3D Printed Complete Removable Dental Prostheses: a Narrative Review

Background: The purpose of this paper is to review the available literature on three-dimensionally printed complete dentures in terms of novel biomaterials, fabrication techniques and workflow, clinical performance and patient satisfaction. Methods: The methodology included applying a search strategy, defining inclusion and exclusion criteria, selecting studies and forming tables to summarize the results. Searches of PubMed, Scopus, and Embase databases were performed independently by two reviewers to gather literature published between 2010 and 2020. Results: A total of 126 titles were obtained from the electronic database, and the application of exclusion criteria resulted in the identification of 21 articles pertaining to printed technology for complete dentures. Current innovations and developments in digital dentistry have successfully led to the fabrication of removable dental prostheses using CAD/CAM technologies. Milled dentures have been studied more than 3D printed ones in the currently available literature. The limited number of clinical studies, mainly case reports, suggest current indications of 3D printing in denture fabrication process to be custom tray, record bases, trial, interim or immediate dentures but not definitive prostheses fabrication. Limitations include poor esthetics and retention, inability to balance occlusion and low printer resolution. Conclusions: Initial studies on digital dentures have shown promising short-term clinical performance, positive patient-related results and reasonable cost-effectiveness. 3D printing has potential to modernize and streamline the denture fabrication techniques, materials and workflows. However, more research is required on the existing and developing materials and printers to allow for advancement and increase its application in removable prosthodontics. © 2020, The Author(s)

3D printed complete removable dental prostheses: a narrative review

Background: The purpose of this paper is to review the available literature on three-dimensionally printed complete dentures in terms of novel biomaterials, fabrication techniques and workflow, clinical performance and patient satisfaction. Methods: The methodology included applying a search strategy, defining inclusion and exclusion criteria, selecting studies and forming tables to summarize the results. Searches of PubMed, Scopus, and Embase databases were performed independently by two reviewers to gather literature published between 2010 and 2020. Results: A total of 126 titles were obtained from the electronic database, and the application of exclusion criteria resulted in the identification of 21 articles pertaining to printed technology for complete dentures. Current innovations and developments in digital dentistry have successfully led to the fabrication of removable dental prostheses using CAD/CAM technologies. Milled dentures have been studied more than 3D printed ones in the currently available literature. The limited number of clinical studies, mainly case reports, suggest current indications of 3D printing in denture fabrication process to be custom tray, record bases, trial, interim or immediate dentures but not definitive prostheses fabrication. Limitations include poor esthetics and retention, inability to balance occlusion and low printer resolution. Conclusions: Initial studies on digital dentures have shown promising short-term clinical performance, positive patient-related results and reasonable cost-effectiveness. 3D printing has potential to modernize and streamline the denture fabrication techniques, materials and workflows. However, more research is required on the existing and developing materials and printers to allow for advancement and increase its application in removable prosthodontics. © 2020, The Author(s)

Bond Strength of Different Self-Adhesive Resin Cements to Zirconia

Objectives: The purpose of the study was to compare the shear bond strength of five self-adhesive resin cements used to bond zirconia. Methods: Seventy-two KATANA Zirconia STML (n=12) specimens were sectioned and sintered in an induction furnace (CEREC SpeedFire, Dentsply Sirona, Germany). Specimen surfaces were ground finished with 800 grit silicon carbide abrasive with cooling water and cleaned with ultrasonication in alcohol. Specimens were air-particle abraded with 50 μm aluminum oxide at 2.8 bar pressure. Cylindrical composite resin specimens (2.1 mm in diameter, 3 mm in height) were bonded to the zirconia samples with self-adhesive resin cements Panavia SA Universal (PSA), TheraCem (TCM), SpeedCem 2.0 (SCM), RelyX Unicem 2 (RCM), PermaCem 2.0 (PCM) and dual-cure multi-step composite resin cement Panavia V5 (control, PV5, after application of ceramic primer) following manufacturers’ instructions. A load of 1000 g was applied to the composite cylinders during bonding in an alignment apparatus, then light cured for 80 s. Samples were stored in distilled water at 37° C for 24 h, then subjected to 10,000 thermal cycles. Shear bond strength was determined using a universal testing machine at a crosshead speed of 0.5 mm/min expressed in MPa. The fractured surfaces of specimens were inspected with a stereo microscope and classified as 8 adhesive, cohesive, or mixed failures. One-way ANOVA test and Tukey test were applied for statistical analysis. Results: Shear bond strength values [MPa] were for PSA 8.64 (1.78 SD), TCM 9.05 (2.64 SD), SCM 8.54 (1.92 SD), RCM 7.60 (1.26 SD), PMC 7.59 (1.10 SD) and PV5 9.59 (1.55 SD). One-way ANOVA test revealed no statistically significant differences in shear bond strength between the resin cements tested (p\u3e0.05). Pair wise comparison using Tukey test revealed that the shear bond strength using RCM was statistically lower than that using PV5 (p\u3c0.05). Conclusions: According to the results of this in vitro study, self-adhesive resin cements can achieve shear bond strengths to zirconia that are comparable multi-step resin cements. In routine clinical application, self-adhesive resin cements can be a user- friendly, less technique sensitive alternative for bonding Zirconia restorations following the APC concept

Marginal Adaptation of CAD/CAM Hybrid Ceramic Crowns Made on Preparations With and Without Surface Finishing

Statement of problem: Studies on previous generations of chair-side Computer Aided Design/Computer Aided Manufacturing (CAD/CAM) systems concluded that preparation quality has an impact on marginal fit of milled restorations. However, as chair-side CAD/CAM technology improves, and newer systems and materials are released, it remains unclear if preparation quality still impacts marginal adaptation of milled restoration. Purpose: This in vitro study evaluated the marginal adaptation of ceramic crowns fabricated with a chair-side CAD/CAM system on preparations completed with and without surface finishing to identify if finishing preparation protocols affect the marginal fit. The null hypothesis was that there was no difference in the mean marginal adaptation of ceramic restorations between the two finishing protocols. Materials and Methods: A total of 10 maxillary right central incisor acrylic teeth were screwed into precision restorative typodont with soft gum and attached to a portable bench mount. Teeth were divided into two groups (Control group CG, Finished group FG) and prepared for all ceramic crowns with medium only/and fine grit burs under dental loupes with 4.5x magnification. The CG was prepared using the medium grit bur only, while the FG was prepared using the medium grit bur and then refined with the fine grit bur for two minutes. Preparations were scanned with an intraoral scanner and hybrid ceramic crowns were designed, milled and hand polished following the manufacturer’s recommendations. The hybrid ceramic crowns were cemented on the prepared teeth using a dual cure resin cement system. Design, milling and cementation were made by the same operator. To measure the vertical marginal gap between the margin of the crown and the finish line of the acrylic tooth, scanning electron microscope (SEM) images were made (Singh Center for Nanotechnology, University of Pennsylvania) with magnification of ×100. A total of 50 measurements were made per tooth: 25 mid-facial margin area and 25 mid-palatal margin area. The data were analyzed with Mann-Whitney Rank Sum Test to determine differences between the groups. A statistical software program was used for the analysis. Results: The FG resulted in a significant decrease in the overall mean marginal gap of CAD/CAM all ceramic crowns compared to the CG (p\u3c0.001). Conclusion: Crown preparation finishing with fine grit bur has a significant impact on the marginal gap of all ceramic restorations

Influence of Surface Modifications on Bacterial Adherence to Implant Abutment Materials

© 2022 by Quintessence Publishing Co Inc.The purpose of this study was to investigate the effects of various titanium and zirconia polishing protocols on the colonization of oral bacteria. Titanium and zirconia discs were divided into five groups: unpolished (control, UNP) and polished with Brownie only (BRO), Brownie plus Greenie (BPG), Brownie plus Greenie plus Supergreenie (BGS), and CeraMaster Coarse plus CeraMaster polishing tips (CER). The samples were sterilized and immersed in unstimulated saliva, then incubated in a liquid suspension of Streptococcus gordonii (S gordonii). The number of attached bacteria were counted 48 hours after the diluted suspensions were inoculated. Data were analyzed with ANOVA and Tukey test (P < .05). For titanium discs, the average number of bacteria from each group (CFU/mm2) was 1.51 x 103 for UNP; 3.71 x 103 for BRO; 5.65 x 103 for BPG; 8.99 x 102 for BGS; and 8.49 x 102 for CER. For zirconia, the averages were 2.87 x 102 for UNP; 3.16 x 102 for BRO; 3.50 x 102 for BPG; 1.83 x 102 for BGS; and 8.73 x 101 for CER. Inadequate polishing roughens surfaces and promotes microbial adhesion to titanium and zirconia. Sequential polishing to the finest-finish polishing tips minimizes bacterial adherence to abutment surfaces. Zirconia exhibited less bacterial adhesion than titanium