Having a set of shell provisional restorations fabricated pre-treatment, can save significant chair time for you and your patient. It is best to make them from a diagnostic wax-up that represents the final outcome of treatment.
This allows the clinician and patient to evaluate the new tooth morphology, esthetics and function, before the definitive restorations are fabricated. I refer to this as trial therapy.
Shell provisional restorations can be made by:
- CAD/CAM milling a copy of the diagnostic wax-up and hollow grinding the inside.
- Making a silicone index of the wax-up and applying a thin layer (0.5 mm) of provisional material on the buccal, lingual and occlusal surfaces of the teeth. Make the walls of the provisionals as thin as possible to ensure that there will be minimal adjusting of the internal aspect of the shell when trying it over the prepared teeth. This shell will appear very translucent and be fragile; it's important to be careful during its original removal from the silicone index.
- Using a stone cast technique. Duplicate the wax-up to make a stone cast. The teeth are then reduced (conservatively prepared) to create space for the provisional material. A liquid tinfoil substitute is applied over the stone to seal the surface and prevent the provisional material from sticking. A silicone index is made from the wax-up. It is filled with the provisional material and seated on the prepared stone cast. Place it into a pressure pot to obtain an improved adaptation of the silicone to the cast. This will create a more accurate provisional. Once it is set, remove the provisional from the stone cast and trim the flash. It is not necessary to trim or contour the gingival one-third or the interproximal areas, as they will be covered by additional material when it is relined intraorally.