Cone-beam computerized tomography (CBCT) imaging of the oral and maxillofacial region: A systematic review of the literature

Boundary of mandibular molar distalization in orthodontic treatment: A systematic review and meta-analysis

To explore the mandibular retromolar space length (MRSL), initial root-inner cortex contact percentage (IRCCP), and the various factors that influence mandibular molar distalization. Searches were undertaken in PubMed, EMBASE, Web of Science, Cochrane Library, Scopus, and grey literature (Google Scholar and OpenGrey) for eligible cross-sectional observational studies measuring the MRSL and IRCCP in healthy adult patients. The risk of bias and evidence quality were evaluated using the Joanna Briggs Institute's checklist and GRADE framework. Thirteen studies involving 1169 patients were included for qualitative synthesis. Seven of these studies were eligible for quantitative analysis. Meta-analysis showed that the mean MRSL at the subfurcation-6 mm plane in Asian normodivergent cases was 3.78 mm (95% confidence interval [CI]: 2.81-4.35; I2 = 79.7%) for skeletal Class-I malocclusions, 3.02 mm (95% CI: 2.10-3.94; I2 = 62.5%) for Class-II, and 4.43 mm (95% CI: 3.14-5.73; I2 = 75.1%) for Class-III. The mean MRSL at the sub-cementoenamel junction (CEJ)-10 mm plane for Asian, Class-I, normodivergent cases was 3.28 mm (95% CI: 2.44-4.12; I2 = 68.9%). The mean IRCCP for Asian, Class-I, normodivergent cases was 27.2% (95% CI: 0.22-0.32; I2 = 0%). In Asian normodivergent cases, MRSL ranges from 3.28 to 4.43 mm with a 27.2% IRCCP for Class-I. Cone-beam computed tomography imaging is recommended for measuring the MRSL in the apex region particularly before molar distalization. Factors influencing MRSL and IRCCP include different races, skeletal patterns, facial types, and third-molar status.

Deep learning-based approach for 3D bone segmentation and prediction of missing tooth region for dental implant planning

Recent studies have shown that dental implants have high long-term survival rates, indicating their effectiveness compared to other treatments. However, there is still a concern regarding treatment failure. Deep learning methods, specifically U-Net models, have been effectively applied to analyze medical and dental images. This study aims to utilize U-Net models to segment bone in regions where teeth are missing in cone-beam computerized tomography (CBCT) scans and predict the positions of implants. The proposed models were applied to a CBCT dataset of Taibah University Dental Hospital (TUDH) patients between 2018 and 2023. They were evaluated using different performance metrics and validated by a domain expert. The experimental results demonstrated outstanding performance in terms of dice, precision, and recall for bone segmentation (0.93, 0.94, and 0.93, respectively) with a low volume error (0.01). The proposed models offer promising automated dental implant planning for dental implantologists.

Evaluation of Bone Thickness and Density Values in Resistance Regions in Rapid Maxillary Expansion Using Computed Tomography

OBJECTIVES

This study used computed tomography (CT) to compare the bone thickness and density values around the zygomaticomaxillary, zygomaticotemporal, and pterygomaxillary sutures that are resistant to rapid maxillary expansion (RME) treatment according to age, sex, and cervical vertebrae maturation (CVM) stage.

METHODS

The study included 200 paranasal sinus records obtained for medical diagnosis and examination in a radiology clinic. The records provided data on 110 males and 90 females aged between 4 and 28 years. Bone thickness and density values around the zygomaticomaxillary, zygomaticotemporal, and pterygomaxillary sutures were measured using CT imaging. The correlations of bone thickness and density values with the variables of age, sex, and CVM stage were evaluated.

RESULTS

No statistically significant difference was revealed between the bone thickness values around the zygomaticomaxillary and zygomaticotemporal sutures and age, sex, CVM stage, and the right and left regions of the same individual ( P >0.05). A strong correlation was identified between Hounsfield units (Hu) values on bone density in all 3 regions and age and sex ( P <0.001). No correlation was found between the CVM stage and density values around the zygomaticomaxillary, zygomaticotemporal, and pterygomaxillary sutures ( P >0.05).

CONCLUSIONS

The Hu values of the records from females were higher than those of males in all age groups. It was observed that with increasing age, bone density values increased in all 3 regions, and thus circummaxillary region's Hu value increased.

Comparison of Two X-ray Analyses for Estimating the Prognosis of Eruption of Impacted Mandibular Third Molars

The objective of this study was to compare the results of the measurements made using two methods for determining the retromolar eruption spaces and the mesiodistal inclinations of impacted mandibular third molars. These are the main parameters based on which the eruption of these teeth can be predicted. A Sirona GALILEOS Compact/Comfort CBCT scanner was used for the study. A total of 127 patients were included in the study. We made the measurements using our integrated method and the standard method used in the dental practice for determining the eruption space and the mesiodistal inclination of these teeth, and then we compared the results. The mean difference between the two methods for estimating the retromolar space deficiency on the left was 1.70 mm and standard deviation (SD) 2.95; mean error of the mean was 0.29; and Student t-test (paired t-test) = 5.86, significant level of the correlation was 0.001, <0.05. Regarding the teeth on the right, it was mean 1.59 mm and standard deviation (SD) 2.98; mean error of the mean was 0.31. The t-test performed found a statistically significant difference between the methods in determining the retromolar eruption spaces (t-test (paired t-test) = 5.13; significant level of the correlation 0.001; p < 0.05). The mean difference (in degrees) between the measurements of the inclinations of the teeth on the left using the two methods was 3, 50°; SD = 7.25; mean error of the mean = 1.81; t-test = 2.481; significant level of the correlation 0.025; and p > 0.05. As for the teeth on the right, it was 2.41°, SD = 9.57, mean error of the mean = 2.39, t-test 0.175, significant level of the correlation = 0.863, and >0.05. No statistically significant difference was found between the two methods in measuring the inclinations of impacted third molars. The conclusion of our study is that the determination of the mesiodistal inclination of the teeth and the available eruption space using the method developed by us is more accurate compared to the standard method, because constant points and planes are used. This method allows for predicting the eruption of impacted mandibular third molars.

AAPM Task Group Report 261: Comprehensive quality control methodology and management of dental and maxillofacial cone beam computed tomography (CBCT) systems

Cone-beam computed tomography (CBCT) systems specifically designed and manufactured for dental, maxillofacial imaging (MFI) and otolaryngology (OLR) applications have been commercially available in the United States since 2001 and have been in widespread clinical use since. Until recently, there has been a lack of professional guidance available for medical physicists about how to assess and evaluate the performance of these systems and about the establishment and management of quality control (QC) programs. The owners and users of dental CBCT systems may have only a rudimentary understanding of this technology, including how it differs from conventional multidetector CT (MDCT) in terms of acceptable radiation safety practices. Dental CBCT systems differ from MDCT in several ways and these differences are described. This report provides guidance to medical physicists and serves as a basis for stakeholders to make informed decisions regarding how to manage and develop a QC program for dental CBCT systems. It is important that a medical physicist with experience in dental CBCT serves as a resource on this technology and the associated radiation protection best practices. The medical physicist should be involved at the pre-installation stage to ensure that a CBCT room configuration allows for a safe and efficient workflow and that structural shielding, if needed, is designed into the architectural plans. Acceptance testing of new installations should include assessment of mechanical alignment of patient positioning lasers and x-ray beam collimation and benchmarking of essential image quality performance parameters such as image uniformity, noise, contrast-to-noise ratio (CNR), spatial resolution, and artifacts. Several approaches for quantifying radiation output from these systems are described, including simply measuring the incident air-kerma (Kair) at the entrance surface of the image receptor. These measurements are to be repeated at least annually as part of routine QC by the medical physicist. QC programs for dental CBCT, at least in the United States, are often driven by state regulations, accreditation program requirements, or manufacturer recommendations.

Comparative Analysis of Examination Methods for Periapical Lesion Diagnostics: Assessing Cone-Beam Computer Tomography, Ultrasound, and Periapical Radiography

INTRODUCTION

Periapical lesions of teeth are typically evaluated using periapical X-rays (PA) or cone-beam computer tomography (CBCT); however, ultrasound imaging (US) can also be used to detect bone defects. A comparative analysis is necessary to establish the diagnostic accuracy of US for the detection of periapical lesions in comparison with PA and CBCT.

OBJECTIVES

This study aimed to evaluate and compare the measurement precision of US against PA and CBCT in detecting periapical lesions.

METHODS

This study included 43 maxillary and mandibular teeth with periapical lesions. All teeth were examined clinically, radiographically, and ultrasonographically. Observers evaluated and measured the periapical lesions on CBCT, PA, and US images.

RESULTS

The comparison of lesion size showed that it differs significantly between the different methods of examination. A statistically significant difference was found between CBCT and US (mean difference = 0.99 mm, 95% CI [0.43-1.55]), as well as between CBCT and PA (mean difference = 0.61 mm, 95% CI [0.17-1.05]). No difference was found between the US and PA methods (p = 0.193).

CONCLUSION

US cannot replace PA radiography in detecting pathologies but it can accurately measure and characterize periapical lesions with minimal radiation exposure. CBCT is the most precise and radiation-intensive method so it should only be used for complex cases.

The Application of Cone Beam Computed Tomography (CBCT) on the Diagnosis and Management of Maxillofacial Trauma

The assessment and management of facial trauma in an acute setting is one of the core services provided by oral and maxillofacial units in the United Kingdom. Imaging is a pre-requisite for appropriate diagnosis and treatment planning, with a combination of plain radiographs and medical-grade CT being the mainstay. However, the emergence of cone beam CT in recent years has led to its wider applications, including facial trauma assessment. It can offer multi-planar reformats and three-dimensional reconstruction at a much lower radiation dose and financial cost than conventional CT. The purpose of this review is to appraise its potential indications in all anatomical areas of maxillofacial trauma and provide our experience at a level 1 trauma centre.

Ultra-low-dose photon-counting CT of paranasal sinus: an in vivo comparison of radiation dose and image quality to cone-beam CT

PURPOSE

This study investigated the differences in subjective and objective image parameters as well as dose exposure of photon-counting CT (PCCT) compared to cone-beam CT (CBCT) in paranasal sinus imaging for the assessment of rhinosinusitis and sinonasal anatomy.

METHODS

This single-centre retrospective study included 100 patients, who underwent either clinically indicated PCCT or CBCT of the paranasal sinus. Two blinded experienced ENT radiologists graded image quality and delineation of specific anatomical structures on a 5-point Likert scale. In addition, contrast-to-noise ratio (CNR) and applied radiation doses were compared among both techniques.

RESULTS

Image quality and delineation of bone structures in paranasal sinus PCCT was subjectively rated superior by both readers compared to CBCT (P < .001). CNR was significantly higher for photon-counting CT (P < .001). Mean effective dose for PCCT examinations was significantly lower than for CBCT (0.038 mSv ± 0.009 vs. 0.14 mSv ± 0.011; P < .001).

CONCLUSION

In a performance comparison of PCCT and a modern CBCT scanner in paranasal sinus imaging, we demonstrated that first-use PCCT in clinical routine provides higher subjective image quality accompanied by higher CNR at close to a quarter of the dose exposure compared to CBCT.

Correlation between craniocervical posture and upper airway dimension in patients with bilateral anterior disc displacement

OBJECTIVE

To investigate the relationship between upper airway dimension and craniocervical posture in adult patients with bilateral anterior disc displacement and to provide some references for clinical diagnosis and plan formulation in orthodontics.

METHODS

Based on RDC/TMD (Research Diagnostic Criteria for Temporomandibular Disorder), 98 Patients were divided into three groups by two experienced TMJ (Temporomandibular Joint) specialists: bilateral disc normal position group (BN), bilateral anterior disc displacement with reduction group (ADDWR) and bilateral anterior disc displacement without reduction group (ADDWoR). Inter-group comparison and correlation analysis were performed after 11 craniocervical posture and 15 upper airway dimension measurements finished with Dolphin and Uceph software in Two or Three-dimensional.

RESULTS

Anterior disc displacement often accompanied with extension of craniocervical posture, as ADDWR and ADDWoR groups have significantly higher cervical curvature and inclination than BN group (P < 0.05). Simultaneously anterior disc displacement often associated with constrained upper airway dimension for the total and each segment upper airway volume were significantly smaller in ADDWR and ADDWoR than BN group (P < 0.05). Correlation analysis revealed that C0-C1 (the distance from the base of the occipital bone (C0) to the posterior arch of the atlas (C1)) is significantly related to the total and each segment upper airway volume reduction (P < 0.05).

CONCLUSION

There exists markedly close correlation between anterior disc displacement and craniocervical posture forward extension, which may be physiologically adaptive cervical extension to keep oropharyngeal airway unobstructed as upper airway dimension constrained by anterior disc displacement.

CLINICAL RELEVANCE

These findings allow us to infer the potential consequences if the treatment of anterior disc displacement would result in an improvement of intervertebral relationships and upper airway constraint.

Determining the safety margin of mandibular lingula in sagittal split ramus osteotomy

PURPOSE

The anatomical position of the lingula is clinically very important to prevent injuries during sagittal split ramus osteotomy. Our study aims to evaluate the localisation of the lingula by cone beam computed tomography (CBCT) and to compare the localisation of the lingula between malocclusion, gender, and lingula types.

METHODS

A retrospective study was conducted to evaluate the shape and location of the lingula using CBCT. A total of 250 CBCT images were included in this study. The lingula was classified as nodular, assimilated, truncated, or triangular type. Six defined distances from the top of the lingula were measured: anterior border of the ramus (L-A), posterior border of the ramus (L-P), internal oblique ridge (L-IOR), mandibular notch (L-N), and distal surface of the mandibular second molar (L-M2) and occlusal plane (L-OP). The measured distances were compared between gender, malocclusion, and lingula types.

RESULTS

The most common type of lingula was nodular (32.4%). The L-N, L-P, L-M2, and L-OP distances between genders were statistically higher in male patients than in female patients. The L-IOR, L-M2, and L-OP distances exhibited statistically significant differences found between malocclusions. No statistically significant difference was found when the distances of the lingula to the anatomical points were compared between the lingula types.

CONCLUSION

These variations in positioning of the lingula depending on the dysmorphoses are developing towards a systematic 3D examination before any mandibular osteotomy to precisely visualize the position and shape of the lingula.

Estimation of age implementing pulp tooth volume ratio in maxillary canines of an Indian population by means of CBCT scans

BACKGROUND

Forensic odontology is a subfield of forensics that can assist in determining age, gender, and other demographic factors.

OBJECTIVE

The focus of this research is to ascertain age by tooth volume ratio of permanent maxillary canines using a CBCT scan.

METHODS

In this retrospective investigation, 1000 CBCT images were gathered and focused on only fully developed maxillary canines. For each of the maxillary canines, the researchers measured and calculated the volume of the pulp chamber, root canal, and entire tooth using the ITK Snap programme. The pulp volume to tooth volume ratio was computed. The equation AGE = 59.208 - (583.652 x pulp volume/tooth volume) was then used to compute age. The samples were divided into 5 age groups; 13-20, 21-30, 31-40, 41-50, and 51-60. The age was calculated for samples in each group and it was compared to the actual age.

RESULTS

Between individuals' actual age and computed age, the study discovered a statistically significant positive association. While groups 3, 4, and 5 demonstrated positive but weaker correlations (r= 0.854, r= 0.658, and r= 0.612, respectively), groups 1 and 2 displayed statistically significant strong positive correlations (r= 0.987 and r= 0.923, respectively). The average total discrepancy between the age that was computed and the actual age was 2.45 1.344.

CONCLUSION

The study found a statistically significant positive correlation between computed age and actual age, with the younger age groups 1 (13-20) and 2 (21-30) showing the strongest relationships. This underlines its potential success in court, particularly when dealing with young criminals.

Effects of sagittal split Ramus osteotomy on condylar position and Ramal orientation in patients with mandibular asymmetry

OBJECTIVE

The purpose of this study is to assess the impact of Sagittal Split Ramus Osteotomy (SSRO) on the alignment of the condyle and orientation of the Ramal segment following surgery in patients operated for the correction of mandibular asymmetry.

METHODS

A total of 27 patients who underwent SSRO were enrolled in this study, and study groups were defined as asymmetric (study group) and symmetric (control group) using linear measurements from the dental midline based on a three-dimensional coordinate system. Differences on preoperative and postoperative values of anterior (AJS), posterior (PJS) and superior joint spaces (SJS), condylar axial angle (CAA), Sagittal Ramal Angle (SRA), and Coronal Ramal Angles (CRA) of study and control groups were measured and compared. The data was analyzed using the "Wilcoxon signed-ranks test" to identify differences between groups.

RESULTS

Differences between preoperative and postoperative values of CRA and SRA of the contralateral group showed statistically significant results with p-values of 0.007 and 0.005, respectively. A statistically significant change in CAA angle was found in the control and deviation groups (p = 0.018 and p = 0.010, respectively).

CONCLUSIONS

SSRO has inevitable effects on the condylar and ramal orientation. Individuals with asymmetry require particular attention throughout the planning process and beyond. Conjunctive modalities and modifications should be considered and utilized when necessary. Future studies with larger sample sizes, homogenous follow-up periods, and more comprehensive clinical data are needed to substantiate understanding of the response of the condylar segment.

CLINICAL RELEVANCE

Orthognathic surgeries inevitably alter the alignment and harmony of temporomandibular structures and may result in change of AJS, PJS, SJS, CAA, SRA, and LRA, which may change the biomechanics of joint and lead to several complications like temporomandibular disorders. Especially in cases with midline asymmetry needs special consideration from planning till the end of the treatment to achieve best results. In severe cases, conjunctive modalities and modifications and other alternatives such as inverted-L osteotomies should be considered.

Evaluation of roots, root canal morphology, and bilateral symmetry of maxillary first molars in a Syrian subpopulation using cone beam computed tomography

OBJECTIVE

Successful endodontic treatments require a comprehensive knowledge of the root canal anatomy, so this study aimed to investigate the number of roots, configurations of root canals, and their bilateral symmetry of maxillary first molars in the Syrian subpopulation, and also the effect of gender on this symmetry.

MATERIALS AND METHODS

The study sample consisted of 250 cone beam computed tomography images (140 for females; and 110 for males), including 500 maxillary first molars. Images were investigated by two endodontists. Root number and canal configuration in each root were recorded, according to Vertucci classification, by studying the image at all levels (axial, coronal, sagittal, oplique, and three-dimensional) to assess the bilateral symmetry and its relation to gender. Statistical analysis was performed with SPSS and the χ2 test was used to compare the bilateral symmetry in males and females.

RESULT

The most common shape of the maxillary first molars was three roots (97.6%). All the roots are symmetrical by 100% in both genders. The root canal configuration was mainly Vertucci type I classification in the distobuccally (73.6%), and palatal root (98%). While the most common types in mesial root were type II (33.3%), this root showed all different types of Vertucci classifications except type VIII, and the proportion of symmetry was (37.2%) without significant difference between the gender (p = .441).

CONCLUSION

Most maxillary first molars in a Syrian population were three-rooted with four root canals (type II), the numbers of roots achieved perfect symmetry 100%, and higher than symmetry ratios in the number of canals and canals configurations (37.2%).

The Role of Cone-Beam Computed Tomography CT Extremity Arthrography in the Preoperative Assessment of Osteoarthritis

Osteoarthritis (OA) is a prevalent disease and the leading cause of pain, disability, and quality of life deterioration. Our study sought to evaluate the image quality and dose of cone-beam computed tomography arthrography (CBCT-A) and compare them to digital radiography (DR) for OA diagnoses. Overall, 32 cases of CBCT-A and DR with OA met the inclusion criteria and were prospectively analyzed. The Kellgren and Lawrence classification (KLC) stage, sclerosis, osteophytes, erosions, and mean joint width (MJW) were compared between CBCT-A and DR. Image quality was excellent in all CBCT-A cases, with excellent inter-observer agreement. OA under-classification was noticed with DR for MJW (p = 0.02), osteophyte detection (<0.0001), and KLC (p < 0.0001). The Hounsfield Unit (HU) values obtained for the cone-beam computed tomography CBCT did not correspond to the values for multi-detector computed tomography (MDCT), with a greater mean deviation obtained with the MDCT HU for Modeled Based Iterative Reconstruction 1st (MBIR1) than for the 2nd generation (MBIR2). CBCT-A has been found to be more reliable for OA diagnosis than DR as revealed by our results using a three-point rating scale for the qualitative image analysis, with higher quality and an acceptable dose. Moreover, the use of this imaging technique permits the preoperative assessment of extremities in an OA diagnosis, with the upright position and bone microarchitecture analysis being two other advantages of CBCT-A.

CBCT Segmentation and Additive Manufacturing for the Management of Root Canals with Ledges: A Case Report and Technique

Cone-beam computed tomography (CBCT) assessment of a ledge could be useful to a clinician; however, using this information effectively during a treatment procedure can be challenging. Advanced additive manufacturing technologies combined with semi-automated segmentation of root canals can help simulate the ledge and help in management of these iatrogenic complications. A patient presented after unsuccessful root canal treatment with a ledge on the left mandibular first molar. A CBCT was taken, and the images imported into a segmentation software (Mimics, Materialise). The canal was isolated, and segmentation performed along with the other structures of the tooth. A 3-dimensional digital model of the internal structures of the canal were used to design a mock-up which was additively manufactured. This was used as a preclinical guide to simulate the procedure, precurve the file, and manage the canal. This novel technique using virtual modeling from CBCT data post ledge formation allowed for successful and quick management of a tooth with ledges.

Virtual Dental Articulation Using Computed Tomography Data and Motion Tracking

Dental articulation holds crucial and fundamental importance in the design of dental restorations and analysis of prosthetic or orthodontic occlusions. However, common traditional and digital articulators are difficult and cumbersome in use to effectively translate the dental cast model to the articulator workspace when using traditional facebows. In this study, we have developed a personalized virtual dental articulator that directly utilizes computed tomography (CT) data to mathematically model the complex jaw movement, providing a more efficient and accurate way of analyzing and designing dental restorations. By utilizing CT data, Frankfurt's horizontal plane was established for the mathematical modeling of virtual articulation, eliminating tedious facebow transfers. After capturing the patients' CT images and tracking their jaw movements prior to dental treatment, the jaw-tracking information was incorporated into the articulation mathematical model. The validation and analysis of the personalized articulation approach were conducted by comparing the jaw movement between simulation data (virtual articulator) and real measurement data. As a result, the proposed virtual articulator achieves two important functions. Firstly, it replaces the traditional facebow transfer process by transferring the digital dental model to the virtual articulator through the anatomical relationship derived from the cranial CT data. Secondly, the jaw movement trajectory provided by optical tracking was incorporated into the mathematical articulation model to create a personalized virtual articulation with a small Fréchet distance of 1.7 mm. This virtual articulator provides a valuable tool that enables dentists to obtain diagnostic information about the temporomandibular joint (TMJ) and configure personalized settings of occlusal analysis for patients.

Morphologic Variability of Bone and Soft Tissue in Microtia With Hemifacial Microsomia

Objective: Microtia patients with hemifacial microsomia (HFM) have a host of distinct anatomical disorder of skeletal and soft tissue asymmetries. The purpose of this study was to assess soft tissue discrepancies in microtia patients with HFM and their correlation with skeletal discrepancies. Methods: A total of 42 patients were enrolled and studied prospectively using a 3-dimensional superimposition and color mapping of the soft and hard tissues. Mirroring techniques created perfectly symmetric models for comparison. Differences between affected and normal sides were evaluated in 5 areas: retroauricular mastoid, malar, maxillary frontal, mandibular frontal, and gonion areas. Pearson correlations were used to assess the relationship between skeletal and soft tissue asymmetry. Results: Hard tissue asymmetry ranged from 0.79 mm (mandibular frontal) to 1.29 mm (malar), while soft tissue asymmetry ranged from 1.34 mm (maxillary frontal) to 5.26 mm (retroauricular mastoid). Correlations between skeletal and soft tissue asymmetry varied, with the strongest correlation observed at the retroauricular mastoid area and the weakest at the maxillary frontal area. Conclusion: There was a high correlation between bone and soft tissue hypoplasia at the retroauricular mastoid area, while the other evaluated areas showed poor correlation between skeletal and soft tissue asymmetries. Clinicians should assess each component separately for optimal treatment planning in microtia patients with HFM.

Evaluation of use of cone beam computed tomography in paediatric patients: A cross-sectional study

BACKGROUND

Cone beam computed tomography (CBCT) is widely used in paediatric dentistry. Appropriate use of CBCT is important because children are more vulnerable to ionizing radiation than adults.

AIM

To investigate the use of CBCT in children by describing reasons for requesting it and its distribution according to age, oral region, and department.

DESIGN

Cone beam computed tomography scans of patients (age < 19 years) who presented to our dental clinic were investigated retrospectively according to sex, age (6-12 [Group 1] and 13-18 [Group 2] years based on dentition), referring department, imaging area (anterior/posterior, mandible/maxilla), and indication. Indications were grouped under five headings according to 2011 SEDENTEXCT guidelines: dental anomalies, impacted teeth, endodontics, bone pathosis, and others.

RESULTS

Overall, 334 CBCT scans at different times and for different reasons in 319 patients were evaluated. In recent years, CBCT requests increased in both age groups. Eighty-five CBCT scans (25.44%) of 78 patients (24.45%) with a mean age of 10.37 ± 1.60 years were examined in Group 1, whereas 249 CBCT scans (%74.55) of 241 patients (75.54%) with a mean age of 15.66 ± 1.70 years were examined in Group 2. The most frequent indication was the assessment of impacted teeth (46.1%). The anterior maxilla was the most frequently monitored region (41.6%). The oral and maxillofacial radiology department was the department that made the most CBCT requests in all the years considered (53.6%).

CONCLUSIONS

The most common indications were the assessment of dentigerous cysts and impacted teeth. There was an increase in the number of referrals to paediatric dentistry.

Importance of 3-dimensional imaging in the early diagnosis of chondroblastic osteosarcoma

The aim of this report is to present a case of chondroblastic osteosarcoma located in the right maxillary premolar region of a 17-year-old female patient. The initial clinical presentation and 2-dimensional (2D) radiographic methods proved inadequate for a definitive diagnosis. However, a cone-beam computed tomography scan revealed a hyperdense, heterogeneous lesion in the right maxillary premolar region, exhibiting a characteristic "sun-ray" appearance. To assess soft tissue involvement, a medical computed tomography scan was subsequently conducted. A positron emission tomography scan detected no metastasis or indications of secondary tumors. T1- and T2-weighted magnetic resonance imaging showed signal heterogeneity within the lesion, including areas of low signal intensity at the periphery. A histological examination conducted after an incisional biopsy confirmed the diagnosis of high-grade chondroblastic osteosarcoma. The patient was then referred to an oncology department for chemotherapy before surgery. In conclusion, these findings suggest that early diagnosis using 3-dimensional imaging can detect chondroblastic osteosarcoma in its early stages, such as before metastasis occurs, thereby improving the patient's prognosis.

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

OBJECTIVE

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.

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSIONS

We successfully developed and validated a fully automatic AI-driven system for upper airway segmentation and CSAmin localisation using 2D radiographic airway images.

Validation of bone mineral density measurement using quantitative CBCT image based on deep learning

The bone mineral density (BMD) measurement is a direct method of estimating human bone mass for diagnosing osteoporosis, and performed to objectively evaluate bone quality before implant surgery in dental clinics. The objective of this study was to validate the accuracy and reliability of BMD measurements made using quantitative cone-beam CT (CBCT) image based on deep learning by applying the method to clinical data from actual patients. Datasets containing 7500 pairs of CT and CBCT axial slice images from 30 patients were used to train a previously developed deep-learning model (QCBCT-NET). We selected 36 volumes of interest in the CBCT images for each patient in the bone regions of potential implants sites on the maxilla and mandible. We compared the BMDs shown in the quantitative CBCT (QCBCT) images with those in the conventional CBCT (CAL_CBCT) images at the various bone sites of interest across the entire field of view (FOV) using the performance metrics of the MAE, RMSE, MAPE (mean absolute percentage error), R² (coefficient of determination), and SEE (standard error of estimation). Compared with the ground truth (QCT) images, the accuracy of the BMD measurements from the QCBCT images showed an RMSE of 83.41 mg/cm³, MAE of 67.94 mg/cm³, and MAPE of 8.32% across all the bone sites of interest, whereas for the CAL_CBCT images, those values were 491.15 mg/cm³, 460.52 mg/cm³, and 54.29%, respectively. The linear regression between the QCBCT and QCT images showed a slope of 1.00 and a R² of 0.85, whereas for the CAL_CBCT images, those values were 0.32 and 0.24, respectively. The overall SEE between the QCBCT images and QCT images was 81.06 mg/cm³, whereas the SEE for the CAL_CBCT images was 109.32 mg/cm³. The QCBCT images thus showed better accuracy, linearity, and uniformity than the CAL_CBCT images across the entire FOV. The BMD measurements from the quantitative CBCT images showed high accuracy, linearity, and uniformity regardless of the relative geometric positions of the bone in the potential implant site. When applied to actual patient CBCT images, the CBCT-based quantitative BMD measurement based on deep learning demonstrated high accuracy and reliability across the entire FOV.

V2-Net: An Attention-guided Volumetric Regression Network for Tooth Landmark Localization on CT Images with Metal Artifacts

For virtual surgical planning in orthognathic surgery, marking tooth landmarks on CT images is an important procedure. However, the manual localization procedure of tooth landmarks is time-consuming, labor-intensive, and requires expert knowledge. Also, direct and automatic tooth landmark localization on CT images is difficult because of the lower resolution and metal artifacts of dental images. The purpose of this study was to propose an attention-guided volumetric regression network (V2-Net) for accurate tooth landmark localization on CT images with metal artifacts and lower resolution. V2-Net has an attention-guided network architecture using a coarse-to-fine-attention mechanism that guided the 3D probability distribution of tooth landmark locations within anatomical structures from the coarse V-Net to the fine V-Net for more focus on tooth landmarks. In addition, we combined attention-guided learning and a 3D attention module with optimal Pseudo Huber loss to improve the localization accuracy. Our results show that the proposed method achieves state-of-the-art accuracy of 0.85 ± 0.40 mm in terms of mean radial error, outperforming previous studies. In ablation studies, we observed that the proposed attention-guided learning and a 3D attention module improved the accuracy of tooth landmark localization in CT images of lower resolution and metal artifacts. Furthermore, our method achieved 97.92% in terms of the success detection rate within the clinically accepted accuracy range of 2.0 mm.

Morphological Studies to Identify the Nasopalatine and Inferior Alveolar Nerve Using a Special Head and Neck MRI Coil

OBJECTIVES

Procedures in oral and maxillofacial surgery bear a high risk of nerve damage. Three-dimensional imaging techniques can optimize surgical planning and help to spare nerves. The aim of this study was to investigate the diagnostic value of a 1.5 T magnetic resonance imaging (MRI) scanner with a dedicated dental signal amplification coil for the assessment of nerves in the oral cavity as compared with cone beam computed tomography (CBCT).

METHODS

Based on 6 predefined criteria, the assessability of the inferior alveolar and nasopalatine nerves in CBCT and MRI with a dedicated 4-channel dental coil were compared in 24 patients.

RESULTS

Compared with CBCT, MRI with the dental coil showed significantly better evaluability of the inferior alveolar nerve in the sagittal and axial plane and the nasopalatine nerve in the axial plane. In the sagittal plane; however, the assessability of the nasopalatine nerve was significantly better in CBCT as compared with MRI. Yet, pertaining to overall assessability, no significant differences between modalities were found.

CONCLUSIONS

In this pilot study, it can be reported that 1.5- T MRI with a dedicated dental coil is at least equivalent, if not superior, to CBCT in imaging nerve structures of the stomatognathic system.

CLINICAL RELEVANCE

Preoperative, 3-dimensional images are known to simplify and refine the planning and execution of operations in maxillofacial surgery. In contrast to computed tomography and CBCT, MRI does not cause radiation exposure while enabling visualization of all relevant hard and soft tissues and, therefore, holds an advantage over well-established techniques.

Morphological Assessment of Nasopalatine Canal Using Cone Beam Computed Tomography: A Retrospective Study of 124 Consecutive Patients

This study aimed to assess and analyze the morphology and dimensions of the nasopalatine canal (NPC), as well as the adjacent buccal osseous plate (BOP), and to investigate the effect of gender, edentulism, NPC types, absence of maxillary central incisors (ACI) and age on the NPC and BOP, using cone beam computed tomography (CBCT). A total of 124 CBCT examinations (67 female and 57 male patients) were retrospectively included and evaluated. The assessment of the dimensions of the NPC, as well as the dimensions of the adjacent BOP, was performed by three Oral and Maxillofacial Radiologists on reconstructed sagittal and coronal CBCT sections under standardized conditions. Regarding the dimensions of the NPC and the adjacent BOP, the mean values were significantly higher among males than females. Furthermore, edentulous patients showed a significant reduction in BOP dimensions. Additionally, NPC types showed a significant effect on the length of the NPC, and the ACI had a significant effect on reducing BOP dimensions. Age had a significant effect on the diameter of the incisive foramen, with the mean values generally increasing with an increasing age. CBCT imaging of this anatomical structure contributes significantly to its full assessment.

Evaluation of cuspid cortical anchorage with different sagittal patterns using cone-beam computed tomography: a retrospective study

BACKGROUND

No studies have focused on cortical anchorage resistance in cuspids, this study aimed to characterize the cortical anchorage according to sagittal skeletal classes using cone-beam computed tomography (CBCT).

METHODS

CBCT images of 104 men and 104 women were divided into skeletal class I, II, and III malocclusion groups. Skeletal and dental evaluations were performed on the sagittal and axial cross-sections. One-way analysis of variance followed by least significant difference post-hoc tests was used for group differences. Multiple linear regression was performed to evaluate the relationship between influential factors and cuspid cortical anchorage.

RESULTS

All cuspids were close to the labial bone cortex in different sagittal skeletal patterns and had different inclinations. There was a significant difference in the apical root position of cuspids in the alveolar bone; however, no significant difference in the middle or cervical portions of the root was found between different sagittal facial patterns. The middle of the cuspid root was embedded to the greatest extent in the labial bone cortex, with no significant difference between the sagittal patterns. For all sagittal patterns, 6.03 ± 4.41° (men) and 6.08 ± 4.45° (women) may be appropriate root control angles to keep maxillary cuspids' roots detached from the labial bone cortex.

CONCLUSIONS

Comparison of skeletal class I, II, and III malocclusion patients showed that dental compensation alleviated sagittal skeletal discrepancies in the cuspid positions of all patients, regardless of the malocclusion class. Detailed treatment procedures and clear treatment boundaries of cuspids with different skeletal patterns can improve the treatment time, periodontal bone remodeling, and post-treatment long-term stability. Future studies on cuspids with different dentofacial patterns and considering cuspid morphology and periodontal condition may provide more evidence for clinical treatment.

Assessment of condylar positional changes in severe skeletal class II malocclusion after surgical-orthodontic treatment

OBJECTIVES

This study aimed to determine the positional changes in the condyle in the temporomandibular joint (TMJ) of severe skeletal class II malocclusion patients treated with surgical-orthodontics.

MATERIALS AND METHODS

The measurements of TMJ space in 97 severe skeletal class II malocclusion patients (20 males, 77 females, mean age, 24.8 years, mean ANB = 7.41°) were assessed using limited cone-beam computed tomography (LCBCT) images acquired before orthodontics (T0) and 12 months after surgery (T1). 3D remodeling of the TMJ and measurements of the anterior space (AS), superior space (SS), and posterior space (PS) were performed to determine the position of the condyle for each joint. All data were analyzed by t test, correlation analysis, and Pearson correlation coefficient.

RESULTS

The mean AS, SS, and PS values after the therapy changed from 1.684 to 1.680 mm (0.24%), 3.086 to 2.748 mm (10.968%), and 2.873 to 2.155 mm (24.985%), respectively. The decreases in SS and PS were statistically significant. Positive correlations were found in the mean AS, SS, and PS values between the right and left sides.

CONCLUSIONS

The combination of orthodontic and surgical treatment makes the condyle move counterclockwise in the TMJ in severe skeletal class II patients.

CLINICAL RELEVANCE

Studies of temporomandibular joint (TMJ) intervals changes in patients with severe skeletal class II after sagittal split ramus osteotomy (SSRO) are limited. The postoperative joint remodeling, resorption, and related complications remain unstudied.

Three-dimensional evaluation of the maxillary sinus in patients with different skeletal classes and cranio-maxillary relationships assessed with cone beam computed tomography

The objective was to evaluate the relationship between the dimensions of the maxillary sinuses (MSs) and various cephalometric parameters. MS volume (MSV), MS surface (MSS), linear maximum depth (LMD), linear maximum width (LMW), and linear maximum height (LMH) were calculated on CBCT scans of 99 adults. Two sets of two-way (ANOVA) assessed the influence respectively of ANB and SNA angles and of the gender on MS dimensions. Pearson's correlation was calculated between MS dimensions and different cephalometric variables. Reliability and accuracy of the proposed method was tested with intra-operator and inter-operator intraclass correlation coefficient (ICC). Two-way ANOVA showed no statistically significant difference in MSV, MSS and LMH between ANB groups, whilst males were associated with bigger sinuses. LMW showed statistically significant difference in both ANB and gender groups. LMD showed no statistically significant difference. The second Two-way ANOVA showed significantly larger MSV, MSS and LMD in patients with increased or reduced SNA angle but not between genders. LMW and LMH also showed a significant difference between genders. All linear measurements showed a significant interaction of the two factors. The intra-observer and inter-observer ICC scored high for all the tested measurements. MSV and MSS showed a positive correlation with S-N, PNS-A, S-Go, N-Me, N-Ans and the distance between Mx points. LMW had a negative correlation with Ba-S-N angle and N-Me, LMH with Ba-S-N angle, S-Go and Mx r-Mx l and LMD with N-Me and N-ANS. LMW had a positive correlation with Mx r-Mx l, LMH with S-N, S-N^Ans-Pns, N-Me, N-Ans and LMD with S-N, Ba-S-N, PNS-A, S-Go and distance between Mx points. In conclusion, MSV and MSS did not differ between the three skeletal classes, males showed significantly larger MS than in females. Concerning the influence of the cranio-maxillary relationship (SNA) and gender on MS dimension, subjects with a retrusion (SNA < 80°) or protusion (SNA > 84°) of the maxillary alveolar bone had larger MSV, MSS, LMW, LMH and LMD than subjects with a normal cranio-maxillary relationship (SNA 82 ± 2°). A statistically significant high positive correlation was observed between S-N, Pns-A, S-Go, Mx-R/Mx-r and MS dimension. Further studies that evaluate similar outcomes in different races may be able to enrich our knowledge on this topic.

Is the volume of the maxillary sinus altered after LeFort I orthognathic surgery? A systematic review and meta-analysis

PURPOSE

This systematic review and meta-analysis aimed to investigate anatomical changes in the maxillary sinus after LeFort I osteotomy.

METHODS

The study protocol was developed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols, and it was registered with the International Prospective Register of Systematic Reviews under registration number CRD42021236412.

RESULTS

Our search strategy yielded 64 articles. Of these, 31 were duplicate studies, and 33 were independently reviewed by two authors for eligibility. Of these 33 studies, 24 were excluded as they did not meet the inclusion criteria. Finally, nine studies met the criteria for inclusion, and they were critically reviewed.

CONCLUSION

This systematic review and meta-analysis revealed that maxillary sinus volume decreases after one-piece and multisegment osteotomies in both skeletal class II and class III male and female patients, with one-piece LeFort I osteotomy technique showing a greater reduction in the sinus volume than the multisegment osteotomy technique. The maxillary sinus thickness remained constant postoperatively.

Assessment of mandibular retromolar space in adults with regard to third molar eruption status

OBJECTIVE

The aim of this study was to compare the difference in length and width of the mandibular retromolar space (RMS) stratified by the different eruption and impaction statuses of the third molars in patients with skeletal Class I malocclusion.

MATERIALS AND METHODS

The right mandibular RMS in 186 adult patients categorized according to the different statuses of the third molar was analyzed by using cone-beam computed tomography (CBCT). The shortest distances between the inner lingual cortex of the mandibular body and second molar root were measured parallel to the posterior occlusal line (POL) at depths of 2, 4, 6, 8, and 10 mm (mandibular retromolar space length in root level, RL_in2,4,6,8,10) on the axial slices with the cementoenamel junction (CEJ) as the reference level. The width of the RMS and second molar root was measured vertical to the POL at the terminal point of the molar distalization at depths of 2, 4, 6, 8, and 10 mm (width of the mandibular retromolar space, BW_2,4,6,8,10/ width of the second molar distal root, TW_2,4,6,8,10) from the CEJ.

RESULTS

RL in different measurement planes was 2.72 ± 2.22 ~ 3.74 ± 2.26 for Group A, 5.27 ± 1.68 ~ 9.10 ± 2.04 for Group B, 1.94 ± 2.34 ~ 5.71 ± 4.37 for Group C, 1.83 ± 2.95 ~ 5.05 ± 4.24 for Group D, and 5.93 ± 3.97 ~ 10.52 ± 2.16 for Group E. The BW measurement results for A ~ E group were 9.71 ± 1.41 ~ 10.51 ± 1.81, 9.83 ± 1.39 ~ 12.55 ± 2.11, 9.96 ± 1.21 ~ 12.17 ± 1.62, 9.82 ± 1.47 ~ 12.28 ± 2.77, and 10.02 ± 1.20 ~ 12.75 ± 0.82, respectively. There was no significant difference between men and women in any measurements (P > 0.05). Patients with normal third molars erupted and those vertically impacted possessed larger RMS lengths than those in which the third molars were missing, horizontally impacted or mesially impacted (P < 0.05). In each measurement plane, TW was significantly smaller than BW (P < 0.05).

CONCLUSIONS

Sex had no effect on the length or width of the mandibular RMS. Different statuses of third molars can also differentially affect the mandibular RMS. The mandibular RMS width is not a limit for mandibular molar distalization.

CLINICAL RELEVANCE

When considering the distalization of mandibular molars, more attention should be directed to the lingual cortex of the mandible, and CBCT scans are recommended for patients who require significant mandibular molar distalization. The mandible buccal shelf and retromolar area maybe a safe zone to insert the miniscrew for molar distalization.

Early detection of external cervical resorption in posterior teeth: a radiographic, cross-sectional study of an adolescent population

OBJECTIVES

To establish the prevalence and severity of external cervical resorption (ECR) in posterior teeth observed in bitewing (BW) radiographs in an epidemiological study of a 17-year-old patient population from community dentistry. Furthermore, to assess the potential predisposing factors for ECR.

METHODS

Posterior BWs from 5596 patients (2717 females, 2879 males; mean age 17.8 years) were assessed by three observers in order to detect ECR (using Heithersay's classification system, severity classes 1-4). When ECR was suspected, cone beam CT (CBCT) was offered to verify diagnosis. Prevalence was estimated based on ECR suspected in BWs and finally in CBCT. Possible predisposing factors (orthodontic treatment, trauma, and periodontal disease) were recorded and assessed for association with ECR.

RESULTS

In 41 patients, ECR was suspected in BWs (suspected prevalence 0.73%). 32 patients accepted CBCT examination, of which eight were verified to have ECR (final prevalence 0.18%). In 24 patients, other disease entities and abnormal tooth morphology, that had mimicked ECR in BWs, excluded ECR in CBCT. ECR severity ranged from class 1-3 in BW and 2-4 in CBCT. All but one case had not been diagnosed by the patient's community dentist. No statistically significant association between predisposing factors and ECR was identified.

CONCLUSIONS

ECR had low prevalence in this adolescent population, as observed in both BWs and CBCT. Still, early detection of ECR is important for treatment prognosis, and attention should be paid to this disease entity when assessing BWs obtained for other diagnostic purposes. CBCT may subsequently aid in verifying the disease.

Factors related to microimplant-assisted rapid palatal expansion in teenagers and young adults: A cone-beam computed tomography study

INTRODUCTION

For patients with maxillary transverse deficiency, selecting an appropriate therapeutic method is important for the treatment effect and prognosis. Our study aimed to explore factors related to microimplant-assisted rapid palatal expansion (MARPE) in teenagers and young adults using cone-beam computed tomography.

METHODS

Twenty-five patients who underwent MARPE were included in this retrospective study from February 2014 to June 2019. Midpalatal suture density (MPSD) ratio, midpalatal suture maturation (MPSM), bone effect, dentoalveolar effect, and dental effect in maxillary first molar were evaluated using cone-beam computed tomography. Spearman correlation analysis was used to analyze the correlation between the MPSD ratio, MPSM, age, and the expansion amount generated by MARPE.

RESULTS

Twenty-five patients (mean age, 19.84 ± 3.96 years; range, 15-29 years) with maxillary transverse deficiency were analyzed. Age was negatively correlated with bone expansion, alveolar expansion, and alveolar change (all P <0.05). There was a negative correlation between MPSM and nasal cavity variation, bone expansion, and alveolar change (all P <0.05). The bone expansion was negatively correlated with MPSD ratio 3 (r = -0.417; P <0.05) and MPSD ratio 4 (all P <0.05).

CONCLUSIONS

Age, MPSM, and MPSD ratio were significantly related to the MARPE effect. Age, MPSM, and MPSD ratio should be considered when choosing MARPE.

Efficacy of low-dose cone beam computed tomography and metal artifact reduction tool for assessment of peri-implant bone defects: an in vitro study

BACKGROUND

Early accurate radiographic assessment of peri-implant bone condition is highly important to avoid excessive loss of supporting bone and implant failure. Cone beam computed tomography (CBCT) is the radiographic technique of choice if peri-implant dehiscence and fenestration defects are suspected. The higher radiation dose and the presence of beam hardening artifacts are the main drawbacks of CBCT imaging techniques. This study aims to evaluate the influence of low-dose cone beam computed tomography (LD-CBCT) and metal artifact reduction (MAR) tool on the assessment of peri-implant dehiscence and fenestration.

METHODOLOGY

Thirty titanium implants were inserted into bovine rib blocks. Twenty had standardized bone defects (10 with dehiscence and 10 with fenestration), while the remaining 10 were used as control group with no defects. Radiographic examinations held with high-definition CBCT (HD-CBCT) and LD-CBCT with and without application of MAR tool. Images were assessed by four examiners for the presence or absence of peri-implant defects. The area under the area under the receiver operating characteristic (ROC) curve (AUC), sensitivity, specificity, and accuracy were calculated for all radiographic protocols.

RESULTS

In the absence of MAR tool, there was no difference in AUC and diagnostic values between LD-CBCT and HD-CBCT for detection of both defects. When the MAR tool was applied, the AUC values, sensitivity, and accuracy were higher in HD-CBCT than in LD-CBCT for the detection of both defects, especially for the dehiscence, while specificity remained the same.

CONCLUSION

LD-CBCT can be used in the evaluation of peri-implant dehiscence and fenestration without any decrease in diagnostic accuracy. The application of MAR tool decrease the diagnostic ability of both defects, especially for the detection of dehiscence defects.

Determination of the Volume and Density of Mandibular Ramus as a Donor Site Using CBCT

Introduction

This study aimed to assess the quantity and quality of available bone to provide the autologous bone graft from mandibular ramus.

Material and Methods

CBCT scans were collected and mandibular ramus was evaluated by measuring a variety of parameters including volume, bone height, cortical, and cancellous bone thickness. Data analysis was performed using descriptive statistics and inferential statistics. We used the Kolmogorov-Smirnov test for the evaluation of data normality. We then applied Pearson correlation and independent t-test for normal variables, and Spearman and Mann-Whitney correlation tests for abnormal variables. Statistical analysis was performed using SPSS version 19 and P value < 0.05 was considered significant.

Results

A total of 52 women and 32 men (aged 21 to 70) were included in this study. The mean bone volume was 2.7 ± 0.70 cm3 [95%confidence interval (CI) 1.3-4.5]. The mean bone density in the middle section was 1016.36 ± 231.58 Gy value (95% CI 475.6-1520.9). Kolmogorov-Smirnov test revealed that the variables such as apical cortical/cancellous ratio (P = 0.005), middle-cancellous bone thickness (P = 0.016), and middle cortical/cancellous ratio (P = 0.005) were abnormal and the rest were normal. Bone density, as well as the amount of cortical bone in the middle and apical regions, had a significant reverse correlation with age (P < 0.001).

Conclusion

The volume, density, and cortical/cancellous ratio are independent of sex. The reverse relationship between age and bone density, as well as the amount of cortical bone in several parts, indicates a decrease in bone quality with aging.

Midpalatal Suture Maturation Method for the Assessment of Maturation before Maxillary Expansion: A Systematic Review

Assessment of midpalatal suture maturation is crucial before deciding which type of maxillary expansion technique will be performed to treat transverse discrepancies. In 2013, Angelieri et al. proposed a new method to evaluate midpalatal maturation using cone-beam computed tomography. The aim of this study was to systematically identify, evaluate, and provide a synthesis of the existing literature about this new method and to rigorously assess the methodological quality of these articles. A bibliographic search was carried out using PubMed, Cochrane Library, SciELO, LILACS, Web of Science, and Scopus using the terms midpalatal suture, cranial sutures, palate, maturation, interdigitation, ossification, maxillary expansion, evaluation, assessment, and assess. Quality assessment was performed using the Observational Cohort and Cross-Sectional Studies tool developed by the National Heart, Lung, and Blood Institute. Hence, 56 articles were obtained, of which only 10 met the selection criteria. We could not include any of the data into an analysis because of the large variation of the data collected and high methodological heterogeneity found among studies. Of all the studies included, 10% had poor quality, 70% fair, and 20% good quality, respectively. Even though age and sex play a role in midpalatal suture obliteration, there is a poor correlation between these variables. Thus, every patient should be assessed individually before choosing the best protocol for maxillary expansion. The midpalatal suture maturation method has the potential to be used for diagnostic purposes, but clinicians should be cautious of routinely using it because an extensive training and calibration program should be performed prior.

Treatment effect analysis of curettage for jaw cysts based on volumetric assessment and image registration

The study was conducted to develop a visual and intuitive quantitative evaluation method for maxillary cystic lesions after curettage. Mimics 16.0 and Geomagic Studio 2013 were used to form a precise reconstruction of the cystic lesion morphology of 60 cases; the average reduction rates and 95% confidence interval were calculated. Computed tomography (CT) registration was performed before and after surgery to observe morphology features of the bone regeneration of the cystic area. The average reduction rates (RR) of the cysts after curettage were (43.56 ± 16.79)%, (54.33 ± 17.15)% and (68.53 ± 15.99)% at 3 months, 6 months and 12 months after surgery, respectively. The average monthly reduction rates (MRR) were (12.07 ± 4.35)%, (8.16 ± 2.84)% and (5.35 ± 1.52)% at 3 months, 6 months and 12 months after surgery, respectively. Correlation analysis by comparing with each group showed that the effect of sex and age in the 3-month group and the initial size in the 12-month group on RR and MRR were statistically significant. Within the limitations of the study it seems that the chosen approach for quantitative evaluation of the therapeutic effect of curettage for jaw cystic lesions might facilitate visual and quantitative follow-up of cyst curettage and timely detection of recurrence.

Deep convolutional neural network-based automated segmentation of the maxillofacial complex from cone-beam computed tomography - A validation study

OBJECTIVES

The present study investigated the accuracy, consistency, and time-efficiency of a novel deep CNN-based model for the automated maxillofacial bone segmentation from CBCT images.

METHOD

A dataset of 144 scans was acquired from two CBCT devices and randomly divided into three subsets: training set (n= 110), validation set (n= 10) and testing set (n=24). A three-dimensional (3D) U-Net (CNN) model was developed, and the achieved automated segmentation was compared with a manual approach.

RESULTS

The average time required for automated segmentation was 39.1 seconds with a 204-fold decrease in time consumption compared to manual segmentation (132.7 minutes). The model is highly accurate for identification of the bony structures of the anatomical region of interest with a dice similarity coefficient (DSC) of 92.6%. Additionally, the fully deterministic nature of the CNN model was able to provide 100% consistency without any variability. The inter-observer consistency for expert-based minor correction of the automated segmentation observed an excellent DSC of 99.7%.

CONCLUSION

The proposed CNN model provided a time-efficient, accurate, and consistent CBCT-based automated segmentation of the maxillofacial complex.

CLINICAL SIGNIFICANCE

Automated segmentation of the maxillofacial complex could act as a potent alternative to the conventional segmentation techniques for improving the efficiency of the digital workflows. This approach could deliver an accurate and ready-to-print three dimensional (3D) models that are essential to patient-specific digital treatment planning for orthodontics, maxillofacial surgery, and implant placement.

Midpalatal Suture CBCT Image Quantitive Characteristics Analysis Based on Machine Learning Algorithm Construction and Optimization

Background: Midpalatal suture maturation and ossification status is the basis for appraising maxillary transverse developmental status. Methods: We established a midpalatal suture cone-beam computed tomography (CBCT) normalized database of the growth population, including 1006 CBCT files from 690 participants younger than 24 years old. The midpalatal suture region of interest (ROI) labeling was completed by two experienced clinical experts. The CBCT image fusion algorithm and image texture feature analysis algorithm were constructed and optimized. The age range prediction convolutional neural network (CNN) was conducted and tested. Results: The midpalatal suture fusion images contain complete semantic information for appraising midpalatal suture maturation and ossification status during the fast growth and development period. Correlation and homogeneity are the two texture features with the strongest relevance to chronological age. The overall performance of the age range prediction CNN model is satisfactory, especially in the 4 to 10 years range and the 17 to 23 years range, while for the 13 to 14 years range, the model performance is compromised. Conclusions: The image fusion algorithm can help show the overall perspective of the midpalatal suture in one fused image effectively. Furthermore, clinical decisions for maxillary transverse deficiency should be appraised by midpalatal suture image features directly rather than by age, especially in the 13 to 14 years range.

Secondary Alveolar Bone Grafting in Patients with Unilateral and Bilateral Complete Cleft Lip and Palate: A Single-Institution Outcomes Evaluation Using Three-Dimensional Cone Beam Computed Tomography

BACKGROUND

Secondary alveolar bone grafting of autologous bone from the iliac crest is a widely accepted modality for repair of residual alveolar cleft in patients with mixed dentition with previously repaired complete cleft lip and palate. There remains debate regarding surgical timing and preoperative, perioperative, and postoperative management of these cases.

METHODS

This retrospective study reviewed patient demographic information in addition to preoperative, perioperative, and postoperative course to evaluate how patient and practice factors impact graft outcomes as assessed by three-dimensional cone beam computed tomographic evaluation at the 6-month postoperative visit.

RESULTS

On univariate analysis, age at operation older than 9 years, history of oronasal fistula, history of cleft lip or palate revision, and history of international adoption were all found to significantly increase likelihood of graft failure (p < 0.05). On multivariate analysis, age older than 9 years was found to be the single most significant predictor of graft failure (p < 0.05). There was no significant difference in graft outcomes between patients with unilateral or bilateral cleft lip and palate, and no single variable was found to significantly correlate to increased complication rates. The graft success rate overall of the authors' practice was 86.2 percent, with a complication rate of 7.7 percent.

CONCLUSIONS

Secondary alveolar bone grafting is an integral part of the cleft lip and palate surgical treatment series; this study identified several outcome predictors for both graft failure and adverse events, the most significant of which was age at operation. Although the mixed dentition phase often extends to 12 years of age, it is recommended that bone grafting be performed before 9 years of age to optimize outcomes.

CLINICAL QUESTIONS/LEVEL OF EVIDENCE

Risk, III.

Impact of acceleration on bone depiction quality by ultrashort echo time magnetic resonance bone imaging sequences in medication-related osteonecrosis of the jaw

Objectives

To assess the impact on bone depiction quality by decreasing number of radial acquisitions (RA) of a UTE MR bone imaging sequence in MRONJ.

Material and methods

UTE MR bone imaging sequences using pointwise encoding time reduction with RA (PETRA) with 60’000, 30’000 and 10’000 RA were acquired in 16 patients with MRONJ and 16 healthy volunteers. Blinded readout sessions were performed by two radiologists. Qualitative analysis compared the detection of osteolytic lesions and productive bony changes in the PETRA sequences of the patients with MRONJ. Quantitative analysis assessed the differences in image artifacts, contrast-to-noise ratio (CNR) and image noise.

Results

Acquisition times were reduced from 315 to 165 and 65 s (60’000, 30’000, 10’000 RA, respectively), resulting in a fewer number of severe motion artifacts. Bone delineation was increasingly blurred when reducing the number of RA but without any trade-off in terms of diagnostic performance. Interreader agreement for the detection of pathognomonic osteolysis was moderate (κ = 0.538) for 60’000 RA and decreased to fair (κ = 0.227 and κ = 0.390) when comparing 30’000 and 10’000 RA, respectively. Image quality between sequences was comparable regarding CNR, image noise and artifact dimensions without significant differences (all P > 0.05).

Conclusions

UTE MR bone imaging sequences with a lower number of RA provide sufficient image quality for detecting osteolytic lesions and productive bony changes in MRONJ subjects at faster acquisition times compared to the respective standard UTE MR bone imaging sequence.

•

Ultrashort echo time MRI can assess medication-related osteonecrosis of the jaw.

•

Sequences with a lower number of radial acquisitions reduce scan times.

•

Image quality for detecting bony changes remains sufficient.

CBCT Evaluation of the maxillary palatine process as a donor site for the regeneration of periodontal defects

Background

The maxillary palatine process (MPP) is an excellent source of autogenous bone transplants for anterior maxillary reconstruction. This research aimed to determine the quantity and quality of accessible MPP as a donor location.

Methods

Cone-beam computed tomography (CBCT) scans of patients referred to the School of Dentistry were evaluated by a certified examiner. The harvestable MPP was defined as the space between the distal surfaces of maxillary first premolars. OnDemand 3D Imaging software was used to determine bone properties. SPSS software was used to investigate the following variables: Bone characteristics are correlated with age and gender, accessible volume, and palatal width and height. P<0.05 was defined as the level of statistical significance.

Results

This study was performed on CBCT scans of 81 subjects (41 females and 40 males). MPP volume and palatal heights were 1.33±0.53 cm3 and 20.86±5.51 mm, respectively. Maximum bone density was observed around lateral incisors. Palatal width was 33.81±2.42 mm between canines and 41.81±2.66 mm between premolars. The MPP volume was significantly greater in males (P<0.001). Additionally, there was a positive correlation between the volume and palatal width (P<0.05).

Conclusion

Within the constraints of this research, there is a limited supply of MMP accessible for use as a graft source, and it is best suited for treating localized bone lesions. The favorable link between palatal breadth and harvestable volume aids the surgeon in estimating the quantity of bone accessible during the first evaluation.

Association between Condylar Bone Density and Disk Displacement in the Temporomandibular Joint

Measuring bone density (BD) is a common method of determining bone quality; however, the relationship between condylar BD and the occurrence of temporomandibular joint (TMJ) disorders has not been investigated. To address this knowledge gap, we aimed to investigate condylar BD in terms of TMJ disk displacement (TMJ DD) using computed tomography (CT) and magnetic resonance imaging (MRI). We classified TMJ MRI results according to the position of the disk: normal disk position (Normal), anterior disk displacement with reduction (ADDR), and anterior disk displacement without reduction (ADDNR). After retrospectively evaluating 86 female condyles, we determined the total, cortical, and trabecular BD in the upper-joint portion of the condyle and the whole condyle using CT data. To standardize condylar BD, we calculated the BD ratios by dividing the condylar BD by the cervical axis BD. The Kruskal-Wallis test analyzed the differences in BD measurements in the TMJ DD patient groups and showed significant between-group differences in condylar BD. The total and trabecular BD was significantly higher in ADDNR condyles than in Normal or ADDR condyles (Normal = ADDR < ADDNR). However, there was no significant difference in the cortical BD among the three TMJ DD groups. The BD ratios showed a similar tendency with condylar BD. These results suggest that increased condylar BD - specifically total and trabecular BD - may be significantly associated with ADDNR condyles. Our findings will help clinicians determine the course of treatment for patients with disk-related TMJ disorders.

Diagnostic accuracy of physical examination findings for midfacial fractures: a systematic review and meta-analysis

Objectives

To conduct a systematic review and meta-analysis to assess the diagnostic accuracy of physical examination findings and related clinical decision aids for midfacial fractures in comparison to computed tomography and cone beam computed tomography.

Material and methods

A systematic review was performed by searching the MEDLINE, Cochrane, EMBASE, and CINAHL databases. Risk of bias was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. Pooled sensitivity, specificity, and diagnostic odds ratios with the corresponding 95% confidence intervals were calculated for each physical examination finding and reported clinical decision aids.

Results

After screening 2367 records, 12 studies were included. High risk of patient selection bias was detected in three studies (25%). Additionally, high concerns regarding applicability were found for the patient selection in five studies (41.7%), and for the reference standard in eleven studies (91.7%). Of the total 42 individual physical examination findings, only 31 were suitable for a meta-analysis. High specificity and low sensitivity were found for most findings. The pooled diagnostic odds ratio ranged from 1.07 to 11.38. Clinical decision aids were reported by 8 studies, but none were constructed specifically for midfacial fractures.

Conclusion

Based on the current available evidence, the absence of physical examination findings can successfully identify patients who do not have a midfacial fracture, but the presence of individual findings does not necessarily mean that the patient has a midfacial fracture. Although various clinical decision aids were presented, none focused on exclusively midfacial fractures.

Clinical relevance

The diagnostic accuracy of physical examination findings can be used to diagnose a midfacial fracture so as to reduce unnecessary imaging, health care costs, and exposure to ionizing radiation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00784-022-04423-y.

A novel approach to assess volumetric bone loss at immediate implant sites and comparison to linear measurements: a pilot study and measurement workflow

OBJECTIVES

Studies have evaluated changes in hard tissue following immediate implant placement (IIP) through cone beam computed tomography (CBCT) imaging, typically examining the amount of two-dimensional (2D) linear, rather than three-dimensional (3D) volumetric bone loss. This study compared the 3D volumetric changes of the alveolar bone at immediate implant sites with 2D linear measurement outcomes by using a novel image analysis workflow.

METHODS

Preoperative and 6-month postoperative CBCT images of patients who underwent IIP and bone grafting in the maxillary esthetic area were acquired. Linear and volumetric measurements of buccal bone dimensions were taken using a specially designed workflow. The 2D and 3D measurements were compared, and their correlations were determined.

RESULTS

Images from 13 patients (13 implants) were analyzed. Linear measurements revealed that the general linear buccal bone loss was less than 1mm in all segments. The 3D volumetric bone reduction (reported as median [first quantile, third quantile]) in the vertical, cervical, middle, and apical segments was 14.27 [11.33, 30.66] mm³ (51.30 [42.78, 66.91]%), 16.20 [10.35, 30.52] mm³ (18.20 [9.88, 24.74]%), 17.48 [8.42, 21.17] mm³ (24.05 [12.39, 28.22]%), and 6.87 [3.88, 9.45] mm³ (11.34 [5.14, 22.54]%), respectively. Significant positive correlations between 2D and 3D measurements were consistently identified in the cervical and middle segments, but no significant correlation was noted in the vertical segment.

CONCLUSIONS

The results revealed that linear measurements could not fully represent volumetric bone dimensional changes. Performing volumetric measurements and 3D rendering could be valuable in presenting the actual amount and topography of peri-implant bone remodeling.

CLINICAL SIGNIFICANCE

Linear measurements only partially represent the real-life event of 3D bone changes at immediate implant sites. Factors affecting hard tissue alterations following IIP should be reassessed using 3D volumetric measurement outcomes.

The Effects of Additional Filtration on Image Quality and Radiation Dose in Cone Beam CT: An In Vivo Preliminary Investigation

Purpose. The aim of this study was to investigate the effect of reduced radiation doses on the image quality of cone-beam computed tomography scans and the suitability of such imaging for orthodontics, oral surgery, dental implantology, periodontology, and endodontology. Materials and Methods. Cone-beam computed tomography scans of a live patient were performed using seven attenuation filters with increased thickness to decrease the effective radiation dose from 22.4 to 1.8 μSv, and the effects of different radiation doses on image quality were further analysed. Quantitative image quality was calculated using dedicated measures, such as signal and contrast-to-noise ratio and sharpness. A panel of five certified raters assessed the cone-beam computed tomography scans qualitatively. Nine anatomical structures relevant to dentistry were identified, and the overall acceptance was assessed. Results. Linear reduction of the effective radiation dose had a nonlinear effect on image quality. A 5-fold reduction in the effective dose led to acceptable quantitative and qualitative image quality measures, and the identification rate of dental anatomical structures was 80% or greater. The use of less than 40% of the reference dose was unacceptable for all dental specialties. Conclusions. The ideal radiation dose for specific diagnostic requirements remains a patient-related and specialty-related decision that must be made on an individual basis. Based on the results of this study, it is possible to reduce exposure in selected patients, and at the same time obtain sufficient quality of images for clinical purposes.

A dose-neutral image quality comparison of different CBCT and CT systems using paranasal sinus imaging protocols and phantoms

Purpose

To compare the image quality produced by equivalent low-dose and default sinus imaging protocols of a conventional dental cone-beam computed tomography (CBCT) scanner, an extremity CBCT scanner and a clinical multidetector computed tomography (MDCT) scanner.

Methods

Three different phantoms were scanned using dose–neutral ultra-low-dose and low-dose sinus imaging protocols, as well as default sinus protocols of each device. Quantified parameters of image quality included modulation transfer function (MTF) to characterize the spatial response of the imaging system, contrast-to-noise ratio, low contrast visibility, image uniformity and Hounsfield unit accuracy. MTF was calculated using the line spread and edge spread functions (LSF and ESF).

Results

The dental CBCT had superior performance over the extremity CBCT in each studied parameter at similar dose levels. The MDCT had better contrast-to-noise ratio, low contrast visibility and image uniformity than the CBCT scanners. However, the CBCT scanners had better resolution compared to the MDCT. Accuracy of HU values for different materials was on the same level between the dental CBCT and MDCT, but substantially poorer performance was observed with the extremity CBCT.

Conclusions

The studied dental CBCT scanner showed superior performance over the studied extremity CBCT scanner when using dose–neutral imaging protocols. In case a dental CBCT is not available, the given extremity CBCT is still a viable option as it provides the benefit of high resolution over a conventional MDCT.