Strut and texture analysis for osteoporosis detection index (ODI) using dental panoramic radiography

Dept. of Dentistry/박사Together with rapid aging of worldwide population, prediction and early diagnosis of osteoporosis became an important health care issue. The aim of this study was to find variables for enabling osteoporosis detection using the strut method, fractal dimension (FD), and the gray level co-occurrence matrix (GLCM) in dental panoramic radiographs (DPRs) using multiple ROIs (regions of interests), including the endosteal margin area, and to develop an osteoporosis detection index (ODI) applicable to DPRs. A total of 454 DPRs from 2012 to 2015 were selected, with 227 drawn from non-osteoporotic patients and 227 drawn from osteoporotic patients, classified by bone mineral density (T-score). After 3 marrow regions and the endosteal margin area were upsampled to 400%, strut features, FD, and GLCM were analyzed using a customized image processing program. Independent samples t-test was used to verify statistical differences between the normal and osteoporotic patients. Logistic regression was performed to compare the diagnostic accuracy of each variable. Finally, decision tree algorithm was used to create and verify the ODI. FD (0.975) and strut features (below 0.926) of the endosteal margin area showed high area under the curve (AUC), whereas GLCM (below 0.580) showed low AUC. The combination of FD and two strut features (number of nodes denominated by number of termini, and number of nodes per square centimeter) showed a high diagnostic accuracy (93.0%) with use of the decision tree. This combination of FD and two strut features in endosteal margin area showed potential as an ODI to be used with DPRs. 전 세계 인구의 빠른 노령화와 함께, 골다공증을 예측하고 조기 진단하는 것은 중요한 보건 이슈가 되었다. 이 연구의 목적은 파노라마에서 골내막 경계부 (endosteal margin area)를 포함한 여러 개의 관심영역에서 스트러트 분석 (strut analysis), 프랙탈 차원 (fractal dimension, FD) 및 회색조 동시발생 매트릭스 (gray level co-occurrence matrix, GLCM)를 이용하여 골다공증을 진단할 수 있는 변수를 찾고, 이를 통해 파노라마를 이용한 골다공증 검출 지수 (ODI)을 개발하는 것이다. 2012년부터 2015년까지 연세대학교 치과 병원을 내원한 환자 중 골밀도지수 (T score)로 정상 및 골다공증으로 분류된 각각 272명씩, 총 454명의 파노라마 사진이 이용되었다. 세 군데의 수질골 부위와 endosteal margin 영역이 400%로 업샘플링 (upsampling)된 후, 스트러트 변수, FD, 그리고 GLCM 이 직접 제작한 이미지 처리 프로그램에 의해 분석되었다. 독립 표본 t검정 (independent samples t-test)은 정상과 골다공증 환자군 사이의 통계적인 차이를 검증하기 위해 사용되었다. 각각의 변수들의 진단 정확성을 비교하기 위해 로지스틱 회귀분석 (logistic regression)이 사용되었다. 마지막으로, 골다공증 검출 지수(ODI)를 만들고 검증하기 위해 판단 트리 (decision tree)가 사용되었다. 골내막 경계부의 FD (0.975)와 스트러트 변수들 (0.926 이하)은 높은 곡선하면적 (area under the curve, AUC) 값을 보인 반면, GLCM (0.580 이하)은 낮은 AUC 값을 보였다. FD와 두 스트러트 변수들 (교점의 수를 종점의 수로 나눈 값, 그리고 1 평방 센티미터 당 교점의 수)의 조합은 결정 트리 방법을 사용하여 높은 진단 정확도 (89.1%)를 보여주었다. 골내막 경계부의 FD와 두 strut 변수의 조합은 파노라마에서 골다공증 검출 지수 (ODI)로써의 가능성을 보여주었다.ope

Paleopathological Study of Dwarfism-Related Skeletal Dysplasia in a Late Joseon Dynasty (South Korean) Population

Skeletal dysplasias related to genetic etiologies have rarely been reported for past populations. This report presents the skeletal characteristics of an individual with dwarfism-related skeletal dysplasia from South Korea. To assess abnormal deformities, morphological features, metric data, and computed tomography scans are analyzed. Differential diagnoses include achondroplasia or hypochondroplasia, chondrodysplasia, multiple epiphyseal dysplasia, thalassemia-related hemolytic anemia, and lysosomal storage disease. The diffused deformities in the upper-limb bones and several coarsened features of the craniofacial bones indicate the most likely diagnosis to have been a certain type of lysosomal storage disease. The skeletal remains of EP-III-4-No.107 from the Eunpyeong site, although incomplete and fragmented, provide important clues to the paleopathological diagnosis of skeletal dysplasias.ope

Change in Image Quality According to the 3D Locations of a CBCT Phantom.

A patient's position changes in every CBCT scan despite patient alignment protocols. However, there have been studies to determine image quality differences when an object is located at the center of the field of view (FOV). To evaluate changes in the image quality of the CBCT scan according to different object positions, the image quality indexes of the Alphard 3030 (Alphard Roentgen Ind., Ltd., Kyoto, Japan) and the Rayscan Symphony (RAY Ind., Ltd., Suwon, Korea) were measured using the Quart DVT_AP phantom at the center of the FOV and 6 peripheral positions under four types of exposure conditions. Anterior, posterior, right, left, upper, and lower positions 1 cm offset from the center of the FOV were used for the peripheral positions. We evaluated and compared the voxel size, homogeneity, contrast to noise ratio (CNR), and the 10% point of the modulation transfer function (MTF10%) of the center and periphery. Because the voxel size, which is determined by the Nyquist frequency, was within tolerance, other image quality indexes were not influenced by the voxel size. For the CNR, homogeneity, and MTF10%, there were peripheral positions which showed considerable differences with statistical significance. The average difference between the center and periphery was up to 31.27% (CNR), 70.49% (homogeneity), and 13.64% (MTF10%). Homogeneity was under tolerance at some of the peripheral locations. Because the CNR, homogeneity, and MTF10% were significantly affected by positional changes of the phantom, an object's position can influence the interpretation of follow up CBCT images. Therefore, efforts to locate the object in the same position are important.ope

Risk factors of osteonecrosis of the jaw after tooth extraction in osteoporotic patients on oral bisphosphonates

PURPOSE: The aim of this study was to investigate the incidence of bisphosphonate-related osteonecrosis of the jaw (BRONJ) after tooth extraction in patients with osteoporosis on oral bisphosphonates in Korea and to evaluate local factors affecting the development of BRONJ. MATERIALS AND METHODS: The clinical records of 320 patients who underwent dental extraction while receiving oral bisphosphonates were reviewed. All patients had a healing period of more than 6 months following the extractions. Each patient's clinical record was used to assess the incidence of BRONJ; if BRONJ occurred, a further radiographic investigation was carried out to obtain a more definitive diagnosis. Various local factors including age, gender, extraction site, drug type, duration of administration, and C-terminal telopeptide (CTx) level were retrieved from the patients' clinical records for evaluating their effect on the incidence of BRONJ. RESULTS: Among the 320 osteoporotic patients who underwent tooth extraction, 11 developed BRONJ, reflecting an incidence rate of 3.44%. Out of the local factors that may affect the incidence of BRONJ, gender, drug type, and CTx level showed no statistically significant effects, while statistically significant associations were found for age, extraction site, and duration of administration. The incidence of BRONJ increased with age, was greater in the mandible than the maxilla, and was associated with a duration of administration of more than 3 years. CONCLUSION: Tooth extraction in patients on oral bisphosphonates requires careful consideration of their age, the extraction site, and the duration of administration, and close postoperative follow-up should be carried out to facilitate effective early management.ope

Comparative Accuracy of STL Conversion Digital Model of DICOM Files according to CBCT Scanning Protocols

Objectives: The purpose of this study is to evaluate the accuracy of the digital models from Cone beam computed tomography (CBCT) scans of orthodontic diagnostic models by comparing the Digital Imaging & Communication in Medicine (DICOM) file to Stereolithography (STL) conversion data obtained by various voxel sized CBCT machines with the digital model obtained by a 3D optical extraoral scanner. Materials and Methods: Three orthodontic diagnostic models were scanned with a 3D optical scanner and stored as STL file data. The three models were scanned with the 5 modes which were Object scan (100 μm), 300, 400 μm of RAYSCAN α+ and 300, 390 μm of Alphard 3030. The DICOM files were converted to STL file data. For each orthodontic model, two digital models obtained by CBCT and optical scanner were paired, and GOM inspect software was used to superimpose and obtain the deviation between two digital models. One way ANOVA test was performed to determine whether there is a statistical difference in the mean value of deviations between digital models by the 5 protocols. Results: In three diagnostic models, the mean values of the deviations between the digital model of the Object scan (100 μm) and the digital model of 3D optical scanner were the smallest in comparison with other image protocols and there was a statistically significant difference (p<0.001). The mean values of the deviations were in the range of 0.0967 ~0.1022 mm. On the other hand, deviations of STL data from 400 μm of RAYSCAN α+ showed the largest mean value from 0.4007 to 0.4534 mm. Conclusions: The STL file data of the Object scan (100 μm) of RAYSCAN α+ is more accurate than those of large voxel sized protocols of CBCT. It shows the availability as an orthodontic digital model.ope

Regulation of root patterns in mammalian teeth

Mammalian teeth have diverse pattern of the crown and root. The patterning mechanism of the root position and number is relatively unknown compared to that of the crown. The root number does not always match to the cusp number, which has prevented the complete understanding of root patterning. In the present study, to elucidate the mechanism of root pattern formation, we examined (1) the pattern of cervical tongues, which are tongue-like epithelial processes extending from cervical loops, (2) factors influencing the cervical tongue pattern and (3) the relationship among patterns of cusp, cervical tongue and root in multi-rooted teeth. We found a simple mechanism of cervical tongue formation in which the lateral growth of dental mesenchyme in the cuspal region pushes the cervical loop outward, and the cervical tongue appears in the intercuspal region subsequently. In contrast, when lateral growth was physically inhibited, cervical tongue formation was suppressed. Furthermore, by building simple formulas to predict the maximum number of cervical tongues and roots based on the cusp pattern, we demonstrated a positive relationship among cusp, cervical tongue and root numbers. These results suggest that the cusp pattern and the lateral growth of cusps are important in the regulation of the root pattern.ope

변화된 두부위치의 콘빔전산화단층영상에서 축재정렬이 교정적 계측점 좌표에 미치는 영향

PURPOSE: The aim of this study was to compare the coordinates of anatomical landmarks on cone-beam computed tomographic (CBCT) images in varied head positions before and after reorientation using image analysis software. MATERIALS AND METHODS: CBCT images were taken in a normal position and four varied head positions using a dry skull marked with 3 points where gutta percha was fixed. In each of the five radiographic images, reference points were set, 20 anatomical landmarks were identified, and each set of coordinates was calculated. Coordinates in the images from the normally positioned head were compared with those in the images obtained from varied head positions using statistical methods. Post-reorientation coordinates calculated using a three-dimensional image analysis program were also compared to the reference coordinates. RESULTS: In the original images, statistically significant differences were found between coordinates in the normal-position and varied-position images. However, post-reorientation, no statistically significant differences were found between coordinates in the normal-position and varied-position images. CONCLUSION: The changes in head position impacted the coordinates of the anatomical landmarks in three-dimensional images. However, reorientation using image analysis software allowed accurate superimposition onto the reference positions.ope

The anomalous canal between two accessory foramina on the mandibular ramus: the temporal crest canal

OBJECTIVES: The temporal crest canal (TCC) is a variation of the bony canal with two accessory foramina that correspond to an entrance and an exit on the mandibular ramus. This study investigated the anatomical characteristics of the TCC using CBCT. METHODS: The study population consisted 446 patients who had undergone CBCT. Sagittal, cross-sectional and three-dimensional images were evaluated for the presence of a TCC. The canals were classified into two types according to the configuration, and the location of the posterior accessory foramen of the TCC was also recorded. RESULTS: 6 TCCs were present in 4 of 446 patients (0.90% of the total population). All of the TCCs were observed in males, and all of the posterior foramina were located superior to the mandibular foramina on the medial aspect of the mandibular ramus. There were five noticeably curved and increasingly narrow canals (Type 1) and one slightly curved and uniformly wide canal (Type 2). CONCLUSIONS: Precise knowledge of the TCC is clinically important for suitable local anaesthetic nerve block and the planning of surgical procedures that involve the mandibular ramus. Three-dimensional images of CBCT data are particularly effective for confirming the presence of this variation.ope

3차원 전산화 단층영상분석에 근거한 다양한 치성낭종 환자에서의 감압술의 효과

OBJECTIVES: The aim of this study is to evaluate the effectiveness of decompression according to reduction parameters by measuring cystic volume changes using computed tomography (CT). STUDY DESIGN: We chose patients who had undergone decompression for a cystic lesion of the jaw at the Department of Oral and Maxillofacial Surgery in our dental hospital between 2006 and 2015. All patients had been examined by CT before and after decompression. We measured the volume of cystic lesions using the threshold method and evaluated the volumetric changes after decompression according to various parameters. RESULTS: The mean reduction rates of 46 cystic cases was 57.95%. There was a statistically significant difference in reduction rates by initial volume; the group with large initial volume reported higher reduction rates. CONCLUSION: Decompression is more effective in larger initial lesions when carried out more than 6 months. CT is an efficient method for evaluating the bony healing within the cyst cavity by measuring changes in cystic volume after decompression. However, due to its high cost and radiation dose, a comparative study using another diagnostic radiographic tool should be considered.restrictio