Surgical Guide Classification for Full Arch Prosthesis (Part 2)

As explained in the previous article, we have classified the surgical guides into two main areas: Analog and CAD/CAM generated.

The decision to use one or the other is based on the availability, experience and access to special equipment for the clinician. We reviewed the advantages and disadvantages of the two different fabrication techniques in our previous article. It is important to mention that there are many design variations for each category depending on the case and the objectives of the surgery, but we decided to divide them into four major categories for clinical efficiency and understanding of the treating dentist. Now, let’s go into detail about each of the different designs:

In order to fabricate a surgical guide, a radiographic template should be utilized for the CBCT scan, which is then converted into a surgical guide template following 3D imaging evaluation. Many techniques have been proposed involving modifications in the following stages of fabrication; namely, material used for the fabrication of the surgical template, radiographic marker used, type of imaging system used and the conversion process involved in converting the radiographic template into a surgical template.

Analog-generated surgical guides

(Images referred to in the following list can be found underneath list.)

• Restrictive flapless/open-flap (Fig. 1):
  • The restrictive flapless design allows the surgeon to use the first osteotomy drill through the surgical guide, providing him with a good understanding of the desired implant position. The remainder of the osteotomy and implant placement is finished freehand by the surgeon, although the surgeon can place guide pins and confirm the implant position and angulation through the guide by making the hole bigger (Fig. 2-3).
• Non-restrictive open flap (Fig. 4):
  • Non-restrictive designs only provide an indication to the surgeon as to where the proposed prosthesis is in relation to the selected implant site, mainly the buccal surface of the proposed teeth position. This design allows for many errors as it has a lot of space for movement, so it is recommended for very experienced surgeons (Fig. 5-6).

CAD/CAM technology uses data from CT scan to plan the implant position. The data acquired from the CT scan is combined with a virtual planning of the future implant position, and then the software transfers this pre-surgical plan to the surgery site using drill guides.

CAD/CAM-based surgical guides offer many advantages. For example, the virtual 3D views of the bony morphology allow the surgeon to visualize the surgical bone site prior to implant placement; the technique promotes flapless surgeries, and allows pre-surgical fabrication of the master cast and provisional prosthesis that facilitates immediate provisional fabrication based on future implant position. Accuracy of CAD/CAM technology in dental implant planning and predictable transfer of the pre-surgical plan to the surgical site has been documented in the literature by many authors.

CAD/CAM-generated surgical guides

(Images referred to in the following list can be found underneath list.)

• Restrictive fully-guided flapless (Fig. 7):
  • The restrictive fully guided flapless design allows the surgeon the go over the whole drilling process through a restrictive metal sleeve utilizing a special guided surgery kit. In order to anchor the guide, three or four pins have to be positioned to stabilize it and avoid movement. Once the implants are in position, the guide is removed (Fig. 8-9).
• Restrictive fully-guided open flap (Fig. 10).:
  • The restrictive fully-guided open flap design is similar to the above mentioned design but is positioned after the flap is raised. This allows the surgeon to perform otectomy by using a specially-designed bone reduction guide. The stabilization is achieved by using three or four anchor pins and the whole drilling process is done through a restrictive metal sleeve. This type of guide allows for fabrication of an immediate prosthesis for immediate loading purposes (Fig. 11-12).

References

• D'Souza K, Aras M. Types of Implant Surgical Guides in Dentistry: A Review. JOI 2012;Vol XXXVIII-No. Five.

• Schneider D, Marquardt P, Zwahlen M, Jung RE. A systematic review on the accuracy and the clinical outcome of computer-guided template-based implant dentistry. Clin Oral Implants Res. 2009;20:73–86.
• Horwitz J, Zuabi O, Machtei EE. Accuracy of a computerized tomography-guided template-assisted implant placement system: an in vitro study. Clin Oral Implants Res. 2009;20:1156–1162. 

(Click this link to read more dental articles by Dr. Ricardo Mitrani.)

Ricardo Mitrani, D.D.S., M.S.D., Spear Faculty and Contributing Author