The present invention relates to a method and a device for non-invasive semi-automatic detection and measurement of periodontal bone defects based on computer tomography (CT) or digital volume tomography (DVT) scan data, the method comprising the following steps:a) receiving the CT or DVT scan data of a jawbone with teeth (10)b) displaying a part of the jawbone with the teeth (10) using the CT or DVT scan datac) adding to the CT or DVT scan data within at least one cross-section of the tooth (10) and the jawbone along a middle reference axis (A0) of the tooth (10) predefined landmarks at measuring positions on a neck of tooth (11) and at the periodontal bone (15), respectivelyd) calculating the periodontal bone defect at each measuring position by said respective landmarks, and thus providing for each measuring position a value of the respective periodontal bone defect as an index of the respective periodontal bone conditione) indicating the periodontal bone defects within the display.
