Cone Beam Computed Tomography Group Research Articles

A CBCT Assessment of Orthodontic Mini-Implant Placement

ABSTRACT Objectives: This study compares the precision of cone beam computed tomography (CBCT) and two-dimensional radiography for mini-implant implantation. Materials and Method: For 30 sites (in 15 patients between the ages of 13 and 26 years), the buccal interradicular region among the 2nd premolar and 1st molar was found to be the best location for mini-implants. Next, two groups of the mini-implant implantation process were created. Mini-implants were positioned at the CBCT data-identified sites in the CBCT group. Mini-implants were inserted in the RVG group by using two-dimensional digital radiography and a specially constructed guide. To assess the precision of the mini-implant implantation, post-placement CBCT images were acquired. The obtained data were statistically analyzed. Result: The two groups showed a statistically considerable variation in the mini-implant placement’s departure from the optimal height. Due to the smaller interradicular space and decreased convenience in the posterior mandibular area, two out of 15 mini-implants in the RVG group demonstrated root contact in the mandibular jaw Conclusion: The two-dimensional intraoral radiograph of the interradicular area provides sufficient information for mini-implant placement even though CBCT accurately visualizes the interradicular space in three dimensions.

The Role of Three-Dimensional Imaging (CBCT) in Enhancing Diagnostic Accuracy in Endodontics: A Randomized Controlled Trial

ABSTRACT Background: In the field of endodontics, accurate diagnosis is pivotal for successful treatment outcomes. This randomized controlled trial (RCT) explores the potential of cone-beam computed tomography (CBCT) as a tool to enhance diagnostic accuracy in endodontic procedures Materials and Methods: An RCT was conducted with a sample of 120 patients presenting with endodontic issues. The patients were divided into two groups: Group A received traditional two-dimensional radiography, while group B underwent CBCT scans. The diagnostic accuracy was assessed by comparing the radiographic findings with the clinical evaluation by experienced endodontists. Results: The results indicated a significant improvement in diagnostic accuracy in the CBCT group (group B) with an arbitrary value of 88% accuracy, compared with the traditional radiography group (group A) with only 65% accuracy. The CBCT group showed a clearer visualization of root canal anatomy, periapical lesions, and the presence of additional canals, contributing to the enhanced diagnostic capability Conclusion: This RCT demonstrates that CBCT significantly enhances diagnostic accuracy in endodontics compared with traditional two-dimensional radiography. The improved visualization of root canal anatomy and periapical regions allows for more precise treatment planning, ultimately leading to better treatment outcomes.

Diagnostic Yield of Cone-beam-Derived Augmented Fluoroscopy and Ultrathin Bronchoscopy Versus Conventional Navigational Bronchoscopy Techniques.

Pulmonary nodules suspicious for lung cancer are frequently diagnosed. Evaluating and optimizing the diagnostic yield of lung nodule biopsy is critical as innovation in bronchoscopy continues to progress. This is a retrospective cohort study. Consecutive patients undergoing guided bronchoscopy for suspicious pulmonary nodule(s) between February 2020 and July 2021 were included. The cone-beam computed tomography (CBCT)+ radial endobronchial ultrasound (r-EBUS) group had their procedure using CBCT-derived augmented fluoroscopy along with r-EBUS. The CBCT+ ultrathin bronchoscope (UTB)+r-EBUS group had the same procedure but with the use of an ultrathin bronchoscope. The r-EBUS group underwent r-EBUS guidance without CBCT or augmented fluoroscopy. We used multivariable logistic regression to compare diagnostic yield, adjusting for confounding variables. A total of 116 patients were included. The median pulmonary lesion diameter was 19.5mm (interquartile range, 15.0 to 27.5mm), and 91 (78.4%) were in the peripheral half of the lung. Thirty patients (25.9%) underwent CBCT+UTB, 27 (23.3%) CBCT, and 59 (50.9%) r-EBUS alone with unadjusted diagnostic yields of 86.7%, 70.4%, and 42.4%, respectively ( P <0.001). The adjusted diagnostic yields were 85.0% (95% CI, 68.6% to 100%), 68.3% (95% CI, 50.1% to 86.6%), and 44.5% (95% CI, 31.0% to 58.0%), respectively. There was significantly more virtual navigational bronchoscopy use in the r-EBUS group (45.8%) compared with the CBCT+UTB (13.3%) and CBCT (18.5%) groups, respectively. CBCT procedures required dose area product radiation doses of 7602.5µGym 2 . Compared with the r-EBUS group, CBCT + UTB + r-EBUS was associated with higher navigational success, fewer nondiagnostic biopsy results, and a higher diagnostic yield. CBCT procedures are associated with a considerable radiation dose.

Comparison of intraoperative CT- and cone beam CT-based spinal navigation for the treatment of atlantoaxial instability

BACKGROUND CONTEXTDue to the complexity of neurovascular structures in the atlantoaxial region, spinal navigation for posterior C1–C2 instrumentation is nowadays a helpful tool to increase accuracy of surgery and safety of patients. Many available intraoperative navigation devices have proven their reliability in this part of the spine. Two main imaging techniques are used: intraoperative CT (iCT) and cone beam computed tomography (CBCT). PURPOSEComparison of iCT- and CBCT-based technologies for navigated posterior instrumentation in C1-C2 instability. STUDY DESIGNRetrospective study. PATIENT SAMPLEA total of 81 consecutive patients from July 2014 to April 2020. OUTCOME MEASURESScrew accuracy and operating time. METHODSPatients with C1–C2 instability received posterior instrumentation using C2 pedicle screws, C1 lateral mass or pedicle screws. All screws were inserted using intraoperative imaging either using iCT or CBCT systems and spinal navigation with autoregistration technology. Following navigated screw insertion, a second intraoperative scan was performed to assess the accuracy of screw placement. Accuracy was defined as the percentage of correctly placed screws or with minor cortical breach (<2 mm) as graded by an independent observer compared to misplaced screws. RESULTSA total of 81 patients with C1–C2 instability were retrospectively analyzed. Of these, 34 patients were operated with the use of iCT and 47 with CBCT. No significant demographic difference was found between groups. In the iCT group, 97.7% of the C1–C2 screws were correctly inserted; 2.3% showed a minor cortical breach (<2 mm); no misplacement (>2 mm). In the CBCT group, 98.9% of screws were correctly inserted; no minor pedicle breach; 1.1% showed misplacement >2 mm. Accuracy of screw placement demonstrated no significant difference between groups. Both technologies allowed sufficient identification of screw misplacement intraoperatively leading to two screw revisions in the iCT and three in the CBCT group. Median time of surgery was significantly shorter using CBCT technology (166.5 minutes [iCT] vs 122 minutes [CBCT]; p<.01). CONCLUSIONSSpinal navigation using either iCT- or CBCT-based systems with autoregistration allows safe and reliable screw placement and intraoperative assessment of screw positioning. Using the herein presented procedural protocols, CBCT systems allow shorter operating time.

Comparison of mesiodistal root angulation of teeth by conventional panoramic and cone beam computed tomography images – A cross-sectional study

Accurate bracket positioning is required for proper root parallelism and for stable orthodontic treatment outcomes. This study aimed to determine the difference in mesiodistal root angulation of teeth measured on three radiographic images. A cross-sectional study was conducted using orthopantomogram (OPG), panoramic images of cone beam computed tomography (Pan-CBCT) and cone beam computed tomography (CBCT). An occlusal plane was constructed in OPG and Pan-CBCT for angular measurements. The axial and sagittal views were used for assessing the mesiodistal root angulation on CBCT. Mesiodistal root angulation differences among three radiographs were assessed using the Kruskal-Wallis test. Mann-Whitney U test was applied for pairwise comparison and multinomial logistic regression was used to determine the association of sexual dimorphism with the direction of root angulation. On comparing the mesiodistal root angulation in degrees (DE) among all three groups, upper right (UR2) and left lateral incisors (UL2) were found to be statistically significant with P=0.033 and P=0.050 respectively. On pair-wise comparison, we found a statistically significant difference for upper right lateral incisor (UR2) between OPG and Pan-CBCT (P=0.045). Upper left lateral (UL2) (P=0.024) was significant in OPG and Pan-CBCT while upper left first molar (UL6) (P=0.043) in OPG and CBCT group. On comparing the sexual dimorphism in the direction of root angulation, females showed a greater tendency of mesial root angulation (5.62) times for upper right second premolar (UR5) as compared to males. There were no significant difference in mesiodistal root angulation between panoramic CBCT and CBCT images. The angulation of the upper lateral incisors was found to be significant between OPG and panoramic CBCT images, whereas the angulation of the upper right lateral incisors and left first molars was significant between OPG and CBCT images. In terms on sexual dimorphism, females showed greater mesial angulation of teeth than males.

Evaluation of Impacted Canines Utilizing Three Radiographic Methods in Orthodontic Patients in Benin City, Nigeria

Background: Impacted canines are one of the most commonly missing teeth in the oral cavity and traditionally, two dimensional (2-D) radiographic views have been utilized in localizing such teeth. The introduction of the 3-D Cone Beam Computed Tomography was to enable localization in three dimensions. A reliable and concise radiographic technique will enable proper diagnosis of the type and extent of impaction and aid in choosing the proper treatment and also monitor treatment progression.&#x0D; Aim: The aim of this study was to evaluate impacted canines in orthodontic patients utilizing three radiographic methods in Benin City, Nigeria.&#x0D; Methods: In this prospective study, 34 pre-orthodontic patients (30 with unilateral and 4 with bilateral impactions) and a total number of 38 impacted canines were selected. The Lateral Cephalometric radiograph was used to determine the patients’ orthodontic problem. Three groups of participants were selected and identified based on the radiographic method utilized; with group 1, the periapical / Occlusal group (POCC, n=13); group 2, the Orthopantomogram group (OPG, n=13). The third group was the Cone Beam Computed Tomography group (CBCT, n=12). Impacted canines were detected and the position assessed and classified utilizing three radiographic methods into classes I to VI. The differences between groups and correlations between variables were determined with the student’s t-test and the Spearman correlation coefficient respectively. Significant values of P&lt;0.05 were applied.&#x0D; Results: The mean age of participants was 18.29±6.15 years. A total number of 30(78.9%) impactions were seen in the upper jaw and 8(21.1%) in the lower jaw. Bilateral impactions were seen in the upper jaw of 3(7.9%) patients and 1(2.6%) in the lower jaw respectively. The position of the canines could only be identified clearly in classes I and II from group 1. Group 2 (OPG) was the least definite in identifying accurately the position of the canines. The CBCT (Group 3) did not record any impaction in the lower jaw. Consecutive paraxial cuts at 1.5mm interval on the CBCT showed the position of the canines to be in Class I in 6(50%), class II in 3(25%) and classes III in 2(16.7%) and VI in 1(8.3%) respectively in the upper jaw.&#x0D; Conclusion: The CBCT appears to be the most reliable method of identifying the position and depth of impacted canines.

Periapical Radiography versus Cone Beam Computed Tomography in Endodontic Disease Detection: A Free-response, Factorial Study

AimTo assess and compare reader performance in interpreting digital periapical (PA) radiography and cone beam computed tomography (CBCT) in endodontic disease detection, using a free-response, factorial model. Materials and MethodsA reader performance study of 2 image test sets was undertaken using a factorial, free-response design, accounting for the independent variables: case type, case severity, reader type, and imaging modality. Twenty-two readers interpreted 60 PA and 60 CBCT images divided into 5 categories: diseased–subtle, diseased–moderate, diseased–obvious, nondiseased–subtle, and nondiseased–obvious. Lesion localization fraction, specificity, false positive (FP) marks, and the weighted alternative free-response receiver operating characteristic figure of merit were calculated. ResultsCBCT had greater specificity than PA in the obvious nondiseased cases (P = .01) and no significant difference in the subtle nondiseased category. Weighted alternative free-response receiver operating characteristic values were higher for PA than CBCT in the subtle diseased (P = .02) and moderate diseased (P = .01) groups with no significant difference between in the obvious diseased groups. CBCT had higher mean FPs than PA (P < .05) in subtle diseased cases. Mean lesion localization fraction in the moderate diseased group was higher in PA than CBCT (P = .003). No relationships were found between clinical experience and all diagnostic performance measures, except for in the obvious diseased CBCT group, where increasing experience was associated mean FP marks (P = .04). ConclusionsReader performance in the detection of endodontic disease is better with PA radiography than CBCT. Clinical experience does not impact upon the accuracy of interpretation of both PA radiography and CBCT.

An in vitro comparison of the marginal fit of provisional crowns using the virtual tooth preparation workflow against the traditional technique.

This study investigates the effectiveness of an innovative virtual tooth preparation workflow for the fabrication of dental crowns using cone-beam computed tomography (CBCT) and intraoral scanners (IOSs) with conventional workflow using extraoral/laboratory scanners. This in vitro experimental study was conducted in the laboratory of a university in Chennai, India. The dental laboratory and research facilities at the institution were utilized for the fabrication of the temporary crowns and the data acquisition process. Institutional approval was obtained from the university. It was basically a comparison between the virtual prep technique using CBCT and IOS and the conventional digital technique using extra oral scanners (EOS) for temporary crown fabrication. The sample size was estimated using an effect size of 1.5004, assuming a normal distribution, a significance level of 0.05, and a power of 0.95 in G power software. Based on this calculation, an extracted second lower molar was used to fabricate 10 samples in each group. The samples were divided into three groups: the CBCT (Group 1), the IOS (Group 2), and laboratory scanner (Group 3 as control) groups. The vertical marginal gap of all the surfaces of the crown was evaluated using a scanning electron microscope. Data were analyzed using one-way ANOVA using the SPSS software version 26.0, IBM, Armonk, NY, USA. Acceptable marginal discrepancy values were obtained in all three groups. There was no significant difference in the marginal discrepancy recorded (P = 0.113). Virtual tooth preparation using CBCT and IOSs can be used as an alternative to the conventional workflow for provisional crown and bridge fabrication.

Quantitative evaluation of training method in placing miniscrews in orthodontic graduate program

BackgroundThe purpose of this study was to assess the effectiveness of training residents in an orthodontic program in the placement of miniscrews by using cone beam computed tomography (CBCT) images. A total of 90 miniscrews were placed in 15 pig mandibles over a 3-year period by 15 first-year orthodontic residents. Miniscrews were divided into three groups (Control group: no radiographs; 2D group: placement with 2D radiographs; CBCT group: placement with CBCT). Proximity of the miniscrew to the neighboring root was measured. The miniscrew success rate was examined in the graduate clinic from 2015 to 2021.ResultsThe percentage of root contact for each group was: 36.7% (11/30), 20.0% (6/30), 0% (0/30), for the Control, 2D, and CBCT groups, respectively. The CBCT group was significantly different from the Control and 2D groups (p < 0.05). For root proximity, the miniscrews were significantly closer to the roots in the Control (p < 0.001) and 2D (p < 0.001) groups compared with the CBCT group. No significant difference was observed between the Control and 2D groups (p = 0.80). There was no significant difference among the years in the miniscrew success rate.ConclusionsTraining the residents in an orthodontic graduate program using CBCT may be helpful to avoid root damage and to decrease the miniscrew failure rate.

Cone beam computed tomography-guided microwave ablation for hepatocellular carcinoma under the hepatic dome: a retrospective case-control study.

BackgroundMicrowave ablation (MWA) for hepatocellular carcinoma (HCC) under the hepatic dome is still clinically challenging. This retrospective control study set out to analyze the technical application and clinical benefits of cone beam computed tomography (CBCT)-guided MWA for HCC under the hepatic dome.MethodsThe study analyzed 76 patients with 110 HCC lesions under the hepatic dome from April 2016 to January 2020. The patients were divided into two groups: (I) the CBCT group (n=31), in which iGuide navigation was used for the puncture, and (II) the conventional computed tomography (cCT) group (n=45), in which a navigation tool was not used for the puncture. The primary endpoints were technical success, puncture score, and the rates of complete ablation (CA), complications, and local tumor progression (LTP). The secondary endpoints were tumor-free survival (TFS) and overall survival (OS).ResultsIn terms of the primary endpoints, the puncture score, occurrence of pleural effusion, and occurrence of right shoulder pain differed significantly between the CBCT group and the cCT group (2.8 vs. 2.2, P=0.002; 12.9% vs. 35.6%, P=0.03; 9.7% vs. 33.3%, P=0.03, respectively). However, the rates of technical success, CA, major complications, and LTP showed no significant differences between the two groups (100% vs. 100%, P>0.009; 0% vs. 0%, P>0.009; 95.6% vs. 89.2%, P=0.30; 4.5% vs. 4.6%, P=0.96, respectively). Regarding the secondary endpoints, the median TFS was 23.0 [95% confidence interval (CI): 19.5–26.5] vs. 22.0 (95% CI: 18.4–25.6) months (P=0.41) and the median OS was 31.0 (95% CI: 21.4–40.6) vs. 33.0 (95% CI: 27.9–38.2) months (P=0.95).ConclusionsCone beam CT is a feasible and effective image guidance tool for MWA of HCC under the hepatic dome.

Morphological Investigation of Mandibular Lingula: A Literature Review.

Purpose: The purpose of the study was to review the literature on the shape of the mandibular lingula. Methods: English articles published from 1970 to 2021 in databases (PubMed, Web of Science, and Embase) were selected. Articles meeting the search strategy were evaluated based on the eligibility criteria (participants aged 18 years and over). Dry mandibles and cone beam computed tomography (CBCT) images were used as research materials. The shapes of mandibular lingula were classified as triangular, truncated, nodular, and assimilated. Results: Based on the eligibility criteria, 10 articles (six with dry mandibles and four with CBCT images) were selected for full-text reading and detailed examination. In the dry mandible group, triangular, truncated, nodular, and assimilated lingula were observed on 446, 398, 232, and 69 sides, respectively. In the CBCT group, nodular, truncated, triangular, and assimilated lingula were observed on 892, 517, 267, and 88 sides, respectively. Therefore, the most common lingula types in the dry mandible and CBCT groups were different. The assimilated type was the least common in both groups. Conclusion: In the dry mandible group, the most common lingula type was triangular, followed by truncated, nodular, and assimilated types. In the CBCT group, the most common lingula type was nodular, followed by truncated, triangular, and assimilated types. There were no significant differences in lingula types between the left and right sides of the mandible.

Comparison of the Accuracies of CBCT, Radiography, and Four Electronic Apex Locators in Working Length Determination

Background: One of the significant stages during endodontic procedures is determining the correct working length (WL). This study aimed to evaluate the accuracy of four electronic apex locators (EALs) (Root ZX mini, Raypex 6, Propex Pixi, and E-Pex Pro) and cone-beam computed tomography (CBCT) and radiographic measurement in determining the actual WL (A-WL). Methods: Thirty extracted single-root mandibular premolars were selected and flattened at the crown. The WL was determined by advancing the #15 K file until its tip was visible from the apical, and the A-WL was established by subtracting 0.5 mm from this length. The WL was also determined using periapical radiography, four EALs, and CBCT. The differences in all measurements were compared with the A-WL. The data were statistically analyzed using one-way analysis of variance (Welch) and Tamhane’s test. The significance level was set at p < 0.05. Results: Compared with other measurement methods, CBCT gave shorter values than the A-WL, and this finding was statistically significant compared with those of the PR and Propex Pixi groups (p = 0.009) (p = 0.024). No significant difference was observed between the other groups (p > 0.05) except the CBCT group (p < 0.05). Conclusions: Root ZX mini and Raypex 6 made measurements close to the A-WL.

Diagnostic usefulness of cone-beam computed tomography versus multi-detector computed tomography for sinonasal structure evaluation.

ObjectiveCone‐beam computed tomography (CBCT) is a promising imaging modality for sinonasal evaluation, with advantages of relatively low radiation dose, low cost, and quick outpatient imaging. Our study aimed to compare the diagnostic performance and image quality of CBCT with those of multi‐detector computed tomography (MDCT) with different slice thickness.MethodsWe retrospectively reviewed 60 consecutive patients who had undergone both CBCT and MDCT. MDCT images was reconstructed with 1 and 3 mm slice thickness. The quantitative image quality parameters (image noise, signal‐to‐noise ratio [SNR], and contrast‐to noise ratio [CNR] were calculated and compared between the two imaging modalities. Two observers (ENT surgeon and neuroradiologist) evaluated the presence of seven sinonasal anatomic variations in each patient and interobserver agreements were analyzed. The diagnostic performance of CBCT (0.3 mm) and MDCT (3 mm) was assessed and compared with that of high resolution MDCT (1 mm), which is considered as the gold standard.ResultsThe image noise was significantly higher and SNR and CNR values were lower in the CBCT (0.3 mm) group than in the MDCT groups (1 and 3 mm). The diagnostic performance of CBCT (0.3 mm) was similar to that of MDCT (1 mm) and superior to that of MDCT (3 mm). The highest interobserver agreement was for high resolution MDCT (1 mm), followed by CBCT (0.3 mm), and MDCT (3 mm).ConclusionConsidering its low radiation dose, low cost, and ease of clinical access, CBCT may be a useful imaging modality for as first line sinonasal evaluation and repeated follow up.Study design: Retrospective study in a tertiary referral university center.Level of evidence: NA.

UNWANTED RADIATION EXPOSURE TO RADIOSENSITIVE ORGANS DURING HAND CT.

This study aimed to investigate unwanted radiation exposure of radiosensitive organs during computed tomography (CT) scans of the hand. Furthermore, we investigated the effectiveness of a shield in reducing unwanted radiation exposure. In a prospective observational study, the patients were randomized to receive a shield during the hand CT scan. Two group of patients were further randomized to undergo multi-detector CT (MDCT) or cone-beam CT (CBCT). The radiation dose was measured in the target point and the nearest skin surface of radiosensitive organs by attached the thermoluminescent dosemeter chips. When shielding was performed, the radiation doses had decreased significantly with a mean of 79% (65-91%) in the MDCT group and 88.6% (85-93%) in the CBCT group. In the non-shielded group, the radiation doses to the radiosensitive organs decreased inversely with increasing distance, which means that the closer the target point is, the more unwanted radiation exposure increases. It is important to keep radiosensitive organs as far as possible from the target point during CT scan. In particular, it is necessary to shield the radiosensitive organs closer to the target point. Level of Evidence: Level II, Prospective observational study.

Cone beam computed tomography (CBCT) guidance is helpful in reducing dose exposure to pediatric patients undergoing radiofrequency ablation of osteoid osteoma

PurposeTo assess efficacy and safety of cone beam computed tomography (CBCT) in the radiofrequency ablation (RFA) of osteoid osteoma (OO) in children and adolescents, and to compare technical success, clinical success, radiation dose and procedure duration time of CBCT guidance to conventional computed tomography (CT) guidance.Materials and methodsBetween 2015 and 2019, 53 consecutive percutaneous RFA were performed on pediatric patients with CBCT or conventional CT guidance, respectively, in 24 and 29 children and adolescents with 24-month follow-up. Dose area product (DAP) and dose length product (DLP) were recorded, respectively, for CBCT and conventional CT and converted to effective doses (ED).ResultsCBCT and conventional CT groups were similar in terms of patient age and weight, tumor size and tumor location. Technical success was achieved in all cases. Primary clinical success was 91.67% (22/24) for the CBCT group and 89.66% (26/29) for the conventional CT group. Mean DAP was 64.75Gycm2 (range 6.0–266.7). Mean DLP was 972.62mGycm (range 337–2344). ED was significantly lower in the CBCT group compared to the conventional CT group (0.34 mSv vs. 5.53 mSv, p = 0.0119). Procedure duration time was not significantly longer in the CBCT group (102.25 min vs. 92.34 min, p = 0.065). No major complication was registered. Minor complications were observed in 4 patients (2 in CBCT; 2 in conventional CT).ConclusionsCompared to conventional CT guidance, CBCT guidance for percutaneous OO ablation shows similar technical and clinical success rates, with reduced radiation dose and equivalent procedure duration time. This technique helps sparing dose exposure to pediatric patients.

Marginal fit of 3-unit CAD-CAM zirconia frameworks fabricated using cone beam computed tomography scans: an experimental study.

Whether cone beam computed tomography (CBCT) scans can be used for the fabrication of computer-aided design and computer-aided manufacturing (CAD-CAM) fixed dental prostheses (FDPs) is not known. The purpose of the present study was to compare the marginal fit of 3-unit zirconia FDPs fabricated by using CBCT or 3-dimensional (3D) laboratory scanning. Extracted second premolar and molar teeth in a maxillary typodont model were prepared. The first molar was removed and the typodont model was scanned with a laboratory or a CBCT scanner to generate two virtual 3D cast groups (3DL and CBCT). Forty four 3-unit zirconia FDPs were designed on virtual casts and milled. The vertical marginal discrepancy (VMD) was measured by ×100-magnification microscopy at seven locations on each abutment. A total of 616 measurements were made at 14 fixed locations in two groups of 22 specimens. The VMD data for 3DL and CBCT groups were statistically analyzed using the Mann-Whitney U test (α = 0.05). The mean VMDs on premolar ranged between 44 and 55µm (median: 43-55µm) in 3DL, and 74 and 100µm (median: 72-93µm) in CBCT; and on the molar, between 47 and 114µm (median: 46-114µm) in 3DL, and 91 and 162µm (median: 93-156µm) in CBCT. There was a significant difference between the gaps in 3DL and CBCT groups (p < 0.001). FDPs fabricated using 3D laboratory scanner had significantly smaller VMDs. Nevertheless, the 3-unit zirconia FDPs fabricated using CBCT scans presented promising marginal integrity.

Comparative accuracy of cone-beam CT and conventional multislice computed tomography for real-time navigation in zygomatic implant surgery.

Cone-beam computed tomography (CBCT) and conventional multislice CT (MSCT) are both used in zygomatic implant navigation surgery but the superiority of one technique versus the other remains unclear. This study compared the accuracy of CBCT and MSCT in zygomatic implant navigation surgery by calculating the deviations of implants. Patients with severely atrophic maxillae were classified into two groups according to the use of CBCT- or MSCT-guided navigation system. The entry and apical distance deviation, and the angle deviation of zygomatic implants were measured on fused operation images. A linear effect model was used for analysis, with statistical significance set at P < .05. A total of 72 zygomatic implants were inserted as planned in 23 patients. The comparison of deviations in CBCT and MSCT groups showed a mean (± SD) entry deviation of 1.69 ± 0.59 mm vs 2.04 ± 0.78 mm (P = .146), apical deviation of 2 ± 0.68 mm vs 2.55 ± 0.85 (P < .001), and angle deviation of 2.32 ± 1.02° vs 3.23 ± 1.21° (P = .038). Real-time zygomatic implant navigation surgery with CBCT may result in higher values for accuracy than MSCT.

Cone-beam computed tomography classification of the mandibular second molar root morphology and its relationship to panoramic radiographic appearance.

This study aimed to clarify the relationship between the panoramic radiographic appearance and the longitudinal cone-beam computed tomography (CBCT) classification of root configurations of the mandibular second molar. Panoramic radiographs of 1058 mandibular second molars were classified into five types according to the number and configuration of the roots. These molars were also examined with CBCT at four levels between the pulp chamber and the root apex, and axial images perpendicular to the root axis were categorized into three patterns: single (fused root with small grooves on both buccal and lingual sides or a round root with one canal); double (two separate roots with a trabecular appearance between them); and C-shaped (root with a deep groove opening only on the lingual or buccal side relative to the opposite side). Based on these patterns and their scan levels, the CBCT root morphology appearance in each tooth unit was classified into seven groups. Relationships were investigated between these seven CBCT groups and the five panoramic root types. In panoramic types 1 and 2 (with separate roots), 85% had roots with a double pattern (groups II and III) on the CBCT images. In panoramic types 3 and 4 (with fused roots), 85% had C-shaped CBCT patterns at the lower scan levels. When panoramic images show fused root types, CBCT examinations should be planned to clarify the root canal configuration.

Evaluation of mercury release from dental amalgam after cone beam computed tomography and magnetic resonance imaging with 3.0-T and 1.5-T magnetic field strengths

This in vitro study aimed to investigate leakage of mercury from amalgam restorations after cone beam computed tomography (CBCT) and magnetic resonance imaging (MRI) examinations. In total, 238 amalgam disks were prepared and placed in saline solution. The samples were allocated randomly to 7 groups, with 34 samples in each group. CBCT imaging was performed for 4 groups with different imaging parameters (narrow/wide field of view [FOV]; standard/high-resolution). MRI procedures were performed with 3.0-T and 1.5-T magnetic field strengths. No imaging was performed for the samples in the control group. The amalgam samples were removed from the tubes 24 hours after imaging and submitted for plasma mass spectrometry analysis. Kruskal-Wallis and Dunn's tests were performed to compare data. A P value less than .05 was accepted as statistically significant. The highest mean mercury value was found in the 3.0-T MRI group, whereas the lowest mean value was found in the narrow FOV, standard-resolution CBCT group. There were no significant differences between the control group and the experimental groups (P ≥ .338) or between the experimental groups (P > .05). CBCT and MRI procedures similar to those used in patient care caused no significantly different mercury release compared with nonexposed samples.

Cone-beam and micro-computed tomography for the assessment of root canal morphology: a systematic review.

This study presents an overview of the accuracy of cone beam computed tomography (CBCT) compared with micro-computed tomography (μCT) in the assessment of root canal morphology of extracted human permanent teeth. A database search in PubMed, PubMed Central, Embase, Scopus, Opengrey, Scielo and Virtual Health Library was conducted which compared root canal morphology of extracted human permanent teeth on the accuracy of CBCT with μCT. In accordance with PRISMA statement guidelines, data were extracted on study characteristics, target mediators, sampling and assay techniques and the parameters associated with obtaining the image and ability to identify the root canal morphology. Amongst 2734 records, ten fulfilled the inclusion criteria. Four studies compared the accuracy of CBCT and μCT in the assessment of root canal morphology using Vertucci's classification, with at least one CBCT group or subgroup of each study presented high agreement compared to the μCT. Six studies assessed more detailed root canal morphology, including two articles that found a lack of agreement between these imaging systems. Risk of bias was deemed low in three studies, moderate in four and high in three. CBCT can be as accurate as μCT in the assessment of several morphological features of extracted human permanent teeth; however there are some exceptions related to the more detailed morphological aspects. Voxel size likely influences the ability to detect these features, though the different aspects of exposure setting used in studies components may be confounding factors. CBCT may be considered for the assessment of root canal morphology ex-vivo.