Radiographic and surgical guide for placement of multiple implants.

It is the responsibility of the restorative dentist to fabricate a surgical guide that dictates to the surgeon exact placement of each implant. Misaligned implants complicate the clinical and laboratory procedures in the fabrication of definitive restorations. The nonparallel placement of implants, especially when multiple implants are placed, can cause nonaxial loading during function, which may compromise the long-term success of the implants. Several types of surgical guides have been reported. Some are designed for placement of a single implant, while other reports present designs for multiple single implants, implant fixed partial dentures, and implant-retained overdentures. Three techniques commonly used for preparing the guide holes and fabricating the radiographic and surgical implant guide are free-hand, milling, and the use of computer-aided design/computer-assisted manufacture (CAD-CAM) technology. In the free-hand technique an acrylic resin bur is used to mark the cast as a guide for parallel insertion without a fixed apparatus stabilizing the bur. This technique poses risks because parallel implant placement cannot be standardized. Two designs using a freehand technique have been reported—slot and individual hole. The slot design provides neither parallel guidance nor precise position for placement of the implants. With this design, implant position depends primarily on the experience of the surgeon. The individual hole design allows for flexibility in implant angle and position due to the preparation of an oversized hole. These techniques allow for error, which may compromise the success of the implants. The milling technique is an accurate technique in which a milling machine is used to drill parallel holes in the surgical guide. This technique requires special equipment not commonly available in private dental practices. In addition, the clinician needs a certain amount of experience to use the machine properly. The computer-guided and CAD-CAM stereolithic models use 3-dimensional images coupled with the appropriate software to allow precise implant placement, especially in situations of inadequate or insufficient jaw bone structure. This technique requires acquisition of software and special training to convert commonly