Bite Records on Prepared Teeth

There are things in practice that can make my day, or set it on end. The occlusal adjustment required when seating final restorations is one of these things. I absolutely love it when the restoration goes to place and needs almost no adjustment to the occlusion. On the other hand when I am trying in the restoration and ask the patient to first close, and can instantly tell it needs a large amount of adjustment, my attitude changes and frustration is the word of the day. Over the years I have worked towards predictably eliminating these frustrating situations and knowing that the majority of the time the occlusion will be extremely close at try-in. There are a lot of pieces to this puzzle, but a key is how the information about the occlusion is sent to the lab.

When you are thinking about taking bite records over preparations, regardless of the material you use to capture the bite, you need to assure you know this one key point. Bite records for the fabrication of restorations must be taken at the vertical dimension of occlusion of the final restoration.  There is great science that explains this looking at hinge axis, distance of the teeth to actual hinge axis and axis or rotation. This is all good stuff to know, but day to day chair side just remember one fact. Any time you are taking a bite over preps, the unprepared teeth need to be fully occluded, to ensure the most accurate reproduction by the lab. This is one of the key reasons that people love taking triple tray impressions, on top of being very efficient, they capture the intercuspal position very accurately as long as the patient gets the rest of their teeth together.

With this in mind, when I am capturing bite records for a limited number of restorations and have not used a triple tray, When capturing the separate bite records I only place  registration material over the teeth that have been prepared. You can use wax or silicone materials for these small sectional bite records. Place the material of choice over the prepped teeth, and then have the patient close until the other teeth occlude. I usually ask my patients to “bite on your back teeth”. It can be useful to have the patient practice without the bite registration material in place, and observe the anterior relationship. If during the registration you notice a discrepancy, take the record again. Once you have the record, if you are using silicone, make sure to trim the record so that it does not cover any of the adjacent teeth. You also need to make certain and trim the record, or have the lab trim it down to cusp tips on the opposing arch of the record so it will seat completely.

This key step in gathering accurate bite records needs to be applied whether you have prepared one tooth, many or are doing an entire arch.