Peripheral osteoma in the ramus of mandible: report of case / Osteoma periférico en la rama mandibular: reporte de caso

The osteomas are benign rare neoplasms, generally asymptomatic which are characterized by the proliferation of a compact or spongy bone. When they are situated in the maxillofacial area, they affect mainly the mandible, the frontal bone and the paranasal sinus. We have described the case of a female caucasian patient who presented an increased volume in the posterior region of the oral vestibule on the left side. During the clinical examination an oral lesion was observed in the region of the left ramus of mandible. This lesion was motionless, consistent, and painless when palpated. In the image obtained from the computed tomography cone-beam (CBCT), we could observe an hyperdense, cylindrical region, with well defined borders, located in the medial surface of the left ramus of mandible, right below the mandibular notch. Based on clinical data and in the obtained images, we could confirm the presence of the peripheral osteoma in the left side of the ramus of mandible region.

Los osteomas son neoplasias benignas, raras, en la mayoría de los casos asintomáticas, que se constan principalmente de hueso maduro, compacto o esponjoso. De acuerdo a su ubicación en la región maxilofacial, la mandibula, el hueso frontal y los senos paranasales son preferentemente afectados. Describimos un caso de un paciente, sexo femenino, caucásica, que presentaba un aumento de volumen en la región posterior del vestíbulo oral en el lado izquierdo. Al examen clínico se observó una lesión inmóvil, consistente e indolora a la palpación. En la imagen obtenida a través del tomógrafo computado volumétrico Cone Beam (CBCT), se observó una región híperdensa, cilíndrica, con márgenes marcados, ubicada en la cara medial de la rama mandibular izquierda, inferior a la escotadura mandibular. Con base en los datos clínicos y las imágenes obtenidas se puede concluir la presencia de osteoma periférico en región de rama mandibular izquierda.

Comparison of CT numbers between cone-beam CT and multi-detector CT / 대한구강악안면방사선학회지

PURPOSE: To compare the CT numbers on 3 cone-beam CT (CBCT) images with those on multi-detector CT (MDCT) image using CT phantom and to develop linear regressive equations using CT numbers to material density for all the CT scanner each. MATERIALS AND METHODS: Mini CT phantom comprised of five 1 inch thick cylindrical models with 1.125 inches diameter of materials with different densities (polyethylene, polystyrene, plastic water, nylon and acrylic) was used. It was scanned in 3 CBCTs (i-CAT, Alphard VEGA, Implagraphy SC) and 1 MDCT (Somatom Emotion). The images were saved as DICOM format and CT numbers were measured using OnDemand 3D. CT numbers obtained from CBCTs and MDCT images were compared and linear regression analysis was performed for the density, rho (g/cm3), as the dependent variable in terms of the CT numbers obtained from CBCTs and MDCT images. RESULTS: CT numbers on i-CAT and Implagraphy CBCT images were smaller than those on Somatom Emotion MDCT image (p<0.05). Linear relationship on a range of materials used for this study were rho=0.001H+1.07 with R2 value of 0.999 for Somatom Emotion, rho=0.002H+1.09 with R2 value of 0.991 for Alphard VEGA, rho=0.001H+1.43 with R2 value of 0.980 for i-CAT and rho=0.001H+1.30 with R2 value of 0.975 for Implagraphy. CONCLUSION: CT numbers on i-CAT and Implagraphy CBCT images were not same as those on Somatom Emotion MDCT image. The linear regressive equations to determine the density from the CT numbers with very high correlation coefficient were obtained on three CBCT and MDCT scan.

Impact of the image quality of conebeam CT on the accelerator for the Bowtie filter / 中华放射肿瘤学杂志

Objective To estimate the impact of the image quality of conebeam CT on the accelerator for the Bowtie filter. Methods This study used the system of conebeam CT on the accelerator,and scaned the phantom of Catphan 500 in the multiplicate scanning conditions with and without the Bowtie filter. The scanning conditions were : voltage :120 kV, 100 kV, 80 kV, electricity:25 mA, 40 mA, 64 mA,time of exposure :40 MHz, collimator: M20, L20, scanning angle :358°. We transmitted the scanning data in the treatment planning systems of Philips Pinnacle 8. 0, and estimated the influence of the image quality.Results With and without the Bowtie filter, all of the images had high geometric precision, and the maximum difference of the nominal and actual distance at the horizontal, vertical and arrowy directions in the transection were 0. 50% and 0. 56% ( t = 0. 44, P ＞ 0. 05 ), 0. 44% and 0. 48% ( t = 1.01, P ＞ 0. 05 ),0. 50% and 0. 56% (t = 1.06,P ＞0. 05 ), respectively. The spatial resolution was 0. 167 cm, immutably.The ununiformity with the Bowtie filter was decreased of 28.0% -76.0% (t=2.53,P＜0. 05)、2.8%-50.0% (t= 3.02,P＜0.01 ) than those without the Bowtie filter, and the contrast-to-noise ratio was increased of 4.0% -41.6% (t=2.70,P＜0.05)、4.0% -50.0% (t=2.14,P＜0.05), using the collimators of M20 and L20, respectively. The Bowtie filter could display clearly the edge of scanning phantom, and improve the CT number of the image edge of phantom. And the linearity of CT number was also improved. Couclusions With the Bowtie filter, the image uniformity, the precision and linearity of CT number and the contrast-to-noise ratio were improved obviously, the edge artifacts were decreased, and the geometric precision and the spacial resolution did not change.

Quantitative assessment of periimplant bone density (HU) on CBCT image / 대한구강악안면방사선학회지

PURPOSE: The primary aims of this retrospective study were to compare subjective bone quality and bone quality based on the Hounsfield scale in different segments of the edentulous jaw, and to establish quantitative and objective assessment of the bone quality. MATERIALS AND METHODS: Twenty eight randomly selected cone-beam computed tomographic (CBCT) scans were analyzed. For evaluation one hundred and twelve edentulous areas were selected. Implant recipient sites were evaluated visually for Lekholm and Zarb classification. The same sites were subsequently evaluated digitally using the Hounsfield scale with Vimplant2.0(TM), and the results were correlated with visual classification. Data was subject for statistical analysis in order to determine correlation between recorded HU and the regions of the mouth with the Kruskal-Wallis test. RESULTS: The highest unit/mean density value (311 HU) was found in the anterior mandible, followed by 259 HU for the posterior mandible, 216 HU for the anterior maxilla, and 127 HU for the posterior maxilla. These results demonstrate a strong correlation for HU depending on the region of the mouth (p<0.001). The relationship between HU and type 4 bone was found to be significant (r=0.74). CONCLUSION: Knowledge of the Hounsfield value as a quantitative measurement of bone density can be helpful as a diagnostic tool by using CBMercuRay(TM) with Vimplant(TM) software.

Comparison of cone beam CT and conventional CT in absorbed and effective dose / 대한구강악안면방사선학회지

PURPOSE: This study provides comparative measurements of absorbed and effective doses for newly developed cone beam computed tomography (CT) in comparison with these doses for conventional CT. MATERIALS AND METHODS: Thermoluminescent dosimeter rods (TLD rod: GR-200, Thermo Fisher Scientific Inc., Waltham, MA, USA) were placed at 25 sites throughout the layers of Male ART Head and Neck Phantom (Radiology Support Devices Inc., Long Beach, USA) for dosimetry. Implagraphy, DCT Pro (Vatech Co., Hwasung, Korea) units, SCT-6800TXL (Shimadzu Corp., Kyoto, Japan), and Cranex 3+ (Soredex Orion Corp., Helsinki, Finland) were used for radiation exposures. Absorption doses were measured with Harshaw 3500TLD reader (Thermo Fisher Scientific Inc., Waltham, MA, USA). Radiation weighted doses and effective doses were measured and calculated by 2005 ICRP tissue weighting factors. RESULTS: Absorbed doses in Rt. submandibular gland were 110.57 mGy for SCT 6800TXL (Implant), 24.56 mGy for SCT 6800TXL (3D), 22.39 mGy for Implagraphy3, 7.19 mGy for DCT Pro, 5.96 mGy for Implagraphy1, 0.70 mGy for Cranex 3+. Effective doses (E2005draft) were 2.551 mSv for SCT 6800TXL (Implant), 1.272 mSv for SCT 6800TXL (3D), 0.598 mSv for Implagraphy3, 0.428 mSv for DCT Pro and 0.146 mSv for Implagraphy1. These are 108.6, 54.1, 25.5, 18.2 and 6.2 times greater than panoramic examination (Cranex 3+) doses (0.023 mSv). CONCLUSION: Cone beam CT machines recently developed in Korea, showed lower effective doses than conventional CT. Cone beam CT provides a lower dose and cost alternative to conventional CT, promising to revolutionize the practice of oral and maxillofacial radiology.

Comparison of the buccolingual inclination in alveolar bone and tooth using dental CBCT / 대한구강악안면방사선학회지

PURPOSE: It is important to determine the bucco-lingual inclination of implants on radiographs before the implant surgery. The purpose of this study was to compare the buccolingual inclination in alveolar bone and the tooth with dental cone beam CT and to prepare the standard for the buccolingual inclination of implant. MATERIALS AND METHODS: Axial, panoramic, and buccolingually sectioned images of 80 implant cases with stent including straight marker using CB Mercuray(TM) (Hitachi, Japan) were evaluated. The comparison of the buccolingual inclination of remained alveolar bone with the tooth and the marker on buccolingually sectioned views was performed statistically. RESULTS: The average buccolingual inclination of remained alveolar bone and tooth was 82.8+/-4.6degrees and 85.8+/-4.7degrees (p0.05, r=0.12) at the 2nd premolar area in upper jaw. The average buccolingual inclination of remained alveolar bone and tooth was 81.3+/-8.3degrees and 87.5+/-6.3degrees (p>0.05, r=0.85) at the lower 2nd premolar area and 94.3+/-6.6degrees and 93.3+/-7.2degrees respectively (p>0.05, r=0.91) at the 1st molar area in lower jaw. The inclinations of markers were very different from those of remained bone at the most of areas except the upper 2nd premolar area (r=0.79). CONCLUSION: We recommend dental CBCT analysis for determining the buccolingual inclination of dental implant, because of significant difference, in average, between the buccolingual inclination of remained alveolar bone and tooth.

Positional change of the condylar heads after wearing complete denture on dental cone beam CT / 대한구강악안면방사선학회지

PURPOSE: The aim of this study was to evaluate the change in the position of the mandibular condyle within articular fossa by a CBCT after wearing complete denture (CD). MATERIALS AND METHODS: CBCT of 34 temporomandibular joints were taken from 9 male and 8 female patients with CB Mercuray(TM) (Hitachi, Japan) before and after wearing a CD for rehabilitation. Position of mandibular condyle within articular fossa at centric occlusion was evaluated with Vimplant2.0(TM) (CyberMed, Korea) on the central parasagittal view and curved panoramic coronal view of the condylar head. A statistical evaluation was done with SPSS. RESULTS: The range of anteroposterior positional rate (AP) of condylar head within articular fossa was -16-5 and -10-12 respectively on the right and left sides. Before wearing CD, the AP rate showed discrepancy between right and left sides (p<0.05). After wearing CD, both condyles showed a tendency to decrease in posterior condylar position (right side; p<0.05). The average discrepancy between right and left side in mediolateral positional rate (MD) was 15.5 and 4.5 respectively before and after wearing CD. The improvement was observed in mediolateral relationship of both condylar heads after wearing CD (p<0.01). Before wearing CD, the average horizontal angle of long axis of condylar head was 79.6+/-2.7degrees and 80.1+/-5.7degrees respectively on the right and left sides. After wearing CD, both condyles were rotated in the same direction in average on axial plane. CONCLUSION: We observed with CBCT the significant clinical evidence in case of positional change of mandibular condyle after wearing complete denture.

Evaluation of imaging reformation with cone beam computed tomography for the assessment of bone density and shape in mandible / 대한구강악안면방사선학회지

PURPOSE: Diagnostic estimation of destruction and formation of bone has the typical limit according to capacity of x-ray generator and image detector. So the aim of this study was to find out how much it can reproduce the shape and the density of bone in the case of using recently developed dental type of cone beam computed tomography, and which image is applied by new detector and mathematic calculation. MATERIALS AND METHODS: Cone beam computed tomography (PSR 9000N, Asahi Roentgen Ind. Co., Ltd., Japan) and soft x-ray radiography were executed on dry mandible that was already decalcified during 5 hours, 10 hours, 15 hours, 20 hours, and 25 hours. Estimating and comparing of those came to the following results. RESULTS: The change of inferior border of mandible and anterior border of ramus in the region of cortical bone was observed between first 5 and 10 hours of decalcification. The reproduction of shape and density in the region of cortical bone and cancellous bone can be hardly observed at cone beam computed tomography compared with soft x-ray radiography. The difference of decrease of bone density according to hours of decalcification increase wasn't reproduced at cone beam computed tomography compared with soft x-ray radiography. CONCLUSION: CBCT images revealed higher spatial resolution. However, contrast resolution in region of low contrast sensitivity is the inferiority of images' property.