Virtual 3-dimensional representation of a completely edentulous patient for computer-aided static implant planning.

A technique is described to create a virtual 3-dimensional representation of an edentulous patient by aligning the facial, intraoral, and cone beam computed tomography scans guided by an additively manufactured scan body. Having the virtual patient facilitated the prosthetically driven implant planning, the additive manufacturing of the surgical implant guides, and the interim dental restorations.

Influence of base design on the manufacturing accuracy of vat-polymerized diagnostic casts: An in vitro study.

STATEMENT OF PROBLEM: Vat-polymerized casts can be designed with different bases, but the influence of the base design on the accuracy of the casts remains unclear. PURPOSE: The purpose of the present in vitro study was to evaluate the influence of various base designs (solid, honeycombed, and hollow) with 2 different wall thicknesses (1 mm and 2 mm) on the accuracy of vat-polymerized diagnostic casts. MATERIAL AND METHODS: A virtual maxillary cast was obtained and used to create 3 different base designs: solid (S group), honeycombed (HC group), and hollow (H group). The HC and H groups were further divided into 2 subgroups based on the wall thickness of the cast designed: 1 mm (HC-1 and H-1) and 2 mm (HC-2 and H-2) (N=50, n=10). All the specimens were manufactured with a vat-polymerized printer (Nexdent 5100) and a resin material (Nexdent Model Ortho). The linear and 3D discrepancies between the virtual cast and each specimen were measured with a coordinate measuring machine. Trueness was defined as the mean of the average absolute dimensional discrepancy between the virtual cast and the AM specimens and precision as the standard deviation of the dimensional discrepancies between the virtual cast and the AM specimens. The Kolmogorov-Smirnov and Shapiro-Wilk tests revealed that the data were not normally distributed. The data were analyzed with Kruskal-Wallis and Mann-Whitney U pairwise comparison tests (α=.05). RESULTS: The trueness ranged from 63.73 µm to 77.17 µm, and the precision ranged from 44.00 µm to 54.24 µm. The Kruskal-Wallis test revealed significant differences on the x- (P<.001), y- (P=.006), and z-axes (P<.001) and on the 3D discrepancy (P<.001). On the x-axis, the Mann-Whitney test revealed significant differences between the S and H-1 groups (P<.001), S and H-2 groups (P<.001), HC-1 and H-1 groups (P<.001), HC-1 and H-2 groups (P<.001), HC-2 and H-1 groups (P<.001), and HC-2 and H-2 groups (P<.001); on the y-axis, between the S and H-1 groups (P<.001), HC-1 and H-1 groups (P=.001), HC-1 and H-2 groups (P=.02), HC-2 and H-1 groups (P<.001), HC-2 and H-2 groups (P=.003); and on the z-axis, between the S and H-1 groups (P=.003). For the 3D discrepancy analysis, significant differences were found between the S and H-1 groups (P<.001), S and H-2 groups (P=.004), HC-1 and H-1 groups (P=.04), and HC-2 and H-1 groups (P=.002). CONCLUSIONS: The base designs tested influenced the manufacturing accuracy of the diagnostic casts fabricated with a vat-polymerization printer, with the solid and honeycombed bases providing the greatest accuracy. However, all the specimens were clinically acceptable.

A vat-polymerized 3-dimensionally printed dual-material occlusal device: A dental technique.

A technique to additively manufacture an occlusal device by using a completely digital workflow is described. Using a computer-aided design program, information captured with an intraoral scanner was used to additively manufacture a dual-material occlusal device by using a vat-polymerization printer. This technique allows for the combination of 2 different materials, resulting in an occlusal device with a resilient intaglio and a hard resin exterior surface. Advantages of the resulting occlusal device compared with a single-material device include improved patient acceptance and comfort, better fit, and minimal adjustments to ensure fit.

A Review of the Applications of Additive Manufacturing Technologies Used to Fabricate Metals in Implant Dentistry.

PURPOSE: To review the primary additive manufacturing (AM) technologies used to fabricate metals in implant dentistry and compare them to conventional casting and subtractive methods. METHODS: The literature on metal AM technologies was reviewed, and the AM procedures and their current applications in implant dentistry were collated and described. Collection of published articles about metal AM in dental field data sources: MEDLINE, EMBASE, EBSCO, and Web of Science searched. All studies related to AM technology description, analysis, and evaluation of applications in implant dentistry, including AM titanium (Ti) dental implants, customized Ti mesh for bone grafting techniques, cobalt-chromium (Co-Cr) frameworks for implant impression procedures, and Co-Cr and Ti frameworks for dental implant-supported prostheses were reviewed. RESULTS: Literature has demonstrated the potential of AM technologies to fabricate dental implants, root-analog implants, and functionally graded implants; as well as the ability to fabricate customized meshes for bone grafting procedures. Metal AM technologies provide a reliable method to manufacture frameworks for implant impression procedures. Co-Cr and Ti AM frameworks for implant-supported prostheses provide a clinically acceptable discrepancy at the implant-prostheses interface. CONCLUSIONS: Additional clinical studies are required to assess the long-term clinical performance, biological and mechanical complications, and prosthetic restoration capabilities of additively manufactured dental implants. Moreover, further studies are needed to evaluate their long-term success and survival rates and biological and mechanical complications of AM implant-supported prostheses.

An update on applications of 3D printing technologies used for processing polymers used in implant dentistry.

Polymer additive manufacturing (AM) technologies have been incorporated in digital workflows within implant dentistry. This article reviews the main polymer AM technologies in implant dentistry, as well as their applications in the field such as manufacturing surgical guides, custom trays, working implant casts, and provisional restorations.

Intraoral digital scans: Part 2-influence of ambient scanning light conditions on the mesh quality of different intraoral scanners.

STATEMENT OF PROBLEM: Digital scans should be able to accurately reproduce the different complex geometries of the patient's mouth. Mesh quality of the digitized mouth is an important factor that influences the capabilities of the geometry reproduction of an intraoral scanner (IOS). However, the mesh quality capabilities of IOSs and the relationship with different ambient light scanning conditions are unclear. PURPOSE: The purpose of this in vitro study was to measure the impact of various light conditions on the mesh quality of different IOSs. MATERIAL AND METHODS: Three IOSs were evaluated-iTero Element, CEREC Omnicam, and TRIOS 3-with 4 lighting conditions-chair light, 10 000 lux; room light, 1003 lux; natural light, 500 lux; and no light, 0 lux. Ten digital scans per group were made of a mandibular typodont. The mesh quality of digital scans was analyzed by using the iso2mesh MATLAB package. Two-way ANOVA and Kruskal-Wallis 1-way ANOVA statistical tests were used to analyze the data (á=.05). RESULTS: Significant differences in mesh quality values were found among the different IOSs under the same lighting conditions and among the different lighting conditions using the same IOS. TRIOS 3 showed the highest consistency and mesh quality mean values across all scanning lighting conditions tested. CEREC Omnicam had the lowest mean mesh quality values across all scanning lighting conditions. iTero Element displayed some consistency in the mesh quality values depending on the scanning lighting conditions: chair light and room light conditions presented good consistency in mesh quality, indicating better mesh quality, and natural light and no light conditions displayed differing consistency in mesh quality values. Nevertheless, no light condition led to the minimal mean mesh quality across all IOS groups. CONCLUSIONS: Differences in the mesh quality between different IOSs should be expected. The photographic scanning techniques evaluated presented higher mesh quality mean values than the video-based scanning technology tested. Moreover, changes in lighting condition significantly affect mesh quality. TRIOS 3 showed the highest consistency in terms of the mean mesh quality, indicating better photographic system in comparison with iTero Element.

Intraoral digital scans-Part 1: Influence of ambient scanning light conditions on the accuracy (trueness and precision) of different intraoral scanners.

STATEMENT OF PROBLEM: Digital scans have increasingly become an alternative to conventional impressions. Although previous studies have analyzed the accuracy of the available intraoral scanners (IOSs), the effect of the light scanning conditions on the accuracy of those IOS systems remains unclear. PURPOSE: The purpose of this in vitro study was to measure the impact of lighting conditions on the accuracy (trueness and precision) of different IOSs. MATERIAL AND METHODS: A typodont was digitized by using an extraoral scanner (L2i; Imetric) to obtain a reference standard tessellation language (STL) file. Three IOSs were evaluated-iTero Element, CEREC Omnicam, and TRIOS 3-with 4 lighting conditions-chair light 10 000 lux, room light 1003 lux, natural light 500 lux, and no light 0 lux. Ten digital scans per group were recorded. The STL file was used as a reference to measure the discrepancy between the digitized typodont and digital scans by using the MeshLab software program. The Kruskal-Wallis, 1-way ANOVA, and pairwise comparison were used to analyze the data. RESULTS: Significant differences for trueness and precision mean values were observed across different IOSs tested with the same lighting conditions and across different lighting conditions for a given IOS. In all groups, precision mean values were higher than their trueness values, indicating low relative precision. CONCLUSIONS: Ambient lighting conditions influenced the accuracy (trueness and precision) of the IOSs tested. The recommended lighting conditions depend on the IOS selected. For iTero Element, chair and room light conditions resulted in better accuracy mean values. For CEREC Omnicam, zero light resulted in better accuracy, and for TRIOS 3, room light resulted in better accuracy.