Clinical Applications of Digital Dental Technology in Oral and Maxillofacial Surgery
Nicholas Callahan, Michael Han, and Michael Miloro
Dentistry has continued to evolve and adapt to new technologies at a rapid pace. Oral and maxillofacial surgeons (OMS) are at the forefront of this technology revolution. Digital and computer methods now permeate the entire scope of OMS practices from the data gathering and assessment stage, through surgical planning and surgical treatment, and into the follow‐up period, and assessment and management of complications. Many of these technologies are not unique to OMS, such as the digitization of three‐dimensional (3D) imaging. The use of digital images has helped improve communications, continuity of care, and enhanced a team‐based approach for patient care. Online webinars have become “virtual operating rooms” during treatment planning where surgical simulations and telesurgery can also now be performed remotely using robotic‐assisted surgical techniques.
Technology has had the greatest impact on facial reconstructive surgical procedures. Craniomaxillofacial reconstruction may be required for oncologic, congenital, dentoalveolar, and/or traumatic defects. Technology has allowed planning of these complex surgeries precisely and accurately before ever entering an operating room. Computer‐aided design/computer‐aided manufacturing (CAD/CAM) technologies allow for the 3D printing of models, guides, and reconstruction plates. New technologies must always be assessed against the current existing standard of practice, or so‐called, traditional methods. Since new technologies are often accompanied by an increased cost, the cost–benefit ratio must always be considered.
15.2 Types of Digital Data
Application of digital technology begins with data acquisition, and the choice of digital data type is dictated by the clinical needs. Digital data can be used in its raw, or native, form or it may be processed post‐acquisition to create a digital patient analog for CAD/CAM usage and planning.
15.3 Digital Imaging
Digital radiography is now pervasive through all fields of dentistry, and the advantages of digital imaging are similar for all dental specialties. Digital radiography allows for dose‐dependent reduction in radiation when compared with conventional radiology. This dose reduction varies between 0% and 50% depending upon the specific unit, field of view, and film speed used. A comparison of digital vs. conventional panoramic radiography revealed a dosage of 5–14 mSv and 16–21 mSv respectively (Sabarudin and Tiau 2013). Imaging acquisition is faster and easier using digital technology, allowing for the immediate evaluation of the image. Digital radiography eliminates the need for a dark room, the maintenance of chemical fixation, and developing solutions. Also, the storage and transfer of imaging is easier with digital technology. This allows for a more efficient communication between the dentist, the patient, and other consultants. Images can be copied and transferred without image degradation or distortion or loss of resolution. Digital technology allows for image analysis and enhancements that may help provide better interpretation of images (Szalma et al. 2012). Image processing tools are available to improve image quality by the manipulation of brightness, contrast, density, magnification, sharpness, noise filters, and color inversion (Raitz et al. 2012).
In‐office cone‐beam computed tomography (CBCT) scan capability has proven to be an extremely valuable asset to the OMS. In addition to having significantly less radiation compared with conventional computed tomography (), excellent accessibility and lower cost have made CBCT the gold standard for three‐dimensional imaging of hard tissues of the craniomaxillofacial region. Cone‐beam computed tomography images have less scatter from dental implants, plates and screws, and metallic restorations, which allows for improved visualization and image interpretation (Bechara et al. 2012). Traditional CT and magnetic resonance imaging (MRI) remain better options for the evaluation of soft tissue anatomy (Figure 15.1a–c).
Three‐dimensional digital imaging data can be processed to create a “surface shell,” which can then be digitally manipulated, 3D‐printed, or used to facilitate design and fabrication of surgical guides or hardware.
15.4 Optical Scans
Similar to other fields in dentistry, optical scans of teeth and other structures are often used to more accurately capture certain structures (Figure 15.2). The most common use is scanning of the dentition, which often lacks detail in CT or CBCT scans, which is worsened if any metal artifacts (e.g. restorations, orthodontic appliances) are present. Other forms of optical scans include the facial scan, which can be used by itself, or be integrated to other forms of data as part of creating a digital analog of the patient. Optical scans have the advantage of being a quick non‐ionizing modality.
15.5 Clinical Applications
15.5.1 Dentoalveolar Surgery
Cone‐beam computed tomography is obtained most commonly before dentoalveolar surgery. There are advantages across all areas of dentoalveolar surgery, from extractions to implant surgery. Cone‐beam computed tomography allows for evaluation of bone quality and quantity and accurate measurements of distance from vital structures (e.g. maxillary sinus and inferior alveolar canal [IAC]). This allows the accurate planning and safe placement of dental implants (Figure 15.3a,b). Cone‐beam computed tomography helps with evaluation of impacted teeth, especially for the localization of the IAC in relation to deeply impacted teeth, or those with panoramic radiographic predictors of root proximity to the IAC (Figure 15.4a,b). The literature does not support the routine use of CBCT imaging for the assessment of the relationship of third molar roots to the IAC (Guerrero et al. 2014). Randomized clinical trials comparing panoramic radiography to CBCT have failed to demonstrate a difference in predicting complications of the third molar removal (Guerrero et al. 2014), but it may allow the surgeon to provide a risk stratification to the patient and more accurately plan surgical extraction vs. a coronectomy procedure, for example.
The localization of impacted canine teeth and supernumerary teeth is a challenge without CBCT imaging, since this eliminates the need to take multiple periapical films that are required to use the “SLOB” (“same lingual – opposite buccal”) rule (Tiwana and Kushner 2005) (Figure 15.5a,b). The CBCT also allows for assessment of adjacent root resorption and estimation of remaining bone support.
15.5.2 Maxillofacial Pathology and Reconstruction
Three‐dimensional assessment of maxillofacial pathology allows for better characterization and extent of the lesions. It can help identify any intra‐lesional calcifications, loculations, or root and nerve proximity to the lesion (Figure 15.6). Cortical expansion can be visualized easily without the need for additional films (Figure 15.7a,b). Even after surgical treatment, CBCT is useful for surveillance for recurrent or persistent lesions and may even allow for earlier discovery of recurrent lesions (Ahmad et al. 2012).
Cone‐beam computed tomography has limited uses for malignant disease, other than as a screening test. Since these lesions have a significant soft tissue component, and evaluation of regional cervical lymph nodes may also be needed, a conventional CT or MRI is a better imaging option. Cone‐beam computed tomography may be used for surgical planning in these cases for resection of the osseous portions of the resection surgery. Three‐dimensional imaging can help delineate the bony margins of inflammatory or infectious diseases such as osteomyelitis, osteoradionecrosis (ORN), or medication‐related osteonecrosis of the jaws ( ). Computed tomography/cone‐beam computed tomography may reveal areas of cortical destruction, periosteal reaction, or bony sequestration. A recent systemic review showed that CT, MRI, and CBCT all had benefit in the diagnosis of MRONJ (Wongratwanich et al. 2021) (Figure 15.8a,b). Also, CBCT is superior to panoramic imaging for the evaluation of maxillary sinus pathology. In patients with radiographic maxillary sinus pathology on CT scans (e.g. mucosal thickening, mucous retention cysts) panoramic radiography was concordant only 4.3% of the time (Maestre‐Ferrin et al. 2011).
The diagnosis of salivary gland pathology benefits from several different imaging modalities, especially for the localization of sialoliths (salivary gland stones). Plain films have the same limitations here as they do for dentoalveolar imaging, and CBCT is preferred for 3D localization of salivary stone either in the ductal system, hilum of the gland, or within the gland itself (Figure 15.9a,b). Sialendoscopy can provide both diagnostic information and can also be used to treat disease by flushing the ductal system of small stones, debris, or mucous plugs. With appropriate instrumentation, salivary ductal stones may be removed with an endoscopic basket and a stricture in the duct may be dilated to ensure patency of salivary flow. This sialoendoscopic technique uses 1–3 mm endoscopes to enter the duct, and then an endoscopic basket can be passed into the ductal system, to allow for retrieval of stones, in cases when traditional methods would not permit retrieval (Chandra 2019) (Figure 15.10a,b). This minimally invasive approach also allows for gland preservation, whereas in the conventional manner, a proximal stone, or one within the hilum or within the gland would necessitate complete removal of the gland itself via an extraoral transcervical approach with additional potential morbidity (Sproll et al. 2019).