For all the info nerds out there here’s a few things written by Dr. Bob you may enjoy…
You can't fool Mother Nature
Invisalign works just like braces, put pressure on the tooth and it will move over time. Invisalign does it gently and with more even forces which makes it more comfortable, but exactly the same biologic processes are involved.
A little science ---
Tooth roots are wrapped by a connective tissue layer filled with nerves and blood vessels that fasten the tooth to the bone. That is why if you grab a tooth and wiggle, you can sense a little motion.
If you hold the pressure and compress that ligament, you will be squeezing the blood vessels and restrict blood flow to that part of the ligament. The body does not like that. Those cells want their oxygen supply. Compress those vessels long enough and your body makes the "decision" that it needs to open up the area so more blood can get in. Since the tooth is not actually living tissue in that area (there are no "tooth cells" on the outside -- they are inside the pulp chamber), the bone must be the thing that changes.
A form of white blood cell gets the signal from the endocrine system to change into an osteoclast, or "bone destruction cell". These cells literally dissolve the bone on the compressed side to make this room. Now the tooth root can be pushed into the new space and the process continues until the pressure is off. On the other side of the tooth, the ligament is being stretched and those same precursor cells are told to become osterblasts, or "bone making cells" to fill in the excess space. Bone is destroyed faster than it is made, and so during orthodontic movement, your teeth will feel loose.
The restricted blood flow causes inflammation, which is the actual signal to the body to do something, and the reason your teeth can get sore during the process. With braces, the forces can be such that the blood supply is entirely cut off initially causing actual necrosis of the ligament tissue. That hurts. Just ask any of us who experienced that when we were wired up. Invisalign tends to be much more gentle and you only need a little signal to the body to get the process going. It is usually the first couple of aligners that cause any discomfort that requires a couple of Tylenol.
Here is the important part of this science lesson-------
Mother Nature is in control here. It takes several hours wear (some say 14 hours) for the actual remodeling of the bone to get started. When you take the pressure off, it immediately starts to return to normal (no bone moving cells -- your body does not waste time or energy doing something it doesn't need to do). If you do not wear for hours, the process will stop completely and the next time you put the pressure on it is basically like starting over, including the sore part. Wear 8 hours, take off for 8, wear 8 and off...........basically nothing will change.
When you wear 21-22 hours a day, the movement will be continuous, comfortable, and quick. Patients that adhere to this rule will change appliances every week in their initial series of aligners. If a refinement of the result is needed (which is usually the case though not always) they will be able to change twice a week. Most cases can be completed well under a year if you do this. Wear for 18-20 hours, you are probably going to need 10 day intervals between aligner changes. Less wear that that becomes unpredictable. Your compliance is the biggest factor in success. We give the appliances instructions on where the teeth are supposed to go. Getting them there requires dedication to wearing.
If you want to be done, it is up to you to make Mother Nature happy. Wasting her time will not get you what you want.