Nextek Dental Studios routinely uses solid models to verify the proximal contacts of your restorations. However, we sometimes run into difficulty creating contacts with appropriate dimensions if the proximal surfaces of the adjacent teeth are not parallel with the path of insertion of the restoration. Often times we are left with the choice of providing a pinpoint contact at marginal ridge height, or giving you a contact that is overly broad occlusal/gingivally that will most likely require a fair amount of adjustment at the seating appointment.
What to do?
We recommend that after you have completed your preparation – and prior to the impression – carefully examine the proximal contacts of the adjacent teeth. First, try to insure that those surfaces are smooth with no obvious imperfections either from a broken down restorative or possibly a slip of the diamond during the prep. Next, try to visualize the proximal surface of the prescribed restoration in relation to the observed path of insertion and adjust accordingly. Most often, we see a molar that is “tipped” towards the prep – a sure sign that the contact will most likely be of the pinpoint type previously described..
In a similar vein, you should also take the time to “correct” the adjacent proximal contacts when they are not parallel to the path of insertion for a screw-retained implant crown.
Here’s a perfect example of a situation that needs correcting. See how the impression coping is angled distally? Unless the proximal surface of the molar is adjusted to be parallel with the impression coping (and thus parallel to the path of insertion of the final restoration), this case is going to be compromised.
In summary – Take a minute and “plane” the proximal contacts of the adjacent teeth to be parallel with your path of insertion. These few seconds will save you valuable minutes later on.