The method for periodontal disease measurement of the present invention includes: using a plurality of cross-sectional images provided by x-ray CT images of teeth and periodontal tissues to detect a contour of each tooth in each cross-sectional image, detect a dentition, and provide a dental formula； detecting the positions of the root apex, the alveolar crest, and the crown of each tooth from the detected tooth contour data； calculating at least one of a distance indicator, a volume indicator, a surface area indicator, a first moment indicator, a center-of-gravity indicator, and an alveolar bone indicator from the detected tooth contour data, and the position data of the root apex, the alveolar crest, and the crown of the tooth； and measuring the progression of periodontal disease based on at least one calculated indicator.
