When Replacing Bonding, Can a Small Layer of the Old Bonding Be Left on the Tooth to Protect the Enamel from Possible Abrasion?

When replacing bonding, many times you can leave the deep layer that is on the enamel as long as it is not discolored or full of stains or decay. 

 

This depends on if you are talking about a deep filling or cosmetic bonding on a natural tooth.On a filling I agree with those who remove all the old bonding to ensure that their is no decay underneath.  That being said if it is extremely deep, then sometimes a judgment call will be to leave a thin layer that covers the nerve.  You can sometimes repair bonding that is done for cosmetics and not remove all the old bonding.  However, I think a stronger bond is obtained by removing the old bonding.  Hope this helps clarify things.

 

 

The old material should be totally removed because I have found things hiding underneath too many times like decay or stains.  Don't worry about enamel abrasion because the new bonding or veneer you are getting will cover it and protect it as well.  Your dentist will also be very careful only to remove what is necessary.