Three-dimensional Cone-beam Computed Tomography Research Articles

Impacted mandibular third molars: a comparison of orthopantomography and cone-beam computed tomography imaging in predicting surgical difficulty.

This study investigated the predictive value of orthopantomography (OPG) for the difficulty of extracting impacted mandibular third molars, in comparison with cone-beam computed tomography (CBCT). In this descriptive quantitative investigation, two oral and maxillofacial radiologists evaluated OPG and three-dimensional CBCT images according to the Pell-Gregory and Winter classifications. The results for the classification were compared using the chi-square test, and the prediction of difficulty was assessed using the Pederson scale, with a significance level of p< 0.05. The study included 30 patients (14 men and 16 women), providing a total of 53 samples of impacted mandibular third molars. Of these, 30 (56.6%) were from the right side and 23 (43.4%) from the left. There was a statistically significant difference between the OPG and CBCT images concerning their relation to the mandibular ramus (p< 0.05). However, evaluations based on occlusal lines and angulation showed no significant differences (p> 0.05). According to the Pederson scale, significant differences were observed between OPG and CBCT in predicting extraction difficulty (p< 0.05). CBCT offered a more accurate assessment of the surgical difficulty associated with mandibular third molars than OPG. OPG views frequently failed to adequately visualize the region of the mandibular ramus, influencing the perceived difficulty of mandibular third molar surgery. In certain cases, the use of CBCT imaging is crucial.

Retrospective Radiographic Evaluation of Implant Complications: CBCT-Based Study

Aim: Dental implants are a popular treatment option for patients with one or more missing teeth. With the increase in dental implant treatments, the complications encountered have increased. Therefore, it is very important to plan the implant by evaluating the anatomy of the area where the implant will be placed in three dimensions with cone beam computed tomography (CBCT). The aim of this study is to evaluate the prevalence of implant complications seen in CBCT after implant applications. Material and Methods: CBCT images of 500 patients obtained for different dental reasons were examined; among these, 300 dental implant images were evaluated retrospectively in terms of complications. The number, location and type of identified complications (perforation in the maxillary sinus, mandibular canal, cortical bone, nasal cavity, and mental canal; contact with the adjacent tooth root) were recorded. The data obtained were analyzed statistically using chi-square tests. Results: At least one complication was detected in 65% of the 300 dental implants evaluated. A total of 272 complications (1.4 complications per implant) were observed in 195 dental implants with complications. The number of implants with complications per patient was found to be 3.9. The most observed complication was found to be vertical bone resorption around the implant (45%). Complications were most frequently detected in the maxillary posterior region (40%). Conclusion: Three-dimensional CBCT evaluation of the area where the implant will be applied before and after treatment is very important to prevent possible complications.

Three-Dimensional Evaluation of Impacted Mandibular Third Molar Angulation and its Impact on Lingual Cortical Bone Thickness: A Retrospective Cone-Beam Computed Tomography Study

Background: The removal of impacted lower third molars surgically can cause complications, and the lingual cortical bone thickness in this region becomes a determining factor in the risk of perforation and injury to the lingual nerve (LN). This study was conducted to assess the relationship between different angulations of impacted lower third molars based on Winter’s classification and the thickness of the lingual cortical bone. Variations in lingual cortical bone thickness among the genders were evaluated as well. Methods: Cone-beam computed tomography (CBCT) scans of 50 impacted lower third molar teeth of 50 patients (26 men and 24 women) were evaluated in this study. The lingual bone thickness surrounding impacted lower mandibular teeth was measured at three key points, namely, the cemento-enamel junction of the second mandibular molar, the mid-root of the impacted third molar, and the root apex of the impacted third molar. Mesiodistal angulation and buccolingual angulations of the impacted mandibular third molars underwent investigation. Statistical analysis was conducted using SPSS 23. Data were analyzed using the independent sample t test, one-way ANOVA, multiple linear regression analysis, and Fisher’s exact test. Results: There was a statistically significant relationship between the means of lingual cortical bone thickness surrounding the third molars based on Winter’s classification of third molars impacted at mesiodistal angulation (P=0.00). Regarding gender, buccolingual angulation demonstrated a statistically significant relationship among the means of lingual bone thickness around the third molars (P=0.022). Conclusion: In our study, the thickness of the lingual cortical bone was notably affected in the middle and apical areas of the impacted third molar region. The variable position of the LN near the mandible third molar region was significant in dental procedures due to its proximity. Three-dimensional (3D) imaging CBCT provides preoperative risk assessment that reduces preventable complications that cannot be answered by 2D imaging.

Imaging and 3D Analysis Based on Two or More Three-Dimensional CBCT Recordings before and after Orthodontic Treatment and Maxillofacial Therapy

Cone beam computed tomography (CBCT) has emerged as a crucial radiographic technique for orthodontic diagnosis and treatment planning, particularly for cases requiring the assessment of complex anatomical relationships. In the first part of the study, we examined metric characteristics measured on 3D cranial models of patients before and after surgery. In the second part, we conducted more complex data processing, analyzing a set of 12 cranial feature points using Procrustes analysis to quantify and visually represent surgical modifications. The third part involved comparing 3D facial surfaces using Iterative Closest Point (ICP) alignment and nearest point-to-point distances. Additionally, we tested point configurations in the facial soft tissues. The study included a group of orthodontic patients from whom CBCT data and 3D facial scans were obtained during treatment. The results demonstrated that each method could assess preoperative and postoperative changes to varying degrees. They also highlighted potential gender differences in surgical modifications that warrant further investigation and consideration during surgical planning. The aim of our study was to compare 3D visualizations of skull and facial models before and after surgery, to assess the degree of relative agreement or similarity, and to identify any morphological differences.

A randomized controlled clinical trial of concentrated growth factor combined with sodium hyaluronate in the treatment of temporomandibular joint osteoarthritis

ObjectiveTo investigate the effect of concentrated growth factor (CGF) combined with sodium hyaluronate (SH) on temporomandibular joint osteoarthritis (TMJOA).MethodsSixty patients with TMJOA who were diagnosed by cone-beam computed tomography (CBCT) between March 2020 and March 2023 at the Stomatological Hospital of Xi’an Jiaotong University were randomly divided into a control group (n = 30) and an experimental group (n = 30). The patients in the experimental group were treated with CGF + SH, and those in the control group were treated with SH only. The visual analogue scale (VAS) score indicating pain in the temporomandibular joint (TMJ) area; the Helkimo Clinical Dysfunction Index (Di); and changes in condylar CBCT at the first visit and 2 weeks, 3 months and 6 months after treatment were recorded. The CBCT data of the patients in the experimental and control groups were collected, and the three-dimensional CBCT image sequences were imported into Mimics Medical 19.0 software in DICOM format for condylar reconstruction.ResultsThe VAS scores at 2 weeks, 3 months and 6 months after treatment were significantly lower in the experimental group than in the control group (P < 0.05), and the pain in the experimental group was significantly relieved. The Di was significantly lower in the experimental group than in the control group (P < 0.05), and the clinical function of the TMJ improved. After treatment, the CBCT score was significantly lower in the experimental group than in the control group (P < 0.05), and the condylar bone cortex was obviously repaired. Observation of the condylar bone cortex by three-dimensional reconstruction showed the same results as those obtained by CBCT.ConclusionCGF combined with SH is effective in the treatment of TMJOA and can improve muscle pain, TMJ pain, Impaired TMJ function, Impaired range of movement, Pain on movement of the mandible and promote bone repair.The registration number (TRN)ChiCTR2400082712.The date of registrationApril 5, 2024.

Clinical validity and precision of deep learning-based cone-beam computed tomography automatic landmarking algorithm.

This study was performed to assess the clinical validity and accuracy of a deep learning-based automatic landmarking algorithm for cone-beam computed tomography (CBCT). Three-dimensional (3D) CBCT head measurements obtained through manual and automatic landmarking were compared. A total of 80 CBCT scans were divided into 3 groups: non-surgical (39 cases); surgical without hardware, namely surgical plates and mini-screws (9 cases); and surgical with hardware (32 cases). Each CBCT scan was analyzed to obtain 53 measurements, comprising 27 lengths, 21 angles, and 5 ratios, which were determined based on 65 landmarks identified using either a manual or a 3D automatic landmark detection method. In comparing measurement values derived from manual and artificial intelligence landmarking, 6 items displayed significant differences: R U6CP-L U6CP, R L3CP-L L3CP, S-N, Or_R-R U3CP, L1L to Me-GoL, and GoR-Gn/S-N (P<0.05). Of the 3 groups, the surgical scans without hardware exhibited the lowest error, reflecting the smallest difference in measurements between human- and artificial intelligence-based landmarking. The time required to identify 65 landmarks was approximately 40-60 minutes per CBCT volume when done manually, compared to 10.9 seconds for the artificial intelligence method (PC specifications: GeForce 2080Ti, 64GB RAM, and an Intel i7 CPU at 3.6 GHz). Measurements obtained with a deep learning-based CBCT automatic landmarking algorithm were similar in accuracy to values derived from manually determined points. By decreasing the time required to calculate these measurements, the efficiency of diagnosis and treatment may be improved.

Prevalence of C-shaped canals and three-rooted mandibular molars in the Iranian population by using cone-beam computed tomography.

This study aimed to evaluate the prevalence of C-shaped canals and three-rooted mandibular molars in the Iranian population using cone-beam computed tomography (CBCT). This study evaluated mandibular teeth on 292 CBCT scans of patients referred to the Department of Radiology, Faculty of Dentistry, Islamic Azad University, Isfahan, Iran. All CBCT scans were obtained with the same three-dimensional CBCT scanner, and sections were reconstructed in all three planes (sagittal, axial, and coronal) with 1 mm slice thickness. A total of 291,402, and 200 first, second, and third molars, respectively, were evaluated. Data were analyzed using SPSS software (version 26.0). Of 291 mandibular first molars, 0.7% were single-rooted, 96.6% were two-rooted, and 2.7% were three-rooted. The prevalence of C-shaped canals was 1.7% in mandibular first molars. Of 402 mandibular second molars, 8.5% were single-rooted, 90.5% were two-rooted, and 1% were three-rooted. The prevalence of C-shaped canals was 2% in mandibular second molars. Of 200 mandibular third molars, 21.5% were single-rooted, 77.5% were two-rooted, and 1% were three-rooted. The prevalence of C-shaped canals was 2% in mandibular third molars. In the present study, the majority of mandibular molars were two-rooted, and three-rooted mandibular molars were less common. The third and second mandibular molars both had an increased prevalence of C-shaped canals. Mandibular first molars had the highest prevalence of three-rooted molars.

Deep Learning Models for Automatic Upper Airway Segmentation and Minimum Cross-Sectional Area Localisation in Two-Dimensional Images.

To develop and validate convolutional neural network algorithms for automatic upper airway segmentation and minimum cross-sectional area (CSAmin) localisation in two-dimensional (2D) radiographic airway images. Two hundred and one 2D airway images acquired using cone-beam computed tomography (CBCT) scanning were randomly assigned to a test group (n = 161) to train artificial intelligence (AI) models and a validation group (n = 40) to evaluate the accuracy of AI processing. Four AI models, UNet18, UNet36, DeepLab50 and DeepLab101, were trained to automatically segment the upper airway 2D images in the test group. Precision, recall, Intersection over Union, the dice similarity coefficient and size difference were used to evaluate the performance of the AI-driven segmentation models. The CSAmin height in each image was manually determined using three-dimensional CBCT data. The nonlinear mathematical morphology technique was used to calculate the CSAmin level. Height errors were assessed to evaluate the CSAmin localisation accuracy in the validation group. The time consumed for airway segmentation and CSAmin localisation was compared between manual and AI processing methods. The precision of all four segmentation models exceeded 90.0%. No significant differences were found in the accuracy of any AI models. The consistency of CSAmin localisation in specific segments between manual and AI processing was 0.944. AI processing was much more efficient than manual processing in terms of airway segmentation and CSAmin localisation. We successfully developed and validated a fully automatic AI-driven system for upper airway segmentation and CSAmin localisation using 2D radiographic airway images.

CBCT for Diagnostics, Treatment Planning and Monitoring of Sinus Floor Elevation Procedures.

Sinus floor elevation (SFE) is a standard surgical technique used to compensate for alveolar bone resorption in the posterior maxilla. Such a surgical procedure requires radiographic imaging pre- and postoperatively for diagnosis, treatment planning, and outcome assessment. Cone beam computed tomography (CBCT) has become a well-established imaging modality in the dentomaxillofacial region. The following narrative review is aimed to provide clinicians with an overview of the role of three-dimensional (3D) CBCT imaging for diagnostics, treatment planning, and postoperative monitoring of SFE procedures. CBCT imaging prior to SFE provides surgeons with a more detailed view of the surgical site, allows for the detection of potential pathologies three-dimensionally, and helps to virtually plan the procedure more precisely while reducing patient morbidity. In addition, it serves as a useful follow-up tool for assessing sinus and bone graft changes. Meanwhile, using CBCT imaging has to be standardized and justified based on the recognized diagnostic imaging guidelines, taking into account both the technical and clinical considerations. Future studies are recommended to incorporate artificial intelligence-based solutions for automating and standardizing the diagnostic and decision-making process in the context of SFE procedures to further improve the standards of patient care.

Intraoperative Radiological Imaging: An Update on Modalities in Trauma and Orthopedic Surgery

Intraoperative radiological imaging plays a key role in the management algorithm of patient care. Different intraoperative modalities have applications in the diagnosis, treatment, and monitoring of patient affected by various medical or surgical conditions. Advances in technology, computer software, and integration of various radiological modalities have extended the applications of intraoperative imaging in health care. Intraoperative radiological imaging have evolved from the initial use of conventional fluoroscopy to current innovations of computed tomography (CT) such as three-dimensional cone-beam CT and magnetic resonance-based imaging. In fact, intraoperative imaging has become integral to most of trauma and orthopedic procedures. Apart from their role in diagnosis of a spectrum of orthopedic conditions like prosthetic joint infection, imaging systems assist orthopedic surgeons to perform minimally invasive procedures, improving patient safety and also enabling higher accuracy and lower revision rates. More importantly, advances in technologies are essential in safeguarding radiation safety regulations, thereby reducing the radiation dose to the patient and surgical team. Integration of various imaging technologies, improving quality of image acquisition, reduction of radiation dose, and seamless image transfer to allow decision-making process are crucial in the delivery of effective patient care.

Automated analysis of three-dimensional CBCT images taken in natural head position that combines facial profile processing and multiple deep-learning models

Background and objectivesAnalyzing three-dimensional cone beam computed tomography (CBCT) images has become an indispensable procedure for diagnosis and treatment planning of orthodontic patients. Artificial intelligence, especially deep-learning techniques for analyzing image data, shows great potential for medical and dental image analysis and diagnosis. To explore the feasibility of automating measurement of 13 geometric parameters from three-dimensional cone beam computed tomography images taken in natural head position (NHP), this study proposed a smart system that combined a facial profile analysis algorithm with deep-learning models. Materials and methodsUsing multiple views extracted from the cone beam computed tomography data of 170 cases as a dataset, our proposed method automatically calculated 13 dental parameters by partitioning, detecting regions of interest, and extracting the facial profile. Subsequently, Mask-RCNN, a trained decentralized convolutional neural network was applied to detect 23 landmarks. All the techniques were integrated into a software application with a graphical user interface designed for user convenience. To demonstrate the system's ability to replace human experts, 30 CBCT data were selected for validation. Two orthodontists and one advanced general dentist located required landmarks by using a commercial dental program. The differences between manual and developed methods were calculated and reported as the errors. ResultsThe intraclass correlation coefficients (ICCs) and 95% confidence interval (95% CI) for intra-observer reliability were 0.98 (0.97–0.99) for observer 1; 0.95 (0.93–0.97) for observer 2; 0.98 (0.97–0.99) for observer 3 after measuring 13 parameters two times at two weeks interval. The combined ICC for intra-observer reliability was 0.97. The ICCs and 95% CI for inter-observer reliability were 0.94 (0.91–0.97). The mean absolute value of deviation was around 1 mm for the length parameters, and smaller than 2° for angle parameters. Furthermore, ANOVA test demonstrated the consistency between the measurements of the proposed method and those of human experts statistically (Fdis=2.68, ɑ=0.05). ConclusionsThe proposed system demonstrated the high consistency with the manual measurements of human experts and its applicability. This method aimed to help human experts save time and efforts for analyzing three-dimensional CBCT images of orthodontic patients.

Cone-Beam Computed Tomography Image Features under Intelligent Three-Dimensional Reconstruction Algorithm in the Evaluation of Intraoperative and Postoperative Curative Effect of Dental Pulp Disease Using Root Canal Therapy

Objective. The objective of this study was to analyze the application effect of algorithm-based three-dimensional reconstruction of cone-beam computed tomography (CBCT) images in the treatment of dental pulp disease (DPD) and the evaluation of the curative effect after treatment. Methods. 120 patients with DPD in hospital were selected as the research objects. In this study, based on the regridding model in the algorithm, the mapping relationship between the undersampled CBCT image and the fully sampled CBCT image was connected, and a model that can be used for image restoration and reconstruction was obtained after training. The algorithm model was used to reconstruct and repair the CBCT images of the research objects, and then, the reconstructed CBCT images were segmented based on the improved level set algorithm. After that, it analyzed and compared the accuracy of X-ray and CBCT based on three-dimensional reconstruction for the diagnosis accuracy of DPD and compared the average bone density of patients and the effect of root canal filling in each time period after root canal treatment. Result. After the image was reconstructed with the regridding model, a CBCT image of the patient’s teeth with less noise and clearer structure was obtained. The segmentation accuracy of the level set algorithm reached 85.5% on average, and the undersegmentation rate (UR) and the over-segmentation rate (OR) were both less than 6%. The diagnostic rates of X-ray and three-dimensional CBCT examination of DPD were 43.7% and 100%, respectively, and the difference was statistically significant ( P &lt; 0.05 ). Under the monitoring of the three-dimensional reconstruction of CBCT technology, the average bone density of the test group patients after 12 months of root canal treatment was the same as that of healthy people. Under X-ray examination, the average bone density of the test group patients was still lower than that of healthy people after 12 months of root canal treatment. Under the three-dimensional reconstruction of CBCT, the underfilling rate of patients after root canal treatment was 5%, the proper filling rate was 85%, and the overfilling rate was 10%. Conclusion. In summary, the CBCT reconstructed by the intelligent three-dimensional algorithm was effectively improved, which enhanced the image quality and segmentation efficiency. Analysis on diagnosis efficiency and treatment effect proved that CBCT can be an effective method to evaluate the initial curative effect of DPD treatment during and after the surgery and can provide valuable information in future dental treatment, thereby enhancing the success rate of DPD using root canal therapy.

The Spheno-Occipital Synchondrosis and Morphometry of Sella Turcica Association with Different Phenotype Factors Related to Ectopic Eye Tooth/Teeth

Objectives: This study investigates the prevalence of Spheno-Occipital Synchondrosis (SOS) and sella turcica morphometry (STM) association with different phenotype factors related to ectopic eye tooth/teeth (EET) using cone beam computed tomography (CBCT) imaging. Methods: This comparative retrospective study analyzed 252 CBCT images. Subjects in the EET group consisted of 197 CBCT images with the phenotype factor in number, i.e., unilateral (13, n = 62; 23, n = 59) or bilateral (1323, n = 76) and matched control (n = 55). SOS and STM were investigated using 3D OnDemand Software. Seven parameters of STM were measured. To test the association X2 used for SOS prevalence, disparities in STM were tested using ANOVA and post hoc Tukey test. Results: The prevalence of unfused SOS was 48.4% and 16.1% in the 1323 and control groups, respectively. Fused SOS prevalence was quite similar in all four groups. Phenotype factor in number, i.e., unilateral 13, 23, or bilateral EET group showed significant disparities in six out of seven parameters (p = 0.044 to p ≥ 0.001). Additionally, phenotype factor in position, i.e., occlusal, buccal, or palatal group showed insignificant disparities (p = 0.463 to p = 1.00). Conclusion: SOS in the ectopic eye tooth group (EETG) was prevalent in the 1323 and buccal position groups. Differing from previous two-dimensional (2D) studies, there were statistically significant disparities in all seven measured variables of STM among control, and three different phenotype factors in numbers were revealed using three-dimensional (3D) CBCT imaging.

Deep Learning-Based Three-Dimensional Oral Conical Beam Computed Tomography for Diagnosis.

In order to deeply study oral three-dimensional cone beam computed tomography (CBCT), the diagnosis of oral and facial surgical diseases based on deep learning was studied. The utility model related to a deep learning-based classification algorithm for oral neck and facial surgery diseases (deep diagnosis of oral and maxillofacial diseases, referred to as DDOM) is brought out; in this method, the DDOM algorithm proposed for patient classification, lesion segmentation, and tooth segmentation, respectively, can effectively process the three-dimensional oral CBCT data of patients and carry out patient-level classification. The segmentation results show that the proposed segmentation method can effectively segment the independent teeth in CBCT images, and the vertical magnification error of tooth CBCT images is clear. The average magnification rate was 7.4%. By correcting the equation of R value and CBCT image vertical magnification rate, the magnification error of tooth image length could be reduced from 7.4. According to the CBCT image length of teeth, the distance R from tooth center to FOV center, and the vertical magnification of CBCT image, the data closer to the real tooth size can be obtained, in which the magnification error is reduced to 1.0%. Therefore, it is proved that the 3D oral cone beam electronic computer based on deep learning can effectively assist doctors in three aspects: patient diagnosis, lesion localization, and surgical planning.

Three-dimensional CBCT based evaluation of the inferior part of the maxillary sinus: Retrospective Study

The maxillary sinus is the largest of the four paranasal sinuses in humans, and its close proximity to the teeth means that caution is required during dental treatment. In particular, implant surgeries involving the maxillary posterior teeth should include evaluating the inferior part of the maxillary sinus. The purpose of this study is to evaluate the differences by comparing the inferior part of the maxillary sinus based on the nasal cavity floor (NCF) between patients (male 30, female 30) genders through the use of the three-dimensional (3-D) program that can facilitate 3-D visualizations. The present study results obtained from 3-D visualizations using cone beam computed tomography (CBCT) data showed that the inferior part of the maxillary sinus was mostly larger in males than in females. In addition, the utilization of 3-D visualization data was more likely to assure accuracy than when using data obtained by two-dimensional (2-D) imaging. Therefore, 3-D visualizations of the inferior part of the maxillary sinus will contribute to accurate analyses of its anatomical structure during implant surgery and other operations. Further studies utilizing 3-D visualization will yield useful fundamental data and guidelines for future research.

3D Evaluation of the Relationship between Different Vertical Growth Patterns and Cranial Base Angulations

Objective This study aimed to compare cranial base angulations in subjects with high-angle, low-angle, and normal-angle vertical growth patterns using cone beam computed tomography (CBCT). Design This study is a retrospective clinical research. Settings This study was carried out at the Dentistry Faculty of Eskisehir Osmangazi University. Participants According to skeletal vertical face growth patterns, 78 subjects (48 females and 30 males, average age: 13.19 ± 1.73 years) were divided equally into three groups: high angle, low angle, and normal angle groups. Main Outcome Measures Cephalometric images were derived from CBCT, and patients were classified according to the SN-GoGn angle (sella-nasion, gonion gnathion angle). Sagittal, axial, and coronal cranial base angulations were measured in three-dimensional (3D) CBCT images. Data were analyzed using the Kolmogorov-Smirnov normality, Kruskal-Wallis, and Mann-Whitney U statistical tests. Results There were statistically significant differences between the low-angle and high-angle groups according to sagittal cranial base angulation parameters ( p = 0.01). Conversely, there were no statistically significant differences between vertical facial growth patterns according to coronal and axial cranial angle variables ( p > 0.05). Conclusion According to the study results, there were no effects of cranial base angulations in two planes (coronal and axial) on different vertical skeletal growth patterns. In the sagittal cranial base angulation parameter, the high-angle group showed greater angulation values than the low-angle group. CBCT may be helpful for evaluating, diagnosing, and predicting 3D cranial base differences.

Long-term follow-up of intersegmental displacement after orthognathic surgery using cone-beam computed tomographic superimposition.

To evaluate intersegmental displacement during long-term follow-up after bilateral sagittal split osteotomy (BSSO) by mandibular body area superimposition. Cone-beam computed tomography (CBCT) images of 23 patients ages 18-37 years with class III malocclusion before orthognathic surgery were obtained. A three-dimensional (3D) CBCT examination was performed at four stages: surgery (T0), 6 months after surgery (T1), 1 year after surgery (T2), and long-term follow-up (6.1 ± 2.1 years, T3). The CBCT datasets were superimposed on the symphyseal area and the lower part of the distal segment of the mandible between T0 and the other time points (T1, T2, and T3). The reference points (both condyle, coronoid, and sigmoid) were estimated by the CBCT analyzed program. The coronoid, condylion, and sigmoid showed changes within 6 months after surgery, but there was no significant change in the intersegmental displacement between 6 months and 6 years after surgery. The distances between the left and right coronoid, condylion, and sigmoid from T0 to T3 were noted. The change in intersegmental displacement between T0 and T3 affecting relapse after orthognathic surgery was not significantly different. This suggests that the mandible itself may have a stable morphology during the follow-up period.

Quantitative Assessment of the Edentulous Posterior Maxilla for Implant Therapy: A Retrospective Cone Beam Computed Tomographic Study.

Dimensional changes of the alveolar bone are often noted in horizontal and vertical planes as a sequel to tooth extraction, particularly in the maxillary posterior region due to alveolar bone resorption combined with pneumatization of the sinus. The aim of this retrospective study was to quantitatively assess the maxillary residual alveolar ridge using cone beam computed tomography (CBCT) scans. A total of 349 edentulous sites from 250 CBCTs were evaluated. The apico-coronal bone height and bucco-palatal crest width were measured in sagittal and coronal slices, respectively. Additionally, the obliqueness of the sinus floor at the edentulous sites was also evaluated. One hundred and twelve (55.45%) of the molar and 74 (54.42%) of the premolar sites had a horizontal ridge dimension < 6mm, whereas 137 (67.83%) of the molar and 61 (44.86%) of the premolar sites showed an apico-coronal height < 8mm. Furthermore, 183 (54.14%) of the evaluated sites had an oblique sinus floor morphology. Additional augmentative procedures are thus required in a high percentage of the population at the edentulous maxillary posterior site for rehabilitation using a standard dimension implant. This study stresses on the need for a three-dimensional CBCT prior to implant surgery for proper treatment planning.

Cyst volume changes measured with a 3D reconstruction after decompression of a mandibular dentigerous cyst with an impacted third molar.

The aim of this article is to describe a large mandibular cyst treated with decompression followed by surgical enucleation. Furthermore, we described the utility of cyst volume measurements by using a 3D reconstruction on Cone Beam Computed Tomography (CBCT). The dentigerous cyst is the most common cyst type of epithelial origin, arising from remnants of odontogenic epithelium, asymptomatic and associated with the crown of an unerupted or partially or completely impacted tooth. However, after a long duration and extension of the cyst volume it may provoke significant bone resorption, cortical expansion, tooth displacement and the vitality of neighboring teeth may be affected. The regular treatment of this lesion is enucleation and extraction of the involved tooth. Marsupialization and decompression are proposed when the volume of the cyst is well developed to release the cystic pressure and allow the bone cavity to progressively decrease in volume with the gradual apposition of bone. This report presents a large dentigerous cyst related to impacted mandibular third molar of a 21-year-old male patient. The cyst was treated successfully by decompression and later by surgical enucleation with surgical extraction of the related molar. In conclusion, the combination of decompression and surgical approach showed on the three-dimensional CBCT investigation a significant correlation between the treatment and volume reduction of the cyst. The clinical case described allows us to observe bone formation after decompression and surgical enucleation was performed with less risk on vital anatomic elements.

Diagnostic accuracy of cone beam computed tomography with different resolution settings for external root resorption

To evaluate the diagnostic accuracy of cone beam computed tomography (CBCT) with different resolution settings in detecting the simulated external root resorption defects. External root resorption defects were simulated in 51 human single rooted premolar teeth. Cavities simulating root resorption defects of 1 mm in diameter and 0.1 mm, 0.2 mm, and 0.3 mm in depth were drilled in the cervical, middle and apical thirds of lingual surfaces of the teeth. In addition to the 51 locations as controls, a total of 102 cavities were obtained in the present study. Specimens were placed in a human dry mandible and scanned by ProMax 3D and DCT PRO CBCT with different resolution settings, respectively. The three-dimensional CBCT images were evaluated by two experienced observers. The data were analyzed with receiver operating characteristics (ROC) analysis. ROC curves were generated and the area under ROC curve (Az) was employed to express the diagnostic accuracy. The diagnostic accuracy (Az value) of ProMax 3D CBCT with high, normal and low resolution settings were 0.867, 0.703 and 0.665 (P < 0.05), respectively. Defects with depths of 0.2 mm and 0.3 mm were easier to be detected than those with depths of 0.1 mm (P < 0.05). The images obtained by high resolution mode scanning had obvious advantages in detecting smaller defects (depth 0.1 mm and 0.2 mm). The DCT PRO CBCT provided 4 resolution settings including normal quality + normal resolution, normal quality + high resolution, high quality + normal resolution and high quality + high resolution. The Az values for those 4 resolution settings were 0.527, 0.725, 0.743, and 0.794 (P < 0.05), respectively. Similar to ProMax 3D CBCT, the scanning mode with high resolution played a better role in detecting the defects with depth of 0.1 mm. Except for the scanning setting mode with normal quality + normal resolution, the other three modes could well be evaluated for the defects with depth of 0.2 mm and 0.3 mm. It is concluded that the diagnostic ability for external root resorption of CBCT could be affected by resolution settings. Computer-aid imaging method can improve the CBCT diagnostic accuracy for external root resorption without increasing the radiation dose level during CBCT scanning.