No abstract

Interest in intraoral scanners (IOSs) has increased in dentistry since the introduction of the CEREC system in 1984. 1 The rapid pace of innovation in digital scanners has increased the indications for use to include more complicated completearch prostheses, removable prostheses, extensive implantsupported prostheses, and orthodontic aligners. 2-6 Intraoral digital scans are now acceptable for complete arch prostheses supported by nonparallel implants, which is a testament to how far the technology has advanced. 7 These expanded indications combined with an increase in the ease of use have increased the adoption of digital workflows. This results in increased patient comfort, shortened treatment time, and the potential for decreased overhead, all while maintaining the quality of conventional systems. 8-11 Additionally, intraoral Declaration of Interest: A.M. and W.R. have lectured for Planmeca at CE events and received honoraria. M.L. has lectured for Dentsply Sirona at CE events and received honoraria.

Objective This in vitro study compares the newest generation of intraoral scanners to their older counterparts, and tests whether material substrates affect the trueness and precision of intraoral scanners (IOS). Material and methods A custom model, used as the reference standard, was fabricated with teeth composed of different dental materials. The reference standard scan was obtained using a three‐dimensional (3D) optical scanner, the ATOS III. Experimental scans were obtained using eight different IOS, operated by experienced clinicians, using the manufacturer's recommended scanning strategy. A comprehensive metrology program, Geomagic Control X, was used to compare the reference standard scan with the experimental scans. Results For all scanners tested, except Trios3, the substrate does influence the trueness and precision of the scan. Furthermore, differences exist when comparing the same substrate across different scanners with some of the latest generation scanners clearly leaping ahead of the older generation regarding both trueness and precision. Conclusions Substrate type affects the trueness and precision of a scan. Active Triangulation scanners are more sensitive to substrate differences than their parallel confocal counterparts. Some scanners scan certain substrates better, but in general the new generation of scanners outperforms the old, across all substrates. Clinical significance The substrates being scanned play an import role in the trueness and precision of the 3D model. The new generation of scanners is remarkably accurate across all substrates and for complete‐arch scanning.

Companies who make digital impression systems often recommend a scan pattern specific for their system. However, every clinical scanning scenario is different and may require a different approach. Knowing how important scan pattern is with regards to accuracy would be helpful for guiding a growing number of practitioners who are utilizing this technology.

Objectives An impression accuracy study using a cadaver maxilla was performed using both prepared and intact teeth as well as palatal tissue. Materials and Methods Three crown preparations were performed on a cadaver maxilla. Seven different digital impression systems along with polyvinylsiloxane impressions were used to create digital models of the maxilla. Three‐dimensional (3D) files of the experimental models were compared to a master model. The 3D files were overlaid and analyzed using a comparison software to create color coded figures that were measured for deviations between the master and experimental models. Results For scanning tooth structure, only the Planscan was significantly less accurate than the rest of impression techniques. No significant differences in accuracy were found between models created using digital impressions and those created from traditional vinyl polysiloxane impressions with cross arch deviations ranging from 18 to 39 μm for each. Conclusions Impressions taken using all digital impression systems, save for the Planscan, were able to accurately replicate the tissues of a complete arch human maxilla. Clinical Significance Studies examining accuracy of digital impression systems have generally been performed on materials other than dental tissues. Optically, materials such as plastic and metal have properties different from enamel and dentin. This study evaluates accuracy of digital impression systems on human dentin, enamel, and soft tissues.

Structured Abstract Objective This study aimed to determine how the accuracy of digital impressions was affected by four common dental substrates using seven prevalent IOS systems to scan the complete arch of a human maxilla. Setting and Sample Population The Department of Oral Rehabilitation at the Medical University of South Carolina. A single cadaver maxilla. Materials and Methods Seven digital intraoral impression systems were used to scan a freshly harvested human maxilla. The maxilla contained several teeth restored with amalgam and composite, as well as unrestored teeth characterized by enamel. Also, three teeth were prepared for full coverage restorations to expose natural dentin. An industrial grade metrology software program that allowed 3D overlay and dimensional computation compared deviations of the complete arch and its substrates on the test model from the reference model. Results Substrates were significantly different from each other when considering scan data as a whole, as well as when comparing IOS devices individually. Only PlanScan failed to reveal trueness differences between the different substrates, while only Emerald revealed precision differences between the substrates. Conclusions Substrate type does impact the overall accuracy of intraoral scans with dentin being the most accurate and enamel being the least accurate. The four substrates scanned impacted the trueness of all IOS devices.

The trueness of intraoral scanners for edentulous complete-arch scans with scan bodies has been investigated with a wide range of deviation from 31 mm to 810 mm, depending on the scanner type and measurement method. [1][2][3][4][5][6][7] High deviation of the digital scan may result in a misfit of an implant prosthesis, which increases stresses and could lead to fracture of the screw, 8 abutments, or the veneer 9 or induce screw loosening. 10 The deviation at each implant should be less than 50 mm. 11,12 In the contemporary laboratory process, fabrication error falls within a range of 25 to 43 mm. [13][14][15] Thus, the intraoral scanner error should be in a similar range to keep the total error less than 50 mm. A clinical study using a completely

Composite resin dots on keratinized tissue were successful at allowing accurate merging of provisional restoration and post-preparation 3D models for the purpose of using the provisional restorations as a guide for final CLINICAL SIGNIFICANCE: Composite resin dots placed temporarily on attached tissue were successful at allowing accurate merging of the provisional restoration 3D models to the preparation 3D models for the purposes of using the provisional restorations as a guide for final restoration design and manufacturing. In this case, they allowed precise superimposition of the 3D models made in the absence of any other hard tissue reference points, resulting in the fabrication of ideal final restorations.