A comparative scanning electron microscopic investigation of the smear layer after the use of sodium hypochlorite gel and solution forms as root canal irrigants.
BACKGROUND
The effect of sodium hypochlorite (NaOCl) gel along with EDTA on the removal of the smear layer has not been studied; therefore, the aim of the present study was to compare the efficacy of gel and solution forms of NaOCl in removal of the smear layer from root canal walls.


METHODS
A total of 40 single-rooted teeth with minimum curvature (<5 degrees) were selected and divided into two experimental groups, each containing 15 teeth and one positive control group containing 10 teeth. The canals of all the teeth were prepared with rotary RaCe instruments up to #35. In the NaOCl solution group, the root canals were flushed with 2.5% NaOCl solution during instrumentation and in NaOCl gel group, the instruments were coated with gel form of NaOCl and used inside the root canals; then saline was used for root canal irrigation. Finally, 1 mL of 17% EDTA was used to rinse inside the root canals and remained in the root canals for 2 minutes in the both experimental groups; in the saline group, only saline was used for irrigation. The amount of the smear layer was quantified according to the Torabinejad method using a scanning electron microscope. Data were analyzed by the Kruskal-Wallis and Mann-Whitney tests. All the statistical analyses were set with a significance level of alpha = 0.05.


RESULTS
There were no significant differences between NaOCl gel and solution forms in the coronal, middle, and apical thirds of root canals. There were significant differences between NaOCl solution and saline groups in the three parts of root canal walls and between NaOCl gel and saline in the coronal, middle, and apical thirds.


CONCLUSIONS
The use of NaOCl gel can be as effective as NaOCl solution along with EDTA in smear layer removal in the three parts of root canal walls.
Zand
Vahid
V
The Department of Endodontics, Tabriz Dental School, Tabriz University of Medical Sciences, Tabriz, Iran.
Lotfi
Mehrdad
M
Rahimi
Saeed
S
Mokhtari
Hadi
H
Kazemi
Ali
A
Sakhamanesh
Vahideh
V
D002614:Chelating Agents / Q000008:administration & dosage; D003804:Dentin / Q000187:drug effects / Q000648:ultrastructure*; D004492:Edetic Acid / Q000008:administration & dosage; D005782:Gels; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D012388:Root Canal Irrigants / Q000008:administration & dosage*; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods; D016369:Smear Layer; D012965:Sodium Chloride / Q000008:administration & dosage; D012973:Sodium Hypochlorite / Q000008:administration & dosage*; D012996:Solutions; D019227:Tooth Apex / Q000187:drug effects / Q000648:ultrastructure
D002614:Chelating Agents; D005782:Gels; D012388:Root Canal Irrigants; D012996:Solutions; D012965:Sodium Chloride; D004492:Edetic Acid; D012973:Sodium Hypochlorite