Discrepancy at the implant abutment-prosthesis interface of complete-arch cobalt-chromium implant frameworks fabricated by additive and subtractive technologies before and after ceramic veneering.

STATEMENT OF PROBLEM: Selective laser melting additive manufacturing (AM) technologies can be used to fabricate complete-arch cobalt-chromium (Co-Cr) implant-supported prostheses. However, the discrepancy at the implant-prosthesis interface with these fabrication techniques and after ceramic veneering remains unclear. PURPOSE: The purpose of the present in vitro investigation was to measure the discrepancy at the implant abutment-prosthesis interface before and after the ceramic veneering of frameworks fabricated by using subtractive and selective laser melting AM technologies. MATERIAL AND METHODS: A completely edentulous cast with 6 implant abutment replicas (Multi-unit Abutment RP Replicas; Nobel Biocare Services AG) was prepared. A total of 20 Co-Cr frameworks were fabricated using subtractive or computer numerical control milling (CNC group) and additive (AM group) technologies (n=10). A coordinate measurement machine was used to measure the linear and angular discrepancy at the implant abutment-prosthesis interface. Subsequently, a ceramic veneer was applied to each framework following the same standardized protocol. A bonding layer (Chromium-Cobalt Bonding; Bredent), 2 opaquer layers (Powder opaque and liquid UF; Creation CC), a layer of dentin ceramic (Dentine A3; Creation CC), a layer of enamel ceramic (Enamel S-59; Creation CC), and a glaze layer (Glaze paste and Liquid GL; Creation CC) were applied following the manufacturer's firing protocol. Coordinate measurement machine assessment was repeated to measure the linear and angular discrepancies after ceramic veneering procedures. Data were analyzed by using the Wilcoxon signedrank and Mann-Whitney U tests (α=.05). RESULTS: No statistically significant differences (P>.05) were demonstrated in assessing the discrepancies at the implant abutment-prosthesis interface between the groups except for the XZ angle of the CNC group (P<.05). Ceramic techniques produced significantly higher linear and angular discrepancies in both groups (P<.001) with a mean ±standard deviation increase in the 3-dimensional gap of 36.9 ±15.6 µm in the CNC group and 38.9 ±16.6 µm in the AM group. The AM group presented significantly higher discrepancy in the x-axis than the CNC group (P<.001). CONCLUSIONS: Manufacturing procedures did not significantly influence the discrepancy at the implant abutment-prosthesis interface, which was significantly increased after ceramic veneering, except for the XZ angle of the CNC group. The differences between the discrepancies at the implant abutment-prosthesis interface before and after ceramic application revealed no significant discrepancies among the groups, except in the AM group that presented a significantly higher discrepancy on the x-axis compared with the CNC group.

Digital tools and 3D printing technologies integrated into the workflow of restorative treatment: A clinical report.

The development of technologies including intraoral scanners, dental software for digital restoration design, and additive manufacturing has improved the digital workflow of restorative treatment. The present article describes a digital workflow with intraoral scanning, computer-aided design (CAD) software, and subtractive and additive manufacturing procedures for a patient receiving lithium disilicate laminate veneers.

A report on a diagnostic digital workflow for esthetic dental rehabilitation using additive manufacturing technologies.

The digital workflow - from the intraoral scanning, through the CAD design of the facially generated diagnostic digital wax-up, to the CAD-designed and 3D-printed silicone index with the diagnostic mock-up - provides a new approach that avoids the conventional manufacturing of casts. The development of the process requires a synchronized workflow and good communication between the dental technician, prosthodontist, and patient. This report describes a protocol for the diagnostic digital sequence for the treatment planning of an esthetic rehabilitation.

Position Accuracy of Implant Analogs on 3D Printed Polymer versus Conventional Dental Stone Casts Measured Using a Coordinate Measuring Machine.

PURPOSE: To compare the accuracy of implant analog positions on complete edentulous maxillary casts made of either dental stone or additive manufactured polymers using a coordinate measuring machine (CMM). MATERIAL AND METHODS: A completely edentulous maxillary model of a patient with 7 implant analogs was obtained. From this model, two types of casts were duplicated, namely conventional dental stone (CDS) using a custom tray impression technique after splinting (N = 5) and polymer cast using additive manufacturing based on the STL file generated. Polymer casts (N = 20; n = 5 per group) were fabricated using 4 different additive manufacturing technologies (multijet printing-MJP1, direct light processing-DLP, stereolithography-SLA, multijet printing-MJP2). CMM was used to measure the correct position of each implant, and distortion was calculated for each system at x-, y-, and z-axes. Measurements were repeated 3 times per specimen in each axis yielding a total of 546 measurements. Data were analyzed using ANOVA, Sheffé tests, and Bonferroni correction (α = 0.05). RESULTS: Compared to CMM, the mean distortion (µm) ranged from 22.7 to 74.9, 23.4 to 49.1, and 11.0 to 85.8 in the x-, y-, and z-axes, respectively. CDS method (x-axis: 37.1; z-axis: 27.62) showed a significant difference compared to DLP on the x-axis (22.7) (p = 0.037) and to MJP1 on the z-axis (11.0) (p = 0.003). Regardless of the cast system, x-axes showed more distortion (42.6) compared to y- (34.6) and z-axes (35.97). Among additive manufacturing technologies, MJP2 presented the highest (64.3 ± 83.6), and MJP1 (21.57 ± 16.3) and DLP (27.07 ± 20.23) the lowest distortion, which was not significantly different from CDS (32.3 ± 22.73) (p > 0.05). CONCLUSION: For the fabrication of the definitive casts for implant prostheses, one of the multijet printing systems and direct light processing additive manufacturing technologies showed similar results to conventional dental stone. CLINICAL SIGNIFICANCE: Conventional dental stone casts could be accurately duplicated using some of the additive manufacturing technologies tested.

Impression technique for a complete-arch prosthesis with multiple implants using additive manufacturing technologies.

This article describes an impression technique for a complete-arch prosthesis supported by multiple implants where additive manufacturing technologies were used to fabricate a splinting framework and a custom tray. The technique presented uses a shim method to control the homogenous splinting acrylic resin and impression material during the procedure, thereby reducing laboratory and chairside time and the number of impression copings and laboratory analogs needed.