we can prevent chances of relapse if the dentist ensures that the bone underneath the gums is 3mm below the newly contoured gum margin. If there is too much bone underneath the gums, it will "push" the gums back to its original position, leading to relapse.
The dentist doing the gum recontouring procedure will check on this biologic distance when your gums are numb. We usually use a measuring instrument called a periodontal probe to determine this.
As X-rays are only 2 dimensional, it is usually difficult to predict if bone needs to be removed on that particular tooth surface. Usually, it is best to confirm if bone needs to be removed during the procedure when you are already numb.
Hope this helps! :)
Marlene
