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CBCT Changing the Practice of Oral and Maxillofacial Surgery
Gary Orentlicher, DMD | Andrew Horowitz, DMD, MD | Batya Goldwaser, DMD, MD
The past decade has seen dental and surgical diagnosis and planning rapidly shift from 2-dimensional (2D) methods to 3-dimensional (3D). Few innovations have impacted the practice of dentistry and oral and maxillofacial surgery as dramatically as cone-beam computed tomography (CBCT) digital technologies. These low-radiation, highly accurate, small-footprint machines have transformed the way clinicians practice daily. Combined with intraoral and model-based optical scanners, 3D printing and stereolithographic technologies, and proprietary software applications that are designed to move these technologies from theory to practice, dentistry and surgery are undergoing a digital transformation.
CBCT and digital technologies have become embedded in the authors’ oral and maxillofacial surgery practice in many ways. Some key examples are discussed in the following paragraphs.
In some situations, determining the location of impacted and supernumerary teeth for the purpose of extraction or surgical exposure can be very difficult. When using 2D periapical and panoramic radiographs alone, it may not be possible to gauge the proximity, angulations, and locations of these teeth relative to surrounding vital structures, adjacent teeth, and/or implants1 (Figure 1 through Figure 3).
Similarly, the relationship between impacted third molars and the mandibular nerve canal is difficult to assess using conventional 2D radiographic techniques.2-4 The buccal-lingual position of the mandibular canal has not been found to be consistently more buccal or lingual; therefore, the clinician often functions on a “best guess” based on panoramic radiographic signs.5 With an overall incidence of inferior alveolar nerve injury secondary to third molar removal of 0.5% to 8%6-8 but a less than 1% incidence of permanent numbness,8-10 being able to preoperatively determine those cases at highest risk with a 3D CT/CBCT can be invaluable.11
Preprosthetic and Dental Implant Surgery
From simple implant site evaluation to full-arch implant reconstruction, CBCT has revolutionized the practice of dental implantology. Three-dimensional–guided surgery techniques and instrumentation have greatly increased the accuracy of implant placement and enabled a multidisciplinary team approach that is restoratively driven. The result is improved patient treatment satisfaction and outcomes.
In implant sites of questionable bone contour or volume, a preoperative CT/CBCT scan aids in determining the need for and the type of bone grafting. Fabricating a scanning appliance for the patient to wear during the scan, and then importing the data into proprietary implant planning software applications, allows the visualization of bone in the planned implant site(s) in relation to the ideal position of the planned restoration(s).12 “Virtual” placement of implants in these images can provide information regarding the location and volume of bone in planned sites. Measurement and bone volume tools can be used for preoperative planning of appropriate graft procedures for site and graft dimensions and volume (ie, block bone, ridge splitting, particulate bone, sinus lift, or distraction osteogenesis).
In the maxilla, anatomic variations such as the lateral maxillary wall thickness, proximity of the maxillary buttress, and size and location of bony septae within the sinus can be determined prior to “sinus lift” graft procedures. Intraoral block bone graft donor sites (ie, chin, external oblique ridge, tuberosity) can be evaluated for bone thickness and proximity to nerves and root apices. Measurements of these relationships can be used to harvest donor bone grafts with less potential patient morbidity.
CT/CBCT data from maxillofacial trauma patients can provide 3D reformatted images that give the trauma surgeon a unique perspective of the nature of the injury and the degree of displacement of the fracture segments, which helps guide the appropriate surgical approaches for the fracture reduction and stabilization13 (Figure 4 through Figure 6). Stereolithographic models can also be made that provide the surgeon with 3D models that can be used for further diagnosis and creation of custom implants and/or plates. In delayed trauma reconstruction, it can be difficult to create symmetry with the uninjured side, making custom plates invaluable.14