THE NOBEL BIOCARE UPDATE USA
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| The placement jig presented in the following article makes it possible for the dentist to accurately place an abutment into the mouth in the same position as on the working cast. Leonard Marotta of Marotta Dental Studio, Inc. in Farmingdale, New York provides the details below. |
| Accurate Placement of Implant Abutments and Custom Casting Placement jig improves positional precision |
| By Leonard Marotta, MDT For some time now, we have been working with a placement jig that facilitates the dentist's efforts to accurately place both custom abutments and pre-machined, manufactured abutments into the mouth in the same position(s) they had on the working cast. Our jig is usually made out of an acrylic based material and will engage one tooth or two teeth on either side of the implant. The jig lies on top of and snaps onto the occlusal ¼ of a tooth. In the event that a single implant is places, it will engage the occlusal ¼ of the teeth mesial and distal of the implant. The jig will only fit in one position. Therefore it can be easily snapped on and off the teeth without any difficulty. In the center of the jig is the seat for the abutment. The abutment will snap into this seat in the middle of the jig and remain there. The jig can then be placed in the mouth. When the jig snaps onto the two natural teeth, the abutment will attach to the implant. Pre machined Abutment and the Placement Jig The periodontist or oral surgeon who places the implants has traditionally placed the abutment as well. Recently, however, the dentist and the lab have begun to have the final say in abutment selection. Quite often, the lab will be required to place an angulated abutment onto a working cast and work directly off theses abutments. While |
 Placement jig with angulated abutment and screws off the model  Master model of implants. the procedure can ensure the selection of the optimal abutment, it may subsequently be difficult to place the abutment as on the model. The placement jig will guide correct positioning by allowing the angulated abutment to be locked inside the jig. There are two occlusal holes built into the jig. One to allow the abutment screw to be screwed into the implant through the jig and the other to allow a guide pin through the thread receptacle on the angulated abutment. |
 Bottom view of placement jig, abutments and screws off the model.  Overview of placement jig. A guide pin is attached to the angulated abutment while the jig is used to place the abutment into the mouth. The pin acts as both a handle and a paralleling jig. A hemostat holds the jig down while the abutment screw is tightened (without the use of a torque driver). When the 17 degree angulated abutment is used, the abutment screw must be placed through the jig after the abutment has been guided into position by the jig and secured to the implant. This procedure is called for because |
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 Side view of placement jig. interfere with insertion of the abutment screw. After the abutment is secured, the direction of the guide pin is evaluated to ensure that it is parallel to the other implants or other teeth in the mouth. It is imperative that an X-ray be taken to ensure the correct seating on top of the implant. The jig and guide pin are removed, and the frame can be tried in. If the case is finished, the frame is secured to the abutment and will duplicate the position it had on the master cast. Custom Abutment and the Placement Jig The custom abutment is on the model, with the placement jig on top of it. The jig can be removed and replaced easily. The jig is used as a placement device to deliver the custom abutment to mouth in the correct position. It is always advisable for the dentist to evaluate the positioning on the model first. Unscrew the custom from the model and then place the abutment inside the jig. It can fit only one way. Use the jig to transfer the abutment to the mouth. The jig should engage the neighboring teeth or abutment. After the screw is tightened, the jig can be removed. To confirm correct positioning of the abutment, remove and then reattach the jig to the teeth. The screw can be torqued with the torque driver. It is imperative that an X ray be taken to ensure the correct seating on top of the implant. |
 Lingual view of placement jig After the abutment is down and verified, the crown can then be place on top of it. It is advisable to treat the case like a regular crown and bridge case. If you are working with a multi-unit bridge, the copings can be picked up in a master impression for solder connections and porcelain application. If the final crown has not been made, the custom abutment post should be treated as a natural tooth. An impression can then be  Occlusal view of placement jig on top of 17 degree angulated abutment with screws in place  Lingual view of placement jig on top of 17 degree angulated abutment with screws in place. |
 Lingual view of 17 degree angulated abutment on model.  Occlusal view of placement jig on top of 17 degree angulated abutment without screws in place.  Buccal view of placement jig on top of 17 degree angulated abutment with screws in place  Buccal-occlusal view of placement jig with 17 degree angulated |