Correlação entre valores de pixel de tomografia computadorizada e a intensidade do sinal proveniente da medula óssea da mandíbula adquiridos por meio da Ressonância Magnética / Correlation between alveolar bone CT pixel values and bone marrow fat content: an MRI analysis

A análise por imagem das condições morfológicas do osso alveolar é essencial para o planejamento de tratamentos de diversas especialidades na odontologia. Porém, a maioria dos métodos de imagem utilizam radiação ionizante. Assim, a ressonância magnética (RM) ganha grande importância na pesquisa do tecido ósseo. O objetivo deste estudo foi correlacionar valores de pixel (VP) da tomografia Computadorizada Espiral (TCE) e Tomografia Computadorizada por Feixe Cônico (TCFC) com o sinal emitido pela medula óssea da mandíbula pela técnica da RM. Neste estudo retrospectivo, foram utilizados exames de RM e tomografia computadorizada do mesmo paciente. Utilizamos um aparelho de TCFC pareado com uma RM de 1,5T e duas marcas de tomógrafos espirais pareados com uma RM de 3T. Para a análise, foi selecionado um corte axial da mesma região do terço inferior da mandíbula nas duas técnicas de imagens. A media dos VP de uma região de interesse compreendendo toda área dos osso trabecular foi utilizada para análise. Foi observada correlação inversa e moderada para os dois aparelhos de TCE e a RM de 3T (0,62 e 0,56 com p<0,006); não foi observada correlação significante ente a TCFC e a RM de 1,5T. Considerando as limitações deste estudo, podemos concluir que, na mandíbula, existe uma relação inversa entre a densidade mineral óssea e medula óssea adiposa.

Comparison of Pixel Values of Maxillary Sinus Grafts and Adjacent Native Bone With Cone-Beam Computed Tomography.

PURPOSE: Pixel values from cone-beam computed tomography (CBCT) are proportional to bone density. This study aimed to correlate and compare pixel values of healed maxillary sinus grafts and adjacent native bone (NB). MATERIAL AND METHODS: This study was conducted on CBCT scan patients referred for maxillary sinus floor augmentation with biphasic calcium phosphate (n = 31). Graft height and width measurements were performed. In addition, mean pixel values were calculated in 3 different regions: NB, sinus graft close to NB (CNB), and sinus graft far from NB (FNB). Micro-CT and histological analyses of bone specimens of a representative case were also performed. RESULTS: Significant correlations were found between CNB and graft height (r = 0.41; P < 0.021); and FNB and graft width (r = 0.519, P < 0.003). In addition, pixel values from both graft groups (CNB and FNB) differed significantly (P < 0.001). Finally, histological sections revealed smaller areas with newly formed bone in the FNB area. CONCLUSIONS: Within the limitations of this study, the present findings suggest that pixel values of sinus grafted areas are directly correlated with the extension of the grafted area.

Simple Bone Cyst Mimicking Stafne Bone Defect.

Stafne bone defects (SBDs) are asymptomatic lingual bony defects in mandible, which are usually detected as an incidental finding in plain radiographs. Similarly, simple bone cysts (SBCs) are most frequently found in posterior region of the mandible and also are asymptomatic. However, due to anatomical structures overlap in plain radiographs, there is a possibility of misdiagnosing SBD that often is diagnosed by presumptive diagnosis observed in plain radiograph. This report shows an unusual case that a SBC resembles a SBD.

Impact of Temporomandibular Joint Discectomy on Condyle Morphology: An Animal Study.

PURPOSE: Temporomandibular disorders lead to parafunctional activity that may alter bone remodeling of mandibular components. This animal study aimed to assess the impact of temporomandibular joint discectomy on condylar bone microarchitecture. MATERIALS AND METHODS: A total of 30 one-month-old Wistar rats were assessed and divided into 3 equal groups (2 test groups and 1 control group) of 10. The first test group underwent disc removal, the second test group underwent disc and condylar cartilage removal, and the 10 remaining rats were analyzed as sham-operated controls, following a split-mouth design. The rats were killed humanely 2 months after surgery, and the respective mandibles were scanned with micro-computed tomography for quantitative morphometric analysis. RESULTS: There were significant differences among the 3 groups analyzed (disc removal, disc and condylar cartilage removal, and sham-operated control) for bone volume fraction (ratio of bone volume to total volume, P = .044), structure model index (P < .001), fractal dimension (P = .024), and porosity (P = .023). In addition, operated and contralateral nonoperated sides significantly differed for all variables in at least 1 of the test groups (P < .05) but not in the control group (P > .05). CONCLUSIONS: Within the limitations of this study, our results suggest that discectomy may lead to alterations of the mandibular condylar morphology.

Assessment of alveolar bone marrow fat content using 15 T MRI.

OBJECTIVES: Bone marrow fat is inversely correlated with bone mineral density. The aim of this study is to present a method to quantify alveolar bone marrow fat content using a 15 T magnetic resonance imaging (MRI) scanner. STUDY DESIGN: A 15 T MRI scanner with a 13-mm inner diameter loop-gap radiofrequency coil was used to scan seven 3-mm diameter alveolar bone biopsy specimens. A 3-D gradient-echo relaxation time (T1)-weighted pulse sequence was chosen to obtain images. All images were obtained with a voxel size (58 µm3) sufficient to resolve trabecular spaces. Automated volume of the bone marrow fat content and derived bone volume fraction (BV/TV) were calculated. Results were compared with actual BV/TV obtained from micro-computed tomography (CT) scans. RESULTS: Mean fat tissue volume was 20.1 ± 11%. There was a significantly strong inverse correlation between fat tissue volume and BV/TV (r = -0.68; P = .045). Furthermore, there was a strong agreement between BV/TV derived from MRI and obtained with micro-CT (interclass correlation coefficient = 0.92; P = .001). CONCLUSIONS: Bone marrow fat of small alveolar bone biopsy specimens can be quantified with sufficient spatial resolution using an ultra-high-field MRI scanner and a T1-weighted pulse sequence.

Comparison of the diagnostic performance of panoramic and occlusal radiographs in detecting submandibular sialoliths.

PURPOSE: The aim of this study was to assess and compare the diagnostic performance of panoramic and occlusal radiographs in detecting submandibular sialoliths. MATERIALS AND METHODS: A total of 40 patients (20 cases and 20 controls) were included in this retrospective study. Cases were defined as subjects with a submandibular sialolith confirmed by computed tomography (CT), whereas controls did not have any submandibular calcifications. Three observers with different expertise levels assessed panoramic and occlusal radiographs of all subjects for the presence of sialoliths. Intraobserver and interobserver agreement were assessed using the kappa test. Sensitivity, specificity, accuracy, positive and negative predictive values, and the diagnostic odds ratio of panoramic and occlusal radiographs in screening for submandibular sialoliths were calculated for each observer. RESULTS: The sensitivity and specificity values for occlusal and panoramic radiographs all ranged from 80% to 100%. The lowest values of sensitivity and specificity observed among the observers were 82.6% and 80%, respectively (P=0.001). Intraobserver and interobserver agreement were higher for occlusal radiographs than for panoramic radiographs, although panoramic radiographs demonstrated a higher overall accuracy. CONCLUSION: Both panoramic and occlusal radiographic techniques displayed satisfactory diagnostic performance and should be considered before using a CT scan to detect submandibular sialoliths.

Diagnostic performance of fractal dimension and radiomorphometric indices from digital panoramic radiographs for screening low bone mineral density

A number of panoramic radiographic measurements have been associated with osteoporotic alterations. However, little is known about the differences in sensitivity and specificity among these measurements for screening low bone mineral density (BMD). Aim: To correlate and compare precision, sensitivity and specificity of panoramic radiomorphometric indices and fractal dimension (FD) for screening low BMD (i.e. osteopenia and osteoporosis). Methods: Sixty-eight female patients (42.78±15.59 years) were included in this study. Body mass index (BMI), mandibular cortical index (MCI), mandibular cortical width (MCW), FD and connectivity (C) were assessed. Low BMD was diagnosed by peripheral dual-energy X-ray absorptiometry (p-DXA). Non-parametric correlations were assessed among all variables. In addition, sensitivity and specificity of MCI, MCW and FD were estimated for screening low BMD. Results: Significant correlation was found between FD and BMI (p=0.013; r=0.269). In addition, FD was the most sensitive method for screening low BMD (70.8%, p=0.001). FD and MCI presented a significant and relatively high sensitivity, whereas MCW presented a high specificity for screening low systemic BMD Conclusions: Among the analyzed methods, FD and MCI offer a significant and relatively high sensitivity, whereas MCW offers a high specificity for screening low BMD (Au)

Reliability and Reproducibility of Manual and Automated Volumetric Measurements of Periapical Lesions.

INTRODUCTION: The present study aimed to test the reliability and reproducibility of 2 methods: manual and automated segmentation (using a threshold-based region growing algorithm) for measuring the volume of periapical lesions. METHODS: A total of 43 cone-beam computed tomographic scans (14 men and 29 women, mean age of 54.6 ± 8.5 years) were analyzed by 3 observers. Intraobserver reproducibility and interobserver reliability were assessed using the intraclass correlation coefficient. Parametric correlation between manual and automated volumetric measurements was performed. In addition, the Student t test was also used to compare the mean time required for manual and automated volumetric measurements. RESULTS: Automated segmentation showed slightly higher intraclass correlation coefficient values for all observers. A strong significant correlation was found between manual and automated volumetric measurements performed by the 3 observers. A significant difference in the mean procedure time was also found between both methods (P = .001). CONCLUSIONS: Within the limitations of this study, the present results suggest that automated segmentation with a region growing algorithm is faster and slightly more reliable to calculate the volume of periapical lesions.

The use of a computed tomographic application for mobile devices in the diagnosis of oral and maxillofacial surgery.

The aim of the current technical report was to introduce a computed tomographic (CT) application for mobile devices as a diagnostic tool for analyzing CT images. An iPad and an iPhone (Apple, Cuppertino, CA) were used to navigate through multiplanar reconstructions of cone beam CT scans, using an application derived from the OsiriX CT software. Tools and advantages of this method were recorded. In addition, images rendered in the iPad were manipulated during dental implant placement and grafting procedures to follow up and confirm the implant digital planning in real time. The study population consisted of 10 patients. In all cases, it was possible to use image manipulation tools, such as changing contrast and brightness, zooming, rotating, panning, performing both linear and area measurements, and analyzing gray-scale values of a region of interest. Furthermore, it was possible to use the OsiriX application in the dental clinic where the study was conducted, to follow-up the analyzed implant placement and grafting procedures at the chairside. The current findings suggest that technological and practical methods to visualize radiographic images are invaluable resources to improve training, teaching, networking, and the performance of real-time follow-up of oral and maxillofacial surgical procedures. This article discusses the advantages and disadvantages of introducing this new technology in the clinical routine.

Efeitos da remoção do disco e cartilagem articular no crescimento e microarquitetura óssea da mandíbula de ratos: análise por microtomografia / Effects of articular disc and cartilage removal on mandible of growing rats: a micro-computed tomography study

Alterações na articulação emporomandibular (ATM) comumente geram desequilíbrios musculares que estão associados à alterações no tecido ósseo. Esta articulação pode sofrer a influência de traumas, fatores congênitos ou desordens de crescimento. Estudos sobre alterações de crescimento do complexo maxilomandibular decorrentes de problemas da ATM são escassos. O objetivo deste trabalho foi avaliar por meio da microtomografia os efeitos da remoção do disco articular e a remoção conjugada do disco e cartilagem articular no crescimento e na microarquitetura óssea da mandíbula de ratos. Trinta ratos da raça Wistar com um mês de idade foram divididos em três grupos: CTR (controle operado); RD (remoção de disco articular) e RDC (remoção conjugada do disco e cartilagem articular). Apenas o lado direito foi operado; o lado esquerdo permaneceu intacto. Após dois meses de acompanhamento, os ratos foram sacrificados e as hemimandíbulas escaneadas em microtomógrafo A remoção do disco articular e a remoção conjugada do disco e cartilagem articular alteram o volume e microestrutura do osso trabecular da mandíbula de ratos jovens. Estas duas intervenções provocaram uma queda na qualidade de parâmetros da microestrutura do trabeculado do processo angular e diminuição do crescimento da hemimandíbula do lado operado.

Changes in the temporomandibular joint (TMJ) lead to muscle dysfunctions that are associated with bone changes. This joint region can be influenced by trauma, congenital factors or growth disorders. Studies linking TMJ problems and growth alterations are scarce. The aim of this study was to evaluate the effects of the articular disc removal or articular disc and cartilage removal on the bone microarchitecture and mandibular growth of young rats. Thirty Wistar rats (one month old) were divided into three groups: CTR (sham operated); RD (disc removal) and RDC (disc and cartilage removal). Only the right side was operated, keeping the left side intact. After two months, the rats were sacrificed and the mandibles scanned on micro-CT for quantitative analysis. Some microstructural parameters were altered by the disc removal or disc and cartilage removal. The right side presented lower growth than the left side.