Guided Bone Reduction to Facilitate Immediate Implant Placement Using CAD/CAM Surgical Guides after Full Mouth Extractions

Guided Bone Reduction to Facilitate Immediate Implant Placement Using CAD/CAM Surgical Guides After Full Arch Extractions

Nima Massoomi DMD, MEd, MD; Fawaz Alzoubi DDS, MA; Anders Nattestad DDS, PhD

Introduction: Bone reduction maybe indicated after full arch extraction of a terminal dentition in order to achieve adequate space for the final prosthesis.  In such instances, the level of bone reduction is critical to establish the desired inter-arch space for the most optimal occlusion and function.  For this reason, the authors propose the use of the Anatomage Invivo 5 CAD/CAM surgical guides to achieve the exact amount of bone reduction, in a predictable manner, followed by immediate placement of implants, with immediate loading of a pre-fabricated hybrid prosthesis.  We coin this method as the “Three-guide technique”.  The authors will present a simple method to improve the accuracy of the bone reduction, along with predictable placement of the immediate implants in the desired location for improved stability of the implants, based on the quantity and quality of bone that is present in the pre-surgical CBCT.

Method: Starting in 2013, six patients were enrolled in the study that met the criteria of the project.  A total of 30 implants were placed in these patients using three CAD/CAM surgical guides that were fabricated by Anatomage.  Starting with a tooth-supported surgical guide, anchor pins were used to fixate the location of all subsequent guides after all the teeth are extracted.  Afterwards, using the same anchor pin holes; the second bone-supported guide was secured to the bone with the same anchor pins.  The bone was then reduced to the desired level through a boney window in the guide.  Lastly, the third, bone-supported guide was placed on the bone and secured with the same anchor pins; and desired number of implants were placed using this last guide.

Results:  Using the “Three-guide technique”, the anchor pins provide the exact positioning for all subsequent guides. This technique provides a precise method of placing the implants in the most optimal position based on the bone quality as noted on the pre-surgical CBCT, while avoiding vital structures, such as the inferior alveolar nerve and the maxillary sinuses.  To test the accuracy of the “Three-guide technique”, both the implants and desired bone reduction levels were evaluated at three points on the jaw in cross-section (right, mid-crest and left) using a pre-surgical and post-surgical CBCT with the simulated and the actual implants in place.  The average overall deviation from the planned bone reduction was only 1.73mm.

Conclusion: CAD/CAM surgical guide fabrication is an emerging tool that may facilitate the surgical process and aid in safe and predictable execution of bone reduction and implant placement.

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