[Comparison of the effects of 5 irragant combinations on cleaning of anterior straight root canal walls].
OBJECTIVE
To evaluate the effect of 5 kinds of irrigant combinations on cleaning of anterior straight root canal walls.


METHODS
25 extracted human maxillary anterior teeth, with a single straight root were randomly divided into 5 groups. They were instrumented with K-files and conventional preparation technique. The irrigations were as follow: in group 1,the canals were irrigated with 1% NaOCl and 3% H2O2 in sequence during and after instrumentation.In group 2,the canals were irrigated with 1% NaOCl during instrumentation and after instrumentation being irrigated with 17% EDTA. In group 3,irrigation during and after instrumentation was accomplished using 17% EDTA and 1% NaOCl in sequence. In group 4,irrigation during instrumentation was accomplished using 17% EDTA and 1% NaOCl in sequence, and after instrumentation being irrigated with 17% EDTA.In group 5,the canals were irrigated with 17% EDTA, 1% Triton X-100 and 1% NaOCl in sequence during instrumentation and irrigated with 17% EDTA after instrumentation. The total amount of irrigant was 22ml and the irrigation time was 7 minutes in each root canal. The root was split longitudinally and 3 specimens in each group were evaluated regarding to the smear layer, debris and erosion of dentinal tubules with SEM at the coronal, middle and apical thirds.


RESULTS
In group 1, typical amorphous smear layer and abundance of debris were seen on the wall of canals. In group 2, the smear layer was removed partly in coronal and middle thirds, but the apical surface of the canal walls were covered with a typical amorphous smear layer. Although irrigants of group 3 could remove smear layer effectively, it resulted in moderate erosion of dentinal tubules. In group 5, part of the smear layer was removed on the surface of coronal and middle thirds but abundance of debris were present on the surface at the apical levels. Severe erosion was noted on the root canal surfaces in this group. Irrigation of group 4 had the best result: it not only removed smear layer effectively ,but also had no erosion on dentinal tubules.


CONCLUSIONS
Using the combination of 17% EDTA and 1% NaOCl can remove smear layer effectively and has no erosion on the dentinal tubules under the condition of strict time control and irrigation sequence. Supported by Phosphor Plan (No.01QB14025) of Science and Technology of Shanghai Municipality.
Li
Chen
C
Department of Oral Medicine, Ninth People's Hospital, School of Stomatology, Shanghai Second Medical University, China.
DU
Rong
R
Zhu
Ya-qin
YQ
D003804:Dentin; D006801:Humans; D012388:Root Canal Irrigants / Q000494:pharmacology*; D018915:Root Canal Preparation; D012390:Root Canal Therapy; D016369:Smear Layer
D012388:Root Canal Irrigants