الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
The present in vitro study was conducted mainly, in an attempt, to demonstrate the effect of different desensitizing toothpastes on dentinal tubule occlusion, dentin microhardness and Calcium (Ca) and Phosphorus (P) ions weight percentages (wt%) of the dentin surface. In addition, a four-day citric acid cycling model with different pH values (pH 3, pH 4 and pH 5) was performed.
NovaMin-containing toothpaste, a laboratory prepared toothpaste containing 30% Moringa Olefeira extract and a laboratory prepared toothpaste containing 30% Propolis extract were brushed onto prepared dentin surfaces for two minutes twice daily for a week using an electrical toothbrush. The specimens were stored in prepared artificial saliva during the whole study which was replaced every 24 hours.
A total of 170 dentin specimens were prepared from bovine anterior teeth then etched with 17% EDTA for five minutes. Specimens were grouped as follows: 10 specimens were used for the baseline evaluation, 80 specimens for scanning electron microscope and energy dispersive x-ray analysis tests and 80 specimens for microhardness testing. For each test, 20 specimens were randomly assigned to the control group where no desensitizing toothpastes were used only brushing with distilled water while the remaining 60 specimens were assigned to the three different experimental groups (n=20) according to the desensitizing toothpaste used. The control group and each of the experimental groups were divided into four subgroups (n=5 specimens each) according to the citric acid challenge performed after brushing; without citric acid challenge (only brushing with distilled water), citric acid challenge with pH 3, citric acid challenge with pH 4 and citric acid challenge with pH 5.
An environmental scanning electron microscope was used in conjunction with an energy dispersive x-ray analysis to evaluate dentinal tubule occlusion and to assess changes in Ca and P ions wt% of the dentin surface. Dentin surface microhardness was evaluated using Digital Vickers hardness tester. Measurements were performed at the different test points: after a week of brushing and following the four-day citric acid cycling with the different pH values (pH 3, pH 4 and pH 5).
The recorded data were collected, tabulated and statistically analyzed. The results showed that; following a week of twice daily brushing, NovaMin- containing toothpaste provided the most satisfactory dentinal tubule occlusion results followed by the laboratory prepared toothpaste containing 30% Propolis and the laboratory prepared toothpaste containing 30% Moringa while the control group did not demonstrate significant difference in dentinal tubule occlusion. After citric acid cycling with pH 3, the three experimental groups presented a significant increase in the number of patent dentinal tubules, on the other hand, NovaMin and Propolis groups showed better results following citric acid cycling with pH 4 and pH 5. Moreover, NovaMin toothpaste demonstrated the highest Ca and P wt% compared to the other tested toothpastes and the control group. Furthermore, NovaMin containing toothpaste was the only toothpaste that was able to increase dentin surface microhardness following a week of twice daily brushing in comparison to the other study groups. However, NovaMin- containing toothpaste showed the highest microhardness values following pH cycling with citric acid of pH 3, 4 and 5 in comparison to the other study groups, but it was not able to resist the acidic challenge at pH 3 and 4 and a partial recovery of dentin microhardness occurred at pH 5.