Cone Beam Computed Tomography Scans Research Articles

Correction of scatter in CBCT with a new grid design

Objective. This study aims at developing a simple and rapid Compton scatter correction approach for cone-beam CT (CBCT) imaging. Approach. In this work, a new Compton scatter estimation model is established based on two distinct CBCT scans: one measures the full primary and scatter signals without anti-scatter grid (ASG), and the other measures a portion of primary and scatter signals with ASG. To accelerate the entire data acquisition speed, a half anti-scatter grid (h-ASG) that covers half of the full detector surface is proposed. As a result, the distribution of scattered x-ray photons could be estimated from a single CBCT scan. Physical phantom experiments are conducted to validate the performance of the newly proposed scatter correction approach. Main results. Results demonstrate that the proposed half grid approach can quickly and precisely estimate the distribution of scattered x-ray photons from only one single CBCT scan, resulting in a significant reduction of shading artifacts. In addition, it is found that the h-ASG approach is less sensitive to the grid transmission fractions, grid ratio and object size, indicating a robust performance of the new method. Significance. In the future, the Compton scatter artifacts can be quickly corrected using a half grid in CBCT imaging.

Anatomical characteristics of mental foramen and canal: A cone-beam computed tomography analysis.

So far, different studies have endeavored to evaluate the position and dimensions of mental foramen and canal using cone-beam computed tomography (CBCT) images with various results. This study aimed to assess the anatomical variations of the mental foramen and canal utilizing CBCT images. In this retrospective observational study, we investigated CBCT scans of 355 patients (710 terminal branches of mental canal and foramen) who were referred to a private dental and maxillofacial radiology center in Babol, during 2020-2022. We recorded different anatomical variations of mental foramina and canals on left (n=355) and right (n=355) mandibles. Most of the mental canals had a distal opening (n=334, 47.0%). The distance between the mental foramen and the lower mandibular border was greater on left mandible (13.92±3.73 mm) than on the right mandible (12.25±3.94 mm) (p<0.001). On left mandible, the vertical diameter of the mental foramen, as well as the distance between the mental foramen and the lower mandibular border, were significantly greater in men than in women. On right mandible, the distance between the mental foramen and the upper alveolar crest edge, as well as the distance between the mental foramen and the lower mandibular border, were significantly greater in men versus women. Finally, on right mandible, the vertical diameter of the mental foramen was significantly greater in subjects aged >45 years compared with those aged ≤45 (p=0.024). There were notable variations in the morphological characteristics of the mental foramen and canal, which should be considered by clinicians. Key words:Mental foramen, mental canal, cone-beam computed tomography.

Exploring the age and gender-based distribution of paranasal sinus osteomas using cone beam computed tomography: A retrospective cross-sectional study

ObjectiveThe objective of this study is to explore the prevalence, size, location and radiographic features of osteomas in the paranasal sinuses using cone beam computed tomography imaging. Study designThis study was planned as retrospective cross-sectional. 499 consecutive cone beam computed tomography scans obtained in a dentomaxillofacial radiology department for various dental indications. Statistical analysis of all data was done with SPSS version 22. Descriptive statistics and chi-square tests were used to determine the prevalence of categorical parameters. ResultsOsteoma was detected in 7 % (n = 35) of the 499 images analyzed. The age of the patients ranged from 6 to 96 years (mean 42.03 ± 18.70). No significant difference was found between the genders (p = 0.77). In terms of localization, it was significantly more common in the ethmoid sinuses (p < 0.01). Cortical type osteoma was observed the most frequently in the analyzed images (p < 0.01). The incidence of osteoma was not significant depending on age (p = 0.50). ConclusionOsteomas in the paranasal sinuses show a 7 % prevalence in CBCT images, with the ethmoid sinus being the most common site. The average size of osteomas was 3.43 ± 1.78 mm, predominantly cortical in type. These findings highlight the necessity for thorough examination of CBCT images by dentomaxillofacial radiologists to avoid overlooking osteomas.

Gender-Specific Variations in Greater Palatine Foramen Anatomy: Insights from CBCT Scans in the North Cyprus Population.

BACKGROUND The greater palatine foramen (GPF) is anatomically located distal to the third maxillary molar tooth, midway between the midline of the palate and the dental arch. The GPF contains the major palatine artery, vein, and nerve, traversing the palatine sulcus. This study aimed to evaluate the anatomical position of the GPF in 93 women and 67 men at a single center in Cyprus using cone beam computed tomography (CBCT). MATERIAL AND METHODS A retrospective analysis was conducted on 160 CBCT scans. Measurements of the GPF's horizontal and vertical diameters, distances from GPF to the incisive foramen, posterior nasal spine, anterior nasal spine, and midaxillary suture, and positional relationships to molars were recorded. Statistical analyses compared these measurements between males and females. RESULTS The study included 93 females and 67 males with an average age of 46.6 (±11.6) years. Significant sex differences were observed in most GPF measurements, with males showing larger dimensions such as the anterior nasal spine, posterior nasal spine, mid-maxillary suture, and incisive foramen to the GPF. The GPF was predominantly located in the third molar region (96.25% on the right, 96.9% on the left). The left GPF showed a significantly larger horizontal diameter than the right (P<0.05). CONCLUSIONS There was a significant difference in the average distances from the anterior nasal spine, posterior nasal spine, mid-maxillary suture, and incisive foramen to the GPF, as well as in the size of the GPF, between males and females. Recognizing these variations enhances clinical planning and reduces the risk of complications.

Alveolar ridge bone changes in patients treated with the split-crest technique with simultaneous implant placement: Aretrospective longitudinal observational study.

To investigate long-term alveolar ridge bone changes in patients treated with the split-crest technique (SCT) with simultaneous implant placement. Alveolar ridge width (ARW) was measured with a caliper immediately before (ARW1) and after SCT (ARW2) with a caliper. Existing CBCT scans taken at least 5 years postoperatively were used to assess the healed ARW (ARWF), buccal bone thickness (BBT), and lingual/palatal bone thickness (L/PBT) at 0, 3, and 5 mm apically from implant platform level (IPL). The distance between IPL and buccal bone crest (IPL-BBC) was also measured. Findings were compared with Wilcoxon and Student's t tests (p < .05). Records of thirty patients with 85 implants were included. Eleven patients (31 implants) presented CBCT scans taken in two separate occasions, resulting in 116 measurements. Tomographic follow-up ranged from 5 to 18 years (11.5 ± 4.18 years). Mean ARW increased from 3.2 ± 0.6 to 6.6 ± 0.48 mm after SCT, but significantly reduced overtime to 4.46 ± 0.83 mm (ARWF) (p < .0001). Mean BBT was 0.5 ± 0.9, 1.3 ± 0.9, and 2.0 ± 1.2 mm, while mean L/PBT was 0.9 ± 0.7, 1.6 ± 0.9, and 2.1 ± 1.0 mm at 0, 3, and 5 mm from IPL, respectively. IPL-BBC distance varied up to 8.7 mm (1.4 ± 2.0 mm), with 56/116 measurements (51/85 implants) showing IPL-BBC = 0 mm. Although SCT with simultaneous implant placement can predictably increase ARW postoperatively, ARW tended to significantly reduce over time, due to reductions in BBT and L/PBT, especially coronally. Nonetheless, 60% of the implants still presented some buccal bone at IPL.

A novel digital way to measure the vertical and horizontal dimensions of the supra-crestal peri-implant soft tissues.

To report on a novel digital superimposition workflow that enables measuring the supra-crestal peri-implant soft tissue dimensions all along implant treatment and afterwards. A preoperative CBCT and intra-oral scans (IOS) are successively taken before surgery, at the end of the healing period, at prosthesis delivery, and over time; they are digitally superposed on a dedicated software. Then, the stereolithography files (STL) of the healing abutment, of the prosthetic abutment and the crown are successively merged into the superposition set of IOSs. The workflow protocol of merging successively the STL of each item into the superposition set of IOSs enables capturing the dimensions of the height and width of the supra-crestal soft tissues, at every level of the healing abutment, the prosthetic abutment and the crown. In addition, it allows measuring the vertical distance that the crown exerts pressure on the gingiva and the thickness of the papillae at every level of the abutment. This novel digital superimposition workflow provides a straightforward method of measuring the vertical and horizontal dimensions of the supra-crestal peri-implant soft tissues, including the papillae, at each stage of the implant treatment process. It allows investigating a certain number of soft tissue variables that were previously inaccessible to clinical research. It should help enhancing our comprehension of the peri-implant soft tissue dynamics.

The Role of Bone Tacks in Sinus Floor Lift Surgery: A Single-Center Experience.

Background: Maxillar atrophy is a prevalent condition associated with diminished bone volume, which precludes the conventional placement of dental implants. Sinus floor lift is a surgical procedure that aims to address this atrophy through the insertion of a graft within the sinus cavity. A multitude of techniques have been documented in the international literature for the management of the sinus bone window, though each approach has its own set of advantages and disadvantages. Methods: The present study is a retrospective analysis of traditional sinus floor lift surgery, comparing the outcomes of two surgical approaches: placement of a collagen membrane over the maxillary lateral bone window with or without bone tacks. The study enrolled a total of 48 consecutive patients. Twenty-four patients underwent sinus floor lift surgery, with the placement of a collagen membrane over the maxillary lateral bone window without bone tacks (control group). The remaining 24 patients underwent the same procedure, but with bone tacks (study group). All patients received an amoxicillin 875 mg + clavulanic acid 125 mg administration for six days and underwent Cone Beam Computed Tomography (CBCT) before the sinus floor lift surgery and six months later before the implant surgery. The parameters measured on the preoperative Cone Beam Computed Tomography (CBCT) scan included residual bone, the preoperative thickness of the lateral bone in the center, and the distance between the lateral wall and the medial wall of the sinus. Only the bone height increment was measured on the postoperative CBCT scan. Postoperative complications and the visual analogue scale (VAS) score were also recorded. A statistical analysis was performed, and the correlation between the parameters was evaluated using Pearson's correlation coefficient. A comparison of the mean of the parameters between the treatment group and the control group was conducted using the t-test. Results and Conclusions: The study group was found to have superior outcomes in terms of bone height increment (p = 0.001) and VAS after 7 days (p = 0.11) compared to the control group. The novel application of bone tacks on the collagen membrane over the bone window following sinus elevation surgery was associated with superior outcomes in terms of bone height and reduced pain at seven days, as measured by the VAS, with no postoperative complications.

Comprehensive analysis of root canal morphology in maxillary premolars among the Pakistani subpopulation: a CBCT-based study

BackgroundUnderstanding the root canal morphology is essential for the success of root canal treatment. Therefore, this study aimed to evaluate and analyze the root canal configuration of maxillary premolars using Cone Beam Computed Tomography in the Pakistani subpopulation.MethodThis cross-sectional study utilized CBCT scans from two distinct centres: Aga Khan University in Karachi and Jinnah MRI and Body Scans in Lahore. The CBCT images were visualized using GALAXIS version 1.9 (SICAT GmbH and Co. KG, Bonn, Germany), integrated within the Sirona Dental System (D-64625 Bensheim, Germany). The scanning parameters were standardized at 85 kV, 7 mA, with a 15-s exposure time and a voxel size of 0.16 mm. A total of 707 CBCT scans were collected, encompassing 2180 maxillary premolars. Root canal configurations were classified based on (Ahmed et al. Int Endod J. 2017;50(8):761–70). Statistical analyses were performed using SPSS version 26, employing the Chi-square test with a significance level set at p < 0.05.ResultsThe distribution of root canal morphologies varied significantly with age and gender. Among maxillary premolars, 50% exhibited the typical configuration of 2MPMB1 L1 (two roots, single canal in each buccal and lingual root), while 26% of maxillary right second premolars displayed 1MPM1 (one root, one canal). Overall, 1MPM1 accounted for 27.4% of the total cases in the second premolars. There was no statistically significant relationship between age and root canal distribution in either first premolars (p = 0.338) or second premolars (p = 0.833). Regarding gender, a significant difference was observed in the distribution of right maxillary 1st premolars (p = 0.022*), with a higher prevalence among females.ConclusionThis study offers significant insights into the anatomical variations of root canals in maxillary premolars across diverse regional subpopulations in Pakistan. While specific root canal configurations were prevalent, the findings indicate no statistically significant correlation between age and root canal morphology in maxillary premolars. However, a notable gender disparity was observed in the distribution of the right maxillary first premolars.

The added value of a new high-performance ring-gantry CBCT imaging system for prostate cancer patients

Background and purposeA novel Cone-Beam Computed Tomography (CBCT) named HyperSight provides superior CBCT image quality compared to conventional ring gantry CBCT imaging, and it is suitable for dose calculations for prostate cancer, but it comes with considerable additional costs. The aim of this study was to determine the added value of HyperSight CBCT imaging compared to conventional CBCT imaging in terms of organ visibility in the male pelvic region. Materials and methodsTwenty prostate cancer patients were included in this prospective clinical study. For each patient three CBCT pairs, consisting of HyperSight and conventional CBCT scans acquired on consecutive days, were included. CBCT scans were evaluated by four observers in terms of visibility of the prostate, bladder, rectum and seminal vesicles. Visibility was scored on a 1-to-5 scale and by annotating axial slices where the organs were hard to delineate. Lastly, observers indicated whether the CBCT scans were of sufficient quality for an online adaptive radiation therapy workflow. ResultsAll four organs were better visible on HyperSight CBCT scans compared to conventional CBCT scans. The mean visibility scores increased from 3.1 to 4.5 on a 1––5 scale of and the mean number of annotated slices reduced from 4.5 to 1.1. 99% Of the HyperSight CBCT scans were considered suitable for an online adaptive workflow vs 25–83% for the conventional CBCT scans. ConclusionHyperSight CBCT scans yielded a visibility of prostate, bladder, rectum and seminal vesicles comparable to planning CT scans and, can replace a repeat planning CT scan in case of anatomical changes requiring a new treatment plan.

Personalized Deep Learning Model for Clinical Target Volume on Daily Cone Beam Computed Tomography in Breast Cancer Patients

PurposeHerein, we developed a deep learning algorithm to improve the segmentation of the clinical target volume (CTV) on daily cone-beam computed tomography (CBCT) scans in breast cancer radiotherapy. By leveraging the Intentional Deep Overfit Learning (IDOL) framework, we aimed to enhance personalized image-guided radiotherapy (IGRT) based on patient-specific learning. MethodsWe utilized 240 CBCT scans from 100 breast cancer patients and employed a two-stage training approach. The first stage involved training a novel general deep learning model (Swin UNETR, UNET, and SegResNET) on 90 patients. The second stage utilized intentional overfitting on the remaining 10 patients for patient-specific CBCT outputs. Quantitative evaluation was conducted using the Dice Similarity Coefficient (DSC), Hausdorff Distance (HD), mean surface distance (MSD), and independent samples t-test with expert contours on CBCT scans from the 1st to 15th fractions. ResultsIDOL integration significantly improved CTV segmentation, particularly with the Swin UNETR model (p-values <0.05). Using patient-specific data, IDOL enhanced the DSC, HD, and MSD metrics. The average DSC for the 15th fraction improved from 0.9611 to 0.9819, the average HD decreased from 4.0118 mm to 1.3935 mm, and the average MSD decreased from 0.8723 to 0.4603. Incorporating CBCT scans from the initial treatments and 1st to 3rd fractions further improved results, with an average DSC of 0.9850, an average HD of 1.2707 mm, and an average MSD of 0.4076 for the 15th fraction, closely aligned with physician-drawn contours. ConclusionCompared with a general model, our patient-specific deep learning-based training algorithm significantly improved CTV segmentation accuracy of CBCT scans in patients with breast cancer. This approach, coupled with continuous deep learning training using daily CBCT scans, demonstrated enhanced CTV delineation accuracy and efficiency. Future studies should explore the adaptability of the IDOL framework to diverse deep learning models, datasets, and cancer sites.

Computer-Assisted Implant Planning: A Review of Data Registration Techniques.

Computer-assisted implant planning allows for a comprehensive treatment plan by combining radiographic data provided by a Cone Beam Computed Tomography (CBCT) with surface optical scan (IOs) data that includes patient intraoral situation and the intended restorative planning. Integrating a tailored restorative design with the patient's anatomical conditions through virtual implant planning allows for an ideal bio-restorative treatment planning to maximize biological, functional, and esthetic outcomes. This article discusses dataset registration techniques that combine radiographic CBCT data with restorative information as the main path to create a virtual patient. The described techniques include the use of removable radiographic templates with radiopaque markers, dual scan technique, and direct digital file registration of intra-oral scans using anatomical references. Depending on the individual clinical situation, different factors must be considered to appropriately select methods that achieve an optimal registration of diverse datasets. An inherent challenge lies in the presence of scattering artifacts in CBCT scans. Two approaches are proposed for these situations - the use of chairside-fabricated composite resin markers or adhesive spot-markers fabricated for the use with CBCT scans. Both techniques exhibit limitations that need to be taken into consideration. Further approaches should be developed for situations involving scattering in CBCT.

Relationship Between Gingival Thickness and Other Periodontal Phenotypical Features: A Cross-Sectional Study.

This study aimed at characterizing the gingival thickness (GT) and determining correlations with other local phenotypical features. Cone-beam computed tomography scans from adult subjects involving the maxillary anterior teeth were obtained to assess buccal GT at different apico-coronal levels, periodontal supracrestal tissue height (STH), the distance from the cementoenamel junction to the alveolar bone crest (CEJ-BC), and bucco-lingual tooth dimensions in mm. A total of 100 subjects and 600 maxillary anterior teeth constituted the study sample. Variations in mean values of GT were observed as a function of apico-coronal level, tooth type, and gender. GT progressively increased apically. Maxillary central incisors and males generally exhibited thicker GT. Contrarily, females exhibited thinner GT and shorter STH. Tooth dimensions were negatively correlated with GT, as the narrower the tooth crown/root in the bucco-lingual dimension, the thicker the gingiva. GT at the level of the CEJ was dichotomized to differentiate between thin (<1mm) and thick (≥1mm) gingival phenotypes (GP). Teeth with a thin GP displayed greater CEJ-BC and buccolingual tooth width dimensions. Conversely, teeth with a thick GP generally exhibited taller STH and narrower tooth dimensions.

Expression of artefacts from different orthodontic brackets and wires in cone beam computed tomography scans-an in vitro study.

To investigate artefacts produced by different orthodontic brackets and wires in cone-beam computed tomography (CBCT) scans. Two dental arches were made using extracted human teeth and plaster. Three pairs of acetate plates containing different brackets - metallic, ceramic, and self-ligating ceramic with NiTi clip - along with a control plate (i.e., without brackets) were prepared. Wire changes (NiTi and steel) were made during CBCT acquisitions, performed with a fixed exposure protocol. Axial slices were selected for mean gray values and standard deviation measurement in three regions of interest (buccal, lingual, and tooth). Noise and contrast-to-noise ratio (CNR) were calculated and compared among the different brackets and wires by ANOVA with a significance level of 5%. Overall, the buccal and tooth region were mostly affected by the metallic and self-ligating brackets, showing higher noise, and lower CNR (p < 0.05). On the other hand, less impact of ceramic brackets in the image quality was observed (p ≥ 0.05). The lingual region did not show expressive differences among the brackets and wire combinations (p ≥ 0.05). The presence of wire associated with the brackets did not worsen image quality (p ≥ 0.05). In conclusion, metallic and self-ligating brackets have greater artefact expression than ceramic brackets. The wire did not influence image quality. One should pay attention to the type of brackets when requesting a CBCT scan during treatment, as metallic and self-ligating brackets may express greater artefacts than ceramic brackets.

Position and root resorption of the incisors following anterior segment retraction using friction versus frictionless mechanics: A randomised controlled trial.

To evaluate the three-dimensional position and root resorption of incisors after anterior segment retraction (ASR) using friction versus frictionless mechanics. Thirty female patients (13-18 years) with bimaxillary protrusion were randomly allocated into two groups. In the intervention group, ASR was undertaken using an elastomeric chain rendering 160 g/side extending between mini-screw implant and a hook crimped on 0.017 × 0.025-inch stainless-steel wire distal to the lateral incisor. In the comparison group, ASR was undertaken using closing T-loops fabricated from 0.017 × 0.025-inch titanium molybdenum alloy (TMA) wire rendering comparable retraction force. In both groups, the canine brackets were ligated after retraction to the mini-screw implants that were inserted in both the upper and lower arches bilaterally. The primary outcome was the three-dimensional changes in the position of the incisors. The secondary outcome was root resorption. These were measured from cone-beam computed tomography scans. Statistically significant decreases in the upper (UI) and lower incisors (LI) crown torque were seen in both groups; however, the difference between groups was not statistically or clinically significant (UI MD -2.04°; 95% confidence interval [CI] = -8.02-3.95; LI MD -0.49°; 95% CI = -7.06-6.08). Significant tipping of upper (MD -1.17°; 95% CI = -2.06--0.27) and lower (MD -1.13°; 95% CI = -1.66--0.60) incisors was found in the friction, but not the frictionless group after retraction; however, the changes were not clinically significant. Significant lower incisor intrusion was found in both groups after retraction; however, the difference between groups was not statistically or clinically significant (MD -0.61°; 95% CI = -1.99-0.77). Statistically significant decreases in the UI and LI root length were seen in both groups. The difference between groups for UI changes was statistically significant (MD 0.54 mm; 95% CI = -0.02-1.07) but probably not clinically significant. Considering the limitations in the current study, there was no advantage of either mechanics over the other regarding the final position of incisors. The likelihood of root resorption should be considered when frictionless mechanics are used for retraction of incisors. Clinicaltrials.gov (NCT04878939).

Modelling systematic anatomical uncertainties of head and neck cancer patients during fractionated radiotherapy treatment

Objective. Head and neck cancer patients experience systematic as well as random day to day anatomical changes during fractionated radiotherapy treatment. Modelling the expected systematic anatomical changes could aid in creating treatment plans which are more robust against such changes. Approach. Inter- patient correspondence aligned all patients to a model space. Intra- patient correspondence between each planning CT scan and on treatment cone beam CT scans was obtained using diffeomorphic deformable image registration. The stationary velocity fields were then used to develop B-Spline based patient specific (SM) and population average (AM) models. The models were evaluated geometrically and dosimetrically. A leave-one-out method was used to compare the training and testing accuracy of the models. Main results. Both SMs and AMs were able to capture systematic changes. The average surface distance between the registration propagated contours and the contours generated by the SM was less than 2 mm, showing that the SM are able to capture the anatomical changes which a patient experiences during the course of radiotherapy. The testing accuracy was lower than the training accuracy of the SM, suggesting that the model overfits to the limited data available and therefore, also captures some of the random day to day changes. For most patients the AMs were a better estimate of the anatomical changes than assuming there were no changes, but the AMs could not capture the variability in the anatomical changes seen in all patients. No difference was seen in the training and testing accuracy of the AMs. These observations were highlighted in both the geometric and dosimetric evaluations and comparisons. Significance. In this work, a SM and AM are presented which are able to capture the systematic anatomical changes of some head and neck cancer patients over the course of radiotherapy treatment. The AM is able to capture the overall trend of the population, but there is large patient variability which highlights the need for more complex, capable population models.

Influence of Examiner Experience on the Measurement of Bone-Loss by Low-Dose Cone-Beam Computed Tomography: An Ex Vivo Study.

The aim of this study was to investigate the influence of examiner experience on measurements of bone-loss using high-dose (HD) and low-dose (LD) CBCT. Three diagnosticians with varying levels of CBCT interpretation experience measured bone-loss from CBCT scans of three cadaveric heads at 30 sites, conducting measurements twice. Between the first and second measurements, diagnostician 2 and diagnostician 3 received training in LD-CBCT diagnostics. The diagnosticians also classified the certainty of their measurements using a three-grade scale. The accuracy of bone-loss measurements was assessed using the absolute difference between observed and clinical measurements and compared among diagnosticians with different experience levels for both HD and LD-CBCT. At baseline, there was a significant difference in measurement accuracy between diagnostician 1 and diagnostician 2, and between diagnostician 1 and diagnostician 3, but not between diagnostician 2 and diagnostician 3. Training improved the accuracy of both HD-CBCT and LD-CBCT measurements in diagnostician 2, and of LD-CBCT measurements in diagnostician 3. Regarding measurement certainty, there was a significant difference among diagnosticians before training. Training enhanced the certainty for diagnosticians 2 and 3, with a significant improvement noted only for diagnostician 3. Examiner experience level significantly impacts the accuracy and certainty of bone-loss measurements using HD- and LD-CBCT.

Is a Pre-Existent Cone-Beam Computed Tomography Able to Detect Metal Dental Posts?

(1) Background: In this study, the efficacy of cone-beam computed tomography (CBCT) in detecting dental posts was compared to periapical radiography. (2) Methods: A retrospective evaluation of 53 patients' periapical radiographs and CBCT images was performed. The presence and type of the intra-canal dental post were initially determined on the periapical images (PA) radiographs' examination and were then compared to the observer's ability to detect the dental post on a CBCT image. The effect of the post's type (metal cast or prefabricated) on its detection on CBCT images was determined. (3) Results: 10.5% of teeth that were identified as having a post on a PA radiograph were not identified as having a post on the CBCT examination (p < 0.05). Approximately 17.6% of teeth that were identified as not having a post on a PA radiograph were identified as having a post on the CBCT examination (p < 0.05). Moreover, 16.3% and 50% of teeth with a prefabricated or cast posts on PA radiographs were falsely identified on the CBCT examination, respectively (p < 0.05). (4) Conclusions: A CBCT image is an insufficient tool for the identification of metal prefabricated and cast posts. A PA image is the recommended radiographic tool for achieving information about the post-endodontic restoration status of teeth candidates for endodontic retreatment in patients with a former CBCT scan.

Accuracy evaluation of dental CBCT and scanned model registration method based on pulp horn mapping surface: an in vitro proof-of-concept

Background and aim3D fusion model of cone-beam computed tomography (CBCT) and oral scanned data can be used for the accurate design of root canal access and guide plates in root canal therapy (RCT). However, the pose accuracy of the dental pulp and crown in data registration has not been investigated, which affects the precise implementation of clinical planning goals. We aimed to establish a novel registration method based on pulp horn mapping surface (PHMSR), to evaluate the accuracy of PHMSR versus traditional methods for crown-pulp registration of CBCT and oral scan data.Materials and methodsThis vitro study collected 8 groups of oral scanned and CBCT data in which the left mandibular teeth were not missing, No. 35 and No. 36 teeth were selected as the target teeth. The CBCT and scanned model were processed to generate equivalent point clouds. For the PHMSR method, the similarity between the feature directions of the pulp horn and the surface normal vectors of the crown were used to determine the mapping points in the CBCT point cloud that have a great influence on the pulp pose. The small surface with adjustable parameters is reconstructed near the mapping point of the crown, and the new matching point pairs between the point and the mapping surface are searched. The sparse iterative closest point (ICP) algorithm is used to solve the new matching point pairs. Then, in the C + + programming environment with a point cloud library (PCL), the PHMSR, the traditional sparse ICP, ICP, and coherent point drift (CPD) algorithms are used to register the point clouds under two different initial deviations. The root square mean error (RSME) of the crown, crown-pulp orientation deviation (CPOD), and position deviation (CPPD) were calculated to evaluate the registration accuracy. The significance between the groups was tested by a two-tailed paired t-test (p < 0.05).ResultsThe crown RSME values of the sparse ICP method (0.257), the ICP method (0.217), and the CPD method (0.209) were not significantly different from the PHMSR method (0.250). The CPOD and CPPD values of the sparse ICP method (4.089 and 0.133), the ICP method (1.787 and 0.700), and the CPD method (1.665 and 0.718) than for the PHMSR method, which suggests that the accuracy of crown-pulp registration is higher with the PHMSR method.ConclusionCompared with the traditional method, the PHMSR method has a smaller crown-pulp registration accuracy and a clinically acceptable deviation range, these results support the use of PHMSR method instead of the traditional method for clinical planning of root canal therapy.

Cone-Beam Computed Tomography Evaluation of Maxillary Sinus Changes in Orthodontic Patients Treated With Extraction of Four First Premolars.

The objective of this study was to assess alterations in maxillary sinus mucosa thickness and the distances between the apexes of specific teeth and the maxillary sinus base in adult patients undergoing orthodontic treatment with the extraction of four first premolars. Twenty-one adults, averaging 24.85 years of age, received orthodontic therapy involving the extraction of all four first premolars. Cone-beam computed tomography scans were conducted before and after treatment to evaluate changes. Notably, post-treatment scans revealed a significant increase (P= 0.044) in the distance between the apex of the second premolar and the maxillary sinus floor, with an average augmentation of 1.0141 millimeters. However, no notable alterations were detected in the distances between the apexes of other teeth and the maxillary sinus or in maxillary sinus mucosa thickness. These findings suggest that orthodontic treatment with the extraction of four first premolars may elevate the distance between the maxillary sinus floor and the second premolar apex, which provides a reference for risk assessment and surgical design of first premolar extraction during orthodontic treatment.

Analysis of the Application Value of Dynamic Navigation Guidance in Oral Implantation.

To investigate the application of dynamic navigation guidance technology in different implantation scenarios, and to provide a scientific basis for the innovation and advancement of implantation techniques. Fifteen cases of patients with malocclusions admitted between January 2021 and February 2023 were selected as the study subjects. All patients underwent dynamic navigation-guided oral implantation interventions. CBCT scans were taken after implantation surgery to record deviations of implantation points, including implantation point deviation, endpoint deviation, and angle deviation. Dynamic navigation guidance effectively improves the reliability and stability of implantation in oral implant patients. CBCT effectively evaluated the state of the patient's periodontal implant, analyzed the state of the patient's lesion area, and improved the quality of implant intervention through CBCT guidance. The implantation point deviation was (0.407±0.193) mm, the endpoint deviation was (0.492±0.201) mm, and the implant angle deviation was (2.162±0.283)°. There was no significant difference in implantation point deviation in the anterior and posterior parts of the upper and lower jaws after intervention (P>0.05). However, there were significant differences in endpoint deviation and implant angle deviation among the anterior and posterior parts of the upper and lower jaws (P<0.05). Dynamic navigation guidance effectively improves the reliability and stability of implantation in oral implant patients. However, there is relatively greater endpoint deviation and implant angle deviation in the posterior part of the upper jaw.