SURGICAL GUIDE (high tech)

Fig. 1

A surgical guide generated from virtual implant placement (Fig.1) data represents the current state of the art. Guided surgery eliminates guess work and relies less on the surgeons intuition during surgery. All anatomical features and factors are discovered before any incision is made. Surgery may be less invasive and with a very high degree of precision. Although guided surgery is precise a margin of error of 0.5mm should be built in to the guided surgery plan. Depending on the support type of the guide the surgery may be performed with and without laying a tissue flap.

Fig.2

The patient is sent for a traditional CT scan or cone beam CT (CBCT) with a CT appliance (Fig.2). The data is then loaded in to a virtual implant placement program on the computer. The jaw bone and teeth then can be virtually sliced in a sgittal and axial plane and examined from any angle in 2D and 3D. Implants may be chosen from a library and placed in the virtual image of the jaw while taking any vital anatomical structures in to consideration in relation to the proposed implant and final restoration.

Fig.3

After the planning session the resulting data will be used to generate a surgical guide. Guides may be dentition, mucosa or bone supported. Mucosa and bone supported surgical guides are anchored through auxiliary fixation pins for stability. The guides themselves can be classified in to two groups and three sub types. Class A surgical guides (Fig.3) are produced by converting the CT appliance itself in to the surgical guide and class B guides (Fig.5) are generated through stereolithography or vacuum form methods. Sometimes it is essential to recontour bone structures before placing implants and a bone reduction guide can be made at the same time as the surgical guide.

Fig.4

Sub type 1 (Fig.3) represents a guide with pilot osteotomy guidance only, affording position, angulation and in some instances depth control. Type 1 guides are removed from the oral environment after the initial pilot osteotomy is completed and successively larger diameter drills are utilized free hand until the desired osteotomy dimensions are achieved.

Sub type 2 guides (Fig.4) utilize drill keys, enabling the surgeon to complete the drill sequence to the desired final osteotomy dimension without removing the guide from the patient. Once the correct osteotomy dimension is realized the guide is removed and the implant installed. Type 2 guides afford position and angulation control. Depth control depends on the drill set utilized.

Fig.5

Sub type 3 surgical guides (Fig.5) also utilize drill keys to achieve proper osteotomy dimensions through successively larger drills. Implants are inserted in to the osteotomy without removing the surgical guide from the patient. The implants are mounted on special implant mounts and delivered through the guide in to the final position. Position and angulation of he osteotomy are controlled through the guide and depth control depends on the implant manufacturers guided surgery kit. Not all manufacturers support precision depth control.

Considerable investments in capital and time for training are necessary for this process. To leverage this technology without committing too many resources, parts of this process can be out sourced. The CT scan can be accomplished at a local imaging center and virtual implant placement can also be outsourced to a third party. These companies will do the planning and generate the surgical guide for you.

Image Fig.1 and Fig.5 courtesy of Nobel Biocare™
Image Fig.3 courtesy of SICAT
Image Fig.4 courtesy of Materialise