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CAD/CAM International magazineof digital dentistry No. 1, 2017

patient record ce article | Fig. 2 Fig. 3 Fig. 4 Fig. 2: A 3M intraoral scan with possible rotation in the three planes. Fig. 3: A 3M intraoral scan of the same patient with varying degrees of rotation. Fig. 4: MaxAlign patient image indicating facial references planes. other records acquisition techniques have gained increasing popularity. Cone beam computed tomography Cone beam computed tomography (CBCT) is a varia- tion of the traditional computed tomography (CT) system.11 With CBCT, an X-ray beam, in the shape of a cone, rotates around the patient to produce a 3-D reconstruction of the craniofacial area.11, 12 Dental CBCT was developed so that dentists could have a small, less expensive machine still capable of produc- ing 3-D images.12 The equipment is used for various clinical applications, including dental implant plan- ning, visualisation of abnormal teeth, evaluation of the jaws and face, cleft palate assessment, diagnosis of dental caries, endodontic assessment and diag- nosis of dental trauma.11 Thus, CBCT provides a fast, non-invasive method of addressing a number of clin- ical questions.11 Moreover, compared to the conven- tional CT, it has a limited X-ray beam, offers a shorter scan time, uses a lower radiation dose, and contains fewer imaging artifacts.13 Nevertheless, to accurately read a soft tissue phenomenon, a 24-bit contrast res- olution is needed. The dynamic range of CBCT for contrast resolution can only reach 14-bit maximally and consequently CBCT is not the best imaging mo- dality to evaluate soft tissues.14 Additionally, it does not provide the full diagnostic information available with conventional CT.12 The aspect of cost, technol- ogy implementation, skills acquisition and radiation exposure also hinder the utilising and implementa- tion of CBCT in the dental office. 3M True Definition Scanner Launched in the USA in October 2012, the 3M True Definition Scanner (Fig. 1) is a relatively new digital intraoral scanner.15 Its 3-D video capture technol- ogy allows the dentist to digitally capture images of the patient's dentition (Fig. 2). The scanner's technology instantaneously stitches the images together to generate an accurate replica of the patient’s oral anatomy.16, 17 Patients can therefore have a better understanding of their oral situation and the treatment procedures.17 Furthermore, the preciseness of the data provides the clinician the required records to design and fabricate prostheses, such as orthodontic appliances, crowns and bridges, all without the need for impressions or models.15, 17 This eliminates the time and cost associated with impressions, model fabrication, potential for mate- rial distortion and the issue of patient discomfort. In addition, the 3M True Definition Scanner digital files can be used with any system that accepts STL files, a common file format used for saving three- dimensional objects.15, 16 Dentists can easily share files and work with laboratories and other open source technologies to design and fabricate pros- theses and delivery quality treatment to the patient.16 However, there are limitations to the technology. Like any new technology, there is the period of skill acquisition for the clinician and, although the unit is mobile, it does require space (note: a compact, tablet-based unit has been recently released). Addi- tionally, while the True Definition Scanner captures the dentition, there is a lack of reference to the pa- tient. Once the scans have been complied into an image, the image has the ability for rotation in three dimensions (Fig. 2). Figure 3 depicts the same clin- ical image but oriented in different positions. The incisal edges of the laterals have been demarcated. Determining which orientation is the ideal one be- comes difficult without reference points. Figure 4 illustrates required references planes of interest for the rehabilitation of complex cases that require facial form as a reference for the predictable and successful fabrication of aesthetic prostheses. MaxAlign Given that it accurately and efficiently captures and documents important patient information for the laboratory, third party insurance, and patients, CAD/CAM 1 2017 39

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