International Journal of Computerized Dentistry, 02/2017

Since Cerec (Chairside Economical Restoration of Esthetic Ceramics) was introduced as the first dental chairside computer-aided design/computer-aided manufacturing (CAD/CAM) system in the mid-1980s, this technology has enjoyed growing popularity, particularly in the recent past. There has been a considerable increase in the number of available chairside systems in only the last few years. One of the main reasons for this is that intraoral scanners have become increasingly better, smaller, and faster, while the design software has become more and more user-friendly. Many work steps are now automated, and a very large range of materials is now available for dental chairside applications. These advances have driven the rapid increase in the range of indications for chairside dentistry in the areas of prosthodontics, dental implantology, and orthodontics, and have paved the way for more novel treatment and treatment planning strategies. Another reason is that intraoral scanner-based digital impression techniques are already superior to conventional impression techniques in certain respects. Moreover, the quality of fit of digitally designed dental restorations is constantly improving because of advances in milling machine technology. Due to the sheer number of new possibilities, it is only a matter of time before chairside systems become a standard component of dental practice. This article reviews the actual advantages and limitations of the chairside workflow, and provides a summary of all the available chairside systems available today. Keywords: chairside systems, digital impression taking, intraoral scanner, grinding/milling units, review

The aim of this study was to compare the accuracy of six intraoral scanners as regards clinically relevant distances using a new method of evaluation. An additional objective was to compare intraoral scanners with the indirect digitization of model scanners. A resin master model was created by 3D printing and drilled in five places to reflect the following distances: intermolar width (IMW), intercanine width (ICW), and arch length (AL). To determine a gold standard, the distances were measured with a coordinate measuring instrument (Zeiss O-Inspect 422). The master model was scanned 37 times with the following intraoral scanners: Apollo DI (Sirona), CS 3500 (Carestream Dental), iTero (Cadent), PlanScan (Planmeca), Trios (3Shape), and True Definition (3M Espe), and indirectly digitized with the OrthoX Scan (Dentaurum). The digital models were then measured, and deviations from the gold standard calculated. Significant differences were found between the devices. Among the intraoral scanners, Trios and iTero showed the most accurate results, although CS 3500, True Definition, and Apollo DI achieved comparable results. PlanScan demonstrated the highest deviations from the gold standard, and presented a high standard deviation (SD). Direct digitization revealed comparable (and, in fact, slightly higher) accuracy than indirect digitization. Both indirect digitization and most of the intraoral scanners were therefore demonstrated to be suitable for use in the orthodontic office, with the exception of PlanScan, which did not meet the demands of individual orthodontic treatment. Keywords: intraoral scanner, indirect digitization, full-arch scan, digital impression, CAD/CAM, accuracy

Aim: The aim of this study was to evaluate the difference in maximum height loss values obtained from datasets based on optical profilometry and intraoral scanning. Additionally, two analysis applications were tested with respect to their correspondence. Materials and methods: To obtain baseline data, the occlusal surface of a metal phantom tooth was scanned by optical profilometry [WLP] and an intraoral scanner [IOS]. Then, wear was simulated at two locations of the tooth, three times each ([wear1], [wear2], and [wear3]), and the surface was captured after each status of wear, applying [WLP] and [IOS]. The maximum vertical height loss was evaluated by comparing the 3D datasets of [WLP] and [IOS] at [wear1], [wear2], and [wear3] with the baseline data of [WLP] and [IOS], respectively. For this purpose, two commercially available applications, Geomagic Qualify and Oracheck, were used. Results: Apart from one outlier of 16% difference between the data obtained from [WLP] and [IOS], the maximum difference was 12.6%, which was equal to a metrical value of 15 µm. For the corresponding values, which were calculated with Geomagic Qualify and Oracheck at identical wear facets, maximum differences between +7% and -6.7% were obtained. Conclusions: According to this in vitro study, the wear measurement on the basis of [IOS] seems to be a cost-effective, quick, and easily applicable tool for clinical screening purposes, with an acceptable reliability. With respect to the minor variations between each other, the Geomagic Qualify and Oracheck measurement applications are equivalent. Keywords: profilometry, wear, digital, intraoral, impression, in vitro, analysis

Since February 2010, intraoral scanning (Lava COS system, 3M ESPE, Seefeld, Germany) has been integrated into the preclinical curriculum at the Department of Prosthodontics of the Justus Liebig University. All students were given a lecture and were trained using a guided scan exercise. After preparing three teeth (mandibular first premolars and mandibular first molar in the 4th quadrant) for cast crowns, the students were asked to scan the maxillary and mandibular teeth. Their acceptance of the new module, "Scanning," was analyzed with the use of a questionnaire (n = 108). The evaluation showed that 63.9% of the students perceived the digital impression to be informative, and had an overall positive opinion of this new digital technology. Concerning the difficulty of the scanning process, approximately 60.2% considered it to be manageable, while 55.6% reported that the magnified view of their preparations improved their understanding of preparing chamfer finish lines. Altogether, the majority of students appreciated this intraoral scanning device as an enhancement of their education. They indicated that this method contributes to a better understanding of crown preparations. In conclusion, the implementation of intraoral scanning seems promising in preclinical education and will be continued in the curriculum. Keywords: digital denture impression, intraoral scanner, Lava COS system, preclinical education in dentistry, learning effect by 3D technology, CAD/CAM

The connection of a device for the registration of mandibular movements depends on the coupling of the teeth with a paraocclusal adapter. This is normally done by individualizing a prefabricated metal support, either directly on the patient or in the dental laboratory. The goal was to create an individual paraocclusal adapter by means of additive computer-assisted design/computer-assisted manufacturing (CAD/CAM) procedures, and to test it clinically. Starting from intraoral scans of the maxillary and mandibular teeth, an individual paraocclusal adapter was constructed by combining an adapter piece adapted to the tooth and jaw shape with a prefabricated standard part. This article describes step by step the design using the 3D CAD software, up until production by means of 3D printing. Initial clinical experience is also discussed. Keywords: CAD/CAM, 3D printing, transfer tray, electronic movement recording, virtual articulation

Chairside computer-aided design/computer-aided manufacturing (CAD/CAM) technology requires an effective technical basis to obtain dental restorations with optimal marginal accuracy, esthetics, and longevity in as short a timeframe as possible. This article describes a compact, 5-axis milling machine based on an innovative milling technology (5XT - five-axis turn-milling technique), which is capable of achieving high-precision milling results within a very short processing time. Furthermore, the device's compact dimensioning and state-of-the-art mode of operation facilitate its use in the dental office. This model is also an option to be considered for use in smaller dental laboratories, especially as the open input format enables it to be quickly and simply integrated into digital processing systems already in use. The possibility of using ceramic and polymer materials with varying properties enables the manufacture of restorations covering all conceivable indications in the field of fixed dental prosthetics. Keywords: CAD/CAM, milling unit, software, dental materials