Temporomandibular joint radiography in private dental clinic

去私人牙科诊所就诊的颞下颌关节紊乱症患者逐年增加。为了开发一种临床上使用全景X线机进行TMJ成像的新技术，从临床角度探讨了全景TMJ成像的基本原理。对848例日本受试者的下颌骨髁间距离进行测量，明确下颌骨头部相对于有效层面的位置。在20岁以上的人群中，髁间距离的平均值每10年不变，女性为101.1(SD4.7)mm，男性为106.1(SD5.3)mm。为了获得清晰的TMJ图像，儿童、女性和男性至少要准备好96 mm、101 mm和106 mm三种大小的图像。在第二项研究中，X线束…的最佳水平角度对更多的TMJ X线片进行了实验测量。11例下颌骨边缘咬合固定的干燥人，沿轴顺时针或逆时针方向旋转5度，每次旋转均显露。检查了每个物种的13个图像，并选择不重叠乳突的最大旋转角作为推荐投影。在第三项研究中，对72个下颌骨髁状突进行了两种不同的全景投照，其中后内侧18°(侧位)和前内侧30度(斜位)。然后，计算每个投影的准确性、敏感度和特异度，并以断层扫描为金标准进行比较。斜位模式检测侵蚀等异常改变的准确性、敏感性和特异度均高于侧位模式。相反，侧向模式对骨赘形成的检测率高于斜向模式，若要获得可靠的TMJs信息，则应同时配备旋转全景单元。较少

Patients with temporomandibular disorsers who visit on a private dental clinic increase year after year. To develope a new technique for the temporomandibular joint (TMJ) radiography using a panoramic x-ray unit in the clinic, basic principles of panoramic TMJ image formation were investigated from a clinical point of view. Mandibular condyle should be put into the image layr of the unit to get a sharp image of the TMJ.Intercondylar distances in 848 Japanese subjects were measured on submentovertical view to make clear the position of mandibular head relative to the effective image layr. The mean value of intercondylar distance was found to be constant in every decades more than 20 years old, that is, 101.1 (SD4.7) mm in female and 106.1 (SD5.3) mm in male respectively. To get a sharp image of TMJ,three size of image layr, 96,101 and 106mm in intercondylar distance, should be at least prepared for child, femal and male.In the second study, a optimum horizontal angulation of x-ray beam … More for TMJ radiography was experimentally surveyed. Eleven human dried speciemen with mandible fixed in edge to edge occlusion were rotated on axis clockwise or counter clockwise step by 5 degrees and exposed in every rotation. Thirteen images of each speciemen were examined and maximum rotation angle without superimposition of mastoid on the condyle was selected for a recommended projection. The angle proved to be less than 32 degrees antero-medially to the frontal plane in 9 out of 11 speciemen.In the third study, 72 autopsy mandibular condyles were radiographed in two different panoramic projections, of which angle is 18 degrees postero-medially (lateral mode) and 30 degrees antero-medially (oblique mode) to frontal plane. And then, accuracy, sensitivity and specificity of each projection were caluculated compared to tomographic findings as a gold standard. Accuracy, sensitivity and specificity of oblique mode in detecting an abnormal finding i.e. erosion are all higer than the lateral mode. On the contrary, those of lateral mode are higer than the oblique mode in detecting osteophyte formation.To get reliable informations of the TMJs with rotational panoramic unit alone, it should be equipped with the two modes. Less