Guided implant surgery is a procedure in which precision surgical instrumentation is used in conjunction with three-dimensional CT images. Dedicated computer software which allows visualization and manipulation of the images of the patient’s jaw bone and surrounding tissue makes possible the most accurate approach to implant surgery. The images obtained by computerized tomography permit the implant surgeon to determine the height and width of available bone, soft-tissue thicknesses, the proximity and root anatomy of adjacent teeth, and other vital structures in 3-D. This enables the clinician to choose the correct implant size and position it appropriately in the arch. Image-guided surgery was originally developed for neurosurgery and is now applied in many medical-dental treatments.
Benefits of Guided Implant Surgery
Guided implant surgery is a breakthrough technology which offers benefits previously unknown in implant dentistry.
1. It is a more precise and accurate procedure for placing implants.
2. Guided surgery preserves vital anatomic structures by allowing visualization of the relationship between the planned restoration and the bony anatomy. Traditional surgical guides are difficult to use predictably when there are no apparent anatomic references.
3. The technique may substantially reduce the time necessary for implant surgery.
In freehand surgery cases, periapical and panoramic radiographs are used to assess the bone available for implant placement as well as the surrounding anatomy. Traditionally, periodontal probes, gauges or calipers have been used during the intraoral examination for bone sounding, which offers a reasonable idea of the height and thickness of the ridge. Further, the surrounding teeth can be used as guides for determining the correct positioning of the implant, noting, for example, that the implant should be placed at least 1.5 mm from any neighboring dentition and 2 mm apical to their cementoenamel junction.
A study cast can be fabricated, upon which measurements can be made to provide a better understanding of the mesial-distal and apico-coronal space available in which to place the implant. Additionally, a diagnostic wax-up can help plan the surgical procedure in a manner that positions the implant to best support the eventual prosthesis. A surgical stent can be fabricated according to the diagnostic wax-up in order to serve as a clinical tool for evaluation of implant position at the time of surgery. During the surgical procedure, the bone underlying the implant site can be evaluated directly and measured with bone calipers after opening the flap.
The availability of CBCT scanning gives practitioners an option that allows for extremely accurate evaluation of these characteristics in three dimensions. Note that although CBCT scanning is most commonly associated with guided surgery, there are cases in which the scan reveals that there is adequate bone and the implant site is a safe distance from critical anatomical landmarks. This indicates a freehand surgical approach in many cases, especially when cost is a concern for the patient. With freehand surgery, the cost to the practitioner is essentially the dental implant and the basic instrumentation needed to place it, resulting in a substantially lower fee for the patient.