Photon-Counting CT Material Decomposition in Bone Imaging.

The accurate screening of osteoporosis is important for identifying persons at risk. The diagnosis of bone conditions using dual X-ray absorptiometry is limited to extracting areal bone mineral density (BMD) and fails to provide any structural information. Computed tomography (CT) is excellent for morphological imaging but not ideal for material quantification. Advanced photon-counting detector CT (PCD-CT) possesses high spectral sensitivity and material decomposition capabilities to simultaneously determine qualitative and quantitative information. In this study, we explored the diagnostic utility of PCD-CT to provide high-resolution 3-D imaging of bone microarchitecture and composition for the sensitive diagnosis of bone in untreated and ovariectomized rats. PCD-CT accurately decomposed the calcium content within hydroxyapatite phantoms (r = 0.99). MicroCT analysis of tibial bone revealed significant differences in the morphological parameters between the untreated and ovariectomized samples. However, differences in the structural parameters of the mandible between the treatment groups were not observed. BMD determined with microCT and calcium concentration decomposed using PCD-CT differed significantly between the treatment groups in both the tibia and mandible. Quantitative analysis with PCD-CT is sensitive in determining the distribution of calcium and water components in bone and may have utility in the screening and diagnosis of bone conditions such as osteoporosis.

Diagnostic application of intraoral ultrasonography to assess furcation involvement in mandibular first molars.

OBJECTIVES: The objectives were to clarify if intraoral ultrasonography (USG) is: (1) more accurate than conventional periodontal examinations in detection of furcation involvement, and (2) comparable to conventional periodontal examinations in accurate horizontal classification of furcation involvement in comparison to cone beam computed tomography (CBCT). METHODS: The buccal furcation in 61 lower first molars were evaluated with conventional periodontal examinations, intraoral USG and CBCT. The presence and classification of the horizontal depth of furcation involvement were defined clinically by assessment with a Nabers periodontal probe and a periapical radiograph with reference to the bone loss under the fornix. The horizontal depth of furcation involvement was measured in intraoral USG and CBCT images. Based on the measurements, presence diagnosis and horizontal classification were performed. Results from conventional periodontal examinationsand intraoral USG were compared with those from CBCT. RESULTS: κ value (κ) for agreement of presence diagnosis of furcation involvement between intraoral USG and CBCT was 0.792, while agreement with conventional periodontal examinations was 0.225. Diagnostic accuracy of intraoral USG exhibited higher values (sensitivity: 98.3%, accuracy: 98.4 %) than conventional periodontal examinations (81.4% and 81.9 %). Weighted κ statistics showed substantial agreement in the classification between intraoral USG and CBCT (κ = 0.674). High agreement (ICC: 0.914) for the measurement of horizontal depth of furcation involvement was found between intraoral USG and CBCT. CONCLUSIONS: Intraoral USG may be a reliable diagnostic tool for assessment of furcation involvement of mandibular molars with a similar performance to CBCT, but without ionizing radiation.

Accuracy of CBCT in the Identification of Mental, Lingual, and Retromolar Foramina: A Comparison with Visual Inspection of Human Dry Mandibles.

The present dry-mandible study evaluated the presence of the mental (MF), lingual (LF), and retromolar (RMF) foramina to assess the accuracy of CBCT in detecting these anatomical structures. In total, 38 human dry mandibles were analyzed (30 men, 8 women; mean age: 61.9 ± 13.7 years). CBCT scans were taken using low-dose parameters, and LF, MF, and RMF were assessed visually and radiographically. Both the presence (yes/no) and the count (n) of each foramen were compared between CBCTs and visual assessment. For the presence assessment, only RMF exhibited a significant difference between CBCT and visual inspection (P = .035). For count, the RMF (P = .049) and paramedian LF (P = .003) exhibited differences between the two methods. The agreement between CBCT and visual inspection was excellent for the MF, moderate-excellent for the LF, and low-moderate for the RMF. Intra- and interassessor agreement varied from excellent (MF), to moderate-excellent (LF), and low-moderate (RMF). The LF and RMF represent challenging structures to identify on CBCT images due to their limited dimension. False negative findings in CBCTs in the assessment of foramina, especially LF, might lead to surgical complications during implant surgery.

Posterior superior alveolar nerves contribute to sensation in the anterior teeth.

BACKGROUND: There is no available data on the occurrence rate of a converged alveolar canal, the detailed three-dimensional (3D) courses of alveolar canals/grooves (ACGs), or the contribution of each superior alveolar nerve to each area in the maxilla. This study aimed to clarify the 3D courses of ACGs, the relationship between ACGs and superior alveolar nerves, and the contribution of posterior superior alveolar nerves (PSANs) using computed tomography (CT) with histological analysis. METHODS: During the gross anatomy course at Niigata University, we investigated nine human cadavers. RESULTS: All anterior and posterior ACGs converged into the common alveolar canal, which contained blood vessels and several nerve bundles surrounded by perineurium, located at the nasal floor near the pyriform aperture. Histometrical analysis clarified that 16.3% of the nerve bundles in this canal were derived from PSANs, and 67% of the bundles were dispersed while they coursed down to the nasal floor. There seems to be no relationship between the density of nerve bundles in the canal and the number of remaining anterior teeth. CONCLUSIONS: Data obtained from observing the detailed 3D courses of anterior and posterior ACGs, and their relationship with superior alveolar nerves, suggest that PSANs partially contribute to the nociception of the anterior teeth.

Clinical guidelines for the application of panoramic radiographs in screening for osteoporosis.

Osteoporotic fractures are associated with an increased risk of subsequent fractures, a higher rate of mortality, and incremental medical costs. Incidental findings, which include some measurements related to the mandibular inferior cortex and the alveolar trabecular bone pattern of the mandible determined on panoramic radiographs, are considered to be a useful tool for identifying asymptomatic individuals at risk of having osteoporosis and/or fragility fractures. We undertook a worldwide literature survey and present the following clinical recommendations. Postmenopausal female dental patients with a mandibular inferior cortical width of less than 3 mm on panoramic radiographs may be at risk of having low skeletal bone mineral density (BMD) or osteoporosis, but not fragility fractures. In addition, those with a severely eroded mandibular inferior cortex may have an increased risk of having low skeletal BMD, osteoporosis, and fragility fractures. The alveolar trabecular bone pattern of the mandible might be useful for identifying female dental patients at risk of having fragility fractures, although further investigation is necessary to confirm this possibility. These incidental findings on panoramic radiographs, when used for identifying asymptomatic postmenopausal female patients at risk of having osteoporosis in general dental practice, may be helpful in reducing the incidence of first fractures, with a consequent reduction in the secondary fractures, medical costs, and mortality associated with osteoporotic fragility fractures, without incurring any additional cost.

Dry Skulls and Cone Beam Computed Tomography (CBCT) for Teaching Orofacial Bone Anatomy to Undergraduate Dental Students.

Learning bone anatomy of the skull is a complex topic involving three-dimensional information. The impact of the use of human dry skulls and cone beam computed tomography (CBCT) imaging was investigated in the teaching of undergraduate dental students. Sixty-four first-year students in the University of Hong Kong were randomly divided into eight groups. Four teaching methods were tested: (1) CBCT followed by standard lecture, (2) CBCT followed by lecture with skulls, (3) standard lecture followed by CBCT, and (4) lecture with skulls followed by CBCT. After each, students were given a multiple-choice questionnaire to assess their objective learning outcome (20 questions) and a questionnaire for their subjective satisfaction (10 statements). Surveys were assessed with Cronbach's alpha, Kendall's tau-b, and principal components analysis. Data were analyzed with Student's t-test and a one-way ANOVA (significance α = 0.05). Standard lecture followed by CBCT showed the highest learning outcome score (81.6% ± 14.1%), but no significant difference was present among four teaching methods. Cone beam computed tomography followed by lecture with skulls scored the highest overall subjective satisfaction (4.9 ± 0.8 out of 6), but no significant difference was present among teaching methods. Nevertheless, students' perception of learning was positively influenced by the use of skulls (P = 0.018). The timing of administration of the CBCT did not affect students' subjective satisfaction or objective learning outcome. Students perceived to learn more by using skulls, but their objective learning outcomes were not significantly affected. A discrepancy seems to exist between students' perception of learning and their effective performance.

Anteroposterior length of the maxillary complex and its relationship with the anterior cranial base.

OBJECTIVES: To use both absolute anteroposterior maxillary complex length (APMCL) and relative APMCL to investigate the relationship between the maxillary complex, its individual bony segments, and their association to the anterior cranial base. In addition, the relationship between length and position of the maxillary complex was analyzed. MATERIALS AND METHODS: Sixty human skulls were analyzed using cone beam computed tomography. The maxillary complex length was measured between anterior and posterior nasal spine (ans-pns), and the average was used as the cut-off to identify a high- and a low-length group based on absolute APMCL. The length ratio between the maxillary complex and the anterior cranial base (ans-pns/SN) was used to identify the two groups based on relative APMCL. The anterior cranial base length and the lengths of the maxillary complex bones were compared between the high- and low-length groups. RESULTS: Based on absolute APMCL, individuals with shorter maxillary complex had shorter anterior cranial base (P = .003), representing normal proportions. Based on relative APMCL, individuals with shorter maxillary complex had longer anterior cranial base and vice versa (P = .014), indicating disproportions. Individuals with shorter maxillary complex exhibited shorter maxilla (Δ = -1.5 mm, P = .014). CONCLUSIONS: When skeletal deformity of the midface is suspected, individual disproportions in the anteroposterior length of the maxillary complex in relation to the anterior cranial base (relative measurements) should be assessed through radiological imaging. A shorter maxillary complex may be associated with a shorter maxilla, and not with a shorter premaxilla or palatine bone.

Mandibular Radiomorphometric Indices and Tooth Loss as Predictors for the Risk of Osteoporosis using Panoramic Radiographs.

PURPOSE: To assess the mandibular cortical width (MCW) and morphology of the mandibular inferior cortex (MIC) on panoramic views from a large sample of males and females in various age groups by using an automated morphometric grading system for assisting osteoporosis screening. Furthermore, possible predictors and concrete cut-off values to identify the risk for osteoporosis were evaluated. MATERIALS AND METHODS: MCW, MIC, tooth loss (TL), and alveolar bone loss (ABL) were retrospectively evaluated in 700 panoramic images from dental patients in Hong Kong using commercially available software. To estimate possible predictors for identifying the risk of osteoporosis, age, TL, and ABL were evaluated with the receiver operating characteristic (ROC) curves for each gender separately. RESULTS: The age groups 60s (sixties), 70s and 80s showed statistically significant gender differences. For example, a smaller MCW and more MIC Class 3 were found in females. Furthermore, females exhibited a statistically significant increase in TL in the age groups 50 years and above. In males, age, TL or ABL did not correlate with MCW, whereas in females it statistically significantly did. Meanwhile, the correlation between ABL and MCW and MIC was weak for both genders. Concrete cut-off values to identify patients at risk of osteoporosis were 60.15 years and 3.5 missing teeth in females, and 72.55 years in males. CONCLUSION: Age and tooth loss were related to MCW and MIC in the population investigated. An age of ≥60 as well as more than 3.5 teeth lost seem to be indicators for a risk of osteoporosis in Chinese females based on panoramic views using artificial-intelligence-based software.

Real-time evaluation of swallowing in patients with oral cancers by using cine-magnetic resonance imaging based on T2-weighted sequences.

OBJECTIVE: The aim of this study was to evaluate whether a new cine-magnetic resonance imaging (CMRI) technique might be useful for evaluating swallowing function in patients with different types of oral cancers by assessing 12 CMRI-related parameters. STUDY DESIGN: In total, 111 patients with oral cancers were evaluated. We examined whether visualization of fluid flow and determination of flow direction to the trachea or the esophagus were possible with CMRI. We evaluated the correlations between CMRI-related parameters and self-reported dysphagia scores as the status of dysphagia, T classification groups as tumor staging for preoperative patients, alterations in CMRI-related parameters between pre- and postoperative patients, and the degree of invasiveness of oral cancer surgery. RESULTS: We could judge the flow direction to the esophagus on CMRI in all 111 patients. Six CMRI-related parameters showed significant correlations with dysphagia status. Increases in CMRI-related parameters were significantly related to deterioration of swallowing status, as shown by a decrease in self-reported dysphagia scores, advances in the T classification, and degree of invasiveness of oral cancer surgery. CONCLUSIONS: The results of the present study suggest that CMRI can be used to directly visualize swallowing dynamics and objectively evaluate the swallowing complaints of patients with oral cancer.

Current Applications, Opportunities, and Limitations of AI for 3D Imaging in Dental Research and Practice.

The increasing use of three-dimensional (3D) imaging techniques in dental medicine has boosted the development and use of artificial intelligence (AI) systems for various clinical problems. Cone beam computed tomography (CBCT) and intraoral/facial scans are potential sources of image data to develop 3D image-based AI systems for automated diagnosis, treatment planning, and prediction of treatment outcome. This review focuses on current developments and performance of AI for 3D imaging in dentomaxillofacial radiology (DMFR) as well as intraoral and facial scanning. In DMFR, machine learning-based algorithms proposed in the literature focus on three main applications, including automated diagnosis of dental and maxillofacial diseases, localization of anatomical landmarks for orthodontic and orthognathic treatment planning, and general improvement of image quality. Automatic recognition of teeth and diagnosis of facial deformations using AI systems based on intraoral and facial scanning will very likely be a field of increased interest in the future. The review is aimed at providing dental practitioners and interested colleagues in healthcare with a comprehensive understanding of the current trend of AI developments in the field of 3D imaging in dental medicine.

Awareness and practice of 2D and 3D diagnostic imaging among dentists in Hong Kong.

Aims To investigate the awareness and practice of 2D and 3D diagnostic imaging, including respective equipment, specifications, number of images acquired, indications for CBCT scans, preference between 2D and 3D imaging, and the confidence in acquiring and interpreting radiographic images among dentists in Hong Kong.Materials and methods A citywide survey was performed with an online questionnaire that was sent via the local dental association to registered dentists in Hong Kong. The anonymous survey focused on: their dental background; number, type and age of their intra-oral, panoramic devices; CBCT indications, field-of-view and consideration of low-dose protocols; and their confidence in taking and interpreting these images.Results From the feedback collected, 65% of dentists used digital intra-oral systems. Around 70% of respondents who perform CBCTs utilised low-dose protocols to reduce radiation dose. Age and years of practising dentistry were significant influencing factors in determining dentists' utilisation of low-dose protocols for CBCT devices. Male dentists and dentists with higher qualifications generally reported being more confident in taking and interpreting CBCT images. Dentists who were older and had more years of practising dentistry were generally more confident in interpreting CBCT images.Conclusion Only half of the dentists feel confident in taking and interpreting CBCT images, and there seems to be a limited knowledge of radiation dose-related risks. Therefore, continuous professional education should specifically focus on the potential of digital imaging and training in CBCT modalities, radiation dose protection and image interpretation.

A comparison of visual identification of dental radiographic and nonradiographic images using eye tracking technology.

OBJECTIVES: Eye tracking has been used in medical radiology to understand observers' gaze patterns during radiological diagnosis. This study examines the visual identification ability of junior hospital dental officers (JHDOs) and dental surgery assistants (DSAs) in radiographic and nonradiographic images using eye tracking technology and examines if there is a correlation. MATERIAL AND METHODS: Nine JHDOs and nine DSAs examined six radiographic images and 16 nonradiographic images using eye tracking. The areas of interest (AOIs) of the radiographic images were rated as easy, medium, and hard, and the nonradiographic images were categorized as pattern recognition, face recognition, and image comparison. The participants were required to identify and locate the AOIs. Data analysis of the two domains, entire slide and AOI, was conducted by evaluating the eye tracking metrics (ETM) and the performance outcomes. ETM consisted of six parameters, and performance outcomes consisted of four parameters. RESULTS: No significant differences were observed for ETMs for JHDOs and DSAs for both radiographic and nonradiographic images. The JHDOs showed significantly higher percentage in identifying AOIs than DSAs for all the radiographic images (72.7% vs. 36.4%, p = .004) and for the easy categorization of radiographic AOIs (85.7% vs. 42.9%, p = .012). JHDOs with higher correct identification percentage in face recognition had a shorter dwell time in AOIs. CONCLUSIONS: Although no significant relation was observed between radiographic and nonradiographic images, there were some evidence that visual recognition skills may impact certain attributes of the visual search pattern in radiographic images.

The use and performance of artificial intelligence applications in dental and maxillofacial radiology: A systematic review.

OBJECTIVES: To investigate the current clinical applications and diagnostic performance of artificial intelligence (AI) in dental and maxillofacial radiology (DMFR). METHODS: Studies using applications related to DMFR to develop or implement AI models were sought by searching five electronic databases and four selected core journals in the field of DMFR. The customized assessment criteria based on QUADAS-2 were adapted for quality analysis of the studies included. RESULTS: The initial electronic search yielded 1862 titles, and 50 studies were eventually included. Most studies focused on AI applications for an automated localization of cephalometric landmarks, diagnosis of osteoporosis, classification/segmentation of maxillofacial cysts and/or tumors, and identification of periodontitis/periapical disease. The performance of AI models varies among different algorithms. CONCLUSION: The AI models proposed in the studies included exhibited wide clinical applications in DMFR. Nevertheless, it is still necessary to further verify the reliability and applicability of the AI models prior to transferring these models into clinical practice.

Antibacterial Additives in Epoxy Resin-Based Root Canal Sealers: A Focused Review.

Dental materials used in root canal treatment have undergone substantial improvements over the past decade. However, one area that still remains to be addressed is the ability of root canal fillings to effectively entomb, kill bacteria, and prevent the formation of a biofilm, all of which will prevent reinfection of the root canal system. Thus far, no published review has analysed the literature on antimicrobial additives to root canal sealers and their influence on physicochemical properties. The aim of this paper was to systematically review the current literature on antimicrobial additives in root canal sealers, their anti-fouling effects, and influence on physicochemical properties. A systematic search was performed in two databases (PubMed and Scopus) to identify studies that investigated the effect of antimicrobial additives in epoxy resin-based root canal sealers. The nature of additives, their antimicrobial effects, methods of antimicrobial testing are critically discussed. The effects on sealer properties have also been reviewed. A total of 31 research papers were reviewed in this work. A variety of antimicrobial agents have been evaluated as additives to epoxy resin-based sealers, including quaternary ammonium compounds, chlorhexidine, calcium hydroxide, iodoform, natural extracts, antibiotics, antifungal drugs, and antimicrobial agent-functionalised nanoparticles. Antimicrobial additives generally improved the antimicrobial effect of epoxy resin-based sealers mainly without deteriorating the physicochemical properties, which mostly remained in accordance with ISO and ANSI/ADA specifications.

Patient-, software-, and observer-related factors associated with the time required for semi-automated measurements of the maxillary sinus volume using cone beam computed tomography (CBCT)

This study aimed to evaluate patient-, software-, and observer-related factors influencing the time required for volumetric measurements of maxillary sinuses using cone beam computed tomography (CBCT) and a commercially available software. The volumes of healthy bilateral maxillary sinuses of adult patients from CBCT images taken during a 15-month study period were measured using dedicated software by two observers. The time required for volumetric assessments was evaluated statistically with respect to the potential influence of gender, age, sinus side, sinus volume, sequence of measurement, and selection threshold of the software. The resulting average sinus volume of the 174 sinuses from 87 patients was 16.9 cm3. The average time required to measure one sinus volume was 91.8 s. Sinuses from male patients required a longer time (median of 95.5 s) for the measurements than their female counterparts (median of 87.5 s). Measurement time increased with increasing age, sinus volume and selection threshold based on calculated grey values provided by the software. The volumetric measurements and measurement times exhibited a high intra-observer agreement. The volumetric measurements were highly reproducible. Each measurement was completed within 4 minutes, though there was a marked difference in the mean measurement time between the two observers. Semi-automated volumetric measurement of the maxillary sinus with commercially available software is feasible, efficient, and reproducible. Based on these favorable findings, practitioners might consider using such volumetric instead of linear measurements to plan and analyse outcomes of sinus grafting procedures in daily clinical practice.