根管治療有相當高的成功率，但是偶發的失敗病例常常造成牙醫師和病患的痛苦和壓力，而糞腸球菌在失敗的病例中有很高的機會被分離出來，本研究企圖加入氫氧化鈣作為根管內敷藥來減少根管中糞腸球菌的數量以增加根管治療的成功率。
第一階段以氫氧化鈣分別和糞腸球菌、變異鏈球菌和綠膿桿菌做抗性分析比較；第二階段從根尖病變的病例沾取細菌樣本，分析其菌種並以氫氧化鈣做治療，追蹤其根管治療後的預後情形；第三階段將臨床分離出來的樣本於口外牙齒容器中培養，再進行氫氧化鈣的抗性分析。
第一階段的實驗結果發現氫氧化鈣對綠膿桿菌有很大的殺傷力；對糞腸球菌和變異鏈球菌也有殺菌效果，但是從兩者的存活率來看，其效果並無顯著的差異。第二階段的實驗結果發現十組有根尖病變且經過氫氧化鈣處理的病例，有五組治療是有效果的，其根尖病兆縮小或消失；有四組治療無效果，病兆持續；有一組因為觀察期太短，持續追蹤。第三階段的結果顯示十組的病例有七組有自根管分離出細菌，其中有六組為糞腸球菌。綜合以上鑑定結果和抗性分析，發現糞腸球菌確為根管治療失敗的主要元兇；而氫氧化鈣對它們的殺菌效果是顯著的。
Although endodontic treatment has a high success rate, but the failure cases cause pain and stress in dentists and patients. The Enterococcus faecalis usually isolate from the canals of endodontic failure cases. The objective of this study is to use calcium hydroxide in canals to decrease the quantity of Enterococcus faecalis and level up the success rate of treatment. Evaluation and analysis the bacteria samples isolating from the canal of failure cases.
The first stage is to evaluate the calcium hydroxide antimicrobial effect on Enterococcus faecalis, Streptococcus mutans and Pseudomona aeruginosa. The second stage is to use calcium hydroxide treat failure cases and isolate the bacterial samples from root canals. The third stage is to analysis the calcium hydroxide antimicrobial effect on the isolated bacterial samples in ex vivo experiment.
The first stage results show calcium hydroxide has effective antimicrobial ability to Pseudomona aeuginosa; moderate antimicrobial ability to Enterococcus faecalis and Streptococcus mutans.the second stage results show there are total ten failure endodontic cases which accepted endodontic retreatment and calcium hydroxide dressing. Five of ten are successful; four of ten are failure and one of ten are invalid because of the short follow time. The third stage results show there are seven cases we can isolate the bacterial samples. Six of seven are Enterococcus faecalis (via 16sRNA). We think Enterococcus faecalis is the main cause of failure cases and calcium hydroxide is antimicrobial effective to them in ex vivo experiment.
