For etching 15 sec, for composite restoration use:
- a. 37% phosphoric acid.***
- b. 15% fluoric acid.
- c. 3% sulfuric acid.
The correct answer is a. 37% phosphoric acid.
37% phosphoric acid is the most commonly used acid for etching enamel for composite restorations. It is a strong acid that can quickly remove the smear layer and create micromechanical retention for the composite.
15% fluoric acid is a weaker acid that is more commonly used for etching dentin. It is not as effective at removing the smear layer as 37% phosphoric acid, but it is less likely to cause sensitivity.
3% sulfuric acid is a very weak acid that is not commonly used for etching enamel. It is not as effective at removing the smear layer as 37% phosphoric acid, and it can cause sensitivity.
Therefore, for etching enamel for composite restorations, 37% phosphoric acid is the best choice.
Note:
It is important to follow the manufacturer's instructions for etching time and technique when using any acid for etching enamel.
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