2D vs. 3D Panoramic Imaging
Dentistry has seen an astounding release of new imaging technologies that changed the way that dentists diagnose and deliver care to patients in the past 20 years. Long gone are the days when dentists stockpiled film cassettes in shielded boxes, warmed up automatic developers sensitive to temperature and fluid levels, and exposed patients to moderate levels of ionizing radiation. In the past decade, we have seen our film replaced by sensors, decreased radiation to our patients, and the introduction of a digital (virtual) representation of the dental environment.
This technology extends not only to intraoral films, but is now available in panoramic and cephalometric, and can provide either a 2-dimensional (2D) or 3-dimensional (3D) view of craniofacial images. However, like all technology that advances rapidly, there is confusion as to what advantages the new technology has over the traditional methods, not to mention the concept of 2D vs. 3D panoramic surveys. A 2D radiographic image is much like the traditional films made in the past. The exposure captures an image in a given plane, and measurements can be made in 2 axes, but it is still much like drawing an image on a piece of paper. The digital imaging software used to view these images often has filters and other systems to enhance bone density, caries detection, and graphic elements to draw on the film. Although this is a great advancement from the plane acetate film of the past, it is limited to the diagnosis and evaluation of a patient.
In contrast, 3D imaging is a volumetric calculation of the craniofacial image. The introduction of the third axis allows the use of many planes rather than just one given plane, which can be used to calculate a 3D reconstruction. This is truly a more interactive tool in the diagnosis, providing the ability to calculate where bone may or may not be located; determining the size and shape of a lesion; tracing larger nerve canals; and tooth placement. As a result, they can be used for virtual surgical manipulation to fabricate surgical guides for reconstruction or implant placement, develop medical models, and as an impression technique for digital prosthetic constructions.
The introduction of low doses of radiation exposure with cone-beam computed tomography has made this technology more accessible to dentists. However, this technology is not without its issues. Unlike traditional computed tomography, the low dose exposures can introduce issues with contrast, artifact, and overall quality of the image, sometimes requiring evaluation by a maxillofacial radiologist.
Both 2D and 3D panoramic images are useful tools in treating dental patients. The key is to determine which imaging technology is most appropriate for the patient’s needs.
About the author
Gerald T. Grant, DMD, MS, FACP
Department of Oral Health and Rehabilitation
University of Louisville
School of Dentistry