الفهرس 
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Abstract
Frequent consumption of acidic beverages, fruit juice and milk is a daily scenario. Moreover tooth-brushing to maintain oral hygiene is a must. This investigation was done to study the effect of different beverages on surface properties of one RMGIC and bovine enamel as well as bond strength of RMGIC to enamel and RMGIC. The enamel and RMGIC specimens were mechanically tested using surface roughness, microhardness, wear and surface topography tests while bond strength test was used to study repair bond strength using different bonding protocols.
For the surface roughness testing, 20 RMGIC specimens and 20 enamel specimens were prepared and divided into 4 groups (n=5) according to beverage used (Distilled water, Coca-Cola, Milk or Orange Juice). RMGIC specimens were prepared with dimension of 7mm diameter and 2mm depth. Specimens were immersed in each solution 3 times/day for 5 minutes each. Mechanical tooth-brushing was performed twice/day, 2 minutes each, after the first and the third immersion periods using custom made tooth-brushing simulating device. Specimens were analyzed using mechanical profilometer. For microhardness testing, RMGIC and enamel specimens were prepared and grouped as same as for surface roughness testing. Five measurements were taken from each top surface using Vicker’s microhardness tester. For the wear testing, RMGIC and enamel specimens were prepared and grouped as same as for surface roughness testing. Wear was evaluated using weight loss method. The weight loss was assessed using an analytic balance. For surface topography testing, eight RMGIC and eight enamel specimens (n=2) were
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prepared and grouped as same as for surface roughness testing. After pH-cycling and mechanical tooth-brushing, they were evaluated using Scanning Electron Microscope.
For bond strength testing, One-hundred and sixty RMGIC specimens were prepared and divided into 16 group each (n=10) according to the two level of study level 1: pH-cycling (four beverages) and mechanical tooth-brushing challenge. Level 2 four different bonding protocols. One-hundred and sixty enamel specimens were also prepared and divided as same as for RMGIC.
Shear bond strength was conducted using Universal Testing Machine.
Surface roughness, microhardness and wear resistance data were analyzed using one-way ANOVA followed by Tukey post-hoc test. Shear bond strength data were analyzed using Two-Way ANOVA and One-Way ANOVA followed by Tukey post-hoc test.
Conclusions:
Under the limitations of this study, several conclusions could be suggested:
1- Surface roughness of RMGIC was greatly influenced by the use of different beverages in association with mechanical tooth-brushing simulation. On the other hand, only Orange Juice influenced the surface roughness of enamel.
2- The use of beverages in association with mechanical tooth-brushing positively influenced the microhardness of
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RMGIC. On the contrary, they had a significant softening effect on enamel.
3- Wear of RMGIC was not affected by beverages and their association mechanical tooth-brushing. However, enamel wear was negatively influenced by the use of Orange Juice.
4- The application of beverages and mechanical tooth-brushing changed surface morphology of both RMGIC and enamel.
5- SBS data depended on the type of surface treatments used and the application of beverages and mechanical tooth-brushing, except for the no-treatment groups, which depended only on the type of beverages and mechanical tooth-brushing simulation.