A CT scan provides us with a 3D image of the structures of the mouth. Traditional x-rays are 2D images and have limitations in the information they provide. In some cases, such as planning for implants, the 3D dimensions are necessary. When a tooth is lost, over time the bone in that area shrinks in all dimensions. When planning for an implant we need to ensure there is sufficient volume to fit an implant into that space. For this reason we use CT scans when a tooth has been lost for many years and we need that 3D information to choose the appropriate sized implants and have the best chances of success.