Historical overview

Since the introduction of the first dental radiographs, dentists have become comfortable with evaluating and diagnosing patients using two-dimensional (2D) images (ie, periapical, bitewing, panoramic, and cephalometric radiographs, and so forth). The obvious limitations of these technologies in evaluating 3D problems required clinician acceptance because few options were available. Because of their hospital-based training, oral and maxillofacial surgeons have long used computed tomography (CT) scans for the 3D evaluation of facial trauma and pathologic lesions. These CT evaluations typically were viewed in 2D as axial or reformatted frontal or coronal slices through the area of interest of a patient’s anatomy, printed on plain films, or viewed as such on a computer screen. The remainder of the dental community had little, if any, exposure to 3D image evaluation.

The first medical-grade helical CT scanners were all single-slice, slower machines that were based in hospitals or private radiology facilities. Typical medical multislice CT scanners of today are capable of performing a scan of the upper and/or lower jaw in a few seconds, but the size and cost of the machines, the radiation exposure, the lack of familiarity and training amongst dentists, and the perceived cost/benefit ratio in patient care made them inappropriate for a dental office setting. With the development and introduction of the New Tom 9000 (Quantitative Radiology, Verona, Italy) in 1998, cone beam volumetric tomography (CBVT/cone beam computed tomography [CBCT]) was introduced to the dental community. Although the first machines were larger than those available today, the advantages were that they produced good 3D images at lower radiation doses, and the footprint of the machines were small enough to fit into a dental office. The disadvantages were that, although the radiation was less than medical-grade CT, it was more than conventional dental radiographs and, because of the reduced radiation, the images produced had less definition than medical CT. Since the first CBCT was introduced, machines with multiple different features have been developed and introduced by various manufacturers. The gold standard for accurate 3D diagnosis continues to be medical-grade CT. The recent introduction of adaptive statistical iterative reconstruction (ASIR) software has been reported to allow up to a 50% radiation dose reduction in medical CT scans, without diminishing image quality. There are different average deviations and percentage error measurements for all CBCT scanners.

In the late 1980s, articles began to appear in the literature discussing the use of DentaScans to evaluate the bone of the maxilla and mandible in preparation for placement of dental implants. Columbia Scientific (CSI) introduced the 3D Dental software in 1988. This software converted CT axial slices into reformatted cross-sectional images of the alveolar ridges for diagnosis and evaluation. In 1991, a combination software was introduced, ImageMaster-101, which allowed the additional feature of placing graphic dental implants on the cross-sectional images. The first version of Sim/Plant was introduced by CSI in 1993, allowing the placement of virtual implants of exact dimensions, on CT images, in cross-sectional, axial, and panoramic views. In 1999, Simplant 6.0 was introduced, adding the creation of 3D reformatted image surface rendering to the software. Materialise (Leuven, Belgium) purchased CSI in 2001, introducing the technology for drilling osteotomies to exact depth and direction through a surgical guide in 2002. NobelBiocare (Zurich, Switzerland) introduced the NobelProcera/NobelGuide technology in 2005. The NobelGuide technology was introduced as a complete implant planning and placement system, for both straight-walled and tapered NobelBiocare implants. Appropriate instrumentation was developed to create osteotomies of accurate depth and direction, as well as the ability to place implants flapless, to accurate depth, through a guide. The system was designed for conventional postimplant insertion treatment (cover screws or healing abutments), immediate loading of implants, and the fabrication of partial or full arch restorations before implant placement. A completely redesigned upgrade of the NobelGuide software, NobelClinician, has been introduced in 2011. Software from other manufacturers, such as EasyGuide (Keystone Dental, Burlington, MA, USA), Straumann coDiagnostiX (Straumann, Basel, Switzerland), VIP Software (BioHorizons, Birmingham, AL, USA), Implant Master (IDent, Foster City, CA, USA), and others, are now available as well. Other implant manufacturers have developed instrument trays for the guided placement of their implants using the Simplant software for implant planning (ie, Facilitate, AstraTech Dental, Molndal, Sweden; Navigator, Biomet 3i, Palm Beach Gardens, FL, USA; ExpertEase, Dentsply Friadent, Mannheim, Germany.)