Why did my dr put gauze in my ears after otoplasty?

Far more important than the technique is the skill and experience of your plastic surgeon. Choose your surgeon rather than the technique and let them explain why one technique may be better than another.  See the below link on some suggestions on finding the most qualified Plastic Surgeon for you.  Always insist on a board certified plastic surgeon.

You may have bolsters, pieces of gauze that are rolled up and sutured onto the ear.  During otoplasty, the skin is separated from the cartilage.  If blood or fluid forms between the skin and cartilage, this can lead to irregularities.  By suturing down a piece of gauze, the compresses the skin to the cartilage so that is less likely to happen.You should ask your surgeon when you see him or her who should be happy to let you know the real reason!Best wishes for your recovery!

That is something you have to ask your surgeon, as only he can know the reason for putting gauze in your ears.