For decades laboratory technicians have fabricated diagnostic wax-ups as treatment planning aids when providing services for comprehensive dentistry. This diagnostic wax-up had multiple uses. First, it enables working out esthetic and function needs on an adjustable articulator. By doing so, many of the treatment plan perameters become obvious. This reduces potential problems with the final restoration. Secondly, the wax up can be used as a tool to show the patient what their final case would look like. In addition, a silicon matrix can easily be fabricated over the wax-up and used to facilitate provision fabrication and an intraoral mock up. This mock can be effectively done on about 50% of cases. In case you’re not familiar with a mock up here is the protocol:
Diagnostic wax up is performed and a silicone matrix is fabricated over the wax up.
Through the more recent advancements in CAD CAM a new, much more accurate, predictable workflow is now available for comprehensive cases. This does not necessarily replace a diagnostic wax up, but in many cases, it can. It involves milling of a CVB prior to fabrication of the definitive restoration. The protocol includes an intraoral try-in of a final case design prior to fabrication of the definitive restoration. By doing so, one can check intraorally all the essential design elements and parameters. A CVB is a milled PMMA (polymethyl methacrylate) try-in bridge. The CVB is essentially a milled acrylic bridge that is milled from a CAD design intended to be used for the final restoration. Once the try-in is performed and evaluated, the original CVB design can be brought back to the CAD stage and altered or tweaked as needed to insure predictability and accuracy of the final restoration. Here is how it works:
The utilization of a CVB will provide a far more predictable result. In addition, the quality of the final prosthesis will be more favorable to both the dentist and patient. Lastly, through the fabrication of a CVB first, clinical appointment objectives are much more likely to be accomplished on a more routine basis.
Do you find bites to be more of a problem with implant cases than traditional crown and bridge? We sure do! This is due to a few factors. First, when taking a bite registration that utilizes the soft tissue or ridge as a stop, the inaccuracy can be quite large. This is caused by compression of the ridge during the impression procedure. This can displace the tissue by a millimeter or more. As a result, subsequent bite registrations do not fit the casts adequately.
In comparison, when taking a crown and bridge bite registration the registration and mounting is performed with bite material placed between the opposing teeth and the tooth preps. NO SOFT TISSUE CONTACT. As a result, the problems of proper vertical are reduced.
A friend of mine, Dene LeBeau, has developed the Implant Bite Post (IBP). The IBP is available in a long and short version and is compatible with many of the most common implant interfaces. This small but insightful innovation has dramatically reduced the problem of obtaining proper vertical for implant supported restorations. In addition, the IBP reduces the need to fabricate base plates and bite rims that require patients to return for an additional appointment just to obtain a bite registration (that is likely not as accurate). The bite procedure can routinely be accomplished on the same visit as the final impression. As a result of all the many advantages of the IBP, CAP now has a complete inventory of Implant Bite Posts for anyone looking to solve the common problems of bite registrations on implants.
You can see both maxillary and mandibular implants have been placed and there is no way to articulate this cases by hand.