本研究利用跨理論模式探討中年人的使用牙線行為。以某牙醫診所年齡介於40〜65歲之門診病患為母群體。隨機方式抽取25﹪的人為郵寄問卷對象，共寄出180份問卷，回收112份問卷。扣除資料填答不完全者，有效問卷為100份。以描述性及推論性統計方法來探討各變項間的關係。結果支持跨理論模式應用於使用牙線行為的適用性。雖然無法完全區辨出「無意圖－意圖期」與「準備期」間受試者對使用牙線知覺利益及障礙的差異，但是「行動－維持期」受試者的知覺利益顯著高於「準備期」及「無意圖－意圖期」；知覺障礙則反之。在自我效能方面，明顯出現「行動－維持期」高於「準備期」，「準備期」又高於「無意圖－意圖期」的關係，符合跨理論模式的論點。並且應用知覺利益、知覺障礙及自我效能等3個變項可對使用牙線行為產生有效的區別效果，為口腔衛生教育介入提供明確的依據。

The study examined the utility of the Transtheoretical Model in understanding dental flossing behavior among the middle-aged. A questionnaire was mailed to 180 subjects that were taken from a dental clinic by random sampling method. 112 subjects who filled out the questionnaire constituted the sample with a response rate of 62.2%. The results offered support for applying the Transtheoretical Model to dental flossing behavior. Although the perceived benefits and barriers couldn’t discriminate "pre-contemplation -- contemplation" with "preparation"but the self-efficacy could discriminate three stages. Classification based on the discriminate analysis accurately identified 66.0% of subjects. The results can afford clear accounts in developing oral health educational interventions.