An image guidance system for tracking a surgical instrument during a surgical procedure. The image guidance system includes a plurality of cameras adapted to be located external to a surgical area for capturing images of optically visible patterns. A processing system receives and processes the images to recognize the patterns and triangulate the locations and orientations of each pattern relative to a camera. The processing system uses a reference dataset which defines a reference coordinate system based on alignment to a portion of the oral anatomy. The processing system determines the location and orientation of the tracked instrument based on the reference dataset.