What is the typical etching depth achieved after 30 seconds of applying orthophosphoric acid for bonding orthodontic brackets?

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10 micrometers to 20 micrometers3 micrometers to 9 micrometers50 micrometers to 110 micrometers200 micrometers to 250 micrometers

Explanation

The usual etching depth with orthophosphoric acid after 30 seconds ranges between 10 and 20 micrometers, which is sufficient for effective bracket bonding. Lower depths such as 3 to 9 micrometers are inadequate, while depths beyond 50 micrometers are excessive and not typical in clinical practice.