الفهرس 
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Abstract
The aim of this study was to evaluate the effect of two types of desensitizing agents
(nano-Amorphous calcium phosphate and nano- Hydroxyapatite) with and without
mixing with fluoride in occluding dentinal tubules during treatment of dentin
hypersensitivity. Six healthy dogs, aged between 12 and 18 months, with intact
dentitions were used for the experimental work. A total of 36 teeth were available for
study by using the six upper anterior teeth of each dog. The 36 teeth included in the
study were divided according to the desensitizing agents used into six groups with 6
teeth in each group as follow:
G (1) Positive control group with EDTA, G (2) Negative control group without
EDTA, G (3) Nano-Amorphous calcium phosphate mixed with distilled-water, G (4)
Nano-Amorphous calcium phosphate mixed with fluoride,
G (5) Nano-Hydroxyapatite mixed with distilled water, G (6) Nano-Hydroxyapatite
mixed with fluoride.
The enamel from the cervical region of the buccal surface of each tooth was removed
to expose the underlying dentin. All dentin surfaces except the negative control group,
were treated using 17% EDTA. The teeth were brushed with desensitizing agents and
kept in place for five minutes; after that, they were washed with distilled water for 15
seconds. The previous procedure was repeated once weekly for one month. At the end of
the experimental period, the dogs were euthanized by injecting an overdose of sodium
thiopental. The anterior part of the upper jaw was sawed out of each dog’s mouth and the
teeth were sectioned below the level of the cemento-enamel junction. The dentinal
tubules were scanned using Environmental Scanning Electronic Microscope. Results of
the study showed that 17% EDTA had a statistically significant effect of increasing the
mean surface area of patent dentinal tubules. The mean surface area value of patent
dentinal tubules was lower in nano hydroxyapatite mixed with fluoride groups than that
of nano hydroxyapatite mixed with distilled water with statistically significant
difference. The mean surface area value of patent dentinal tubules was lower in nano amorphous calcium phosphate mixed with fluoride groups than that of nano amorphous
calcium phosphate mixed with distilled water with statistically significant difference.
The mean surface area value of patent dentinal tubules was lower in nano-amorphous
calcium phosphate groups than that of nano-hydroxyapatite with statistically significant
difference. The result revealed that a statistically significant difference between fluoride
and water.
Conclusion: EDTA helps in removing smear layer and increases the mean surface
area of patent dentinal tubules. Fluoride enhance the effectiveness of nano amorphous
calcium phosphate and nano Hydroxyapatite in obliteration of dentinal tubules. Nano
amorphous calcium phosphate obliterate the dentinal tubules better than that of the
nano hydroxyapatite.