I saw a comment on the boards the other day that asked this question. It was funny because I am going through a case right now that I had some issues with this.
I don't exactly know how to answer the question to be honest. There are many different things i've heard.... things like the blanching goes away in 20 min or less,etc... The way that I have done it in the past was just by "feel". That is... I want to put pressure on the tissue and I can usually feel if it's too much by how it seats. If I have trouble, then I will adjust. It also will depend on anterior vs posterior and how much tissue I need to move.
Here is a case replacing 2 congenitally missing lateral incisors. He has been wearing a flipper for over 10 years and finally wanted some teeth. Here is the initial preop photo...
After doing the plan, we placed the implants guided in the site
I let heal about 3 months. Since he had a flipper, I just used healing caps that were flush with the tissue and adjusted his flipper for the provisional.
Here is how the tissue looked at full healing:
As you can see, I have a lot of tissue to move, especially on tooth #10. Now, here is the mistake that I made. I tried to move it too quickly. Meaning, I pushed on the tissue way way too hard. It was difficult and painful for the patient (I did not numb up). #7 was still painful, but not that bad because I didn't have to go as far...
Here are the initial provisionals:
How do I know I pushed too much too fast? Here is an iphone picture my assistant sent me two days later (it's her brother in law)
Yikes.... I had to have the patient in immediately, get the provisional out, recontour it quite a bit and put it back in. That with a chlorohexidine rinse healed the problem in about 4 days.... Here he is as of Monday:
So.. be careful. If you need to move the tissue a lot, do it in a couple stages and not all at once. You may get lucky and it will work... or you may end up having a significant issue like I did on this case.