Cone-beam Computed Tomography Data Research Articles

Prevalence of delayed tooth eruption of permanent maxillary anterior teeth among Ukrainian children: retrospective radiographic study using CBCT data

Background. Tooth eruption is a complex, multi-staged, and well-regulated biological and age specific process that can be affected and influenced by many systemic and local factors. The deviation more than ±2SD from the established norm of tooth eruption terms, while also taking account racial, ethnic, and gender factors, is important for the clinician. 
 Objective. To estimate the prevalence of delayed tooth eruption (DTE) of permanent maxillary anterior teeth among Ukrainian children sample and to investigate the epidemiology distribution of delayed eruption cases according to their causes based on CBCT data.
 Materials and Methods. Cone Beam Computed Tomography (CBCT) data sets of 684 children (304 boys and 380 girls) aged 7–14 years old, who previously have sought for orthodontic diagnostics in Central Laboratory Diagnosis of the Head (CLDH), were collected and examined to detect any delayed eruption of the permanent maxillary anterior teeth. Signs of delayed eruption were identified considering tooth developmental stages, relationships between the chronologic age and dental developmental age, eruption sequence. 
 Results. The total prevalence of delayed tooth eruption of permanent maxillary anterior teeth among the 684 children was 42.84%. 293 children (155 boys and 138 girls) had at least one impacted or retained tooth. The maxillary canines the most frequently demonstrated signs of delayed eruption and compiled 30.7% of all examined cases and 71.67% of all delayed eruption cases, followed by the lateral incisors of the maxilla – 6.58% and 15.36% respectively, and the central incisors – 5.56% and 12.97% respectively. Loss of space in dental arch and the ectopic eruption pathway were the most causative factor of delayed eruption of permanent maxillary anterior teeth. 
 Conclusions. Delayed tooth eruption of permanent maxillary anterior teeth is frequently seen in everyday orthodontic practice and requires a multidisciplinary approach of diagnostics to avoid many treatment-related complications. CBCT data is essential for timely diagnostics of DTE and primary for the causative factors identification in order to provide optimal and effective management plan for each patient.

The evaluation of lateral incisor adjacent to treated labial inversely impacted maxillary central incisor: A retrospective follow-up study

This retrospective study aimed to evaluate the further development of the lateral incisor and its associated periodontium adjacent to the treated labial inversely impacted maxillary central incisor. We enrolled 23 participants (average age, 8.24 ± 1.43 years) undergoing a mean follow-up period of 31.10 ± 13.05 months. Each participant had an unimpacted lateral incisor and a successfully treated unilateral labial inversely impacted maxillary central incisor. The contralateral lateral incisors served as controls. Cone-beam computed tomography data were available for treatment completion and follow-up stages. The variables (including root length, dental age, root canal width, root-crown angulation, and alveolar bone loss and thickness) were evaluated with Dolphin Imaging software (version 11.95; Dolphin Imaging and Management Solutions, Chatsworth, Calif). At the follow-up stage, the lateral incisors in the impacted side had significantly longer root lengths, smaller root canal widths, and thinner labial bone widths at the apex than at the posttreatment stage (P<0.001, P= 0.036, and P= 0.001, respectively). A significant lateral incisor root length reduction was noted when comparing the impacted and contralateral sides, although no variation was observed in root canal width. Similarly, crown-root angulation of the lateral incisor on the impacted side was significantly larger than that of the contralateral lateral incisor. The lateral incisor on the impacted side also had thicker labial and thinner lingual bone widths at the apex than the contralateral lateral incisor. The lateral incisor adjacent to the successfully treated labial inversely impacted maxillary central incisor showed continuous growth during follow-up stages, exhibiting a similar morphology and alveolar bone quality but shorter root length, larger root angulation, and thinner lingual bone width at the apex than those of the contralateral lateral incisors.

Digital planning for two-implant-supported overdenture and bone reduction guide using cone-beam computed tomography: Simple features for predictable outcomes.

The two-implant-supported mandibular overdenture is considered a reliable treatment option to restore masticatory function. Digital planning has been shown to improve the precision and accuracy of the surgical procedure. The outcomes are indeed pertinent to the ideal three-dimentionalpositioning of the implant placement. Recently, the uses of cone-beam computed tomography (CBCT) and intraoral scan have improved greatly the workflow of digital planning; however, the sophisticated technology caused confusion among clinicians. The purpose of this case series was to exhibit the efficacy of a bone-supported guide in applying simultaneous implant placement and bone reduction, solely based on CBCT data. The bone reduction can therefore be determined accordingly, by adding windows to the guide, allowing the clinician to decide the amount of bone reduction as well as the location for implant placement. This novel surgical guide would not only fit properly on the bone but also providethe benefits of less-invasive surgery and the opportunity to place implants parallel. The digital workflow described not only simplifies the fabrication process but also yields predictable surgical outcomes.

Hard and Soft Tissue Asymmetry in Patients with Skeletal Class III Malocclusion: A Cone-Beam Computed Tomography Study.

This study aims to investigate hard and soft tissue asymmetry in skeletal Class III patients to elucidate how soft tissue thickness alters overall asymmetry and whether menton deviation is correlated with bilateral differences in hard and soft tissue prominence and soft tissue thickness. The cone-beam computed tomography data of 50 skeletal Class III adults were divided based on menton deviation into symmetric (n = 25; deviation ≤ 2.0 mm) and asymmetric (n = 25; deviation > 2.0 mm) groups. Forty-four corresponding hard and soft tissue points were identified. Bilateral hard and soft tissue prominence and soft tissue thickness were compared using paired t-tests. The correlations between bilateral differences in these variables and menton deviation were examined using Pearson's correlation analysis. In the symmetric group, no significant bilateral differences in soft and hard tissue prominence and soft tissue thickness were observed. In the asymmetric group, both hard and soft tissue prominence were significantly greater on the deviated side than the non-deviated side at most of the points; however, no significant differences in soft tissue thickness were detected except at point 9 (ST9/ST'9, p = 0.011). The difference of hard and soft tissue prominence at point 8 (H8/H'8 and S8/S'8) was positively correlated with menton deviation, whereas the soft tissue thickness at point 5 (ST5/ST'5) and point 9 (ST9/ST'9) was negatively correlated with menton deviation (p = 0.05). Soft tissue thickness does not affect overall asymmetry in the presence of underlying hard tissue asymmetry. Soft tissue thickness at the centre of the ramus may be correlated with the degree of menton deviation in patients with asymmetry; however, this correlation needs to be confirmed by further studies.

Maxillary transverse deficiency diagnosed by 3 methods and its relationship with molar angulation in patients with skeletal Class III malocclusion

The objective of this study was to evaluate the relationship between maxillary transverse deficiency (MTD) diagnosed by 3 methods and molar angulation measured in 3-dimensions in patients with skeletal Class III malocclusion, which could give reference to the selection of diagnostic methods in MTD patients. Cone-beam computed tomography data of 65 patients with skeletal Class III malocclusion (mean age 17.35 ± 4.45 years) were selected and imported into MIMICS software. Transverse deficiencies were evaluated by 3 methods, and molar angulations were measured after reconstructing 3-dimensional planes. Two examiners performed repeated measurements to assess the intraexaminer and interexaminer reliability. Pearson correlation coefficient analyses and linear regressions were performed to determine the relationship between a transverse deficiency and molar angulations. One-way analysis of variance was used to compare the diagnostic results of 3 methods. The novel molar angulation measurement method and 3 MTD diagnostic methods have the interexaminer and intraexaminer intraclass correlation coefficient values>0.6. The transverse deficiency diagnosed by 3 methods was significantly and positively correlated with the sum of molar angulation. There was a statistically significant difference for the transverse deficiencies diagnosed by the 3 methods. The transverse deficiency was significantly higher in Boston University's analysis than in Yonsei's analysis. Clinicians ought to choose the diagnostic methods properly, considering the feature of the 3 methods and the individual difference of each patient.

Abstract TMP78: Using Interventional CT Perfusion Imaging To Evaluate Cerebral Blood Volume Surrounding Intracerebral Hemorrhage Site Following Minimally Invasive Evacuation

Introduction: Computed tomography perfusion (CTP) characterizes hemodynamic changes within brain tissue, particularly after stroke. This study aims to quantify cerebral blood volume (CBV) changes and identify predictors of CBV increase in the pericavity parenchyma after minimally invasive intracerebral hemorrhage evacuation (MIS for ICH). Methods: Thirty-two patients underwent MIS for ICH with pre/postoperative native CT imaging and intraoperative perfusion imaging (DynaCT PBV Neuro, Artis Q, Siemens). Scans were segmented using ITK-SNAP software to calculate hematoma volumes pre/post-evacuation and to delineate the pericavity tissue. Helical CT segmentations were registered to cone beam CT data using elastix software. Mean CBVs were computed inside subvolumes by dilating the segmentations with spheres with varying diameters. Results: In 27 patients with complete imaging, CTP analysis demonstrated significant increases in CBV from the 6 mm to 20 mm pericavity regions. CBV increased on average 32.7% from 2.27 mL/100mg (IQR 1.87-3.02) to 2.80 mL/100mg (2.41-3.61) in the 10 mm pericavity region (P=0.003). Factors associated with increased CBV in the univariate analysis (P≤0.10) included age (P=0.082) and percentage of hematoma evacuation (P=0.078). Upon multivariate linear regression, age (OR 4.49, [95% CI, 1.01-1.98], P=0.048) and percentage of hematoma evacuation (OR 4.09, [95% CI, 1.70-9.84], P=0.046) remained significantly predictive of increased CBV. Conclusions: CTP analysis demonstrated a significant increase in pericavity cerebral blood volume after MIS for ICH. Patient age and hematoma evacuation percentage may be predictive of CBV increase after MIS for ICH. Figure 1: Topographic map showing blood flow improvement at different distances from the lesion.

Three-dimensional evaluation of the pharyngeal airway space in patients with anterior open bite.

: This study aimed to three-dimensionally evaluate the pharyngeal airway space (PAS) of patients with anterior open bite (AOB) by using cone-beam computed tomography (CBCT) and compare the findings with those obtained in individuals with normal occlusion. : The open bite group (OBG, n = 25) consisted of patients with an anterior overbite of -3 mm or less, while the control group (n = 25) consisted of age- and sex-matched individuals with an anterior overbite of 1-3 mm, Angle Class I malocclusion (1° ≤ point A-nasion-point B angle ≤ 4°), and a normodivergent profile (22° ≤ Frankfort mandibular plane angle ≤ 28°). After the CBCT data were reconstructed into a three-dimensional image, the PAS was segmented into four parts, and the volume of each part was measured. Pharyngeal airway length (PAL) and the area and transverse width of the part showing minimal constriction were also measured. Pearson's correlation analysis was used to evaluate the correlation between changes in the PAS and the amount of anterior overbite. : The OBG showed a significantly narrower airway space in the nasopharyngeal, hypopharyngeal, and total airway volumes. The OBG also showed a significantly smaller area and transverse width of the part with minimal constriction. The OBG showed a significantly longer PAL, but there was no correlation between the amount of anterior overbite and the changes in PAS. : The PAS was associated with AOB. Patients with AOB had a narrower PAS and a smaller part showing minimal constriction.

Radiographic analysis of critical anatomical structures for pterygoid implant placement in Chinese patients with a severely atrophied maxilla

The pterygoid implant is a feasible alternative for posterior dental rehabilitation without grafting; however, the ideal pterygoid implant placement continues to be debated. The aim of this study was to identify effective landmarks and establish valid guidelines to determine the ideal pterygoid implant placement. Cone beam computed tomography (CBCT) data of 100 severely atrophied maxillae requiring implant rehabilitation, obtained between January 2015 and December 2018, were included. The CBCT data were obtained in DICOM format from the radiographic database and imported into Nobel Clinician software (Nobel Biocare) for radiographic analysis. Virtual pterygoid implant placement was successful in 67 maxillae: a 13-mm virtual implant in four maxillae (6.0%), 15-mm in 52 maxillae (77.6%), and 18-mm in 11 maxillae (16.4%). For the virtual pterygoid implant, the mean implant angulation± standard deviation in the anteroposterior axis (sagittal view) was 45.08 ± 2.56° relative to the Frankfort plane. In the buccopalatal axis (coronal view), the mean implant angulation was 64.30 ± 4.99° relative to the Frankfort plane and the mean value for the shortest linear distance between the palatine canal and apical tip of the virtual implant was 3.91 ± 0.62 mm. A 15-mm pterygoid implant placed at 45° in the anteroposterior axis and 60° in the buccopalatal axis (relative to the Frankfort plane), is generally recommended in this Chinese patient population.

Thoracic motion-compensated cone-beam computed tomography in under 20 seconds on a fast-rotating linac: A simulation study.

Rapid kV cone-beam computed tomography (CBCT) scans are achievable in under 20 s on select linear accelerator systems to generate volumetric images in three dimensions (3D). Daily pre-treatment four-dimensional CBCT (4DCBCT) is recommended in image-guided lung radiotherapy to mitigate the detrimental effects of respiratory motion on treatment quality. To demonstrate the potential for thoracic 4DCBCT reconstruction using projection data that was simulated using a clinical rapid 3DCBCT acquisition protocol. We simulated conventional (1320 projections over 4 min) and rapid (491 projections over 16.6 s) CBCT acquisitions using 4D computed tomography (CT) volumes of 14 lung cancer patients. Conventional acquisition data were reconstructed using the 4D Feldkamp-Davis-Kress (FDK) algorithm. Rapid acquisition data were reconstructed using 3DFDK, 4DFDK, and Motion-Compensated FDK (MCFDK). Image quality was evaluated using Contrast-to-Noise Ratio (CNR), Tissue Interface Width (TIW), Root-Mean-Square Error (RMSE), and Structural SIMilarity (SSIM). The conventional acquisition 4DFDK reconstructions had median phase averaged CNR, TIW, RMSE, and SSIM of 2.96, 8.02mm, 83.5, and 0.54, respectively. The rapid acquisition 3DFDK reconstructions had median CNR, TIW, RMSE, and SSIM of 2.99, 13.6mm, 112, and 0.44 respectively. The rapid acquisition MCFDK reconstructions had median phase averaged CNR, TIW, RMSE, and SSIM of 2.98, 10.2mm, 103, and 0.46, respectively. Rapid acquisition 4DFDK reconstruction quality was insufficient for any practical use due to sparse angular projection sampling. Results suggest that 4D motion-compensated reconstruction of rapid acquisition thoracic CBCT data are feasible with image quality approaching conventional acquisition CBCT data reconstructed using standard 4DFDK.

Accuracy and reproducibility of a cone beam CT-based virtual parenchymal perfusion algorithm in the prediction of SPECT/CT anatomical and volumetric results during the planification of radioembolization for HCC.

To evaluate anatomical and volumetric predictability of a cone beam computed tomography (CBCT)-based virtual parenchymal perfusion (VPP) software for the single-photon-emission computed tomography (SPECT)/CT imaging results during the work-up for transarterial radioembolization (TARE) procedure in patients with hepatocellular carcinoma (HCC). VPP was evaluated retrospectively on CBCT data of patients treated by TARE for HCC. 99mTc macroaggregated albumin particles (99mTc-MAA) uptake territories on work-up SPECT/CT was used as ground truth for the evaluation. Semi-quantitative evaluation consisted of the ranking of visual consistency of the parenchymal enhancement and portal vein tumoral involvement on VPP and 99mTc-MAA SPECT/CT, using a three-rank scale and two-rank scale, respectively. Inter-reader agreement was evaluated using a kappa coefficient. Quantitative evaluation included absolute volume error calculation and Pearson correlation between volumes enhanced territories on VPP and 99mTc-MAA SPECT/CT. Fifty-two CBCTs were performed in 33 included patients. Semi-quantitative evaluation showed a good concordance between actual 99mTc-MAA uptake and the virtual enhanced territories in 73% and 75% of cases; a mild concordance in 12% and 10% and a poor concordance in 15%, for the two readers. Kappa coefficient was 0.86. Portal vein involvement evaluation showed a good concordance in 58.3% and 66.7% for the two readers, respectively, with a kappa coefficient of 0.82. Quantitative evaluation showed a volume error of 0.46 ± 0.78mL [0.01-3.55], and Pearson R2 factor at 0.75 with a p value < 0.01. CBCT-based VPP software is accurate and reliable to predict 99mTc-MAA SPECT/CT anatomical and volumetric results in HCC patients during TARE. • Virtual parenchymal perfusion (VPP) software is accurate and reliable in the prediction of 99mTc-MAA SPECT volumetric and targeting results in HCC patients during transarterial radioembolization (TARE). • VPP software may be used per-operatively to optimize the microcatheter position for 90Y infusion allowing precise tumor targeting while preserving non-tumoral parenchyma. • Post-operatively, VPP software may allow an accurate estimation of the perfused volume by each arterial branch and, thus, a precise 90Y dosimetry for TARE procedures.

Features of three-dimensional cephalometric analysis according to cone beam computed tomography data in patients with class II malocclusion

The most accurate method of diagnostic examination of an orthodontic patient is cone beam computed tomography (CBCT), which allows measurements in three planes. When conducting cephalometric analysis, it is necessary to evaluate both angular and linear cephalometric parameters to make a diagnosis and plan of orthodontic treatment. Purpose of the study: to determine the main morphometric features of class II malocclusion of the dentoalveolar and gnathic forms and to highlight the most informative cephalometric parameters of three-dimensional analysis based on CBCT data. Materials and methods of research. The material studied was data from 30 CBCT scans, which were studied in the Dolphin Imaging &amp; Management Solutions program. All patients were divided into two groups: the first group consisted of 15 patients with distal occlusion and the first skeletal class, the second group — 15 patients with distal occlusion and the second skeletal class.Results. In patients of the second group, a more posterior position of the lower jaw is noted (the SNB parameter was 77.9±2.93°) against the background of a more anterior position of the upper jaw (the SNA parameter was 83.05±3.10°), as well as an elongation of the base of the upper jaw (CoA parameter was 84.7±0.83 mm) and shortening of the effective length of the lower jaw (Co-Gn parameter was 104±2 mm). Conclusion. In patients with a distal gnathic bite, more pronounced skeletal and dentoalveolar changes are observed. When performing three-dimensional cephalometry, it is necessary to carry out a comprehensive cephalometric analysis with Co-A calculation (total length of the upper jaw), Co-Gn (effective length of the lower jaw)

Morphometric Analysis of Greater Palatine Foramen and the Adjacent Structures: Forensic Odontology Study using CBCT

Introduction: Sexual dimorphism plays a pivotal role in many instances, including solving medicolegal problems, anthropological studies, sorting out victims of natural calamities and man-made calamities. Among various parameters available for sexual dimorphism, structures of the oral cavity play an important role. The use of Cone Beam Computed Tomography (CBCT) is convenient and provides accurate measurements with the help of digital software. Aim: To determine the role of Greater Palatine Foramen (GPF), its Greater Palatine Canal (GPC) and relation with the adjacent structures like Naso-Palatine Foramen (NPF) and Lesser Palatine Foramen (LPF) in elucidating the level of sexual dimorphism using CBCT images, while enhancing the information on anatomy of Greater Palatine Foramen (GPF). Materials and Methods: This cross-sectional forensic odontology study was conducted in the Department of Oral Medicine and Radiology, CSI College of Dental Sciences and Research, Madurai, Tamil Nadu, India, and was performed using 50 males and 50 females CBCT images of patients between age 18 to 45. The CBCT data were collected from January 2021 till January 2022, and the obtained data were analysed from March 2022 till April 15, 2022. These were analysed using Planmeca imaging software. Measurements of GPF length, angulation with respect to Hard Palate (HP), relation between NPC and GPF, distance between GPC and Mid Maxillary Suture (MMS). Its relation to LPF and dimensions of GPF at opening of oral cavity were done. Finally, all measures were subjected to statistical analysis using IBM Statistical Package for the Social Sciences (SPSS), version 28.0. Independent t-test was used for analysis of difference between male and female measurements. Results: The GPC length on right (male:13.2570, female:12.3628) and left (male:12.8089, female:12.2780), angulation of GPC left (male: 61.1379, female: 57.4964), angle between GPF and NPC left (male: 28.6208, female: 26.5024), distance between GPC and MMS left (male: 15.1625, female: 14.5350) and Anteroposterior (AP) dimensions of GPF on right (male: 5.5402, female: 4.2314) and left-side (5.4934, female: 4.4576), Transverse (TR) dimension of GPF on right (male: 2.6752, female: 2.0528) and left (male: 5.4943, female: 4.4576) showed statistically significant difference between male and female CBCT images, while the measures were significantly higher in males. Conclusion: The CBCT images provided reliable measurements of the areas of interest. The present study results highlight a statistically significant difference between male and female, where males showed higher measurements in most instances. A more precise morphological measurement of GPF in relation to adjacent structures such as NPC, MMS proves to have sexual dimorphism in humans.

Role of Pulp Volume Method in Assessment of Age and Gender: An Observational Study from Lucknow, India

Introduction: In forensics, age and gender determination are required for victim identification. Secondary dentine deposition occurs throughout life, resulting in decreased pulp volume and size. Evaluation of pulp volume using Cone Beam Computed Tomography (CBCT) is a non invasive method used to evaluate age and gender. Aim: To evaluate the efficacy of the pulp volume method in determining age and gender. Materials and Methods: An observational study was conducted in the Oral Medicine and Radiology Department of King George’s Medical University, Lucknow, Uttar Pradesh, India from July 2019 to August 2020. Pulp volume measurements were obtained from CBCT data of randomly selected individuals (n=90) aged 18-70 years, focusing on maxillary Central Incisors (CI) and maxillary Canine (C). Statistical analyses, including Chisquare test, Pearson’s correlation, linear regression, and logistic regression, were performed on the data. Results: The CBCT data from 90 individuals, aged 18-70 years, were evaluated for pulp volume of maxillary CI and C. The Pearson correlation coefficient indicated a decrease in pulp volume with age. The validation of the equations for sex determination revealed higher prediction accuracy for CI (56.70%) compared to C (53.30%). Conclusion: Pulp volume obtained from CBCT can serve as a reliable indicator for age estimation and gender prediction.

Synchrotron Analysis of Damaged Extraction Sockets Augmented Using a Synthetic Bone Block: A Pilot Study.

This study aimed to investigate the dimensional stability and quality of the alveolar ridge augmented using a synthetic bone block (SBB) at damaged extraction sockets. Four participants were included, and socket augmentation was performed using SBB and a collagen membrane. Intraoral and CBCT scans were performed before extraction (baseline), immediately postoperative (IP), and at 6 months postoperative (6M). At 6M, a trephine biopsy sample was obtained during implant placement, and the sample was observed using synchrotron. Soft tissue profile changes were assessed using profilometric analysis of the intraoral scan data, while dimensional changes in hard tissue were evaluated based on CBCT measurements. Bone quality was analyzed using synchrotron imaging. There were minimal changes in the soft tissue profile between baseline and IP, baseline and 6M, and IP and 6M (0.11 ± 1.08 mm3, 0.02 ± 0.8 mm3, and -0.65 ± 0.82 mm3, respectively). Horizontal bone width was measured at 1-mm increments from the augmented bone crest to 5 mm apically and revealed only a slight reduction (< 1 mm) at all levels between IP and 6M. The augmented bone height was well maintained from IP until 6M (-0.21 ± 0.53 mm). Synchrotron analysis revealed low to moderate bone quality after 6M (percentage of new bone: 16.49% ± 4.91%). Socket augmentation using SBB appears to be a viable technique for regenerating damaged extraction sockets, with the augmented ridge dimensions maintained up to 6M. Further long-term randomized clinical trials are needed.

Simple and effective immobilization for radiation treatment of choroidal melanoma.

At our institution, patients diagnosed with choroidal melanoma requiring external beam radiation therapy are treated with two 6 MV volumetric-modulated arcs delivering 50 Gy over 5 daily fractions. The patient is immobilized using an Orfit head and neck mask and is directed to look at a light emitting diode (LED) during CT simulation and treatment to minimize eye movement. Patient positioning is checked with cone beam computed tomography (CBCT) daily. Translational and rotational displacements greater than 1 mm or 1° off the planned isocenter position are corrected using a Hexapod couch. The aim of this study is to verify that the mask system provides adequate immobilization and to verify our 2-mm planning target volume (PTV) margins are sufficient. Residual displacements provided by pretreatment verification and post-treatment CBCT data sets were used to assess the impact of patient mobility during treatment on the reconstructed delivered dose to the target and organs at risk. The PTV margin calculated using van Herk's method1 was used to assess patient motion plus other factors that affect treatment position, such as kV-MV isocenter coincidence. Patient position variations were small and were shown to not cause significant dose variations between the planned and reconstructed dose to the target and organs at risk. The PTV margin analysis showed patient translational motion alone required a PTV margin of 1 mm. Given other factors that affect treatment delivery accuracy, a 2-mm PTV margin was shown to be sufficient for treatment of 95% of our patients with 100% of dose delivered to the GTV. The mask immobilization with LED focus is robust and we showed a 2-mm PTV margin is adequate with this technique.

Maxillary Sinus Volume and Its Effect on Treated Impacted Canines.

The goal of study was to explore the role of 3D CBCT (cone beam computer tomography) in detecting impacted canines and their movement to evaluate the influence of orthodontic therapy parameters on treatment options, and to monitor quality of healing process based on shape and size of sinus maxillae volume. It is known that the volume of maxillary sinus plays an important role in patients with impacted teeth. The prospective study consisted of 26 individuals. For each individual, pre-treatment and post-treatment CBCT data were acquired. Changes of size, and position of impacted canine in 3D CBCT image before and after therapy were prepared using 3D reconstruction. Volumetric measurements of the maxillary sinuses were performed before and after orthodontic therapy of impacted canines, using InVivo6 software. The main effects MANOVA performed on linear measurements showed metric differences between pre-op and post-op images. A paired t-test showed no statistically significant differences between pre-op and post-op values of the sinus volume. Changes of size and position of impacted canine in 3D image before and after therapy were precise and reproducible, using 3D reconstruction in three planes - horizontal, midsagittal, and coronal. The linear measurements showed metric differences between pre-op and post-op images.

Immediate Implants, Immediate Loading, and Milled Double Bar Prosthesis (Titanium, Biohpp): A Case Report

Abstract To rehabilitate lower arch by placing immediate implants and immediate milled provisionals and provide double bar prosthesis for the long-term survival of implants. Full-mouth rehabilitation by integrating cone-beam computed tomography data three-dimensional printing technology helps in precise placement and predictable outcomes to the longevity of implants. Six immediate implants were placed in the lower arch using digitally guided surgery. Computer-aided design-computer-aided manufacture milled temporary prosthesis was also given within 24 h of the surgery. After allowing for osseointegration, the final prosthesis was made up of materials such as titanium (primary bar), PEEK (secondary bar), and high-impact polymer composite crowns. Splinting all the implants together with such framework designs reduces the loads on implants and addition of two bars produces a dampening effect and helps long-term survival of the same. Strategies used to preserve alveolar bone and soft tissue by immediate implant placement in fresh extraction sockets shorten the treatment span. Immediate loading of implants using temporary prosthesis can be done after attaining adequate primary stability. This case has a follow-up of 6 years. The milled double bars made out of titanium and BioHPP h provide dampening effect and thus long-term survival of the implant.

Structural and functional changes of nasal cavity and maxillary sinus in patients with skeletal class III malocclusion 1year after bimaxillary surgery.

This study aimed to analyse changes in the nasal cavity and maxillary sinus structure and function in patients with skeletal class III malocclusion 1 year after bimaxillary surgery. In this study, cone-beam computed tomography (CBCT) images of 20 patients (10 men and 10 women; mean age 24.3± 3.4 years) with skeletal class III malocclusion who underwent Le Fort I osteotomy and bilateral sagittal split osteotomy were obtained before and 1 year after the surgery. CBCT data were stored opened with element 3D (E3D) to establish a nasal airway model (the paranasal sinus includes only the maxillary sinus). Ansys (ANSYS) software is used for simulation and analysis. The maxillary sinus and nasal cavity volumes decreased significantly 1 year after the surgery. After surgery, the volume of nasal cavity decreased by 13.5%, and the average volume of maxillary sinus decreased by 7.8%. There was no significant difference in the degree of deviation of the septum and nasal cavity resistance, and air distribution in the maxillary sinus did not change. The nasal cavity wall shear stress change was similar to that before surgery. The maxillary sinus volume and nasal cavity volume of patients with skeletal class III malocclusion changed significantly after bimaxillary surgery, but there was no significant change in nasal ventilation function 1 year after surgery.

Evaluation of Cortical Bone Formation on Mandibular Condyle in Asymptomatic Adolescents and Young Adults Using Cone-Beam Computed Tomography.

The aim of this study was to evaluate cortical bone formation on the mandibular condyle using cone-beam computed tomography (CBCT) in asymptomatic adolescents and young adults and to evaluate the relationship between age and sex. CBCT images that can evaluate the shape of the mandibular condyle were selected from asymptomatic patients aged 13-25. The degree of cortication on the mandibular condyle (CMC) was evaluated using CBCT images reconstructed in the axial, sagittal, and coronal planes. CBCT data of 829 patients (413 males, 416 females) were selected and then the left and right images of all patients were acquired; consequently, a total of 1658 temporomandibular joint-related images were evaluated in this study. The degree of CMC was correlated with age in men and women (p &lt; 0.05). The frequency of CMC 0 disappeared in woman aged 20 years and in men aged 21 years. Cortical bone formation of the mandibular condyle was completed at age 22 years in women and 24 years in men. The degrees of cortical bone formation of the mandibular condyle between men and women showed significant differences between the ages of 15-19 and 22 years. This difference can be interpreted as a different mandible growth period between the sexes.

Three-dimensional position changes of unopposed molars before implant rehabilitation: a short-term retrospective cohort analysis

ObjectiveTo investigate the spatial changes of unopposed molars within the period between the antagonist extraction and the final implant restoration using data from cone beam computed tomography.MethodsA total of 59 patients with 68 unopposed molars were included in this study. Three-dimensional models reconstructed from cone beam computed tomography data before and after loss of the antagonist were superimposed to measure the spatial changes. The overeruption and tipping of target teeth were calculated by coordinate values.ResultsThe result of overeruption over the study period (9.2 ± 4.3 months) was expressed by two values: the mean overeruption of molar cups (0.432 mm) and the maximum overeruption of cusps (0.753 mm), which were statistically significant compared to the baseline level (p < 0.001). The average tipping was 1.717 degrees in the buccal direction.ConclusionsUnopposed molars displayed overeruption throughout the study period (9.2 ± 4.3 months), which indicates that the clinicians should pay attention to the possibilities of overeruption and make appropriate interventions in their clinical practice. The establishment of three-dimensional measuring methods using cone beam computed tomography data helps analyze spatial changes.