The factors influencing long-term prognosis of teeth must be carefully considered. Among these, attachment level is strongly associated with tooth loss. The purpose of the present study was to estimate pattern of attachment loss based on attachment area in extracted teeth. 197 satisfied the criteria for assessment after staining. The protocol described by Waerhaug(1975) was performed. An indir ect method, based on digital image abstracted from digital camera and digital imaging software program, was used to calculate the root surface area and the attachment loss area. The data were analysed using SPSS. Except maxillary central incisior and mandibular canine, no statistical significant differences between each root surfaces were observed in anterior teeth. In posterior teeth, statistical significant differences in palatal surface of maxillary molar and mandibular molar compared with others were observed. Statistical significant difference in buccal surface compared with others was lowly observed in single and multi rooted.

This study did not reveal progressive loss pattern of attachment area in each root surface but clarified root surface that has relative high loss rate of attachment area at extraction. Thus understanding this pattern of attachment loss is helpful for dentist to treat the periodontitis.