Tight contacts exist when there is tension between two teeth and it is undetected by impressions and 3D models.
Here's an example of tight contacts:
0.3mm of IPR is requested between teeth 8 & 9, but there is tension (hidden pressure) between 9 &10. When space was created with 0.3mm of IPR, the pressure was released between 9 & 10 now creating normal contact levels since tooth number 9 has been given space to move over. This means depending on how much tension was between 9 & 10, the IPR space is now smaller, 0.2 or 0.1mm, but still not the amount required by the treatment plan.
Tight contacts between teeth exist naturally when the ‘collective’ size of the teeth (the cumulative total of the mesiodistal width of all teeth in an arch) is larger than the amount of room available for those teeth in the supporting bone. This imbalance may result in the tight interproximal contacts and/or crowding of the teeth to some degree.
One of the consequences of tight contacts is that the planned treatment may go off track. Or in the case of the last aligner, you may still need some slight movement to get them into their final position.
How to check if you have tight contacts
When flossing between teeth if the floss has a hard time popping in and out then you know that you have a tight contact. (If the floss pops in and out easily then this is light to moderate contact.)
What to do with tight contacts
When you have tight contacts, you do not necessarily need to request a case revision, which could be lengthy and delay treatment. Try the following actions:
- Floss between the suspect teeth (areas of misalignment) to check for tight contacts as described above.
- If tight contact exists, you can do some hand stripping to create approximately 0.1mm of IPR.
- If there are no tight contacts (but there is some misalignment), you can still do a little IPR (0.1mm) to help create some needed space.
- If you have tried the above, and feel you've created sufficient space, but still have misalignment, at this point you may need to submit a revision.
Note: IPR is done at your discretion. We advise doing hand stripping which creates 0.1mm of space. If you do 0.1 mm of IPR at a time, any excess space created by additional hand stripping (not on treatment plan), will be fairly easy to close at the end of treatment with a revision by requesting a digital power chain.