In vivo quantification of mandibular bone remodeling and vascular changes in a Wistar rat model: A novel HR-MRI and micro-CT fusion technique

Purpose@#This study was performed to introduce an in vivo hybrid multimodality technique involving the coregistration of micro-computed tomography (micro-CT) and high-resolution magnetic resonance imaging (HR-MRI) to concomitantly visualize and quantify mineralization and vascularization at follow-up in a rat model. @*Materials and Methods@#Three adult female rats were randomly assigned as test subjects, with 1 rat serving as a control subject. For 20 weeks, the test rats received a weekly intravenous injection of 30 μg/kg zoledronic acid, and the control rat was administered a similar dose of normal saline. Bilateral extraction of the lower first and second molarswas performed after 10 weeks. All rats were scanned once every 4 weeks with both micro-CT and HR-MRI. Micro-CT and HR-MRI images were registered and fused in the same 3-dimensional region to quantify blood flow velocity and trabecular bone thickness at T0 (baseline), T4 (4 weeks), T8 (8 weeks), T12 (12 weeks), T16 (16 weeks), and T20 (20 weeks). Histological assessment was the gold standard with which the findings were compared. @*Results@#The histomorphometric images at T20 aligned with the HR-MRI findings, with both test and control rats demonstrating reduced trabecular bone vasculature and blood vessel density. The micro-CT findings were also consistent with the histomorphometric changes, which revealed that the test rats had thicker trabecular bone and smaller marrow spaces than the control rat. @*Conclusion@#The combination of micro-CT and HR-MRI may be considered a powerful non-invasive novel technique for the longitudinal quantification of localized mineralization and vascularization.

How image-processing parameters can influence the assessment of dental materials using micro-CT

Purpose@#The aim of this study was to evaluate the influence of voxel size and different post-processing algorithms on the analysis of dental materials using micro-computed tomography (micro-CT). @*Materials and Methods@#Root-end cavities were prepared in extracted maxillary premolars, filled with mineral trioxide aggregate (MTA), Biodentine, and Intermediate Restorative Material (IRM), and scanned using micro-CT. The volume and porosity of materials were evaluated and compared using voxel sizes of 5, 10, and 20 µm, as well as different software tools (post-processing algorithms). The CTAn or MeVisLab/Materialise 3-matic software package was used to perform volume and morphological analyses, and the CTAn or MeVisLab/Amira software was used to evaluate porosity. Data were analyzed using 1-way ANOVA and the Tukey test (p<0.05). @*Results@#Using MeVisLab/Materialise 3-matic, a consistent tendency was observed for volume to increase at larger voxel sizes. CTAn showed higher volumes for MTA and IRM at 20 µm. Using CTAn, porosity values decreased as voxel size increased, with statistically significant differences for all materials. MeVisLab/Amira showed a difference for MTA and IRM at 5 µm, and for Biodentine at 20 µm. Significant differences in volume and porosity were observed in all software packages for Biodentine across all voxel sizes. @*Conclusion@#Some differences in volume and porosity were found according to voxel size, image-processing software, and the radiopacity of the material. Consistent protocols are needed for research evaluating dental materials.

Accuracy and reliability of 2-dimensional photography versus 3-dimensional soft tissue imaging

PURPOSE: This study was conducted to objectively and subjectively compare the accuracy and reliability of 2-dimensional (2D) photography and 3-dimensional (3D) soft tissue imaging.MATERIALS AND METHODS: Facial images of 50 volunteers (25 males, 25 females) were captured with a Nikon D800 2D camera (Nikon Corporation, Tokyo, Japan), 3D stereophotogrammetry (SPG), and laser scanning (LS). All subjects were imaged in a relaxed, closed-mouth position with a normal smile. The 2D images were then exported to Mirror® Software (Canfield Scientific, Inc, NJ, USA) and the 3D images into Proplan CMF® software (version 2.1, Materialise HQ, Leuven, Belgium) for further evaluation. For an objective evaluation, 2 observers identified soft tissue landmarks and performed linear measurements on subjects' faces (direct measurements) and both linear and angular measurements on all images (indirect measurements). For a qualitative analysis, 10 dental observers and an expert in facial imaging (subjective gold standard) completed a questionnaire regarding facial characteristics. The reliability of the quantitative data was evaluated using intraclass correlation coefficients, whereas the Fleiss kappa was calculated for qualitative data.RESULTS: Linear and angular measurements carried out on 2D and 3D images showed excellent inter-observer and intra-observer reliability. The 2D photographs displayed the highest combined total error for linear measurements. SPG performed better than LS, with borderline significance (P=0.052). The qualitative assessment showed no significant differences among the 2D and 3D imaging modalities.CONCLUSION: SPG was found to a reliable and accurate tool for the morphological evaluation of soft tissue in comparison to 2D imaging and laser scanning.

Image quality assessment of pre-processed and post-processed digital panoramic radiographs in paediatric patients with mixed dentition

PURPOSE: To determine the impact of an image processing technique on diagnostic accuracy of digital panoramic radiographs for the assessment of anatomical structures in paediatric patients with mixed dentition. MATERIALS AND METHODS: The study consisted of 50 digital panoramic radiographs of children aged from 6 to 12 years, which were later on processed using a dedicated image processing method. A modified clinical image quality evaluation chart was used to evaluate the diagnostic accuracy of anatomical structures in maxillary and mandibular anterior and maxillary premolar region of processed images. RESULTS: A statistically significant difference was observed between pre and post-processed evaluation of anatomical structures (P 0.05). The Inter-observer and intra-observer reliability of both pre and post processed images were excellent (>0.82) for anterior region and good (>0.63) for premolar region. CONCLUSION: The application of image processing technique in digital panoramic radiography can be considered a reliable method for improving the quality of anatomical structures in paediatric patients with mixed dentition.

Sensory innervation around immediately vs. delayed loaded implants: a pilot study / 国际口腔科学杂志·英文版

Although neurophysiological and psychophysical proof of osseoperception is accumulating, histomorphometric evidence for the neural mechanisms of functional compensation following immediate and delayed implant loading is still lacking. For this randomized split-mouth study, six mongrel dogs randomly received one of four treatment protocols at 36 implant-recipient sites over 16 weeks (third maxillary incisor, third and fourth mandibular premolar): immediate implant placement and immediate loading (IIP+IL); delayed implant placement and delayed loading (DIP+DL); delayed implant placement and immediate loading (DIP+IL); and natural extraction socket healing (control). Histomorphometry was performed in the peri-implant bone and soft tissues within 300 µm around the implants. Immunocytochemistry and transmission electron microscopy were used to confirm the presence of neural structures and to reveal their ultrastructural characteristics, respectively. Myelinated nerve fibres densely populated the peri-implant crestal gingival and apical regions, although they were also identified in the woven bone and in the osteons near the implant threads. Compared with the control group in the mandible, the group that received IIP+IL showed a higher innervation (in N⋅mm⁻², 5.94 ± 1.12 vs. 3.15 ± 0.63, P<0.001) and smaller fibre diameter (in µm, 1.37 ± 0.05 vs. 1.64 ± 0.13, P=0.016), smaller axon diameter (in µm, 0.89 ± 0.05 vs. 1.24 ± 0.10, P=0.009) and g-ratio (0.64 ± 0.04 vs. 0.76 ± 0.05, P<0.001) in the middle region around the implants. Compared with DIP+IL in the mandible, IIP+IL had a higher nerve density (in N⋅mm⁻², 13.23 ± 2.54 vs. 9.64 ± 1.86, P=0.027), greater fibre diameter (in µm, 1.32 ± 0.02 vs. 1.20 ± 0.04, P=0.021), greater axon diameter (in µm, 0.92 ± 0.01 vs. 0.89 ± 0.03, P=0.035) and lower g-ratio (0.69 ± 0.01 vs. 0.74 ± 0.01, P=0.033) in the apical region around the implants. It may be assumed that the treatment protocol with IIP+IL is the preferred method to allow optimized peri-implant re-innervation, but further functional measurements are still required.

Cephalometric landmark variability among orthodontists and dentomaxillofacial radiologists: a comparative study

PURPOSE: The aim this study was to compare the accuracy of orthodontists and dentomaxillofacial radiologists in identifying 17 commonly used cephalometric landmarks, and to determine the extent of variability associated with each of those landmarks. MATERIALS AND METHODS: Twenty digital lateral cephalometric radiographs were evaluated by two groups of dental specialists, and 17 cephalometric landmarks were identified. The x and y coordinates of each landmark were recorded. The mean value for each landmark was considered the best estimate and used as the standard. Variation in measurements of the distance between landmarks and measurements of the angles associated with certain landmarks was also assessed by a subset of two observers, and intraobserver and interobserver agreement were evaluated. RESULTS: Intraclass correlation coefficients were excellent for intraobserver agreement, but only good for interobserver agreement. The least reliable landmark for orthodontists was the gnathion (Gn) point (standard deviation [SD], 5.92 mm), while the orbitale (Or) was the least reliable landmark (SD, 4.41 mm) for dentomaxillofacial radiologists. Furthermore, the condylion (Co)-Gn plane was the least consistent (SD, 4.43 mm). CONCLUSION: We established that some landmarks were not as reproducible as others, both horizontally and vertically. The most consistently identified landmark in both groups was the lower incisor border, while the least reliable points were Co, Gn, Or, and the anterior nasal spine. Overall, a lower level of reproducibility in the identification of cephalometric landmarks was observed among orthodontists.

Proinflammatory cytokine levels in oral lichen planus, oral leukoplakia, and oral submucous fibrosis

OBJECTIVES: The objective of this study was to identify salivary and serum concentrations of interleukin (IL)-8, IL-6, and tumor necrosis factor alpha (TNF-alpha) in patients with oral lichen planus, oral leukoplakia, oral submucous fibrosis, and healthy controls. MATERIALS AND METHODS: Patients selected included 54 oral lichen planus (41 to 65 years), 50 oral leukoplakia (42 to 65 years), 51 oral submucous fibrosis (41 to 65 years), and 50 healthy controls (42 to 65 years). Oral lichen planus, oral leukoplakia, and oral submucous fibrosis cases were diagnosed using histopathological analysis. Salivary and serum cytokine concentrations were measured using enzyme-linked immunoassay kits in all subjects. RESULTS: The levels of serum and salivary TNF-alpha, IL-6, and IL-8 were statistically significantly increased in oral leukoplakia, submucous fibrosis, and lichen planus in contrast to normal healthy subjects (P<0.05). Serum and salivary correlation analysis revealed strong and highly significant correlations for TNF-alpha, IL-6, and IL-8 in all groups (r=0.72-0.82, P<0.05). CONCLUSION: Salivary and serum cytokines were also elevated when analyzed in oral precancerous lesions. Thus, salivary and serum IL-8, IL-6, and TNF-alpha levels might act as diagnostic markers for detection of oral precancer.

Reproducibility of the sella turcica landmark in three dimensions using a sella turcica-specific reference system

PURPOSE: This study was performed to assess the reproducibility of identifying the sella turcica landmark in a threedimensional (3D) model by using a new sella-specific landmark reference system. MATERIALS AND METHODS: Thirty-two cone-beam computed tomographic scans (3D Accuitomo(R) 170, J. Morita, Kyoto, Japan) were retrospectively collected. The 3D data were exported into the Digital Imaging and Communications in Medicine standard and then imported into the Maxilim(R) software (Medicim NV, Sint-Niklaas, Belgium) to create 3D surface models. Five observers identified four osseous landmarks in order to create the reference frame and then identified two sella landmarks. The x, y, and z coordinates of each landmark were exported. The observations were repeated after four weeks. Statistical analysis was performed using the multiple paired t-test with Bonferroni correction (intraobserver precision: p50% precision in locating the landmark within 1 mm. CONCLUSION: A newly developed reference system offers high precision and reproducibility for sella turcica identification in a 3D model without being based on two-dimensional images derived from 3D data.

Can pterygoid plate asymmetry be linked to temporomandibular joint disorders?

PURPOSE: This study was performed to evaluate the relationship between pterygoid plate asymmetry and temporomandibular joint disorders. MATERIALS AND METHODS: Cone-beam computed tomography (CBCT) images of 60 patients with temporomandibular disorders (TMD) involving pain were analyzed and compared with images of 60 age- and gender-matched controls. Three observers performed linear measurements of the lateral pterygoid plates. RESULTS: Statistically significant differences were found between measurements of the lateral pterygoid plates on the site that had pain and the contralateral site (p<0.05). The average length of the lateral pterygoid plates (LPPs) in patients with TMD was 17.01+/-3.64 mm on the right side and 16.21+/-3.51 mm on the left side, and in patients without TMD, it was 11.86+/-1.97 mm on the right side and 11.98+/-1.85 mm on the left side. Statistically significant differences in the LPP length, measured on CBCT, were found between patients with and without TMD (p<0.05). The inter-examiner reliability obtained in this study was very high for all the examiners (0.99, 95% confidence interval: 0.98-0.99). CONCLUSION: Within the limits of the present study, CBCT lateral pterygoid plate measurements at the side with TMD were found to be significantly different from those on the side without TMD. More research is needed to explore potential etiological correlations and implications for treatment.

Characterization of mandibular molar root and canal morphology using cone beam computed tomography and its variability in Belgian and Chilean population samples

PURPOSE: This study used cone-beam computed tomography (CBCT) to characterize mandibular molar root and canal morphology and its variability in Belgian and Chilean population samples. MATERIALS AND METHODS: We analyzed the CBCT images of 515 mandibular molars (257 from Belgium and 258 from Chile). Molars meeting the inclusion criteria were analyzed to determine (1) the number of roots; (2) the root canal configuration; (3) the presence of a curved canal in the cross-sectional image of the distal root in the mandibular first molar and (4) the presence of a C-shaped canal in the second mandibular molar. A descriptive analysis was performed. The association between national origin and the presence of a curved or C-shaped canal was evaluated using the chi-squared test. RESULTS: The most common configurations in the mesial root of both molars were type V and type III. In the distal root, type I canal configuration was the most common. Curvature in the cross-sectional image was found in 25% of the distal canals of the mandibular first molars in the Belgian population, compared to 11% in the Chilean population. The prevalence of C-shaped canals was 10% or less in both populations. CONCLUSION: In cases of unclear or complex root and canal morphology in the mandibular molars, CBCT imaging might assist endodontic specialists in making an accurate diagnosis and in treatment planning.

Does cone-beam CT alter treatment plans? Comparison of preoperative implant planning using panoramic versus cone-beam CT images

PURPOSE: The present study was performed to compare the planning of implant placement based on panoramic radiography (PAN) and cone-beam computed tomography (CBCT) images, and to study the impact of the image dataset on the treatment planning. MATERIALS AND METHODS: One hundred five partially edentulous patients (77 males, 28 females, mean age: 46 years, range: 26-67 years) seeking oral implant rehabilitation were referred for presurgical imaging. Imaging consisted of PAN and CBCT imaging. Four observers planned implant treatment based on the two-dimensional (2D) image datasets and at least one month later on the three-dimensional (3D) image dataset. Apart from presurgical diagnostic and dimensional measurement tasks, the observers needed to indicate the surgical confidence levels and assess the image quality in relation to the presurgical needs. RESULTS: All observers confirmed that both imaging modalities (PAN and CBCT) gave similar values when planning implant diameter. Also, the results showed no differences between both imaging modalities for the length of implants with an anterior location. However, significant differences were found in the length of implants with a posterior location. For implant dimensions, longer lengths of the implants were planned with PAN, as confirmed by two observers. CBCT provided images with improved scores for subjective image quality and surgical confidence levels. CONCLUSION: Within the limitations of this study, there was a trend toward PAN-based preoperative planning of implant placement leading towards the use of longer implants within the posterior jaw bone.

Gold-wire artifacts on diagnostic radiographs: A case report

This report described a case in which diagnostic radiographs showed irregular dense radiopaque strings and curved lines in the head and neck area. These artifacts could lead to misinterpretation since they may obscure anatomical structures and/or mask critical structures/pathologies. A more detailed history of the patient indicated that these strings originated from a facelift procedure in which a gold-wire technique was used. Considering that such intervention may cause a radiodiagnostic burden, it should be included in the anamnesis prior to radiography.

Preoperative implant planning considering alveolar bone grafting needs and complication prediction using panoramic versus CBCT images

PURPOSE: This study was performed to determine the efficacy of observers' prediction for the need of bone grafting and presence of perioperative complications on the basis of cone-beam computed tomography (CBCT) and panoramic radiographic (PAN) planning as compared to the surgical outcome. MATERIALS AND METHODS: One hundred and eight partially edentulous patients with a need for implant rehabilitation were referred for preoperative imaging. Imaging consisted of PAN and CBCT images. Four observers carried out implant planning using PAN image datasets, and at least one month later, using CBCT image datasets. Based on their own planning, the observers assessed the need for bone graft augmentation as well as complication prediction. The implant length and diameter, the need for bone graft augmentation, and the occurrence of anatomical complications during planning and implant placement were statistically compared. RESULTS: In the 108 patients, 365 implants were installed. Receiver operating characteristic analyses of both PAN and CBCT preoperative planning showed that CBCT performed better than PAN-based planning with respect to the need for bone graft augmentation and perioperative complications. The sensitivity and the specificity of CBCT for implant complications were 96.5% and 90.5%, respectively, and for bone graft augmentation, they were 95.2% and 96.3%, respectively. Significant differences were found between PAN-based planning and the surgery of posterior implant lengths. CONCLUSION: Our findings indicated that CBCT-based preoperative implant planning enabled treatment planning with a higher degree of prediction and agreement as compared to the surgical standard. In PAN-based surgery, the prediction of implant length was poor.