Easy entry

March 21, 2012

During my travels across the country I come in contact with many removables laboratories feeling a disconnect between themselves and how they will fit into and service the developing technologies used in dental practices. My advice is to become a student of the game and look for opportunities that accommodate how deep you want to get involved. 

During my travels across the country I come in contact with many removables laboratories feeling a disconnect between themselves and how they will fit into and service the developing technologies used in dental practices. My advice is to become a student of the game and look for opportunities that accommodate how deep you want to get involved. 

Radiological templates, or “Scanoguides” as I refer to them, used in conjunction with a CT scan for dialing in implant placement, are a good example of the easy entry product offerings available to removables dental laboratories via emerging technologies. Because most dentists and fixed laboratories want to avoid anything that has to do with acrylic and monomer, fabricating these types of appliances is an ideal way to offer an entry level service to not only dentists but fixed laboratories as well.

Scanoguides are radiopaque reproductions of planned singular, multiple or full arch prosthetics, in regard to final tooth contour, emergence profile, esthetics and functional position. The guides provide the determination of needed tissue dimension for a finished restoration and aid in the placement of implants to accommodate those restorative positions. They must also be flush to the tissue to approximate restoration to implant head distance.

Creating a guide

On the following page I present a step-by-step walk through for single or multiple single unit guides:

01    The working model(s) is analyzed for tooth size (mesiodistal/buccalingual), bone mass and opposing dentition. Once tooth size is determined, a denture tooth is selected for matching characteristics (Figs. A and B).

02     Placed in the edentulous area indicated for implant placement, the tooth is luted with wax into position and carved to reflect emergence at tissue level (Fig. C).

03    Duplicate the model with positioned teeth in hydrocolloid or silicone for later use in making a positioning/retention matrix (Figs. D and E).

04    Using lab putty, impress the denture teeth and encompass adjacent teeth or edentulous land areas for later positioning and creation of tooth duplication mold (Fig. F).

05    Trim the putty to a sharp finish line to reveal the intimacy of fit during reposition and coat the model with alginate based separator (Fig. G).

06    Drill/perforate the mold in a high/low fashion to provide escape hole(2) and a hole to accept the tip size of a monoject syringe(1) as you will be injecting Scanocryl (i.e.; pre-mixed barium infiltrated acrylic), or hand mixed barium and self cure resin into the mold to create a radiopaque replication of copied denture teeth and their position(s) (Figs. H, I, J and K).

07    Cure in heated pressure vessel at 120°F at 20 psi for 20 minutes (Fig. L).

08    Remove and trim any flash, and check tissue fit and emergence from the ridge to ensure replication of the tooth and emergence profile mimics the desired characteristics of final restorations (Fig. M).

09    Take the earlier duplicated tooth position model, and using a Pro-form Model IV vacuum former, heat and pull Pro-form .100 Splint Material (polyesther teraphalate) over the entire model, encompassing an indexing of tooth positions. Allow to cool before removing from former (Fig. N).

10    Trim tray material to just incisal and occlusal thirds of all duplicated teeth, including pontics (Fig. O).

11    Transfer the positioning matrix over the master model with barium pontics in their predetermined positions. Check the positioning matrix, it should be stable and fit snug enough to maintain appliance and pontic position throughout the scanning process without movement (Fig. P).

12    Once confirmed, remove the positioning matrix, place cyanoacrylate adhesive into the pontic intaglios and reseat the appliance including pontics, back on the master and allow for the setting of adhesive.

13    The completed Scanoguide (Fig. Q). A CBCT scan with Scanoguide in place (Fig. R).

Visit youtube.com/user/TomZale56 for a video explanation on fabricating this and full arch Scanoguides. 

Benchtop Editor Tom Zaleske can be reached at matrixdental@comcast.net.