Imaging Science in Dentistry最新文献

Purpose: This study aimed to evaluate the number of roots and type of root canals in maxillary first and second premolars within a selected Korean population utilizing cone-beam computed tomography (CBCT). Additionally, it sought to investigate potential differences in these features according to sex and tooth type.

Materials and methods: CBCT images of 585 maxillary first premolars and 578 maxillary second premolars from 303 patients were retrospectively reviewed. The number of roots was classified based on root morphology, and canal configurations were categorized into 8 types according to the Vertucci classification. For statistical analysis, chi-square or Fisher exact tests were employed to compare root number and canal morphology according to sex and tooth type.

Results: CBCT analysis revealed that 71.5% of maxillary first premolars and 97.6% of maxillary second premolars had 1 root. The most common canal configuration in maxillary first premolars was Vertucci type IV (42.6%), whereas type I predominated in maxillary second premolars (76.5%). Significant differences in root number and canal configurations were found between men and women (P<0.05), with single roots and Vertucci type I canals more commonly observed in women.

Conclusion: Both maxillary first premolars and maxillary second premolars typically had 1 root, with a smaller percentage possessing 2 roots. Significant sex differences were observed in root number and canal type. This study highlights the variability in root number and canal configuration, emphasizing the importance of recognizing these variations to achieve successful endodontic treatment.

Purpose: This study was performed to evaluate the expression of beam hardening artifacts generated by high atomic number materials in stitched cone-beam computed tomography (CBCT) images, compared to the traditional acquisition mode.

Materials and methods: CBCT volumes were acquired using an acrylic resin phantom embedded with pairs of cylinders made from amalgam dental alloy, cobalt-chromium alloy, gutta-percha, titanium, and zirconium. These cylinders were placed within the overlapping zones of the stitching reconstruction area. For each material, 3 acquisitions were conducted: 1 utilizing the automatic stitching process with a FOV of 80×37 mm, and 2 with smaller FOVs of 50×37 mm. For the smaller FOVs, 1 scan targeted the anterior region, while the other focused on the left posterior region. Thus, 3 groups were formed: stitched FOV, anterior FOV, and posterior FOV. Artifact expression was assessed by calculating the means and standard deviations (SDs) of the gray values in 4 regions of interest located anteriorly, posteriorly, medially, and laterally to the cylinders. Analysis of variance was used to compare the data, with an alpha level of 5%.

Results: The stitched FOV exhibited lower SD values than the posterior and anterior FOVs (P<0.05). Regarding the materials evaluated, amalgam, cobalt-chromium, and zirconium generally demonstrated higher SDs of the gray values than gutta-percha and titanium (P<0.05).

Conclusion: Horizontally stitched CBCT images demonstrated lower artifact expression compared to the traditional mode of acquisition.

Purpose: This study aimed to evaluate the quality of clinically indicated digital dental panoramic radiographs (DPRs) of children with mixed dentition. Despite the likely widespread use of this modality, recent research detailing errors on DPRs is scarce.

Materials and methods: A consecutive case series was performed, including 178 DPRs from patients aged 6 to 12 years. Each DPR was reviewed for 10 distinct errors. The findings were analyzed to identify potential solutions.

Results: Nearly three-quarters of the DPRs contained multiple errors. Linear regression analysis indicated that the number of errors decreased with increasing patient age; however, this trend was not statistically significant. Notably, 3 groups of errors (2 errors each) frequently appeared together on the same DPR. When similar errors were grouped, the error incidence decreased significantly with age. Both leftward head tilting and rightward head rotation were observed, likely attributable to the design of the DPR room and the door location. The inter-rater and intra-rater reliability agreements were deemed "substantial" or "almost perfect, beyond chance" for the detection of most errors, particularly the most frequent types, which involved the "chin," "tongue," and "lips-open" positions.

Conclusion: As a pediatric patient ages, the number of DPR errors decreases. The results suggest several pre-exposure strategies that could reduce the error rate. These include, monitoring for a "lips-open" position as an indicator of a potential "tongue" error (occluding the palate-glossal space), and implementing dry runs. Asymmetries observed on DPR must be documented and should prompt re-examination, as they may be genuine.

Purpose: This study was performed to introduce, evaluate, and compare various novel assessment protocols designed for straightforward, reliable, and reproducible measurement of alveolar bone levels. These protocols are intended for standardized periodontal assessment and follow-up, utilizing cone-beam computed tomography (CBCT) images and manipulation of Digital Imaging and Communications in Medicine (DICOM) viewer software.

Materials and methods: Two experienced oral and maxillofacial radiologists developed 5 distinct radiographic measurement protocols. These techniques were established to assess the alveolar bone level of a periodontally affected upper central incisor using a method that is consistently repeatable across observers. Two additional assessors, blinded to the details of the study, independently applied the protocols to retrieved DICOM files that met the eligibility criteria. A scoring system with 3 subscores was created and used to compare the protocols.

Results: Statistically excellent inter-observer reliability was observed for all protocols, other than protocol 1, which demonstrated moderate reliability. The average discrepancy between measurements taken by the 2 observers was 1.2 mm for protocol 1, 0.81 mm for protocol 2, and less than 0.5 mm for the remaining 3 protocols. All approaches except protocol 4 were straightforward to apply.

Conclusion: This study introduces multiple reliable protocols for the evaluation of periodontal bone levels that ensure consistency across observers. Based on the findings, the double axial lines and incisocrestal distance protocols are recommended. These new assessment approaches, along with any future modifications, may be useful in periodontal assessment, dental implant follow-up, orthodontic evaluation, research, and artificial intelligence model generation.

Purpose: This study aimed to evaluate the impact of a metal artifact reduction (MAR) algorithm on cone-beam computed tomography (CBCT) scans of titanium and zirconia implants, both within and outside the field of view (FOV).

Materials and methods: In this in vitro study, a dry human mandible was positioned in a CBCT scanner with only its left quadrant included in the FOV. Each type of implant (titanium and zirconia) was placed once in the right second premolar extraction socket and once in the left second premolar extraction socket of the mandible. CBCT scans were acquired with and without MAR. Three regions of interest (ROIs) were defined in relation to a resin block, and the contrast-to-noise ratio (CNR) was calculated for each ROI. Data were analyzed using 2-way analysis of variance with an alpha level of 0.05.

Results: Application of a MAR algorithm significantly increased the CNR within and outside the FOV for both implant types (P<0.05). Relative to titanium implants, zirconia implants were associated with significantly lower CNRs in both positions (P<0.05) and generated more artifacts. Implant placement outside the FOV was associated with slightly lower image quality than positioning within the FOV, although this finding was not significant (P>0.05).

Conclusion: The results suggest that application of a MAR algorithm in CBCT significantly impacts artifact generation. Titanium implants exhibited significantly lower metal artifact generation compared to zirconia implants. Positioning either implant type outside the FOV, as opposed to inside it, slightly increased artifact generation; however, this was not statistically significant.

Purpose: This study was performed to assess the clinical validity and accuracy of a deep learning-based automatic landmarking algorithm for cone-beam computed tomography (CBCT). Three-dimensional (3D) CBCT head measurements obtained through manual and automatic landmarking were compared.

Materials and methods: A total of 80 CBCT scans were divided into 3 groups: non-surgical (39 cases); surgical without hardware, namely surgical plates and mini-screws (9 cases); and surgical with hardware (32 cases). Each CBCT scan was analyzed to obtain 53 measurements, comprising 27 lengths, 21 angles, and 5 ratios, which were determined based on 65 landmarks identified using either a manual or a 3D automatic landmark detection method.

Results: In comparing measurement values derived from manual and artificial intelligence landmarking, 6 items displayed significant differences: R U6CP-L U6CP, R L3CP-L L3CP, S-N, Or_R-R U3CP, L1L to Me-GoL, and GoR-Gn/S-N (P<0.05). Of the 3 groups, the surgical scans without hardware exhibited the lowest error, reflecting the smallest difference in measurements between human- and artificial intelligence-based landmarking. The time required to identify 65 landmarks was approximately 40-60 minutes per CBCT volume when done manually, compared to 10.9 seconds for the artificial intelligence method (PC specifications: GeForce 2080Ti, 64GB RAM, and an Intel i7 CPU at 3.6 GHz).

Conclusion: Measurements obtained with a deep learning-based CBCT automatic landmarking algorithm were similar in accuracy to values derived from manually determined points. By decreasing the time required to calculate these measurements, the efficiency of diagnosis and treatment may be improved.

Purpose: This study aimed to propose a methodological approach for reducing the radiation dose in pediatric conebeam computed tomography (CBCT), focusing exclusively on balancing image quality with dose optimization.

Materials and methods: The dose-area product (DAP) for exposure was reduced using copper-plate attenuation of an X-ray source. The thickness of copper (Cu) was increased from 0 to 2.2 mm, and 10 different DAP levels were used. The QUART DVT_AP phantom and pediatric radiologic dentiform were scanned under the respective DAP levels. The contrast-to-noise ratio (CNR), image homogeneity, and modulation transfer function (MTF) were analyzed using the QUART DVT_AP phantom. An expert evaluation (overall image grade, appropriateness of field of view, artifacts, noise, and resolution) was conducted using pediatric dentiform images. The critical DAP level was determined based on phantom and dentiform analysis results.

Results: CNR and image homogeneity decreased as the DAP was reduced; however, there was an inflection point of image homogeneity at Cu 1.6 mm (DAP=138.00 mGy·cm²), where the value started increasing. The MTF showed constant values as the DAP decreased. The expert evaluation of overall image grades showed "no diagnostic value" for dentiform images with Cu 1.9-2.2 mm (DAP=78.00-103.33 mGy·cm²). The images with Cu 0-1.6 mm (DAP=138.00-1697.67 mGy·cm²) had a "good," "moderate," or "poor but interpretable" grade.

Conclusion: Reducing DAP beyond a 1.6-mm Cu thickness degraded CBCT image quality. Image homogeneity and clinical image grades indicated crucial decision points for DAP reduction in pediatric CBCT scans.

Purpose: Given the growing use of cone-beam computed tomography (CBCT) scans, this study assessed radiation exposure from these scans in the context of national guidelines and recommended dose limits.

Materials and methods: The current literature was reviewed to quantify the benefit of opportunistic diagnosis of carotid artery calcification relative to the potential risk of radiation-induced cancer.

Results: The average radiation from CBCT at its largest field of view and highest resolution possible amounts to a reasonable but still low ionizing radiation exposure. This exposure is comparable to 22 days of background radiation and is notably lower than the radiation exposure from medical CT scans. According to the risk assessment analysis, the risk of stroke events involving internal and external carotid artery calcification (CAC) was 202 and 67 per 100,000 individuals, respectively. In contrast, the estimated risk of radiation-induced cancer associated with CBCT was notably lower, at 0.6 per 100,000.

Conclusion: The present study advocates for a comprehensive assessment of CBCT scans encompassing the areas of the internal and external carotid arteries by a knowledgeable professional, given the potential advantages of early detection of vascular abnormalities. Dental professionals who take scans involving these areas need to be mindful of reporting these findings and refer patients to their primary care physician for further investigation.

Purpose: This study was performed to investigate the pattern of condylar pressure distribution in the discs of a patient diagnosed with disc displacement without reduction.

Materials and methods: This research consisted of a pre- and post-test observational clinical study. A patient diagnosed with disc displacement without reduction underwent treatment with an occlusal splint for 3 months. Finite element analysis employed a 3-dimensional model constructed from magnetic resonance images of the patient, taken both before the application of the splint and 3 months after its use.

Results: The post-test model demonstrated a decrease in condylar pressure on the disc, with measurements dropping to 72 MPa from the pre-test level of 143 MPa. In the pre-test, the pressure distribution pattern was concentrated on the lateral posterior border, whereas in the post-test, it shifted toward the intermediate zone of the disc.

Conclusion: Utilization of a stabilization splint for 3 months resulted in decreased pressure and a marked change in the pressure distribution pattern on the temporomandibular disc.