rate of the treatment difficulty coefficient was 90.48%. The proposed methods all achieved favorable results, which can provide an important reference for clinical application.
Cone-Beam Computed Tomography/methods* ; Deep Learning ; Humans ; Dental Pulp Cavity/diagnostic imaging* ; Image Processing, Computer-Assisted/methods*

OBJECTIVES: This study aims to compare the effects of two orthodontic treatment modalities for skeletal class Ⅲ malocclusion on specific changes in airway volume, morphology, palatal angle, mandibular rotation, and bone displacement. Results provide scientific evidence for the selection of orthodontic treatment plans and reduce the risk of developing obstructive sleep apnea hypopnea syndrome (OSAHS). METHODS: Thirty-six patients diagnosed with skeletal class Ⅲ malocclusion at the Department of Orthodontics, the Affiliated Stomatological Hospital of Nanjing Medical University from September 2018 to December 2023 were divided into two groups: orthodontic-orthognathic treatment group (18 patients) and camouflage orthodontic treatment group (18 patients). Changes in airway volume, cross-sectional area, palatal angle, mandibular, and tongue positions were observed through pre- and post-operative cone beam computed tomography and 3D cephalometric measurements. RESULTS: In the camouflage orthodontic treatment group, nasopharyngeal volume and oropharyngeal volume statistically increased after treatment (P<0.05). In the orthodontic-orthognathic treatment group, changes in nasopharyngeal volume, nasopharyngeal airway, distance from posterior tongue to pharyngeal wall, palatal angle, mandibular rotation, and hyoid bone displacement were statistically significant after surgery (P<0.05). In the comparison between the two groups after treatment, changes in the distance from posterior tongue to pharyngeal wall, palatal angle, and distance from hyoid bone to sella turcica point were statistically significant (P<0.05). CONCLUSIONS Patients in the orthodontic-orthognathic treatment group showed significantly greater changes in oropharyngeal cross-sectional area, palate angle, and tongue position compared with patients in the camouflage orthodontic treatment group. As individuals susceptible to OSAHS often exhibit mandibular retrusion and decreased minimum airway cross-sectional area, special attention should be paid to airway morphology changes when adopting orthodontic-orthognathic treatment to avoid adverse consequences.
Humans ; Hyoid Bone/diagnostic imaging* ; Malocclusion, Angle Class III/therapy* ; Male ; Female ; Cone-Beam Computed Tomography ; Cephalometry ; Orthodontics, Corrective/methods* ; Adult ; Mandible ; Pharynx/diagnostic imaging* ; Sleep Apnea, Obstructive/etiology* ; Orthognathic Surgical Procedures

OBJECTIVES: This study aims to evaluate the changes in the mandibular canal following the treatment of large odontogenic keratocysts through decompression and curettage, providing a theoretical basis for sequential treatment. METHODS: Twenty patients were selected for each decompression and curettage treatment of large odontogenic keratocysts in the mandible. Postoperative follow-up with was conducted every three months, during which cone beam computed tomography (CBCT) scans were performed. Then, the data were imported into MIMICS software to observe 3D changes in the position and structure of the mandibular nerve canal, followed by a comparative analysis. RESULTS: The total displacement of the mandibular canal was (1.89±0.21) mm on the decompression side and (0.80±0.19) mm on the curettage side. Vertically, the displacement range of the mandibular canal on the decompression side (M=1.03, SD=0.17) was larger than on the curettage side (M=0.52, SD=0.010) within nine months post-operation. In the buccal-lingual direction, the ratio of the thickness of the buccal plate to the lingual plate gradually increased with time. The amount of bone reconstruction at the part of the mandibular nerve canal closest to the cyst was (1.75±0.15) mm on the decompression side and (1.45±0.09) mm on the curettage side after nine months. CONCLUSIONS The mandibular nerve canal showed varying degrees of recovery and "relocation" after two surgical procedures. Osteogenesis around the mandibular nerve canal was more remarkable after decompression than after curettage. Therefore, for large odontogenic keratocyst, decompression is recommended as the initial treatment, followed by secondary curettage nine months later.
Humans ; Odontogenic Cysts/diagnostic imaging* ; Retrospective Studies ; Cone-Beam Computed Tomography ; Decompression, Surgical/methods* ; Mandibular Nerve/surgery* ; Mandible/innervation* ; Curettage ; Male ; Female ; Adult ; Middle Aged

OBJECTIVES: The objective of this study is to measuring the morphology and position of bilateral temporomandibular joints in patients with unilateral and bilateral molar scissor bite and simulating the deformation of the mandible during occlusion, in order to provide thesis for the diagnosis of temporomandibular joint disease in patients with unilateral and bilateral molar scissor bite. METHODS: This study was a retrospective study. A total of 10 patients with unilateral molar scissor bite (the unilateral molar scissor bite group) and 10 patients with bilateral molar scissor bite (the bilateral molar scissor bite group) were selected as the experimental group, and 20 adult patients with classⅠ of angle classification of similar ages were selected as the control group. All patients underwent cone beam computed tomography scans, by measuring the width of the fossa, height of the fossa, articular eminence inclination, long axis of the condyle, minor axis of the condyle, horizontal angle of the condyle and the space of the temporomandibular joint, compare temporomandibular joint morphology and position. The three-dimensional finite element analysis of the mandible morphology was carried out to evaluate the force and deformation of the mandible by using software to simulate the occlusion of the patients. It was further explored the relationship between the force of the mandible morphology and the possible temporomandibular joint disorder symptoms of the patients. RESULTS: Intergroup comparisons for the unilateral molar scissor bite group and left sides of the other groups revealed that the superior articular space in the group with unilateral molar scissor bite was shorter than that in the control group (P<0.05); the long axis of the condyle in the unilateral and bilateral molar scissor bite group were both shorter than that of the control group (P<0.05); among which the unilateral group was larger than the bilateral group, and the minor axis of the condyle in bilateral molar scissor bite group was smaller than in the control group (P<0.05), and the unilateral and bilateral condylar groups were larger than the control group (P<0.05); and the condylar horizontal angle in the unilateral and bilateral groups were larger than that in the control group (P<0.05). The normal sides of the unilateral molar scissor bite group and right sides of the other groups had smaller superior articular space than the control group (P<0.05); and the condylar long-axis in bilateral group was smaller than the control group (P<0.05); and the normal side of the condylar short-axis unilateral group was larger than that of the bilateral condylar group. Three-dimensional finite element analysis: the condyle of patients with molar scissor bite was a concentrated area of deformation during the bite of the mandible, when the first molar occlusion of the scissors bite side was simulated, the maximum deformation was located in the condyle in the X-axis and Z-axis directions. The amount of deformation was greater than that of the scissor bite side in the X-axis direction, while in the Z-axis direction, the normal side was greater than the scissor bite side. The maximum sites of local deformation in the X-axis direction were located in anterior and posterior the transverse crest of scissor bite side, and the minimum sites of local deformation was at 1/3 of the anterior slope of the inner pole of the normal side, the maximum local deformation sites in the Z-axis direction were located in the outer pole and below the outer pole of the normal side. The X-axis deformation value was the largest in the molars occlusion on the normal side, the Y-axis deformation value was in the premolars occlusion on the normal side, and the Z-axis deformation value was the largest in the centric occlusion, the deformation value of the condyle was not most significant in molar scissor bite. CONCLUSIONS Unilateral and bilateral molar scissor bite resulting in a short condyle morphology, and the bilateral group had a shorter condylar morphology than the unilateral group. The condyle of the patient with molar scissor bite is a concentrated area of poor occlusal deformation, and the largest sites of deformation are distributed near the transverse ridge of the inner and outer poles of the condyle. Different occlusion conditions have an effect on condylar deformation values, but do not indicate whether there is a clear association between them.
Humans ; Finite Element Analysis ; Retrospective Studies ; Temporomandibular Joint/pathology* ; Cone-Beam Computed Tomography ; Mandible/pathology* ; Imaging, Three-Dimensional ; Adult ; Temporomandibular Joint Disorders/diagnostic imaging* ; Mandibular Condyle/diagnostic imaging* ; Female ; Male ; Molar

Fused teeth are usually formed by the partial or complete fusion of two normal tooth germs during the development process and belong to dental developmental abnormalities. Fused teeth are relatively rare clinically, and those occurring in the posterior tooth area are even rarer. This article reports a case of fused teeth between the first permanent molar and the second permanent molar in the right mandible. This fused tooth had a complex root canal anatomical structure (seven root canals). The number and location of the root canals were analyzed by cone beam computed tomography, and root canal treatment was successfully completed with the assistance of microscope.
Humans ; Molar/diagnostic imaging* ; Mandible ; Dental Pulp Cavity/abnormalities* ; Cone-Beam Computed Tomography ; Root Canal Therapy/methods* ; Fused Teeth/surgery*

OBJECTIVES: This study aims to evaluate the short- to medium-term clinical efficacy of demineralized dentin matrix (DDM) particles applied during the immediate implantation of alveolar bone defects in the posterior region. METHODS: A total of 76 patients with 110 simple taper retentive implants were included in the conducted study and divided into Groups A and B in accordance with the bone grafting materials. Cone beam computed tomography and panoramic radiographs were taken immediately after implant surgery, immediate crown repair, and final follow-up time. The average follow-up time for Groups A and B was recorded. The primary observed clinical indicators were overall survival rate of the implant, bone resorption of the mesial and distal margins of the implant, buccal bone width resorption at the platform level and 1 mm below the platform, and bone height of the implant. Implant complication was a secondary observed clinical indicator. RESULTS: During the 1-to-5-year follow-up observation period, the mean follow-up of Group A was 38.2 months while that of Group B was 39.9 months. In Group A, two implants failed, one of which fractured, and implant overall survival rate was 96.4%. Four implants failed in Group B due to peri-implantitis, and implant overall survival rate was 92.6%. No statistically significant difference in implant overall survival rate was found between the two groups (P>0.05). In Group A, the average bone resorption in the mesial and distal margins of the implants was (1.011±2.047) mm and (0.841±2.183) mm, respectively. In Group B, the average bone resorption of the mesial and distal margins of the implants was (1.546±1.778) mm and (1.431±1.909) mm, respectively. No statistically significant difference was noted between the two groups (P>0.05). In Group A, buccal bone width resorption at the platform level and 1 mm below the platform of the implant was (0.782±2.084) mm and (0.681±2.307) mm, respectively. In Group B, buccal bone width resorption at the platform level and 1 mm below the platform of implant was (1.071±1.474) mm and (0.949±1.909) mm, respectively. No statistically significant difference was found between the two groups (P>0.05). In Group A, the buccal bone height of resorption of the implant was (1.044±2.214) mm. In Group B, the buccal bone height of resorption of the implant was (1.075±1.456) mm. No statistically significant difference in bone height was observed between the two groups (P>0.05). CONCLUSIONS During the 1-to-5-year follow-up observation period, DDM particles can effectively increase the height and width of alveolar bone, and they can achieve the same effect of maintaining alveolar bone contour and bone augmentation compared with deproteinized inorganic calf bone. DDM particles can be used as a potential new bone grafting material for the treatment of bone defects in clinical practice.
Humans ; Follow-Up Studies ; Dentin ; Cone-Beam Computed Tomography ; Dental Implants ; Male ; Female ; Adult ; Alveolar Bone Loss/surgery* ; Middle Aged ; Bone Transplantation ; Radiography, Panoramic ; Dental Implantation, Endosseous/methods* ; Immediate Dental Implant Loading

OBJECTIVES: To evaluate the osteogenic efficacy of three-dimensional printing individualized titanium mesh (3D-PITM) as a scaffold material in guided bone regeneration (GBR). METHODS: 1) Patients undergoing GBR for alveolar bone defects were enrolled as study subjects, and postoperative healing complications were recorded. 2) Postoperative cone beam computed tomography (CBCT) scans acquired at least 6 months post-surgery were used to calculate the percentage of actual bone formation volume. 3) Alveolar bone specimens were collected during the first-stage implant surgery for histomorphometric analysis. This analysis quantitatively measured the proportions of newly formed bone and newly formed unmineralized bone within the specimens. Specimens were categorized into three groups based on healing complications (good healing group, wound dehiscence group, 3D-PITM exposure group) to compare differences in the proportions of newly formed bone and newly formed unmineralized bone. RESULTS: 1) Twelve patients were included. Guided bone regeneration failed in one patient, and 3D-PITM exposure occurred in three patients (exposure rate: 25%). 2) The mean percentage of actual bone formation volume in the 11 successful guided bone regeneration cases was 95.23%±28.85%. 3) Histomorphometric analysis revealed that newly formed bone constituted 40.35% of the alveolar bone specimens, with newly formed unmineralized bone accounting for 13.84% of the newly formed bone. Intergroup comparisons showed no statistically significant differences (P>0.05) in the proportions of newly formed bone or newly formed unmineralized bone between the good healing group and the wound dehiscence group or the 3D-PITM exposure group. CONCLUSIONS 3D-PITM enables effective bone augmentation. Radiographic assessment demonstrated favorable bone formation volume, while histological analysis confirmed substantial formation of newly formed mineralized bone within the surgical site.
Humans ; Printing, Three-Dimensional ; Titanium ; Cone-Beam Computed Tomography ; Bone Regeneration ; Osteogenesis ; Surgical Mesh ; Tissue Scaffolds ; Alveolar Process/surgery* ; Adult ; Male ; Middle Aged ; Female ; Wound Healing ; Guided Tissue Regeneration, Periodontal/methods* ; Alveolar Bone Loss/surgery*