CT APPLIANCE

Fig. 1

Each virtual implant placement software system has its own design requirements for the CT appliance (Fig.1) and is specific to each software provider. Regardless of the CT appliance requirements and virtual implant placement software used, the appliance should represent the tooth position and dimension of the proposed final restoration with a well adapted basal surface. Restoration of a edentulous arch will require the same process as if a traditional full denture were the treatment goal and the finished denture being used as a CT appliance or duplicated to the software purveyors CT appliance specifications.

Fig. 2

Some advocate utilizing a preexisting denture and just add fiducial markers. In theory this can be accomplished but one should consider the disadvantages to this practice. Old and worn dentures are often ill fitting, poorly adapted to the soft tissue and no longer represent the ideal vertical dimension resulting in a poorly fitting surgical guide. Since the implant placement should be driven by the final restorations position and dimensions it is best to start with a mock up of the ideal restoration as the CT appliance (Fig.2).

Fig. 3

The appliance serves a dual purpose in some instances; CT appliance and surgical guide (Fig.3). Once the scan is taken, the finished virtual plan, CT appliance and the model the CT appliance was fabricated on are forwarded to the software providers dedicated conversion facility. Others electronically duplicate the CT appliance from the CT scan data and add drill guide bushings in the appropriate position according to the virtual implant placement plan.

Fig. 4

Fabricating the CT appliance may require the addition of fiducial markers (Fig.1) such as gutta percha, cold cure acrylic mixed with barium sulfate or Biocryl X (Great Lakes Orthodontics) into the periphery of the appliance while others demand the addition of prefabricated CT plates (SICAT). CT appliances for fully and partially edentulous cases may also be crafted with denture teeth made of barium sulfate containing acrylic (Fig.4) while the base is plain acrylic. Others postulate the base be made of acrylic containing 10 percent barium sulfate and the denture teeth contain 20 percent barium sulfate.

Materialise

BioHorizons®

Biomet 3i™™

Nobel Biocare™™

SICAT

Image Fig. 3 courtesy of Nobel Biocare®
Image Fig. 4 courtesy of SICAT