From Mock-Up to Provisional Restorations. A Step by Step Guide to bis-acryl resins
For the functional and aesthetic success of indirect restorations, a correct multi-step protocol should start with planning of the treatment, and include a wax-up, and a mock-up. In particular, the latter is not only useful as a tool for communication with the patient, but also with the dental lab. Moreover, it helps the clinician be conservative during preparation of the tooth structure while ensuring enough space is provided for the veneering material.
This patient came asking for both an aesthetic and a functional improvement.
Initial situation of the patient’s smile, and the intra-oral view highlight some problems mainly related to dental erosion.
After placing the silicone index in the mouth and stabilizing it, excess material flows through the v-shape cuts on the silicone index. These cuts are very important and should follow the cervical embrasure anatomy to allow for easy cleaning and removal of the resin excess.
Recommended time for removal is when the bis-acryl excess enters the gel phase. At this time it’s easy to remove with an instrument or a microbrush. Then we should wait for complete setting of the material (around two minutes) before removing the silicone index.
After removing the silicone index, the Protemp 4 (3M) mock-up can be polished with sof-lex discs (3M), sof-lex diamond spiral wheels (3M) and soft felt with polishing paste.
As for a provisional restoration, some more aesthetic details, such as color stains, can be applied to improve the outcome.
After aesthetic check and modifications, together with the patient, the mock-up is the ideal starting point for a controlled-thickness preparation. Creating calibrated (0.5 mm) grooves right through the mock up allows for accurate and minimally invasive depth preparation.
A pencil can be really useful to highlight the deepest part of the grooves to achieve full control over the final preparation while removing the rest of the resin.
After incisal reduction.
Now the last pieces of the mock up can be removed and the preparation can be finalised until complete removal of the pencil marks.
A silicone index fabricated on the wax up allows for full control over preparation depth through an occlusal cut. The more even the final veneer thickness, the better.
Teeth prepared and ready for impression.
Impression is taken with high and low viscosity silicones. The light body material should be carefully injected into the sulcus tailing delicate removal of the retraction cord. This will allow the material to copy more details of the cervical area of the preparation and soft tissues. When a provisional restoration is needed, to make Protemp 4 (3M) last until cementation day, a spot-etching of the buccal surface and incisal edge of the tooth preparation are advised before applying the bis-acryl resin in the mouth.
Feldspathic ceramic veneers were fabricated by the dental lab. Credits to Pedro Brito CDT.
Try-in of the feldspathic ceramic veneers prior to isolation.
Feldspathic ceramic veneers after cementation under rubber dam isolation.
Final situation after cementation and rehydration.
Final situation. Natural smile of the patient with the aesthetics and function reestablished.
Bis-acryl resin materials are the easy and fast solution to fabricate provisional indirect restorations and mock-ups. Using these materials for the mock-up allows us to communicate with the patient while creating a starting point for a minimally invasive preparation.
Note: This case was preformed in the International Restorative Post-Graduation course (DAMI) in Instituto Universitário Egas Moniz, Portugal.
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