The applicability Computed Tomography to endodontics

Research Project

Project/Area Number	63570898
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	Conservative dentistry
Research Institution	Kanagawa Dental College
Principal Investigator	HIRABAYASHI Masamichi Kanagawa Dental College, associate professor, 歯学部, 助教授 (20104482)
Co-Investigator(Kenkyū-buntansha)	YOSHIMURA Yasunao Kanagawa Dental College, assistant, 歯学部, 助手 (30191646) TAKAGI Toshimitu Kanagawa Dental College, assistant professor, 歯学部, 講師 (70104346)
Project Period (FY)	1988 – 1989
Project Status	Completed (Fiscal Year 1989)
Budget Amount *help	¥2,100,000 (Direct Cost: ¥2,100,000) Fiscal Year 1989: ¥400,000 (Direct Cost: ¥400,000) Fiscal Year 1988: ¥1,700,000 (Direct Cost: ¥1,700,000)
Keywords	Computed Tomography / Endodontics / Radiation dose / Protector / Periapical lesion / Medullary bone / Cortical bone / C.T. / 被爆線量 / 三次元表示 / C.T.像 / 歯内療法領域
Research Abstract	Computerized Tomography (C T) has recently been developed making it possible to observe slice view of human body segmentally. However, it seems difficult to analyze a detailed image of small area in human body. The purpose of this study was to investigate fundamentally the applicability and usefulness of C T to endodontics. It assessed the following : (1) observation of C T images to bone defect surrounding root, (2) measurement of radiation dose, (3) reading of changing periapical lesion. The result obtained were as follows: 1, C T was performed that over 3mm in diameter bone defect of periapical tissue and furcation to simulate lesion using dry human mandible could be seen obviously. Also, it was possible to detect localized defect in madullary bone. Over 6mm defect spreading to cortical bone was visible in conventional dental X-ray images. 2, C T images for diagnosing, which was location and expansion of bone defect, distinction between defect and the anatomical configuration, and the root canal morphology, were more useful than conventional X-ray photography. 3, The surface dose of C T radiation exposure by TLD method was approximately 35.OmGy. It indicated 7 times higher than one radiation exposure of conventional dental X-ray. 4, Absorbed dose of C T to the lenses and thyroid grand were even or under radiation dose of conventional dental X-ray. In addition, when to use newly manufactured protector to them, the dose was reduced low level to disregard radiation risk. 5, In experimental study using dogs, it may be possible to follow up changing periapical lesion by C T; localized preliminary bone defect in medullary bone, the state of its expansion, spreading to cortical bone.