![]() ![]() Some scanners allow only acquisition of data, which is then sent to the laboratory for further processing and manufacturing. The advantage is that since the configuration, collection, and manipulation of the data is by the same manufacturer, it provides security and a single place for delivery. ![]() In a closed system, the digital impressions are sent to the manufacturing company, at a fee. On the other hand, OBJ and PLY formats can store properties such as color and texture and benefit from improved 3D printers. The STL file format is simple and small, thus making its processing faster, but without representation of color or texture. Open systems allow practitioners to work with different laboratories and maximize the potential of their investment with options. If the IOS allows the digital impression to be sent directly via export of source files such as STL (Standard Tessellation Language or “send-to-lab”), PLY (Polygon File Format), and OBJ (Object File Format) to different laboratory units giving the desired flexibility, it is known as an open system, and if not, it is a closed system. Therefore, some systems require the use of titanium dioxide powder as a contrast medium to correct the problem of light triangulation, whereas others do not.Ĭurrent systems use different light source technologies, including laser, structured (striped) light, or LED illumination.ĭigital impression data transfer systems using IOS can be classified in different ways. Light triangulation limits accuracy when scanning curved surfaces especially those that do not reflect light evenly, such as teeth with amalgam restorations. Some systems such as CEREC base its imaging on triangulation, a technique in which a light source is reflected off an object. Intraoral scanning systems use different imaging technologies (either a laser or a video) to capture their 3D images. 6.4 Technology of Digital Impression Systems Recently, less deviation for short span restorations were observed using current IOS compared to conventional impressions, but this does not apply for long span restorations where conventional impression techniques still provide the lowest deviation Consequently, a recent systematic review investigating accuracy of digital impressions in fixed prosthodontics concluded that conventional impressions performed using high-precision impression materials showed greater accuracy than digital impressions. They also concluded that restorations produced from digital dies had smaller marginal and internal discrepancy compared to stereolithography apparatus (SLA) polyurethane dies. ![]() 6.3 Comparison between Conventional and Digital ImpressionsĪ meta-analysis and systematic review found most of the studies included in their study to be in vitro studies that gained better marginal and internal fit of fixed restorations with digital rather than conventional impression techniques. Either the impression itself is scanned, the impression is poured with stone and scanned, or a model is printed and scanned, to create a digital 3D file. When using extraoral scanners, there is no need for any change to the clinical workflow for taking conventional impressions. They were originally a part of CAD/CAM systems which produce a digital impression of prepared teeth. Intraoral scanners were introduced as stand-alone devices that capture a digital impression and send the file to a dental laboratory for prosthesis fabrication. Higher economics than a scanner alone, and require training for the entire staffĪny type of restoration can be created using a digital impression, from all ceramic crowns to gold inlaysįinal prosthesis is milled from a ceramic or composite blockĭigital impression systems can be further be divided into either direct digitalization (intraoral scanners) or indirect digitalization (extraoral scanners) depending on the requirement. Significantly lower cost than CAD CAM system The finished restoration can be cemented during the same appointment The file is sent to an in-office milling machine, for computer-aided manufacturing (CAM) for the final prosthesis. The data file is electronically transmitted to the dental laboratory or the manufacturing company (open or closed system) along with a prescriptionĪs opposed to electronically sending the data to the laboratory, computer-aided design (CAD) can be done and completed chairside. This system offers methods and tools to modify the restoration, such as adjusting contacts, height, color, and occlusion Practitioner can even re-scan the image if needed These can be reviewed instantly, and changes made. ![]() With these systems, clinicians can scan, design, and mill a full-contour restoration in-office Differences between digital impressions and CAD CAM systemsĪ scanner wand is used intraorally to record a digital image of the preparationĬhairside CAD/CAM systems include both a scanner and a mill for fabricating a restoration. ![]()
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