الفهرس 
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Abstract
The aim of this study was to evaluate and compare different irrigating
solutions namely; MCJ, 17% EDTA, 2.5% NaOCl and QMixTM2in1
regarding:
A- The cytotoxic effects of these irrigating solutions, using the MTT
tetrazolium assay.
B- The smear layer removing capacity at different areas of the root canal.
This was evaluated by the stereomicroscope and the scanning electron
microscope.
In the first part of the study, the investigations involved dilution of
MCJ with pyrogen free distilled water to produce different concentrations,
and NaOCl with normal saline to produce a concentration of 2.5%, while
QMixTM2in1 and 17% EDTA were utilized without dilution. Incubation was
continued for 24, 48 and 72 hours. Photometric determination of the
absorbance was achieved at 570 nm using micro plate ELISA reader. The
experiment was repeated three times independently. The results concerning
various concentrations of MCJ showed the least cytotoxic effects on the
BHK cells followed by QMixTM2in1 which showed less cytotoxic behavior
compared to 2.5% NaOCl and 17% EDTA showed the most cytotoxic
behavior.
Summary and Conclusion
88
In the second part of the study, fifty five extracted single rooted
human permenant teeth with completely formed roots were used. The teeth
were enlarged to an apical size of 40/0.06 (F4).
The samples were divided randomly into six groups according to the
type of irrigants and flushes used after instrumentation as follows:
group A: Were irrigated with 6.25% MCJ, followed by a flush of the same
irrigant.
group B: Were irrigated with 6.25% MCJ, followed by a flush of 17%
EDTA.
group C: Were irrigated with 2.5% NaOCl, followed by a flush of the same
irrigant.
group D: Were irrigated with 2.5% NaOCl, followed by a flush of QMix™
2 in 1.
group E: Were irrigated with 2.5% NaOCl followed by a flush of 17%
EDTA.
group F (control group): Were irrigated with normal saline.
Each tooth was then split into two halves and examined under the
stereomicroscope to view debris and determine morphologically different
areas for SEM analysis. Then each half was examined under scanning
electron microscope SEM to detect smear layer. Results revealed that root
canal surfaces were free of debris and smear layer with opened dentinal
Summary and Conclusion
89
tubules in group D (NaOCl/ QMix), followed by group E (NaOCl/EDTA)
and group B (MCJ/EDTA) respectively. A moderate amount of debris and
smear layer was found in group A (MCJ), while a heavy smear layer was
found throughout the entire length of the root canals in control group F
(Saline) and group C (NaOCl).
The conclusions of the present study were:
1- The concept of using MCJ as a natural solution for root canal
irrigation is acceptable from the biological point of view.
2- 6.25% concentration of MCJ which is the clinically used
concentration proved to be biologically satisfactory. On the other
hand, higher concentrations should be avoided as it may show a
cytotoxic effect on the living cells.
3- MCJ can be considered an alternative to NaOCl to remove the
smear layer when used with 17% EDTA.
4- Although QMix™2in1 is more cytotoxic than 6.25% MCJ, it is
less cytotoxic than both 17% EDTA and 2.5% NaOCl, and can be
considered safe for use as a final irrigant.
5- Compared to 17% EDTA, QMix™2in1 proved to be a good
chelating agent which is able to remove the smear layer effectively
when used after NaOCl.