Periodontal index creation method, periodontal index creation apparatus, periodontal index creation program, and recording medium having records of periodontal index creation program, and periodontitis diagnosis method periodontitis diagnosis apparatus

The present invention includes calculating a lost periodontal membrane area (SL) based on a sample attachment level (M) and a total periodontal membrane area (S), wherein the sample attachment level (M) of each tooth is measured after a plurality of tooth are sampled for each tooth type, with respect to a plurality of teeth which can not be conserved and have been extracted. Furthermore, the relation between the bite force coefficient (B) which is different only due to tooth type and reflects the bite force of each tooth, and a lost periodontal membrane area (SLB) at the time of loss of each tooth is statistically processed for each tooth type, and a linear equation showing the relation between the bite force coefficient (B) and the lost periodontal membrane area (SLE) at the time of loss of each tooth is prepared by use of the presence of a linear relation between both parameters (remaining periodontal membrane area (SSB) /total periodontal membrane area (S) x 100 (%), is calculated as a periodontal index BP