Evaluation Of Different Endodontic Irrigants

OBJECTIVES:Extracted teeth were chosen as the research subjects,to compare the cleaning efficiency of six different kinds of combined irrigants by SEM(scanning electron microscope),value the apical sealing ability by using quantitative analysis of glucose,and provide lab evidence for clinic application.METHODS:1.SEM observation:6 extracted human maxillary anterior teeth,with a singe straight root,were instrumented and irrigated differently by groups.Group A:The root canals were irrigated with 17% Ethylenediaminetetraacetic acid(EDTA)and 1%sodium hypochlorite (NaClO)in sequence during the instrumentation,17%EDTA after the instrumentation;Group B:The root canals were irritated with 3%hydrogen peroxide (H₂O₂)and 1%NaClO during the instrumentation,3%H₂O₂ after the instrumentation;Group C:The root canals were irrigated with 10%citric acid and 1% NaClO during the instrumentation,10%citric acid after the instrumentation;Group D:The root canals were irrigated with 1%tetracycline hydrochloride and 1%NaClO during the instrumentation,1% tetracycline after the instrumentation;Group E:The root canals were irrigated with 1%NaClO during and after the instrumentation;Group F:The root canals were irrigated with normal saline(NS) during and after the instrumentation.The total amount of irrigant was 25ml and the irrigation time was 8 minutes in each canal.The roots were split longitudinally,scored at 3mm, 6mm and 9mm,normally made for scanning electron microscopy(SEM) specimens,and then photographed at different regions of every specimen: the upper 1/3 of canal,the intermediate 1/3 of canal and the root apex 1/3 of canal.2.The microleakage experimentation:61 extracted human maxillary anterior teeth,with a singe straight root were divided into 6 groups, instrumented and irrigated differently by groups above-mentioned(The irrigation method of group G was the same as group F).After dried,the roots were filled with AH-PLUS and gutta-percha by cold lateral compaction.All the roots were fixed on the glucose penetration models. The root apical leakage was measured by the concentration of glucose in 1,2,4,7,10,15,20,30 days with glucose oxidase-peroxidase(GOD) method.RESULTS:1.Group D got the best cleaning effect,with no debris or smear layer observed on the root canal wall and a lot of open dentinal tubules observed without demineralization.A small amount of debris but no smear layer were observed in Group A and Group C,and the dentinal tubules were open mostly but erose partly in coronal third.Moderate amount of debris and only small quantity opening dentinal tubules were observed in Group B.The surface of root canal walls in Group E and Group F were covered a great quantity debris,smear layer and bacterium, and small amount of opening dentinal tubules were just present in coronal third of Group E.2.The sequence of microleakage was:Group F＞Group E＞Group B＞Group D＞Group A＞Group C.Using repeated measure ANOVA,the leakage was significantly different between Group A,Group B,Group C, Group D,Group E and Group F at above-mentioned days.Group A and Group C had statistic difference with Group E and Group F at days 10th, 15th,20th,30th.Group A,Group C,Group D and Group B,Group E, Group F had significantly difference at day 20th,30th,and Group B have significantly difference with Group E and Group F.But there was no difference among Group A,Group C,Group D. CONCLUTIONS:1.The combination of two kinds of irrigants made better effect than the single irrigant.2.Removal of smear layer could decrease the root apical microleakage.3.17%EDTA+1%NaClO made the same effect as 10%citric acid +1%NaClO,but it easily caused the erosion of peritubular dentinal.So it must pay attention to strictly control the washing time in clinical applications.4.1%tetracycline+1%NaClO had a better cleaning effect and could significantly decrease the apical microleakage,so it could be widely used in clinical.