Cone Beam Computed Tomography Research Articles

Measurement and analysis of condylar morphology and thickness of the roof of the glenoid fossa in patients with unilateral second molar scissor bite

Objective The objective of this study was to measure and analyze the joint space, condylar morphology, and thickness of the roof of the glenoid fossa (RGF) in patients with unilateral second molar scissor bite using cone beam CT (CBCT). Methods A total of 80 patients were included in this study. Forty patients with a normal posterior occlusal relationship, who attended the Department of Orthodontics at the First Hospital of Shanxi Medical University from December 2021 to August 2023, were selected as the control group. The experimental group consisted of 40 patients with unilateral second molar scissor bite during the same period. All patients underwent CBCT scanning, and the resulting images were analyzed using the NNT viewer software in multiplanar reconstruction (MPR). Axial, coronal, and sagittal adjustments were made for each patient. Results In the control group, the right and left joint spaces (PS, SS, AS), the height of the upper part of the condyle, and the depth of the glenoid fossa did not show statistically significant differences (P > 0.05). When comparing bilateral condylar morphology and joint space in the experimental group, it was found that the posterior joint space on the scissor bite side was greater than that on the normal occlusion side, while the anterior joint space on the scissor bite side was smaller than that on the normal occlusal side. Additionally, the height of the upper condyle and the depth of the glenoid fossa on the scissor bite side were greater than that on the normal occlusal side, with statistically significant differences (P < 0.05). However, there were no statistically significant differences in SS, internal and external joint diameter, as well as anterior and posterior diameters (P > 0.05). The comparison of the minimum thickness of the roof of the glenoid fossa in both the sagittal and coronal directions between the patients in the experimental group and the control group showed no statistically significant difference (P > 0.05). Furthermore, the asymmetry index of the supracondylar height in the control group was significantly smaller than that in the experimental group, displaying a statistically significant difference (P < 0.05). The differences in the asymmetry indices of the anterior and posterior diameters of the condyle, as well as the inner and outer diameters, were not statistically significant (P > 0.05). When analyzing the position of the condyle in the sagittal direction of the glenoid fossa in the patients of the control group, it was observed that the majority were in the anterior and medial positions, with only 10% and 5% being in the posterior position. However, the analysis of the condyle position in the sagittal direction of the glenoid fossa in the experimental group revealed statistically significant differences (P < 0.05), with the condyle position on the scissor bite side being more anterior. Conclusion Unilateral second molar scissor bite can result in anterior displacement of the condyle, greater height of the condyle superiorly as well as the depth of the glenoid fossa.

Dosimetric benefit and clinical feasibility of deep inspiration breath-hold and volumetric modulated arc therapy-based postmastectomy radiotherapy for left-sided breast cancer

To evaluate the dosimetric benefits and clinical feasibility of deep inspiratory breath-hold (DIBH) combined with volumetric modulated arc therapy (VMAT) in left-sided postmastectomy radiotherapy (PMRT). Eligible patients with left-sided breast cancer undergoing DIBH-based PMRT were prospectively included. Chest wall, supra/infraclavicular fossa, and/or internal mammary node irradiation (IMNI) were planned with a prescription dose of 43.5 Gy in 15 fractions. VMAT plans were designed on free breathing (FB)—and DIBH-CT to compare dosimetric parameters in heart, left anterior descending artery (LAD) and lung. Cone-beam computed tomography (CBCT) was performed before and after treatment to evaluate inter- and intra-fractional setup errors. Heart position and dose variations during treatment were estimated by fusing CBCT with DIBH-CT scans.Twenty patients were included with 10 receiving IMNI. In total, 193 pre-treatment and 39 pairs pre- and post-treatment CBCT scans were analyzed. The Dmean, Dmax, and V5−40 of the heart, LAD, and left lung were significantly lower in DIBH than FB (p < 0.05 for all), except for V5 of LAD (p = 0.167). The cardiopulmonary dosimetric benefits were maintained regardless of IMNI. The inter- and intra-fractional setup errors were < 0.3 cm; and the overall estimated PTV margins were < 1.0 cm. During treatment, the mean dice similarity coefficient of heart position and the mean ratio of heart Dmean between CBCT and DIBH-CT plans was 0.95 (0.88–1.00) and 100% (70.6–119.5%), respectively. DIBH-VMAT could effectively reduce the cardiopulmonary doses with acceptable reproducibility and stability in left-sided PMRT regardless of IMNI.

Impacted mandibular third molars: a comparison of orthopantomography and cone-beam computed tomography imaging in predicting surgical difficulty

Background: This study investigated the predictive value of orthopantomography (OPG) for the difficulty of extracting impacted mandibular third molars, in comparison with cone-beam computed tomography (CBCT).Methods: In this descriptive quantitative investigation, two oral and maxillofacial radiologists evaluated OPG and three-dimensional CBCT images according to the Pell-Gregory and Winter classifications. The results for the classification were compared using the chi-square test, and the prediction of difficulty was assessed using the Pederson scale, with a significance level of &lt;i&gt;p&lt;/i&gt;&lt; 0.05.Results: The study included 30 patients (14 men and 16 women), providing a total of 53 samples of impacted mandibular third molars. Of these, 30 (56.6%) were from the right side and 23 (43.4%) from the left. There was a statistically significant difference between the OPG and CBCT images concerning their relation to the mandibular ramus (&lt;i&gt;p&lt;/i&gt;&lt; 0.05). However, evaluations based on occlusal lines and angulation showed no significant differences (&lt;i&gt;p&lt;/i&gt;&gt; 0.05). According to the Pederson scale, significant differences were observed between OPG and CBCT in predicting extraction difficulty (&lt;i&gt;p&lt;/i&gt;&lt; 0.05).Conclusion: CBCT offered a more accurate assessment of the surgical difficulty associated with mandibular third molars than OPG. OPG views frequently failed to adequately visualize the region of the mandibular ramus, influencing the perceived difficulty of mandibular third molar surgery. In certain cases, the use of CBCT imaging is crucial.

Assessment of Condylar Changes in Patients with Degenerative Joint Disease of the TMJ After Stabilizing Splint Therapy: A Retrospective CBCT Study.

Degenerative joint disease (DJD) of the TMJ can impact patients' quality of life and complicate orthodontic treatment. Stabilizing splints are a common conservative treatment in managing TMDs symptoms, although their long-term effects on condylar morphology are poorly studied. This study aimed to assess the impact of stabilizing splints on condyle morphology using cone-beam computed tomography (CBCT) in patients with various stages of DJD. Forty-two condyles with pre- (T1) and post- (T2) splint therapy scans were analyzed. CBCT scans were sectioned into sagittal and coronal slices for condyle classification and measurement. T1 and T2 CBCTs were superimposed before linear and area measurements at different poles. Our results indicate that condyles in the normal group remain unchanged after splint therapy. The majority of subjects in the degenerative groups remained in the same classification group: six out of fourteen degenerative-active patients became degenerative-repair, while three out of twenty-two degenerative-repair patients progressed to degenerative-active. There is no significant remodeling of condylar width pre- and post-splint therapy. On average, there is more bone deposition than reduction in condylar height after splint therapy, although individual variation exists. Stabilizing splints offer a low-risk intervention for managing DJD and may contribute to favorable adaptive changes in the condyles.

Three-dimensional assessment of the skeletal characteristics accompanying unilateral maxillary canine impaction: a retrospective cone-beam computed tomography study

BackgroundEnvironmental and genetic factors associated with canine impaction have been extensively researched, whereas the bone characteristics in the impaction area have not been thoroughly studied. Accordingly, the objective of this investigation was to provide a skeletal assessment in terms of bone density, bone microstructure, bone volume, and palatal volume in subjects with unilaterally impacted maxillary canines.MethodsA retrospective design has been employed to address the aim of this study, where the initial pre-treatment cone-beam computed tomography (CBCT) scans of 30 patients with unilateral maxillary canine impaction were assessed. The obtained patients’ data were equally divided according to the location of the impaction into 2 groups, one with buccally impacted canines, and another with palatal impactions, with the contra-lateral sides in both groups serving as the controls. Skeletal measurements such as bone density (BD), bone microstructure in terms of fractal dimension (FD), maxillary bone volume (MBV), and palatal volume (PV) were evaluated from the acquired CBCTs in both groups and compared to the controls.ResultsWith buccal impactions, significantly greater BD and FD have been reported (p < 0.001), whereas non-significant differences were found regarding the PV when compared with controls (p = 0.56). MBV was significantly greater on the non-impaction side in comparison with buccal impaction sides (p < 0.001). For palatal impactions: BD, FD, and MBV were significantly greater on the impaction sides (p < 0.001), and conversely with PV which has been reported to be significantly greater on the non-impaction sides (p < 0.001).ConclusionsAs per the obtained results, buccally impacted canines are associated with greater BD and FD, and less MBV, whereas palatally impacted canines are accompanied with greater BD, FD, and MBV, in addition to less PV, when both conditions are compared with the non-impaction sides.

Exploring dual energy CT synthesis in CBCT-based adaptive radiotherapy and proton therapy: application of denoising diffusion probabilistic models

Background.Adaptive radiotherapy (ART) requires precise tissue characterization to optimize treatment plans and enhance the efficacy of radiation delivery while minimizing exposure to organs at risk. Traditional imaging techniques such as cone beam computed tomography (CBCT) used in ART settings often lack the resolution and detail necessary for accurate dosimetry, especially in proton therapy.Purpose.This study aims to enhance ART by introducing an innovative approach that synthesizes dual-energy computed tomography (DECT) images from CBCT scans using a novel 3D conditional denoising diffusion probabilistic model (DDPM) multi-decoder. This method seeks to improve dose calculations in ART planning, enhancing tissue characterization.Methods.We utilized a paired CBCT-DECT dataset from 54 head and neck cancer patients to train and validate our DDPM model. The model employs a multi-decoder Swin-UNET architecture that synthesizes high-resolution DECT images by progressively reducing noise and artifacts in CBCT scans through a controlled diffusion process.Results.The proposed method demonstrated superior performance in synthesizing DECT images (High DECT MAE 39.582 ± 0.855 and Low DECT MAE 48.540± 1.833) with significantly enhanced signal-to-noise ratio and reduced artifacts compared to traditional GAN-based methods. It showed marked improvements in tissue characterization and anatomical structure similarity, critical for precise proton and radiation therapy planning.Conclusions.This research has opened a new avenue in CBCT-CT synthesis for ART/APT by generating DECT images using an enhanced DDPM approach. The demonstrated similarity between the synthesized DECT images and ground truth images suggests that these synthetic volumes can be used for accurate dose calculations, leading to better adaptation in treatment planning.

IPEM topical report: the first UK survey of cone beam CT dose indices in radiotherapy verification imaging for adult patients.

Cone beam CT is integral to most modern radiotherapy treatments. The application of daily and repeat CBCT imaging can lead to high imaging doses over a large volume of tissue that extends beyond the treatment site. Hence, it is important to ensure exposures are optimised to keep doses as low as reasonably achievable, whilst ensuring images are suitable for the clinical task. &#xD;This IPEM topical report presents the results of the first UK survey of dose indices in radiotherapy CBCT. Dose measurements, as defined by the Cone Beam Dose Index (CBDIw), were collected along with protocol information for seven treatment sites. Where a range of optimised protocols were available in a centre, a sample of patient data demonstrating the variation in protocol use were requested. Protocol CBDIw values were determined from the average dosimetry data for each type of linear accelerator, and median CBDIw and scan length were calculated for each treatment site at each centre. Median CBDIw values were compared and summary statistics derived that enable the setting of national dose reference levels (DRLs). &#xD;A total of 63 UK radiotherapy centres contributed data. The proposed CBDIw DRLs are; prostate 20.6 mGy, gynaecological 20.8 mGy, breast 5.0 mGy, 3D-lung 6.0 mGy, 4D-lung 11.8 mGy, brain 3.5 mGy and head/neck 4.2 mGy. However, large differences between models of imaging system were noted. Where centres had pro-active optimisation strategies in place, such as sized based protocols with selection criteria, dose reductions on the 'average' patient were possible compared with vendor defaults. Optimisation of scan length was noted in some clinical sites, with Elekta users tending to fit different collimators for prostate imaging (relatively short) compared with gynaecological treatments (longest). This contrasts with most Varian users who apply the default scan length in most cases.

Accuracy and Efficiency of the Surgical-Guide-Assisted Fiber Post Removal Technique for Anterior Teeth: An Ex Vivo Study.

This study compared the accuracy and efficiency of different surgical-guide (SG)-assisted and freehand drilling techniques for removing fiber posts from maxillary anterior teeth performed by differently experienced operators. A fiber post was bonded to the root canal of 54 extracted maxillary anterior teeth. After mounting the teeth in the jaw models, SGs were designed by integrating cone-beam computed tomography (CBCT) and intraoral scanner data. Each SG included a custom sleeve. An experienced or inexperienced operator drilled the post using three different techniques: (i) SG-assisted incremental drilling at 2-3 mm (SG1), (ii) SG-assisted one-time drilling to a predetermined depth (SG2), and (iii) freehand incremental drilling without SG (FH; n = 9 in each group). Deviations in coronal, sagittal, and horizontal planes and the angle of deviation were measured. The SG1 and SG2 groups showed significantly smaller sagittal and horizontal deviations than the FH group, regardless of the operator's experience. The SG2 group had a significantly shorter working time than the SG1 and FH groups. In the FH group, the experienced operator required a significantly shorter working time than the inexperienced operator. SG-assisted drilling techniques enhanced the accuracy and efficiency of removing fiber posts from the anterior teeth, irrespective of the operator's experience.

Cone-beam CT volumetry: a new method for evaluating osteotomy healing - a clinical evaluation and MDCT comparison.

Fracture healing complications remain a major problem in trauma monitoring. An open wedge osteotomy of the distal radius provides a unique way of evaluating fracture healing. Since the introduction of cone-beam computed tomography (CBCT) at our institution, it has become the method of choice for assessing hand and wrist bones. To date, CT volumetry has been validated for multidetector CT (MDCT) but not for CBCT. To assess osteotomy healing using CBCT volumetry and to evaluate two different segmentation techniques. A total of 36 patients were surgically treated for malunited distal radius fractures with open-wedge osteotomy either leaving the void empty (open wedge empty [OWE]) or filled with bone graft substitutes (BGS). They were scanned using CBCT and MDCT postoperatively and after 3, 6, and 12 months. Segmentation was performed both manually and semi-automatically for volumetric measurement. Inter- and intra-observer reliability were assessed using intraclass correlation (ICC). The median osteotomy volume in the OWE group postoperatively was 0.87 cm3 (range=0.42-2.72). At 3 months, all but one of the OWE volumes had diminished to half or less of their initial volume. In the BGS group, the median postoperative volume was 1.30 cm3 (range=0.73-1.81) and at 12 months, 76% of the initial volume remained. Reliability between CBCT and MDCT volumetry expressed as ICC was ≥0.96. ICC for the two segmentation techniques was ≥0.99 and ICC for inter-observer reliability ≥0.97. CBCT volumetry is a reliable tool and comparable to MDCT to quantify bone healing of an osteotomy.

Is palatal cavity volume affected by maxillary sinus pathologies? A CBCT study

AimThis study uses cone beam computed tomography (CBCT) to determine whether pathology in the maxillary sinus (MS) affects the volume of the palatal cavity.Methods188 individuals, 95 women and 93 men, aged between 17 and 63, were included in the study. MS pathology in the patients and the open-closed status of the maxillary sinus ostium (MSO) were recorded. Palatal volume measurements were performed using open-access ITK-SNAP via CBCT images. Statistical analysis of the study was conducted using SPSS v.21 software (IBM. Chicago. IL. USA), and p<0.05 was considered statistically significant.ResultsThe average palatal volume was 1375.29±313.38 mm3 in male patients and 1235.33±250.40 mm3 in females, and it was found to be statistically significant between genders (p=0.001). MS pathology was detected in 114 (60.6%) of the patients. It was determined that the most frequently observed pathology in both the right (n = 58, 30.9%) and left (n = 65, 34.6%) side MS of individuals was mucosal hypertrophy. It was determined that the mean palatal volume was higher when the MSO was closed (p = 0.000). As a result of the correlation analysis, it was shown that the presence of MS pathology had a positive effect in explaining palate volume by 38.6% (R2 = 0.386).ConclusionPalatal cavity volume was affected by maxillary sinus pathologies. Palatal cavity volume increases in the presence of MS pathologies and when MSOs are closed.

Stress Distribution in Proclined Anterior Teeth of Pediatric Patients With and Without Mouthguard Use: A 3D Finite Element Analysis.

Traumatic dental injuries related to sports are a significant concern, as they can have severe physical and psychological impacts on children. Using mouthguards is essential, particularly in sports like skating, where high-impact forces are common. The study aimed to evaluate how stress is distributed on the teeth and surrounding bone in children with proclined anterior teeth when a force of 614.12 N was applied to two different regions of the jaws. The evaluation was conducted using finite element analysis (FEA), both with and without the use of a mouthguard. A 3-dimensional finite element analysis (FEA) model was constructed using a cone beam computed tomography (CBCT) scan of a 12-year-old male patient. An average standardized force of 614.12 N was calculated, based on the average weight of children aged 11 to 13 years and the average speed of 13.4 m/s with which the children skate. The force was applied in two different directions and areas of the jaws: a lateral blow, perpendicular to the crown and root with the maxillary and mandibular teeth in occlusion (between the first molar and second premolar), and a blow obliquely at the pogonion point on the chin. Static simulations were then performed for four realistic scenarios-two with mouthguards and two without mouthguards. The Von Mises stresses were evaluated under all conditions. When the applied force was directed laterally, the stress values observed were 126.76 MPa with a mouthguard and 140 MPa without a mouthguard. When the force was applied to the chin region, the stress values were 37.997 MPa with a mouthguard and 40.67 MPa without a mouthguard. The use of a mouthguard in children is beneficial for protecting teeth and surrounding structures, especially in cases of proclined anterior teeth, as it helps dampen the generated stresses.

Hybrid modality dual-energy imaging aggregating complementary advantages of kV-CT and MV-CBCT: concept proposal and clinical validation

Megavoltage cone-beam CT (MV-CBCT) is advantageous in metal artifact reduction during Image-Guided Radiotherapy (IGRT), although it is limited by poor soft tissue contrast. This study proposed and evaluated a novel hybrid modality dual-energy (DE) imaging method combining the complementary advantages of kV-CT and MV-CBCT.&#xD;Approach: The kV-CT and MV-CBCT images were acquired on a planning CT scanner and a Halcyon linear accelerator respectively. After rigid registration, images of basis materials were generated using the iterative decomposition method in the volumetric images. The decomposition accuracy was quantitatively evaluated on a Gammex 1472 phantom. The performance of contrast enhancement and metal artifact reduction in virtual monochromatic images were evaluated on both phantom and patient studies.&#xD;Main results: Using the proposed method, the mean percentage errors for RED and SPR were 0.90% and 0.81%, outperforming the clinical single-energy mapping method with mean errors of 1.28% and 1.07%, respectively. The contrasts of soft-tissue insets were enhanced by a factor of 2~3 at 40 keV compared to kV-CT. The standard deviation in the metal artifact area was reduced by ~67%, from 42 HU (kV-CT) to 14 HU (150 keV monochromatic). The head and neck patient test showed that the percent error of soft-tissue RED in the metal artifact area was reduced from 18.1% (HU-RED conversion) to less than 1.0% (the proposed method), which was equivalent to the maximum dosimetric difference of 28.7% based on the patient-specific plan.&#xD;Significance: Without hardware modification or extra imaging dose, the proposed hybrid modality method enabled kV-MV DE imaging, providing improved accuracy of quantitative analysis, soft-tissue contrast and metal artifact suppression for more accurate IGRT.&#xD.

Longitudinal study of root resorption on incisors caused by impacted maxillary canines-a clinical and cone beam CT assessment.

To evaluate the long-term status of incisors with canine-induced root resorption (CIRR). Subjects with impacted maxillary canines (IMC) and persisting incisors with CIRR examined with cone beam computed tomography (CBCT), diagnosed ≥ 5 years earlier, were recalled. The resorption grade in the horizontal and vertical plane was assessed on CBCT images at baseline (T0) and follow-up (T1). Clinical examination was done at T1 which included probing depth, gingival retraction, mobility, ankylosis, discoloration and vitality test. In addition, patients completed a questionnaire regarding symptoms from the incisors. Forty subjects (mean age 13.7 ± 2.1 years) with 43 IMC and 47 incisors with CIRR were recruited. The IMC either spontaneously erupted, were surgically exposed or surgically removed. Thirty-four of the patients were treated with a fixed appliance and six had no orthodontic treatment. The follow-up range was 5.5-14.6 years. None of the incisors were lost or endodontically treated at T1. The horizontal resorption grade was unchanged in 38, improved in 7, and worsened in 2 teeth. The corresponding results for the vertical resorption grade were unchanged in 20 and worsened in 27 teeth. Three incisors with severe horizontal resorption at T0 were significantly more obliterated at T1 (P = .01). No significant differences were found in clinical parameters or patient-reported outcomes between incisors with CIRR and non-resorbed contralateral incisors at T1. The extent of root resorption during active orthodontic treatment was not possible to assess as only CBCT images from T0 and T1 were available. Incisors with CIRR caused by IMC have a high survival rate in a long-term perspective and do not cause more symptoms or exhibit more signs of pathology than non-resorbed contralateral incisors. Extraction of asymptomatic incisors based solely on root resorption should not be performed routinely.

A prospective randomized study on the efficacy of real-time dynamic navigation in deep horizontal mandibular third molar extractions

PurposeThis study aimed to evaluate the clinical efficacy of applying real-time dynamic navigation (RDN) in the extraction of deep horizontal mandibular impacted third molars, hypothesizing that RDN reduces surgical time and minimizes the risk of injury to adjacent anatomical structures.MethodsA prospective study was conducted on 160 patients aged between 18 and 37 years with deep horizontal impaction of the mandibular third molar. The participants were randomly assigned to either the experimental group (receiving RDN-assisted extractions) or the control group (undergoing traditional extraction methods). Preoperative planning utilized cone beam computed tomography (CBCT) and Mimics software for the accurate localization and segmentation of impacted teeth. Parametric data were analysed via an independent t test for intergroup comparisons, and significance was set to p < 0.05.ResultsIn the experimental group, an average of 11 ± 1 min was required for preoperative planning via RDN, which was not required in the control group. The setup of the navigation system took an average of 4 ± 1 min in the experimental group and 0 min in the control group. The experimental group demonstrated a significantly shorter average surgical time (22 ± 3 min) than did the control group (36 ± 3 min). The differences in the preoperative design time, surgical time, and complication rates between the two groups were statistically significant (p = 0.005). Additionally, the RDN group reported no complications related to adjacent tooth damage or nerve injury.ConclusionThe precision, safety, real-time guidance of RDN supports its use in complicated dental extractions, which would introduce a new era of oral and maxillofacial surgery.Graphical

Intraoral Approach for Dental Implant Placement in Pneumatized Maxillary Sinuses with Postoperative Maxillary Cysts: A Report of Two Cases.

A postoperative maxillary cyst (POMC) is a delayed complication of the original Caldwell Luc operation, which was once widely performed to treat chronic rhinosinusitis. Two patients who had previously undergone Caldwell Luc operations desired dental implant treatment. In both cases, preoperative conebeam computed tomography (CBCT) revealed a POMC occupying the entire maxillary sinus on the side where the implants were to be placed. The residual bone height was 3-4 mm. Furthermore, the sinuses were divided into compartments by septum-like structures. An intraoral approach was applied for POMC enucleation and implant placement. The implants were placed with sinus floor penetration due to the small residual bone height. No bone substitute material was grafted in the sinus. Post-operative healing was uneventful. All implants were successfully osseointegrated and performed well (4 and 5 years for each patient). No sino-nasal complications were reported. Follow-up CBCTs showed that the exposed implant parts were covered by newly formed bone. The intraoral approach is a feasible option for implant placement in a pneumatized maxillary sinus with POMC.

Retrospective Radiographic Evaluation of Implant Complications: CBCT-Based Study

Aim: Dental implants are a popular treatment option for patients with one or more missing teeth. With the increase in dental implant treatments, the complications encountered have increased. Therefore, it is very important to plan the implant by evaluating the anatomy of the area where the implant will be placed in three dimensions with cone beam computed tomography (CBCT). The aim of this study is to evaluate the prevalence of implant complications seen in CBCT after implant applications. Material and Methods: CBCT images of 500 patients obtained for different dental reasons were examined; among these, 300 dental implant images were evaluated retrospectively in terms of complications. The number, location and type of identified complications (perforation in the maxillary sinus, mandibular canal, cortical bone, nasal cavity, and mental canal; contact with the adjacent tooth root) were recorded. The data obtained were analyzed statistically using chi-square tests. Results: At least one complication was detected in 65% of the 300 dental implants evaluated. A total of 272 complications (1.4 complications per implant) were observed in 195 dental implants with complications. The number of implants with complications per patient was found to be 3.9. The most observed complication was found to be vertical bone resorption around the implant (45%). Complications were most frequently detected in the maxillary posterior region (40%). Conclusion: Three-dimensional CBCT evaluation of the area where the implant will be applied before and after treatment is very important to prevent possible complications.

Deep learning architecture for scatter estimation in cone-beam computed tomography head imaging with varying field-of-measurement settings.

X-ray scatter causes considerable degradation in the cone-beam computed tomography (CBCT) image quality. To estimate the scatter, deep learning-based methods have been demonstrated to be effective. Modern CBCT systems can scan a wide range of field-of-measurement (FOM) sizes. Variations in the size of FOM can cause a major shift in the scatter-to-primary ratio in CBCT. However, the scatter estimation performance of deep learning networks has not been extensively evaluated under varying FOMs. Therefore, we train the state-of-the-art scatter estimation neural networks for varying FOMs and develop a method to utilize FOM size information to improve performance. We used FOM size information as additional features by converting it into two channels and then concatenating it to the encoder of the networks. We compared our approach for a U-Net, Spline-Net, and DSE-Net, by training them with and without the FOM information. We utilized a Monte Carlo-simulated dataset to train the networks on 18 FOM sizes and test on 30 unseen FOM sizes. In addition, we evaluated the models on the water phantoms and real clinical CBCT scans. The simulation study demonstrates that our method reduced average mean-absolute-percentage-error for U-Net by 38%, Spline-Net by 40%, and DSE-net by 33% for the scatter estimation in the 2D projection domain. Furthermore, the root-mean-square error on the 3D reconstructed volumes was improved for U-Net by 43%, Spline-Net by 30%, and DSE-Net by 23%. Furthermore, our method improved contrast and image quality on real datasets such as water phantom and clinical data. Providing additional information about FOM size improves the robustness of the neural networks for scatter estimation. Our approach is not limited to utilizing only FOM size information; more variables such as tube voltage, scanning geometry, and patient size can be added to improve the robustness of a single network.

Clinical outcomes of using operating microscope for alveolar ridge preservation: A randomized controlled trial.

The use of the operating microscope (OM) for extraction and alveolar ridge augmentation (ARP) is increasing due to enhanced magnification and illumination. The primary objective was to compare the wound healing and crestal bone quality after the use of OM and dental loupes (DL) for ARP. Forty non-molar teeth with periapical lesions in need of extraction and ARP from 33 patients were randomly assigned to 2 groups: DL (control) or OM (test). All procedures were performed by 1 surgeon and assessments done by masked examiners. ARP was performed with an allograft and a resorbable collagen membrane. The presence of granulomatous tissue remnants after debridement was recorded. Cone-beam computed tomography (CBCT) and ultrasound (US) scans were taken during the healing phase up to 16-week visits. Bone cores were retrieved from implant osteotomies for histologic analysis. Patient-reported outcome measurements (PROMs) were assessed. All patients completed all study visits except 1 who dropped out before the last visit. After socket debridement, the test group exhibited significantly fewer sites with tissue remnants (p=0.01) and a better healing score at 2-week (p=0.04) and 4-week (p=0.01) time points. There were no significant differences in 12-week crestal bone healing by histology (p=0.1), US (p=0.85), and CBCT healing (p=0.64) at 12weeks, as well as PROMs (p>0.1). Within the limitation of the study, the use of OM for ARP resulted in significantly fewer tissue remnants and favorable early visual wound healing. CBCT and US-derived-crestal bone quality did not show a difference between the 2 groups. Alveolar ridge preservation (ARP) by placing bone particulates in the extraction socket, covered by a wound dressing material, is commonly applied immediately after tooth extraction to reduce jawbone shrinkage in preparation for implant placement later. The jawbone healing varies, depending largely on the ability to remove the etiology, socket features, extent of surgical trauma, and wound stability. Healed jawbone with good quality is favorable for easiness of implant placement and could be related to maintenance of long-term implant health. The surgical microscope with high magnification (up to ∼25×) and co-axial illumination is ideal for assistance in the removal of granulomatous tissue that is believed to interfere with healing, performance of minimally invasive extraction, and stabilization of the wound with meticulous tissue management and fine sutures. This study compared the use of the surgical microscope to dental loupes for ARP in a randomized controlled design. The microscope-assisted ARP is associated with a significantly higher chance of removing granulomatous tissue, favorable early healing, and similar crestal bone quality. Removal of granulomatous tissue is significant for immediate implant placement. This study serves as a model for testing the benefits of the surgical microscope for encouraging early healing in more challenging intraoral surgical procedures.

Fast reconstruction 3D computed tomography image of stacked cell under faster scanning by dual-branch cross-fusion flat bottom network

Abstract Cone beam computed tomography (CBCT) fast scanning and reconstruction is a key step to achieve rapid detection of internal defects in batteries. In this work, we have achieved a faster CT scanning just in 5 seconds by reducing the X-ray exposure time in sparse view CT. However, the CT data is extremely incomplete by faster scanning; the existing reconstruction methods are difficult to reconstruct a high quality three-dimensional (3D) CT image of stacked cells. To address this issue, we propose a 3D CT image reconstruction network, which can reconstruct higher quality CT images from low quality 3D volume data. The input data of the reconstruction network is not 2D projection data, but 3D volume data. In this network, a high and low resolution dual-branch cross-fusion flat bottom structure is designed. The high resolution flat bottom branch aims to preserve detailed information, while the low resolution flat bottom branch focuses on capturing more semantic information. Cross-fusion between these branches mitigates the loss of semantic details. Additionally, the auxiliary loss function, the main loss function, and the 3D attention module are designed to enhance semantic accuracy and the learning performance of the network. The 3D training data is collected under a fast scanning strategy spanning 5-60 seconds. During the training phase, we use clipping block technology to cut the 3D volume data, enabling direct training on the 3D volume data. Our experimental results demonstrate that our 3D reconstruction network outperforms mainstream algorithms under this faster scanning strategy, which is able to reconstruct higher quality 3D CT images just in 15 seconds. Ablation experiments confirm the positive impact of the dual-branch cross-fusion flat bottom structure, attention module, and loss functions on improving the quality of 3D CT images.

Marginal Bone Loss and Clinical Evaluation of Angled Implants: A Retrospective Study

Aim: The volume of the edentulous crest and its proximity to critical anatomical structures are important limiting factors for implant surgery. Surgical procedures with complications can be avoided by placing angled implants. The aim of this clinical study was to evaluate marginal bone loss and the complications of angled implants. Materials and Methods: Fifty-eight dental implants were examined in 32 patients (16 females, 16 males) with cone beam computed tomography (CBCT) images from patients with angled implants and complete edentation. The marginal bone loss in angled implants that were functional for 15 to 30 months was evaluated according to factors such as implant angle, connection type, opposing arch restoration type and planning of superstructure restoration. Marginal bone loss measurements were recorded from CBCT sections. Results: It was determined that 3.44% of the implants placed had an inclination of less than 15°, 75.86% had an inclination between 15° and 30° and 20.68% had an inclination of more than 30°. While there was no marginal bone loss on the mesial and distal surfaces, the average marginal bone loss was 0.66 on the buccal surfaces and 0.93 in the lingual region. Only one of the implants examined failed. No pain or infection was observed in any of the implants examined. Conclusion: According to the results of this retrospective clinical study, further clinical studies with larger sample sizes are needed to evaluate angled implants supported by full arch fixed prostheses as a predictable and valid treatment method in the prosthetic rehabilitation of edentulous jaws.