Hirokazu Iwasaki

A radiological study on the adaptive changes in the functional temporomandibular Joint

SummaryIt is important for planning the treatment of patients with TMJ dysfunctions to know the location and the distribution of remodeling on the articular surfaces so that the direction of the load may be assessed.The aim of this study is to radiologically clarify the location and the distribution of articular remodeling, in order to investigate the correlation between joint morphology and oral function.The material used in this study was selective lateral tomograms of 110 arthritic patients ranging in age from 12 to 78 years.Three tomograms indicating the lateral, medial and central portion of the condylar heads were selected from 10 simultaneous serial tomograms. The incidence of flattening, concavity and irregularity of articular surfaces was examined on each anterior and posterior surfaces of both condylar heads and articular eminences.Articular remodeling occurred most frequently on the central portion of the condylar heads on the lateral tomograms. A number of flattened surfaces with or without concavity were unexpectedly found on the posterior surfaces of the condylar heads.

Bone, blood vessels and muscle detection algorithm and creating database based on dynamic and non-dynamic multi-slice CT image of head and neck

Nowadays, dental CT images play more and more important roles in oral clinical applications. Our research is important particularly in the field of dentistry. We are using non-dynamic and dynamic CT image for our research. We are creating our database of bone, blood vessels and muscles of head and neck. This database contains easy case and difficult case of head and necks bone, blood vessels and muscle. There are lots of difficult cases in our database. Teeth separation and condylar process separation is difficult case. External carotid artery has many branches and they are attached with vain so it is difficult to separate. All muscle threshold value is same and they are attaching with each other so muscle separation is very difficult. These databases also contain different ages patients. For this reason our database becomes an important tool for dental students and also important assets for diagnosis. After completion our database we can link it with other dental application.

A method for three-dimensional measurement by cineradiography

SummaryThe purpose of this study was to devise a method for three-dimensional (3-D) measurement of the craniofacial complex by means of cineradiography, and to assess the errors of this method.A perspective transformation method was applied to biplane cineradiography in combination with the correction of geometric distortion of cineradiographic images by the quadratic transformation. As an aid in determining the errors, landmarks on a dry skull surrounded by geometric reference points were imaged by both conventional and cineradiography in the two planes. Distance error dD (differences between calculated distances from reconstructed 3-D coordinates and measured distances by slide caliper) and displacement error dP (differences between reconstructed 3-D coordinates and those calculated from distances measured by slide caliper) by conventional, cineradiographic, and a combined method of the two were compared. These results indicate that the accuracy of the perspective transformation method by conventional, cineradiographic and the combined method would result in 0.3 mm, 0.4 mm, 0.7 mm respectively in space.