Cone Beam Computed Tomography Scans Research Articles

Does the outcome of graft materials at dental implant sites differ between patients with normal and compromised bone health?

To assess the outcome of bone graft material at alveolar bone augmentation sites combined with dental implants in postmenopausal women with compromised bone health by evaluating cone beam computed tomography (CBCT) scans at multiple time points. CBCT scans were analyzed on 55 postmenopausal women with compromised bone health status to determine the fate of alveolar bone augmentation. CBCT scans were taken immediately after surgery and 9 and 24 months post-operatively. The patient's medication regimens and durations were recorded, and the pixel intensity value (PIV) was measured and standardized using scoring criteria and visual assessment. Statistical analyses included two-sample t-tests for continuous variables and Fisher's exact tests for categorical variables. Among the normal patients, 73% received a grade 2 visual score, and 27% received a grade 1 visual score. After 24 months, 45% of patients received a grade 2 score, and 27% received a grade 3 score. In the osteoporotic group receiving medication, 77% of participants received a grade 1 visual score at the 9-month postoperative evaluation, while 23% received a grade 2 score. At the 24-month assessment, 55% of patients received a grade 1 score, 41% received a grade 2 score, and only 5% received a grade 3 score. Notably, although the graft material did not remodel into native bone, it was a scaffold for implants in controlled osteoporotic patients. The study's results show that the pixel intensity values of particulate graft materials are similar across the three different time points, suggesting that the graft material's pixel intensity value remains constant in postmenopausal women with osteoporosis. The study's limitations include a small sample size and a restricted 24-month follow-up period. This limited time frame may need to capture long-term changes or variations in graft materials adequately. Future research should include a larger sample size and have a longer follow-up duration to provide a more comprehensive understanding of the change in graft materials between patients with normal and compromised bone health.

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

To compare digital panoramic radiography (DPR) and cone beam computed tomography (CBCT) in the detection and classification of pulp calcifications in posterior teeth in relation to tooth condition and its location. 250 patients with simultaneous DPR and CBCT scans were selected from a dental image bank. For each posterior tooth, its condition was registered (healthy, restored, or decayed). The presence of calcifications was assessed and classified according to location (coronal or radicular) and type (total obliteration, partial obliteration, narrowing, and no calcification). Chi-square and McNemar tests were used to compare DPR and CBCT results, with a significance level of 5%. DPR diagnostic values were calculated using CBCT as reference. Decayed and restored teeth showed a significantly (p < 0.001) higher prevalence of pulp calcifications than healthy teeth in both imaging exams. There was a significant discrepancy between the imaging modalities in the identification of calcifications (p < 0.001), especially for radicular calcifications of maxillary teeth (DPR = 55.2%; CBCT = 30.9%). In the case of coronal calcifications, there was a greater discrepancy between CBCT and DPR in the mandibular teeth (10.7%) than in the maxillary teeth (7.7%). Overall, DPR presents higher sensitivity (0.855) than specificity (0.483) for pulp calcifications detection. DPR considerably overestimates pulp calcifications in posterior teeth, as compared to CBCT. A higher prevalence of pulp calcifications is related to decayed and restored teeth.

Create virtual dentoskeletal model by superimposing digital dental cast into cone-beam computed tomography scan.

Many artifacts and obstacles associated with cone-beam computed tomography (CBCT) scan can obscure or distort the details of the teeth and occlusal surface, like distorted teeth, streak artifacts, noise, and some malocclusion cases with excessive overlapping between jaws cause decrease the interocclusal space, which can impact diagnosis and treatment planning, and the 3D reconstruction accuracy. Optimizing dental precision by Integrating CBCT scans with other imaging modalities, supply more information to enhance CBCT accuracy, mainly in dental areas with limited clarity. Performing the Structure-from-Motion (SfM) photogrammetry method, using phone camera and photograph studio setup using simple hardware, to digitize the dental casts and obtain an accurate digital dental model. Using this digital dental model to enhance dental precision in the CBCT data by performing the superimposition process, using a surface-based registration method and integration process to create a virtual dentoskeletal model. Evaluate the accuracy and quality of the superimposition results using qualitative (visual inspection) and quantitative measures. The differences between the virtual dentoskeletal model and the reference CBCT model are calculating by the 3D Euclidean distance, the mean ± SD are 0.212 ± 0.169mm and 0.26 ± 0.149mm for the maxilla and mandible, respectively. The color-coded map shows that the two surfaces are similar, but the extremist values are concentrated in the dental region due to the presence of the noise in the reference model and the gingiva in the virtual dentoskeletal model. The resulting virtual dentoskeletal model can be viewed and manipulated on a computer screen, allowing for a detailed analysis of the teeth and supporting structures. The 3D model generated by the SfM photogrammetry technique did well during the superimposition process, representing a reliable method for virtual-based processing such as orthognathic surgery planning and splint design.

IMPORTANCE OF ASSESSING THE POSITION OF THE INFRA-ORBITAL FORAMEN IN QUAD ZYGOMA OR UNILATERAL DOUBLE ZYGOMA IMPLANT SURGERY.

Evaluate the frequency of occurrence of extreme inferior positioning of the Infraorbital foramen from the infra-orbital rim that can potentially interfere with the placement of Quad or Unilateral Double Zygomatic implants. CBCT scans of 60 patients were read to identify the Infraorbital foramen (IOF)and Infra-orbital rim (IOR). The distances between the two were measured. In cases with increased values, virtual surgical planning was done to evaluate whether two Zygoma implants could be placed in one zygomatic bone. Two out of the 60 cases showed a more inferior location of the IOF, reducing the amount of bone available , thus rendering quad zygoma or unilateral; double zygomatic implants infeasible. Measurement of the distance of the IOF from the IOR is an important step worth incorporating in Quad Zygoma or unilateral double zygoma implant surgery planning.

The relation between persistent foramen tympanicum and degenerative bone alterations in temporomandibular joint region.

The aim of this study was to evaluate, using cone-beam computed tomography (CBCT), the relationship of persistent foramen tympanicum (PFT) with degenerative changes in the temporomandibular joint (TMJ) and the presence of pneumatized glenoid fossae and articular eminences. Two experienced oral and maxillofacial radiologists evaluated 510 CBCT scans, from which 94 patients were divided into two groups: G1-patients with PFT and G2-control group. The location of the PFT, presence, or absence of degenerative TMJ changes and morphology were evaluated. Similarly, all images were evaluated for the presence of pneumatized articular eminence and glenoid fossa. The Chi-square test and Fisher's Exact test were used for the categorical variables. A multinomial logistic regression model was performed for subgroup analysis. To assess the estimation-chance occurrence of TMJ alterations the Odds Ratio analysis was used. Statistically significant results were found for erosion, planning, and subchondral cyst. Regarding TMJ morphology, significant results were found for: round, flat, and others. Moreover, it was possible to observe that patients who had the PFT were approximately 48 times more likely to manifest TMJ alterations and approximately 3 times more likely to manifest articular eminence pneumatization. Since individuals who have FTP have a greater chance of having TMJ and PEA changes, it is important for the dental radiologist to be aware of these signs in CBCT scans for a correct diagnosis. CAAE: 34328214.3.0000.0104 (11/30/2014).

Age estimation by volumetric analysis of teeth using cone beam computed tomography.

To evaluate the feasibility of using the pulp volume (Pv) to total volume (Tv) ratio (Pv:Tv), obtained from cone beam computed tomography (CBCT) scans of single-rooted teeth, for age estimation in a Brazilian population sample. After obtaining approval from the ethics committee, the study commenced by applying inclusion criteria to screen CBCT scans, resulting in a probability-based sample of participants aged 18years and older (ranging from 18 to 82years, with a mean age of 46.44years). A total of 517 single-rooted teeth, including maxillary central incisors (CI), mandibular canines (C), and mandibular first premolars (FP), were chosen based on excellent agreement values (> 0.9). Pv and Tv measurements were conducted using semi-automatic segmentation with ITK-SNAP 3.8 software. Statistical analysis was performed using Jamovi software, with a significance level set at 5% (α = 0.05). A strong negative correlation (r > -0.7) was observed between chronological age and the Pv:Tv ratio across all examined teeth. However, when conducting regression analysis with Pv:Tv data and chronological age as the independent variable, only the mandibular FP teeth exhibited a normal distribution. The resulting linear model demonstrated moderate predictive value (approximately 64%) in explaining the variance in chronological age, but caution should be exercised when interpreting these findings. The method of measuring individual tooth volume using CBCT to estimate chronological age via Pv:Tv has been demonstrated as effective and reproducible within the Brazilian population sample.

Study of the mandibular canal and its surrounding canals by multi-view cone-beam computed tomography

ObjectivesTo determine the mandibular anatomical structures by observing cone-beam computed tomography (CBCT) from multiple angles.Materials and methodsThis retrospective study analyzed 1593 consecutive CBCT images. Ultimately, 95 CBCTs met the inclusion criteria. The mandibular, inferior lingual, and bony canals at the tooth apex were studied by multi-angle observation CBCT. Descriptive statistics were used for statistical analysis.ResultsIt is beneficial to further observe the anastomosis of the mandibular, lingual, and mandibular canals when the course of the mandibular lingual canal is observed on CBCT cross-section. The frequency of the inferior lingual canal anastomosis with the mandibular canal was 43.2% (95% confidence interval (CI) 33, 53.3) in the sample. The mental foramen was located below the long axis of the tooth in a few samples, with an occurrence rate of 29.5% (95% CI 20.1, 38.8). The occurrence rate of various types of the bony canal at the apex of the tooth in canines, first premolars, second premolars, first molars, and second molars under the root apex was recorded through the multi-angle observation of the dental volume reformat (DVR) and three-dimensional (3D) levels in CBCT.ConclusionThis study demonstrates the utility of CBCT imaging in examining mandibular anatomy from multiple angles, providing valuable insights into anatomical variations, and enhancing our understanding of mandibular structures. This research emphasizes the crucial role of meticulous CBCT examination in precisely identifying and understanding key anatomical structures, ultimately reducing the risk of surgical complications.Critical relevance statementBy examining cone-beam computed tomography scans from various perspectives, it is possible to determine the precise position of anatomical structures within the jaw. This allows for a more accurate assessment, reducing the risk of harm to these structures during treatment.Key points• It is crucial to utilize image data effectively to enhance the comprehension of human anatomy.• We captured detailed images of the mandible from different angles and orientations utilizing cone-beam computed tomography (CBCT).• This study provides essential anatomical information for procedural planning to ensure optimal outcomes and patient safety.Graphical

Influence of augmented reality technique on the accuracy of autotransplanted teeth in surgically created sockets

BackgroundThe objective of the present study was to evaluate the reliability of an augmented reality drilling approach and a freehand drilling technique for the autotransplantation of single-rooted teeth. Materials and methodsForty samples were assigned to the following surgical techniques for drilling guidance of the artificial sockets: A. augmented reality technique (AR) (n = 20) and B. conventional free-hand technique (FT) (n = 20). Then, two models with 10 teeth each were submitted to a preoperative cone-beam computed tomography (CBCT) scan and a digital impression by a 3D intraoral scan. Afterwards, the autotrasplanted teeth were planned in a 3D dental implant planning software and transferred to the augmented reality device. Then, a postoperative CBCT scan was performed. Data sets from postoperative CBCT scans were aligned to the planning in the 3D implant planning software to analize the coronal, apical and angular deviations. Student’s t-test and Mann–Whitney non-parametric statistical analysis were used to analyze the results.ResultsNo statistically significant differences were shown at coronal (p = 0.123) and angular (p = 0.340) level; however, apical deviations between AR and FT study groups (p = 0.008) were statistically significant different.ConclusionThe augmented reality appliance provides higher accuracy in the positioning of single-root autotransplanted teeth compared to the conventional free-hand technique.

Cone Beam Computed Tomography-Assisted Percutaneous Nephrolithotomy in a Hybrid Operating Room: Optimization of Patient Selection.

Background: Cone beam computed tomography (CBCT) enables intraoperative cross-sectional and three-dimensional imaging of the urinary tract. CBCT in a hybrid operating room can be used for intraoperative detection of residual stones and potential additional stone extraction at the end of percutaneous nephrolithotomy (PCNL). This study describes our initial experience with intraoperative CBCT during PCNL and analyzes its role in potentially improving its outcomes. Methods: We conducted a single-center retrospective cohort study at a tertiary referral hospital between 2018 and 2021. The study aimed to evaluate the outcome of patients who underwent intraoperative noncontrast CBCT scan during PCNL. The CBCT scan was performed when the urologist determined the kidney to be endoscopically stone-free. In case any residual fragments were imaged, an additional effort was made to extract them. Patients were divided into three groups based on treatment outcome: stone-free upon CBCT, not stone-free with additional stone extraction after CBCT, and not stone-free without additional stone extraction. Procedure and patient characteristics were recorded to identify factors associated with additional stone extraction during CBCT-assisted PCNL. Results: A total of 102 procedures were included in this study. Intraoperative CBCT scans showed residual calcifications in 58 (57%) cases. In 39 cases, which is 38% of the total population and 61% of the cases with residual calcifications, one or more residual fragments imaged on the intraoperative CBCT-scan were extracted additionally within the same procedure. A higher Guy's Stone Score was associated with a higher likelihood of additionally extracting stones as a result of the CBCT. Conclusions: CBCT-assisted PCNL in a hybrid operating room can lead to additional stone extraction in the same procedure in 37% of all cases and in over 60% of the cases in which residual fragments are imaged. The value of CBCT-assisted PCNL appears to increase in the case of more complex stone surgery cases.

The Use of a New Safe Angle Concept for Immediate Implant Placement in the Anterior Maxilla: A Cross-sectional Cone Beam Computed Tomography Study.

The current cross-sectional study aims to introduce a new method for the labiopalatal positioning and angulation of immediately placed dental implants in the anterior maxilla with relation to the type of abutment used (straight/angled abutment). Cone beam computed tomography scans from the database of a private practice were searched for patients who received immediate implants in anterior maxilla. After superimposition of the initial and post-operative scans, incisal/root angle (IRA), incisal/implant angle (IIA) and the difference between both angles were measured. Furthermore, assessment of whether the implant position would be lying within the safe angle or not. Age, gender, tooth/implant site and type of prosthetic abutment (straight/angled) were retrieved from patients' records. Seventy-four patients with a total of 95 immediate implants were selected for analysis. In regard to the type of abutment, 76 (80%) were straight, while 19 abutments (20%) were angled. Regardless of abutment type, 72 implants (75.8%) lay within the safe angle while 23 implants (24.2%) did not lie within the safe angle. All 19 implants with angled abutments were not lying within the safe angle. There was a statistically significant association between type of abutment, IRA, difference between IIA and IRA, gender and lying within the safe angle (P-value <0.001, OR = 19, P-value <0.001, Effect size = 0.904, P-value <0.001, Effect size = 1.209 and P-value <0.001, OR = 2.995 respectively). There was no statistically significant association between IIA, site or age and lying within the safe angle (P-value = 0.757, Effect size = 0.063, P-value = 0.200, Effect size = 0.184 and P-value = 0.387 Effect size = 0.208, respectively). There was a statistically significant association between IRA, difference between IIA and IRA and type of abutment (P-value = 0.001, Effect size = 0.762, P-value <0.001, Effect size = 1.056, respectively). The Safe Angle Concept can be used as a reliable planning tool to choose the correct IIP position in the anterior maxilla. Applying the safe angle concept will decrease the use of angled abutment for prosthetic correction.

Comparing Radiation Doses in CBCT and Medical CT Imaging for Dental Applications

ABSTRACT Background: Dental imaging plays a crucial role in diagnosis and treatment planning, with cone-beam computed tomography (CBCT) and medical computed tomography (CT) being two common modalities. This study aims to compare the radiation doses associated with CBCT and medical CT imaging in dental applications to assess their relative safety and efficacy. Materials and Methods: We conducted a retrospective study using data from 100 patients who underwent both CBCT and medical CT scans for dental purposes. The radiation doses were measured in terms of dose-length product (DLP) for medical CT and dose-area product (DAP) for CBCT. The effective dose (ED) was calculated using appropriate conversion factors. Patient demographics, scan parameters, and radiation doses were recorded and analyzed. Results: The results indicated that the mean DLP for medical CT scans was 220 mGycm, whereas the mean DAP for CBCT scans was 150 mGycm². The corresponding mean effective doses for medical CT and CBCT were 2.5 mSv and 1.8 mSv, respectively. The radiation dose from CBCT was found to be approximately 28% lower than that from medical CT. Conclusion: This study demonstrates that CBCT imaging for dental applications results in significantly lower radiation doses compared to medical CT. While both modalities provide valuable diagnostic information, the choice of imaging technique should consider the balance between diagnostic quality and radiation exposure, especially for pediatric and high-risk patients. Dental practitioners should be aware of the potential dose reduction benefits associated with CBCT when appropriate for the clinical scenario.

The Relationship Between Crown Shape and Root Canal Morphology of Maxillary Second Molars in an Iraqi Sub-population Using Cone Beam Computed Tomography (CBCT)

Objective: This study aimed to look into how crown shape affected the architecture of the root canals.&#x0D; Methods: Nine hundred and fifty-four CBCT scans of maxillary second molars were evaluated. The relation between the crown shapeand sex, root number, and root canals was determined. The frequency of the second canal in the mesiobuccal root (MB2), its agerelation, and the symmetry of the concurrence of anatomical variations in contralateral molars were analyzed. The chi-square test wasused for the analysis of the outcomes. It was deemed significant at P&lt; 0.05.&#x0D; Results: Overall, rhomboidal-shaped crowns comprised 60.1% of all crowns, while heart-shaped crowns made up 39.9%. Three-rootedteeth were the most common (74.5%), followed by two-rooted teeth (11.9%) and one-rooted teeth (8.5%), while four-rooted teeth madeup only 5% of all samples. The most prevalent result in terms of the canal number was three canals (67%), followed by four canals(24.8%), two canals (7.3%), one canal (0.6%), and five canals (0.4%). Males were less likely to have crowns with a heart-shapedstructure than females. The rhomboidal crown (22%) had a higher occurrence of MB2 canals when compared to the heart-shaped crown (2.8%).&#x0D; Conclusions: Given the constraints of this research, it would seem that the rhomboid form of the upper second molar crown is moreprevalent, with a greater tendency to have three and four roots and the presence of MB2 than the heart-shaped form.

Morphometric analysis of the relationship between maxillary posterior teeth and maxillary sinus floor in central Indian population: A cone-beam computed tomography study

Abstract Background: The relationship between the maxillary sinus (MS) and the root apices of posterior teeth is of significant clinical relevance as it influences the diagnosis and treatment planning when operating in the posterior areas of the maxilla. The aim of this study, therefore, is to assess this anatomic relationship and evaluate the propensity of roots of posterior maxillary teeth to be intruded into the MS space using cone-beam computed tomography (CBCT) scanning. Materials and Methods: One thousand CBCT scans of patients, aged 20 years or above, were analyzed in the study. The distance from the MS floor to the root apices of the posterior teeth was measured and the relationship between the MS and the posterior teeth roots were recorded, based on Kwak’s and Didilescu’s classification. Results: Based on Kwak’s classification, type I configuration was frequently observed in the maxillary posterior teeth, followed by type II. Based on Didilescu’s classification, the longest distance, among premolars, was observed between the palatal root of the left 1st premolar and MS, i.e., 8.2467 mm. Among molars, the longest distance was observed between mesiobuccal root of the right first molar and MS, i.e., 5.8966 mm. The shortest distance, among premolars, was observed between the buccal root of the left second premolar and MS, i.e., 3.5500 mm, and among molars, the shortest distance was between the mesiobuccal root of the left second molar and MS, i.e., 1.3556 mm. Conclusion: From the present study, it may be concluded that, among the central Indian population, mesiobuccal root of the second molars and buccal root of the second premolars show the closest proximity to the MS floor. Therefore, any surgical or endodontic intervention in the vicinity of these roots must be performed with utmost care.

Accuracy of augmented reality-guided needle placement for pulsed radiofrequency treatment of pudendal neuralgia: a pilot study on a phantom model.

Pudendal neuralgia (PN) is a chronic neuropathy that causes pain, numbness, and dysfunction in the pelvic region. The current state-of-the-art treatment is pulsed radiofrequency (PRF) in which a needle is supposed to be placed close to the pudendal nerve for neuromodulation. Given the effective range of PRF of 5 mm, the accuracy of needle placement is important. This study aimed to investigate the potential of augmented reality guidance for improving the accuracy of needle placement in pulsed radiofrequency treatment for pudendal neuralgia. In this pilot study, eight subjects performed needle placements onto an in-house developed phantom model of the pelvis using AR guidance. AR guidance is provided using an in-house developed application on the HoloLens 2. The accuracy of needle placement was calculated based on the virtual 3D models of the needle and targeted phantom nerve, derived from CBCT scans. The median Euclidean distance between the tip of the needle and the target is found to be 4.37 (IQR 5.16) mm, the median lateral distance is 3.25 (IQR 4.62) mm and the median depth distance is 1.94 (IQR 7.07) mm. In this study, the first method is described in which the accuracy of patient-specific needle placement using AR guidance is determined. This method could potentially improve the accuracy of PRF needle placement for pudendal neuralgia, resulting in improved treatment outcomes.

Accuracy of cone-beam computed tomography in imaging the components of the periodontal phenotype.

The components and dimensions of the periodontal and peri-implant phenotype have a high relevance in contemporary dental research and should be taken into consideration in the decision-making process in the management of a variety of clinical scenarios to optimize the outcomes of therapy. Various assessment methods for quantifying and classifying the phenotypical dimensions have emerged and developed in recent decades. Nevertheless, the use of cone-beam computed tomography (CBCT) scans remains the most commonly used approach worldwide. However, the accuracy to adequately imaging and measuring the dimensions of the hard and soft tissue components around teeth may represent a significant challenge in different clinical scenarios due to factors such as the age of the patient and motion during the scan, presence of metallic artifacts causing streaks and gray-value distortion, overlapping of soft tissue structures, machine performance, file processing, and small voxel size among others. These factors pose a particular challenge when tiny structures are under investigation, for example, the buccal/lingual bony or soft tissue layer of lower/upper incisors. Therefore, this review addresses the underlying technical information of the use of CBCT scans, and suggests some recommendations on the utilization of this method of assessment to optimally use it despite its' system-inherent limitations.

Estimation of organ and effective doses of CBCT scans of radiotherapy using size-specific field of view (FOV): a Monte Carlo study.

The kV cone beam computed tomography (CBCT) is one of the most common imaging modalities used for image-guided radiation therapy (IGRT) procedures. Additional doses are delivered to patients, thus assessment and optimization of the imaging doses should be taken into consideration. This study aimed to investigate the influence of using fixed and patient-specific FOVs on the patient dose. Monte Carlo simulations were performed to simulate kV beams of the imaging system integrated into Truebeam linear accelerator using BEAMnrc code. Organ and size-specific effective doses resulting from chest and pelvis scanning protocols were estimated with DOSXYZnrc code using a phantom library developed by the National Cancer Institute (NCI) of the US. The library contains 193 (100 male and 93 female) mesh-type computational human adult phantoms, and it covers a large ratio of patient sizes with heights and weights ranging from 150 to 190cm and 40 to 125kg. The imaging doses were assessed using variable FOV of three sizes, small (S), medium (M), and large (L) for each scan region. The results show that the FOV and the patient size played a major role in the scan dose. The average percentage differences (PDs) for doses of organs that were fully inside the different FOVs were relatively low, all within 11% for both protocols. However, doses to organs that were scanned partially or near the FOVs were affected significantly. For the chest protocol, the inclusion of the thyroid in the scan field could give a dose of 1-7mGy/100mAs to the thyroid, compared to 0.4-1mGy/100mAs when it was excluded. Similarly, on average, testes doses could be 6mGy/100mAs for the male pelvis protocol compared to 3mGy/100mAs when it did not lie in the field irradiated. These dose differences resulted in an average increase of up to 27% in the size-specific effective dose of the protocols. Since changing the field size is possible for CBCT scans, the results suggest that patient-specific scanning protocols could be applied for each scan area in a manner similar to that used for CT scans. Adjustment of the FOV size should be subject to the clinical needs, and assist in improving the treatment accuracy. The patient's height and weight might be considered as the main factors upon which, the selection of the appropriate patient-specific protocol is based. This approach should optimize the imaging doses used for IGRT procedures by minimizing doses of a large ratio of patients.

Evaluation of 3D C-Arm Fluoroscopy versus Diagnostic CT for Deep Brain Stimulation Stereotactic Registration and Post-Operative Lead Localization

Introduction: DBS efficacy depends on accuracy. CT-MRI fusion is established for both stereotactic registration and electrode placement verification. The desire to streamline DBS workflows, reduce operative time, and minimize patient transfers has increased interest in portable imaging modalities such as the Medtronic O-arm^® and mobile CT. However, these remain expensive and bulky. 3D C-arm fluoroscopy (3DXT) units are a smaller and less costly alternative, albeit incompatible with traditional frame-based localization and without useful soft tissue resolution. We aimed to compare fusion of 3DXT and CT with pre-operative MRI to evaluate if 3DXT-MRI fusion alone is sufficient for accurate registration and reliable targeting verification. We further assess DBS targeting accuracy using a 3DXT workflow and compare radiation dosimetry between modalities. Methods: Patients underwent robot-assisted DBS implantation using a workflow incorporating 3DXT which we describe. Two intra-operative 3DXT spins were performed for registration and accuracy verification followed by conventional CT post-operatively. Post-operative 3DXT and CT images were independently fused to the same pre-operative MRI sequence and co-ordinates generated for comparison. Registration accuracy was compared to 15 consecutive controls who underwent CT-based registration. Radial targeting accuracy was calculated and radiation dosimetry recorded. Results: Data were obtained from 29 leads in 15 consecutive patients. 3DXT registration accuracy was significantly superior to CT with mean error 0.22 ± 0.03 mm (p < 0.0001). Mean Euclidean electrode tip position variation for CT to MRI versus 3DXT to MRI fusion was 0.62 ± 0.40 mm (range 0.0 mm–1.7 mm). In comparison, direct CT to 3DXT fusion showed electrode tip Euclidean variance of 0.23 ± 0.09 mm. Mean radial targeting accuracy assessed on 3DXT was 0.97 ± 0.54 mm versus 1.15 ± 0.55 mm on CT with differences insignificant (p = 0.30). Mean patient radiation doses were around 80% lower with 3DXT versus CT (p < 0.0001). Discussion: Mobile 3D C-arm fluoroscopy can be safely incorporated into DBS workflows for both registration and lead verification. For registration, the limited field of view requires the use of frameless transient fiducials and is highly accurate. For lead position verification based on MRI co-registration, we estimate there is around a 0.4 mm discrepancy between lead position seen on 3DXT versus CT when corrected for brain shift. This is similar to that described in O-arm^® or mobile CT series. For units where logistical or financial considerations preclude the acquisition of a cone beam CT or mobile CT scanner, our data support portable 3D C-arm fluoroscopy as an acceptable alternative with significantly lower radiation exposure.

Three-dimensional evaluation of interproximal contacts of permanent dentition: a cone beam computed tomography study.

To assess the various patterns of the inter-proximal contact areas of the permanent dentition using the available cone beam computed tomography (CBCT) images. A retrospective cross-sectional study was performed on existing CBCT images from a University hospital and teaching department. Three thousand two hundred and fifty inter-proximal contacts were assessed from 125 existing CBCT scans of patients (age range: 14years 3months-29years 9months) who had matched the eligibility criteria. The types of inter-proximal contacts of the permanent dentition were scored at occlusal, middle, and cervical thirds, according to the OXIS inter-proximal contacts classification. Chi-square test was used to assess the contacts and gender/arches. The most prevalent contact was type I for the posterior teeth contacts, and types S1 and S2 for the anterior teeth contacts. Statistical significance was not observed between the contacts on the left and right sides (P > 0.05), while statistical significance was observed between the inter-proximal contacts of the maxilla and mandible (P < 0.05). The CBCT-based three-dimensional assessment of the inter-proximal contact areas of the permanent dentition is representative of the OXIS classification. The occlusal level contact was predominantly representative of the overall type of the contact.

A carbon nanotube x-ray source array designed for a new multisource cone beam computed tomography scanner

Cone beam computed tomography (CBCT) is known to suffer from strong scatter and cone beam artifacts. The purpose of this study is to develop and characterize a rapidly scanning carbon nanotube (CNT) field emission x-ray source array to enable a multisource CBCT (ms-CBCT) image acquisition scheme which has been demonstrated to overcome these limitations. A CNT x-ray source array with eight evenly spaced focal spots was designed and fabricated for a medium field of view ms-CBCT for maxillofacial imaging. An external multisource collimator was used to confine the radiation from each focal spot to a narrow cone angle. For ms-CBCT imaging, the array was placed in the axial direction and rapidly scanned while rotating continuously around the object with a flat panel detector. The x-ray beam profile, temporal and spatial resolutions, energy and dose rate were characterized and evaluated for maxillofacial imaging. The CNT x-ray source array achieved a consistent focal spot size of 1.10 ± 0.04 mm × 0.84 ± 0.03 mm and individual beam cone angle of 2.4° ± 0.08 after collimation. The x-ray beams were rapidly switched with a rising and damping times of 0.21 ms and 0.19 ms, respectively. Under the designed operating condition of 110 kVp and 15 mA, a dose rate of 8245 μGy s−1 was obtained at the detector surface with the inherent Al filtration and 2312 μGy s−1 with an additional 0.3 mm Cu filter. There was negligible change of the x-ray dose rate over many operating cycles. A ms-CBCT scan of an adult head phantom was completed in 14.4 s total exposure time for the imaging dose in the range of that of a clinical CBCT scanner. A spatially distributed CNT x-ray source array was designed and fabricated. It has enabled a new multisource CBCT to overcome some of the main inherent limitations of the conventional CBCT.

Is there an advantage to delayed molar implant placement in those with chronic apical periodontitis?

This paper is a single-centre, double-blinded, prospective randomised control trial, comparing immediate vs delayed implant placement clinically and radiographically in patients with chronic periodontitis, specifically assessing the molar region. Seventy-four patients were recruited to the study over a one-year period, all of whom returned for follow up throughout the study. The study adhered to the principles outlined in the Declaration of Helsinki and obtained ethical approval from the affiliated University Hospital of Qingdao. Written consent was gained from patients in line with the CONSORT guidance. The patients were recruited from the Department of Oral and Maxillofacial Surgery at the University of Qingdao between January 2019 and January 2020. The study included anyone above the age of 18, who had a molar with chronic apical periodontitis and lesions of less than 8 mm. Exclusions included pregnancy, uncontrolled diabetes, smokers, bisphosphonate use, history of head/neck tumours, coagulation disorders, and acute infections of adjacent teeth/tissue. Of the patients who met the inclusion criteria, all were randomly numbered by a stomatologist and placed into either the control group or the experimental group by a computerised system (Microsoft Excel). This study looked at the placement of 74 implants in 74 patients, including 40 female and 34 malepatients in total. The delayed implant placement allowed for healing of 3 months in the mandible and 6 months in the maxilla. The width of the implants placed was 6 mm and the lengths were between 7 mm and 12 mm.The periodontal probing depth, modified sulcus bleeding index, andmodified plaque index were all clinically examined. In terms of other parameters assessed, CBCT was used to look at alveolar bone mass. All surgery and implant placement was carried out by the same surgeon and the clinical measurements were all taken by one dentist. The results showed no significant difference in implant stability quotient immediately and 6 months post-surgery (0.110 and 0.066, respectively), when comparing the experimental and control group. Similarly, there was no significant difference in PD, mSBI or mPI between the groups. On assessment of CBCT scans however there was a significant difference between the two groups in the buccal horizontal marginal bone loss (P = 0.003), lingually there was not. Vertical bone loss also showed no significant difference in comparison. At one-year post-implant placement, there was a survival rate of 100% in both groups assessed. IBM SPSS statistics was used for statistical analysis. Multiple tests including the Shapirowilk test, the student t-test and the Mann-Whitney U-test were carried out on the data and all statistical tests were two tailed. Statistical significance was set at <0.05 throughout study of results. The conclusion of this study suggests that immediate implant placement in chronic periodontitis patients, specifically in the molar region, may be clinically viable. With flap surgery and complete removal of inflammatory granulation tissue, the study suggests no significant disadvantage to alveolar bone healing or osseointegration. The various limiting factors of this study should be taken into consideration, and it must be highlighted that longer and larger studies are necessary to allow for more accurate understanding of the long-term outcomes.