الفهرس 
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Abstract
This in vitro study was conducted to examine different methods of surface treatments for bonding focusing on chemical agents that have not been tested in previous studies and comparing them to a mechanical method which is roughening with bur
Using a custom made Teflon mould, 60 Restorative composite resin discs, 6 mm in diameter and 2 mm thick were prepared from a hybrid-filled resin composite (Te-Econom plus). Specimens were aged in distilled water for 4 weeks. Thereafter, the discs were mounted in cold cure acrylic resin. The specimens were randomly divided into four groups of 15 specimens each according to the following surface treatment methods: group 1: Control with no surface treatment, group 2: 99% acetone solution for 1 minute, group 3: cold-cured methyl-methacrylate monomer (Acrostone cold cure) for 3 minutes, group 4: The discs surfaces was roughened at high speed with a 1 mm round diamond bur under water cooling, the rotating bur was passed over the composite surface three times.
A thin layer of Ortho solo bonding agent was applied and thinned then, adhesive composite resin paste (Grēngloo) was then placed on the bracket base and subjected to a 300g compressive force using a force gauge for 10 seconds. Excess adhesive was removed and light polymerization was done. Then, All specimens was stored in distilled water for 1 week. Shear bond strength was evaluated and recorded using a universal testing machine at a crosshead speed of 1 mm/minute. The maximum load necessary to debond was recorded in Newtons and converted to megapascals (MPa) as a ratio of Newtons to surface area of the bracket base. After debonding the bracket base and corresponding RC discs were examined under stereomicroscope at 10X magnification to determine the amount of adhesives remaining on bracket bases and on composite discs surfaces.
The analysis of variance (ANOVA) showed no statistically significant difference in SBS between study groups. However, all the groups achieved a clinically acceptable SBS for bonding orthodontic brackets to RC surfaces in vitro. Concerning the ARI scores, The result of Chi-square test with Monte Carlo correction for ARI scores between the four groups showed a statistically significant difference (MCp = 0.039). Chi square comparisons of ARI scores showed that there was only a statistically significant difference between group 1 compared to group 3 (P1= 0.003) and group 4 (P1= 0.046), all other comparisons were statistically insignificant. There was a predominant cohesive failure in restorative composite in group 1 (60%), in group 2 score 7 achieved the largest percentage (40%), adhesive failure at the bracket/adhesive interfaces dominated group 3 (53.3%) and group 4 (46%).
Conclusion
Surface treatment with acetone, MMA monomer or roughening with diamond bur does not affect the SBS of RC stored in water for 4 weeks.
Recommendations
1. In future studies examining SBS to RC surfaces aging by thermo-cycling is recommended to mimic the dynamic oral environment to a large extent.
2. Including a group without bonding agent in future studies to evaluate the advantage of using the bonding agent as an intermediate resin, when bonding orthodontic brackets to RC surface. The effectiveness of flowable composite as intermediate agent can be evaluated as well.
3. Evaluating different combinations of brackets, adhesives and composite types.