Cone Beam Computed Tomography Analysis Research Articles

Comparative Evaluation of a Dynamic Navigation System versus a Three-dimensional Microscope in Retrieving Separated Endodontic Files: An In Vitro Study

IntroductionThis study aimed to compare the effectiveness of a dynamic navigation system and a three-dimensional microscope in retrieving broken rotary Nickel-Titanium files when using trepan burs and the extractor system. Materials and MethodsThirty maxillary first bicuspids with 60 separate roots were split into 2 comparable groups based on a comprehensive cone beam computed tomography analysis of the root length and curvature. After standardized access opening, glide paths, and patency attainment with the K file (sizes 10 and 15), the teeth were arranged on 3D models (three per quadrant, six per model). Subsequently, controlled-memory heat-treated Nickel-Titanium rotary files (#25/0.04) were notched 4 mm from the tips and fractured at the apical third of the roots. The C-FR1 Endo file removal system was employed under both guidance to retrieve the fragments, and the success rate, canal aberration, treatment time, and volumetric changes were measured. The statistical analysis was performed using IBM SPSS software at a significance level of 0.05. ResultsThe microscope-guided group had a higher success rate than the dynamic navigation system guidance, but the difference was insignificant (P > .05). In addition, the microscope-guided drills resulted in a substantially lower proportion of canal aberration, shorter time to retrieve the fragments and less change in the root canal volume (P < .05). ConclusionAlthough dynamically guided trephining with the extractor can retrieve separated instruments, it is inferior to three-dimensional microscope guidance regarding treatment time, procedural errors, and volume change.

Sphenoid sinuses' volume and area analysis of Brazilian individuals' CBCTs, related to sex, age, skin color, and nutritional status using DDS-Pro™ software.

The purpose of this study was to analyze the volume and area of sphenoid sinuses of Brazilian individuals' cone-beam computed tomography (CBCT) images using the beta version of the DDS-Pro™ 2.14.2_2022 software (DPP Systems, Czestochowa, Poland), to assess a potential correlation to sex, age, skin color, and nutritional status, and to evaluate differences between the right and left sides. Three-dimensional volume and area measurements were made with the software using CBCT images of 113 living Brazilian individuals of both sexes (67 females and 46 males). TEM, rTEM, and R were used to assess the reproducibility of inter- and intra-examiner measurements. The measurement means were estimated with 95% confidence intervals according to sex and age group. There were no significant differences between the left and right sides for both volume and area and between the sexes and black and white individuals. Volume and area were significantly higher in 18years or older (p < 0.05) and in individuals with normal body mass index (BMI) (p < 0.05). The obtained results do not allow indicating the use of sphenoid sinuses volume and area measurements to estimate sexual dimorphism, and the same occurred for skin color. However, such measures can help to estimate age. Further studies are suggested with a larger sample, especially for the nutritional status variable.

The effect of myotonic dystrophy type 1 on temporomandibular joint and dentofacial morphology: A CBCT analysis.

Myotonic dystrophy type 1 (DM1) is a neuromuscular multisystem disease. Early involvement of facial muscles may produce an extra load on the temporomandibular joint (TMJ) in DM1. This study aimed to investigate the morphological analyses of the bone components of temporomandibular joint (TMJ), and dentofacial morphology in myotonic dystrophy type 1 (DM1) patients by cone-beam computed tomography (CBCT). Sixty-six individuals (33 DM1, and 33 healthy subjects) age ranging from 20 to 69 were included in the study. Clinical examinations of the patients' TMJ regions and evaluation of dentofacial morphology (maxillary deficiency, open-bite, deep palate and cross-bite) were performed. Dental occlusion was determined based on Angle's classification. CBCT images were evaluated regarding mandibular condyle morphology (convex, angled, flat and round) and osseous changes observed in the condyle (normal, osteophyte, erosion, flattening, sclerosis). DM1-specific morphological and bony TMJ alterations were determined. DM1 patients showed a high prevalence of morphological and osseous TMJ changes, and statistically significant skeletal alterations. The analysis of CBCT scans indicated the prevalent condylar shape among patients with DM1 was flat, the main osseous abnormality was flattening, there was a tendency towards skeletal Class II and a posterior cross-bite was frequently detected in DM1 patients. There was no statistically significant difference between the genders on the parameters evaluated in both groups. Adult patients with DM1 presented a high frequency of crossbite, tendency to skeletal Class II and morphological osseous alterations of TMJ. The analysis of the morphological condylar alterations in patients with DM1 may be beneficial in the diagnosis of TMJ disorders. This study reveals DM1-specific morphological and osseous TMJ alterations to provide an appropriate orthodontic/orthognathic treatment planning to patients.

The Application of Deep Learning on CBCT in Dentistry.

Cone beam computed tomography (CBCT) has become an essential tool in modern dentistry, allowing dentists to analyze the relationship between teeth and the surrounding tissues. However, traditional manual analysis can be time-consuming and its accuracy depends on the user's proficiency. To address these limitations, deep learning (DL) systems have been integrated into CBCT analysis to improve accuracy and efficiency. Numerous DL models have been developed for tasks such as automatic diagnosis, segmentation, classification of teeth, inferior alveolar nerve, bone, airway, and preoperative planning. All research articles summarized were from Pubmed, IEEE, Google Scholar, and Web of Science up to December 2022. Many studies have demonstrated that the application of deep learning technology in CBCT examination in dentistry has achieved significant progress, and its accuracy in radiology image analysis has reached the level of clinicians. However, in some fields, its accuracy still needs to be improved. Furthermore, ethical issues and CBCT device differences may prohibit its extensive use. DL models have the potential to be used clinically as medical decision-making aids. The combination of DL and CBCT can highly reduce the workload of image reading. This review provides an up-to-date overview of the current applications of DL on CBCT images in dentistry, highlighting its potential and suggesting directions for future research.

Intraradicular Diameter, Remnant Dentin Thickness, and Endodontic Post to Dentin Distance: CBCT and Microscopic Analyses

The objective of this work was to measure the tooth root canals’ diameter, remnant dentin thickness, endodontic post to dentin distance, and resin-matrix cement layer after three types of root canal shaping. Thirty extracted human premolars were endodontically treated and groups of specimens were divided according to the cementation with two different endodontic posts as follow: A) Fibio Fiberglass Post™, Anthogyr, France; B) multi-filament GFRC (Rebilda GT™, VOCO, Germany). Cone beam computed tomography (CBCT) and conventional X-ray analyses were performed before and after the endodontic post cementation. After cementation, specimens were cross-sectioned and inspected by optical microscopy and scanning electron microscopy at magnification ranging from × 30 up to × 2000. Changes in shaping of the root canals caused a decrease in the thickness of the remnant tooth tissues. CBCT and microscopic analyses also revealed a clear variation of resin-matrix cement around the glass fiber-reinforced composite (GFRC) posts. A multi-filament GFRC post provided an adequate distribution of filaments although the resin-matrix cement revealed a high volume among the filaments. An increase in thickness and volume of resin-matrix cement was noticed at the coronal third since the fitting was compromised due to tooth anatomic variations and root canal preparation. Defects such macro-scale pores, cracks, and voids were also detected by microscopic analyses. The root canal shaping can promote a decrease in the thickness of the remnant tooth tissues that can increase the risks of clinical failures by fracture. The thickness and volume of resin-matrix cement varied around both GFRC posts and increased from the apex up to the coronal third due to the lack of fitting.Graphical

Comparative Evaluation of Eustachian Tube Changes in Oral Submucous Fibrosis Patients.

Aim and Objective:Oral submucous fibrosis (OSMF) is a potentially premalignant disorder affecting the oral cavity and its adjacent structures. The present study was aimed at a comparative evaluation of eustachian tube (ET) changes in OSMF patients using audiometry and cone-beam computed tomography (CBCT). Materials and Methods:A total of 40 patients who were clinically diagnosed with OSMF were taken for the study and were graded into clinical and functional staging. After grading, the patients were subjected to audiometry to evaluate their hearing deficit. Subsequently, the patients were subjected to CBCT analysis for the evaluation of the length and volume of the ET. The length of ET was measured in the axial sections of the full-face CBCT images taken at the level of the root tip of the upper first molar. The radiolucency from the nasopharyngeal opening to the maximum distance was considered. The volume of ET was measured using third-party software (ITK-SNAP) in the radiolucent area. Result:The age group in which a higher number of OSMF cases were seen was between 41 and 50 years. There was mild to moderate hearing loss observed in the right and/or left ear, with little variation between right and left ear changes in audiometry. The CBCT analysis did not show a significant difference in the mean length of the eustachian tube when comparing OSMF cases with normal. However, as the disease worsened, the length on the right and left sides significantly decreased. Additionally, there was no statistically significant difference in the mean eustachian tube volume between disease cases and controls. According to the clinical subgrades, the overall volume decreased from lower grade to higher grade, but there was no discernible difference between the left and right ear. The volume on function sub-grading between the right and left ear, however, was significantly reduced. Thus, the length and volume of ET decreased as the disease severity increased, but the mild to moderate hearing loss found in different clinical and functional grades of OSMF cases was not statistically significant. Conclusion:Therefore, from the present study, it can be concluded that all OSMF cases should be evaluated for hearing deficit, and imaging of the eustachian tube should be part of the OSMF assessment for morphological changes of the ET that may cause hearing deficit.

Effect of orthodontic treatment on the periapical radiolucency of endodontically treated teeth: a CBCT analysis

BackgroundThis study aimed to evaluate periapical radiolucency of endodontically treated teeth before and after orthodontic treatment using cone-beam computed tomography (CBCT).MethodsPatients who underwent orthodontic treatment at Wonkwang University Daejeon Dental Hospital between January 2009 and June 2022 were included based on the following criteria: root canal treatment, and availability of CBCT images taken before and after orthodontic treatment with an interval of > 1 year between both scans. Patients with primary teeth or orthodontic tooth extractions were excluded. The size of the periapical radiolucency (SPR) of the endodontically treated tooth was evaluated using CBCT. Pre-orthodontic treatment CBCT images and the latest post-orthodontic treatment CBCT images were analyzed. The selected teeth were further categorized based on the orthodontic duration, CBCT interval, the patient sex and age, the tooth type and position (maxilla or mandible), and quality of root canal obturation. Statistical analyses were performed to evaluate changes in SPR using the paired t-test and multiple regression analysis.ResultsIn total, 115 teeth (37 anterior teeth, 22 premolars and 56 molars) from 61 patients (age, 14–54 years) were included, with 39 teeth from male patients and 76 teeth from female patients. The age was ranged between 14 and 54 years old, and mean age was 25.87 years old. The mean CBCT interval and orthodontic treatment period were 43.32 months and 36.84 months, respectively. Seventy-five teeth showed good obturation quality, 80 were not used as anchors during orthodontic treatment, and 71 were maxillary. The SPR size increased after orthodontic treatment for 56 teeth and decreased for 59 cases. The average change in SPR was -0.102 mm and the difference was not significant. Significant decrease of SPR were observed between female patients (p = 0.036) and maxillary teeth (p = 0.040).ConclusionOrthodontic treatment had no significant impact on the changes in the SPR in endodontically treated teeth in most categories. However, there was a significant difference among females and the maxillary teeth. In both categories, the size of radiolucency decreased significantly.

Revisiting Premolars Using Cone-Beam Computed Tomography Analysis and Classifying Their Roots and Root Canal Morphology Using Newer Classification.

The objective is to compare the internal morphology of premolars while applyingthe Vertucci andrecent classification systemfor root canal variations in the Gujarat populationusing CBCT. A sample size of 537 CBCT images collected from various diagnostic centers in Gujarat was analyzed. The root canal morphology was then classifiedby using two methods - Ahmed et al. and Vertucci classification system. Fisher's exact test and Chi-square test were used for statistical analysis. All the premolars revealed a varied canal configuration. More than halfof maxillary first and 42% of maxillary second premolars were double rooted. Vertucci type IV classification was the most common infirst maxillary premolars and Type I and type IV were commonly seen in second premolars. According to the new system, the code 2N B1 P1 wascommonly seen for first maxillarypremolars. The majority of mandibular premolars were single rooted. Classification wise type I Vertucci and 1 N1 were themost common types observed. Premolars - both maxillary and mandibular - in this subpopulation had a wide range of root canal anatomical variations.Clinicians should be aware of this for a successful treatment outcome.The new system for classifying canal morphology describes the root and canal configurations in a more accurate and practical manner compared to the Vertucci classificationand hence can be used routinely.

Alternative Ridge Augmentation for Esthetic Implant Placement: Case Series

&lt;p&gt;Backgrounds: With the advantage of maximizing esthetic results and minimizing treatment procedures, immediate implant placement and provisionalization (IIPP) would be the first choice when planning to replace failing teeth in esthetic zone. However, the previous cone-beam computed tomography (CBCT) analysis of maxillary anterior teeth in Taiwanese patients revealed that the higher probability of labial bony perforation (LBP) when immediate implant surgery due to undesirable labial ridge concavity. Therefore, this case series demonstrated an alternative strategic approach that combined prophylactic root resection and simultaneous guided bone regeneration (GBR), which could effectively achieve the prerequisites for IIPP and decrease the risks of LBP. Materials and Methods: In this retrospective case-series study, four clinical cases with one or more failing anterior teeth were included. Following the initial CBCT analysis, all cases showed insufficient implant bone support due to apical lesion or buccal bone concavity. Besides, all patient were highly esthetic demand. Thus, we performed the prophylactic root resection with an attempt to maintain gingiva contour, and simultaneous GBR for ridge augmentation. After 8-month uneventful healing, IIPP was accomplished in all cases. The change of bone volume was compared by the preoperative computed tomography scans with those obtained eight months later. The quantitative analysis was calculated by Wilcoxon Signed-Rank Test and Kruskal-Wallis Test. Results: In all cases, significant bone fill was observed and adequate bone volume for IIPP in ideal position in CBCT planning after our alternative bone augmentation procedure. There were no biological or mechanical complications of implant restoration upon clinical and radiographic examination at follow up. Conclusion: This approach could not only preserve the architecture of hard and soft tissue, fulfill the patients&amp;rsquo; expectation, but also achieve esthetic and functional outcomes.&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

Effect of the pulsed electromagnetic field in the repair of a calvaria critical bone defect in rats: cone beam computed tomographic and histomorphometric analysis.: PEMF in the repair of a calvaria critical bone defect: CBCT analyses.

IntroductionThe present study evaluated the effect of two protocols of Pulsed Electromagnetic Field (PEMF) therapy on bone neoformation on calvaria critical defects in rats. Material & methods96 rats were randomly divided into 3 groups: Control Group (CG; n=32); Test Group – PEMF 1 hour (TG1h; n=32) and Test Group – PEMF 3 hour (TG3h; n=32). A Critical-size Bone Defect (CSD) was surgically created in the calvaria of rats. The animals in the test groups were exposure to PEMF for 5 days a week. The animals were euthanized at 14, 21, 45 and 60 days. The specimens were processed for volume and texture (TAn) analysis, by Cone Beam Computed Tomography (CBCT) and histomorphometric analysis, ResultsHistomorphometric and volume analyses revealed that there was no statistically significant difference in the repair of bone defects between groups receiving PEMF therapy and CG. TAn revealed a statistically significant difference between the groups only for the entropy parameter, in which TG1h group presented a higher value compared to CG on 21 days. TG1h and TG3h did not accelerate bone repair in calvarial critical size defect and the parameters of PEMF should be considered. DiscussionThis study showed that PEMF application on CSD in rats does not accelerate bone repair. Although literature showed a positive association in biostimulation on bone tissue with the parameters applied, studies with other PEMF parameters are essential to verify improving this study design.

A Multi-Centre Randomized Controlled Trial Comparing Connective Tissue Graft with Collagen Matrix to Increase Buccal Soft Tissue Thickness: A Cone-Beam CT Analysis.

(1) Aim: a cross-linked porcine-derived collagen matrix (CMX) has been developed for soft tissue augmentation. Although this grafting material does not require a second surgical site, recent findings have indicated deeper pockets, more marginal bone loss and more midfacial recession in the short term when compared to connective tissue graft (CTG). Hence, the aim of the present study was to evaluate the safety of CMX based on buccal bone loss over a one-year period. (2) Methods: Patients who were missing a single tooth in the anterior maxilla were included, in whom the failing tooth had been removed at least 3 months prior and who presented a horizontal mucosa defect. All sites had a bucco-palatal bone dimension of at least 6 mm as assessed on Cone-Beam Computed Tomography (CBCT) to ensure complete embedding of an implant by bone. All patients received a single implant and an immediate implant restoration using a full digital workflow. Sites were randomly allocated to the control (CTG) or test group (CMX) to increase buccal soft tissue thickness. All surgeries were performed by means of full thickness mucoperiosteal flap elevation, placing CTG and CMX in contact with the buccal bone wall. Safety was assessed by evaluating the impact of CTG and CMX on buccal bone loss over a one-year period using superimposed CBCT scans. (3) Results: thirty patients were included per group (control: 50% females, mean age 50; test: 53% females, mean age 48) and 51 (control: 25; test: 26) could be analyzed for buccal bone loss. At 1 mm apical to the implant-abutment interface (IAI), most horizontal resorption was found pointing to 0.44 mm in the control group and 0.59 mm in the test group. The difference of 0.14 mm (95% CI: -0.17-0.46) was not statistically significant (p = 0.366). At 3 mm and 5 mm apical to the IAI, the difference between the groups was 0.18 mm (95% CI: -0.05-0.40; p = 0.128) and 0.02 mm (95% CI: -0.24-0.28; p = 0.899), respectively. Vertical buccal bone loss amounted to 1.12 mm in the control group and 1.14 mm in the test group. The difference of 0.02 mm (95% CI: -0.53-0.49) was not statistically significant (p = 0.926). (4) Conclusions: In the short term, soft tissue augmentation with CTG or CMX results in limited buccal bone loss. CMX is a safe alternative to CTG. Longer follow-up is needed to assess the impact of soft tissue augmentation on buccal bone.

Cone Beam Computed Tomography Analysis of Posterior-Superior Alveolar Canal from a Fixed Reference Point: Implications for Sinus Floor Elevation Procedure through Lateral Approach.

Sinus floor elevation is commonly done in the maxillary posterior region prior to dental implant placement. This study primarily aimed at assessing the location of the posterior superior alveolar artery (PSAA) canal on cone beam computed tomography (CBCT) scans and its relation to the alveolar ridge and maxillary sinus from a fixed reference point. A total of 226 edentulous maxillary molar sites were included in this retrospective analysis. The distance from the PSAA to the sinus floor (SF), alveolar crest (AC) and a fixed reference point, that is, the roof of sinus (RS) were measured. The alveolar bone height (ABH), thickness of the crestal keratinized mucosa (CKM) and thickness of Schneiderian membrane (SM) were also evaluated. 54 sites (23.89%) were excluded from the study. The SF, AC, RS and ABH values averaged at 11.91mm ± 3.63mm, 16.05mm ± 3.96mm, 25.32mm ± 7.13mm and 4.93mm ± 4.27mm respectively. SF and AC was higher in second molar than first molar region (p < 0.001), but RS did not show significant difference (p = 0.85). CKM and SM averaged at 2.02mm ± 0.68mm and 1.31mm ± 0.81mm respectively. The PSAA can be visualized in CBCT scans with a prevalence of 76.11% and may not be detected when adherent to the sinus membrane. This study stresses on the need for a CBCT, prior to sinus surgeries through lateral approach, to assess the PSAA.

Characteristics of Medial Depression of the Mandibular Ramus: A CBCT Analysis in Different Sagittal Skeletal Patterns.

Medial depression of the mandibular ramus (MDMR) as a normal anatomical variation might complicate orthognatic surgeries that involve ramus. When planning an orthognatic surgery, it is clinically valuable to notice MDMR in osteotomy site to decrease the risk of failure. The aim of present study was to evaluate the prevalence as well as characteristics of MDMR in three skeletal sagittal classifications. This cross sectional study evaluated 530 cone beam computed tomography (CBCT) scans, of which 220 were enrolled. The skeletal sagittal classification, the presence of MDMR, the shape, depth, and width of MDMR were recorded for each patient by two examiners. Chi-square test was performed to determine the differences between three skeletal sagittal groups and between two genders. The overall prevalence of MDMR was 60.45%. MDMR was mostly detected in class III (76.92%), followed by class II (76.66%), and class I (54.87%). In the analyzed CBCT scans, semi-lunar was the most common shape detected (42.85%), followed by triangular (30.82%), circular (18.04%), and tear-drop (8.27%). The depth of MDMR was not significantly different between three sagittal groups and between genders; however, the width of MDMR was higher in class III group and in male patients. In the present study, MDMR was found to be more common in patients with class II and class III skeletal classifications. Although, MDMR was more frequent in class III, the difference between class II and class III was not significant. More caution is needed during orthognatic surgery in patients with dentoskeletal deformities during the splitting of the ramus. Moreover, higher width of MDMR in class III and male patients should be concerned when planning an orthognatic surgery for these patients.

What Is the Linear Accuracy of Regional Voxel-Based Registration for Orthognathic Surgery Landmarks?

While regional voxel-based registration (R-VBR) has been shown to have excellent reproducibility and angular accuracy, there are limited data on the linear accuracy of R-VBR for common orthognathic surgery landmarks, or on whether angular accuracy correlates with linear accuracy. The purpose of this study was to estimate the linear accuracy of R-VBR for several skeletal landmarks commonly used in orthognathic surgical planning, and to measure the correlation between angular and linear discrepancies. This is a retrospective cross-sectional study of consecutive patients treated at a single center with nonsegmental LeFort I and bilateral sagittal split osteotomy surgery from January 2019 to November 2020. Cone beam computed tomography at the preoperative (T0) and immediate postoperative (T1) stages were analyzed to measure the postoperative positional changes of 11 orthognathic landmarks in 4 regions of interest (ROI) using R-VBR performed twice by two examiners. Pairwise correlation analysis and canonical correlation analysis were performed for the angular discrepancies (primary predictor variable) and the linear discrepancies (primary outcome variable) to measure the correlation between the two. In cone beam computed tomography analysis of 28 eligible subjects (16 males, 12 females; mean age 18.9years, range 15 to 25), the mean absolute (MA) angular discrepancies ranged from 0.15° to 0.55°, while the corresponding MA linear discrepancies ranged from 0.05 to 0.41mm. There was a strong correlation between angular and linear discrepancies that was statistically significant (P=.001 to .04, Spearman's rank correlation coefficient 0.38 to 0.87). For nonsegmental LeFort I osteotomies and bilateral sagittal split osteotomy, R-VBR has excellent linear accuracy within a single voxel size (0.3mm) for commonly used orthognathic landmarks in the maxillary and distal mandibular ROI. The MA linear discrepancy for the proximal mandibular segment ROI was greater than a single voxel size, with a maximum of 0.41mm.

Dentin Thickness of the Danger Zone in the Mesial Roots of the Mandibular Molars: A Cone Beam Computed Tomography Analysis

Mandibular first molars appear to be the most commonly tooth subjected to a root canal treatment, therefore a better understanding of the anatomy critical zones for resistance of this teeth may decrease the treatment's failure rate. So, this study was conducted to evaluate the dentin thickness of the danger zone in mesial roots of mandibular first molars using cone beam computed tomography in an Iranian population. In this cross-sectional study, 210 Cone Beam Computed Tomography acquisition of the mandibular first molars were collected from a radiology center in Qazvin. The dentin thickness of the mesial roots (mesiobuccal and mesiolingual canals) was measured from the furcation to 5 mm below. The relationship between the dentin thickness in the danger zone and parameters, like age, gender, placement side, root length, the curvature of the canal, canal type, presence of middle mesial canal, and distance between the orifices of the mesial canals was investigated. Frequency, mean and standard deviation for variables were calculated, and data analysis was done by SPSS using simple and multiple linear regression and Pearson correlation coefficient. Also, two-sample t-test was used to compare mesiobuccal and mesiolingual on two sides. The significant level was also considered at (p < 0.05). The average minimum thickness of danger zone dentin was found to be 0.885 ± 0.259 mm in the mesiobuccal canal and 0.906 ± 0.206 mm in the mesiolingualcanal. Also, the minimum thickness of dentin in the mesiobuccal and mesiolingual canals in the range of 0 to 1 mm from the furcation was more than in other areas. There was no significant relationship between the minimum dentin thickness of the danger zone with gender, placement side, root length, canal type, and mesial canal entrance distance. But with increasing age, the thickness of dentin in the danger zone in the mesiolingualcanal increased significantly (p = 0.008). It was also observed that with the increase in the curvature of the canal, the thickness of the dentin in the danger zone in the mesiobuccal canal decreased (moderately curved (p = 0.008), severely curved (p = 0.046)). In addition, the thickness of the dentin in the mesiobuccal and mesiolingual canal was less in the samples with the middle mesial canal (p = 0.047, 0.044). Less dentin thickness in the danger zone in the mesial roots of mesiolingual mandibular first molars was seen in younger patients in mesiolingual canal, with a greater degree of canal curvature in the mesiobuccal canal and teeth with a middle mesial canal. Therefore, it is suggested that large taper instruments should be used with more precision to prevent complications.

Three dimensional condylar positional and morphological changes following mandibular reconstruction based on CBCT analysis: a prospective study

ObjectiveThis study aimed to evaluate the condylar positional changes following mandibular reconstruction with preservation of the condylar head using Cone-Beam Computed Tomography (CBCT). Also, to assess joint space changes and the overall volumetric space compared to the preoperative status.MethodologyThis prospective study included 30 patients (60 joints) subjected to unilateral mandibular resection and reconstruction with preservation of the condylar head. The Helkimo index and preoperative (T1), two weeks postoperative (T2), and follow-up CBCTs (T3) after at least six months were gathered and processed to evaluate the condylar position and TMJ joint space using Anatomage Invivo 6. A student’s t-test and repeated-measures ANOVA statistics were used. A P value of less than 0.05 was considered statistically significant.ResultsThirty patients (14 males, 16 females) with a mean age of 40.01 ± 12.7 years (a range of 18.1–62.9 years) were included. On the tumor side, there were significant variances in the vertical and mediolateral condylar positions between the three-time points (T1, T2, T3). Immediately after the operation, the condyles were significantly displaced in a downward direction at T2, which became larger after the last follow-up period (T3) (p = 0.007). The condylar positions at the anteroposterior direction were relatively stable without significant differences between the three times points (p = 0.915). On the non-tumor side, the condylar positions were relatively stable in the mediolateral and anteroposterior positions.In the tumor side, all of the TMJ spaces were significantly increased in size following the mandibular reconstructions (T2 and T3). However, on the non-tumor side, the anterior, posterior, and medial joint spaces were significantly changed postoperatively.ConclusionAfter mandibular reconstruction with condylar preservation, the condylar position and volumetric measurement immediately changed noticeably and continued to be a permanent change over time compared to relatively stable condyles on the non-tumor side. According to Helkimo index, patients become adapted to the postoperative changes without significant differences between the two sides.

Cone-Bean Computed Tomography and Light Microscopic Examination of Human Extracted Molars - An in Vitro Study

Introduction: For appropriate root canal therapy, understanding the anatomical and morphological aspects of the endodontic area is critical. Therefore, the study and analysis of images is an important step in the assessment and current clinical treatment of endodontic problems. Furthermore, microscopic-assisted endodontic therapy, particularly for multirooted teeth, is becoming more common in contemporary endodontic clinical practice. The aim of this in vitro study was to examine the distinct types of isthmuses using a light microscope and Cone-Beam Computed Tomography (CBCT). Method: Fifty-five extracted human molars were used for this study. CBCT was used to realize the study. After the CBCT analysis, all teeth were inspected under a light microscope, and the results were compared with those of the CBCT examination. Results: The results from the CBCT at the coronary third of the root canals were as follows: Types I, II, III, IV, and V isthmuses were found in 50.9%, 16.4%, 1.8%, 7.3%, and 23.6% of all samples, respectively. For the middle third, we found Types I, II, III, IV, and V isthmuses in 40.0%, 23.6%, 1.8%, 16.4%, and 18.2% of the samples, respectively. For the apical third, we found Types I, II, III, IV, and V isthmuses in 60.0%, 29.1%, 5.5%, 1.8%, and 3.6% of all samples, respectively. The results obtained from the microscopic examination were similar to those from the CBCT study. There is no confirmed statistically significant difference between the examination methods (p = 0.07). Conclusion: Three-dimensional examinations have a significant role among the methods for diagnosing and detecting an isthmus in the complex root canal system, especially in the apical part.

A cone-beam CT analysis of the vertical distance between the maxillary first molars and the maxillary sinus floor in skeletal Class Ⅱ malocclusion patients

A cone-beam CT analysis of the vertical distance between the maxillary first molars and the maxillary sinus floor in skeletal Class Ⅱ malocclusion patients

Cone Beam CT Analysis of Haller Cells: Prevalence and Relationship with Orbital Floor Dehiscence.

CBCT images of 120 patients were interpreted in coronal plane for the presence of Haller cells and orbital floor dehiscence. The prevalence of Haller cell, presence of dehiscence, unilateral, or bilateral frequency were assessed. In addition, the size was categorized in three groups of small, medium, and large. Chi-square and Cochran-Mantel-Haenszel tests were used for statistical analysis of the data, and p < 0.05 was considered to be significant. A total of 51 male and 69 female with mean ± SD age of 38.84 ± 68.14 were assessed. The overall prevalence of Haller cells was 56.7%, of which 44 (64.7%) were unilateral and 24 were bilateral (35.3%). The majority of the cells (70.7%) were seen in medium (2-4 mm) sized. There was a significant association between Haller cells and orbital floor dehiscence (p ≤ 0.001). The prevalence of Haller cells was remarkably high and the presence of Haller cells was strongly associated with ipsilateral orbital floor dehiscence. Based on the findings of this study, CBCT can be useful in delineation of the bony anatomy of sinonasal complex.

Development of Machine-Learning Prediction Programs for Delivering Adaptive Radiation Therapy With Tumor Geometry and Body Shape Changes in Head and Neck Volumetric Modulated Arc Therapy

During radiation therapy for head and neck cancer using volumetric modulated arc therapy, excessive dosing or underdosing occurs as a result of the decrease in tumor volume and changes in body weight. Adaptive radiation therapy (ART) is performed when significant changes are observed; however, the decision to implement ART depends on the oncologist's subjective judgment. The purpose of this study was to present objective indicators for ART and develop a program to predict the need for ART. The study included 47 patients in the non-ART group and 21 patients in the ART group with shape changes. Patients who received ART could not be covered with the prescribed radiation therapy dose due to shape changes. For each patient, 1112 6-dimensional lists were created, including the number of irradiations, amount of change in the clinical target volume (CTV), rate of change in CTV, mean oral cavity dose, age, and body mass index. Support vector machine and k-nearest neighbor were used for machine learning. The random number of test data to be extracted varied from 1 to 9, and a mean accuracy score was calculated. These programs could predict the need for ART if the accuracy score was high. The classification accuracy of the list, including the amount of change in the CTV and rate of change in CTV up to 20 fractions, was 0.963 and 0.967 for support vector machine and k-nearest neighbor, respectively. This program predicted the need for ART with more than 90% accuracy based on shape changes over time in cone beam computed tomography analysis for up to 20 fractions. This may provide significant support for objective decisions to implement ART based on the amount of change over time during treatment.