在製作固定假牙時，牙齒要修形。修形之後，必須要印模。印模前要壓排牙齦，這樣印模才會精準。臨床上排齦線為了要更好的效果，通常會添加一些化學藥品，使其具有止血、排齦的功能。排齦線置入牙齦溝內，通常會釋放化學藥品，造成牙周組織的傷害，進而影響組織的修復。本篇是從添加化學藥品對於組織細胞的傷害及全身系統的影響來探討臨床上使用添加何種化學藥劑的排齦線較適合。

Fixed prosthodontic preparation often require subgingival margine The gingival tissues must be displaced to allow sufficient impression material to be injected into the expanded gingival crevice. One of the most used methods to obtain gingival retraction is by means of medicated cord packed into the sulcus. Clinically, we add some chemical substance into gingival retraction cord to get better treatment effect like hemastasis and gingival retraction. But when we put gingival retraction cord into gingival sulcus, those chemical substances are usually released and make damage to periodontal tissue, and disturb an the tissue repair. This article tell us the gingival retraction cord impregnated with chemical may effect cell repair and systemic condition. And tell us how to select gingival retraction cord.