A review of 4D printing

https://www.zora.uzh.ch/id/eprint/110791/1/All-ceramic%20or%20metal-ceramic%20tooth-supported_acc.pdf

All-ceramic or metal-ceramic tooth-supported fixed dental prostheses (FDPs)? A systematic review of the survival and complication rates. Part I: Single crowns (SCs)

Self-adhesive resin cements were introduced to dentistry within the past decade but have gained rapidly in popularity with more than a dozen commercial brands now available. This review article explores their chemical composition and its effect on the setting reaction and adhesion to various substrates, their physical and biological properties that may help to predict their ultimate performance and their clinical performance to date and handling characteristics. The result of this review of self-adhesive resin cements would suggest that these materials may be expected to show similar clinical performance as other resin-based and non-resin based dental cements.

Self-adhesive resin cements - chemistry, properties and clinical considerations.

Intraoral scanners (IOS) are devices for capturing direct optical impressions in dentistry. The purpose of this narrative review on the use of IOS was to: (1) identify the advantages/disadvantages of using optical impressions compared to conventional impressions; (2) investigate if optical impressions are as accurate as conventional impressions; (3) evaluate the differences between the IOS currently available commercially; (4) determine the current clinical applications/limitations in the use of IOS. Electronic database searches were performed using specific keywords and MeSH terms. The searches were confined to full-text articles written in English and published in peer-reviewed journals between January 2007 and June 2017. One hundred thirty-two studies were included in the present review; among them, 20 were previous literature reviews, 78 were in vivo clinical studies (6 randomized controlled/crossover trials, 31 controlled/comparative studies; 24 cohort studies/case series; 17 case reports) and 34 were in vitro comparative studies. Optical impressions reduce patient discomfort; IOS are time-efficient and simplify clinical procedures for the dentist, eliminating plaster models and allowing better communication with the dental technician and with patients; however, with IOS, it can be difficult to detect deep margin lines in prepared teeth and/or in case of bleeding, there is a learning curve, and there are purchasing and managing costs. The current IOS are sufficiently accurate for capturing impressions for fabricating a whole series of prosthetic restorations (inlays/onlays, copings and frameworks, single crowns and fixed partial dentures) on both natural teeth and implants; in addition, they can be used for smile design, and to fabricate posts and cores, removable partial prostheses and obturators. The literature to date does not support the use of IOS in long-span restorations with natural teeth or implants. Finally, IOS can be integrated in implant dentistry for guided surgery and in orthodontics for fabricating aligners and custom-made devices.

/pdf/intraoral-scanners-in-dentistry-a-review-of-the-current-26q4ueb6fl.pdf

Intraoral scanners in dentistry: a review of the current literature

Three-dimensional (3D) printing enables the production of anatomically matched and patient-specific devices and constructs with high tunability and complexity. It also allows on-demand fabrication with high productivity in a cost-effective manner. As a result, 3D printing has become a leading manufacturing technique in healthcare and medicine for a wide range of applications including dentistry, tissue engineering and regenerative medicine, engineered tissue models, medical devices, anatomical models and drug formulation. Today, 3D printing is widely adopted by the healthcare industry and academia. It provides commercially available medical products and a platform for emerging research areas including tissue and organ printing. In this review, our goal is to discuss the current and emerging applications of 3D printing in medicine. A brief summary on additive manufacturing technologies and available printable materials is also given. The technological and regulatory barriers that are slowing down the full implementation of 3D printing in the medical field are also discussed.

https://iopscience.iop.org/article/10.1088/1758-5090/aa7279/pdf

Current and emerging applications of 3D printing in medicine.

10-year Survival Evaluation for Glass-fiber–supported Postendodontic Restoration: A Prospective Observational Clinical Study

Direct and indirect digitalization offer two options for computer-aided design (CAD)/ computer-aided manufacturing (CAM)-generated restorations. The aim of this study was to evaluate the accuracy of different intraoral scanners and compare them to the process of indirect digitalization. A titanium testing model was directly digitized 12 times with each intraoral scanner: (1) CS 3500 (CS), (2) Zfx Intrascan (ZFX), (3) CEREC AC Bluecam (BLU), (4) CEREC AC Omnicam (OC) and (5) True Definition (TD). As control, 12 polyether impressions were taken and the referring plaster casts were digitized indirectly with the D-810 laboratory scanner (CON). The accuracy (trueness/precision) of the datasets was evaluated by an analysing software (Geomagic Qualify 12.1) using a “best fit alignment” of the datasets with a highly accurate reference dataset of the testing model, received from industrial computed tomography. Direct digitalization using the TD showed the significant highest overall “trueness”, followed by CS. Both performed better than CON. BLU, ZFX and OC showed higher differences from the reference dataset than CON. Regarding the overall “precision”, the CS 3500 intraoral scanner and the True Definition showed the best performance. CON, BLU and OC resulted in significantly higher precision than ZFX did. Within the limitations of this in vitro study, the accuracy of the ascertained datasets was dependent on the scanning system. The direct digitalization was not superior to indirect digitalization for all tested systems. Regarding the accuracy, all tested intraoral scanning technologies seem to be able to reproduce a single quadrant within clinical acceptable accuracy. However, differences were detected between the tested systems.

Accuracy of five intraoral scanners compared to indirect digitalization.

Is adhesive cementation of endodontic posts necessary

Complex rehabilitations represent a particular challenge for the restorative team, especially if the vertical dimension of occlusion (VDO) needs to be reconstructed or redefined. The use of provisional acrylic or composite materials allows clinicians to evaluate the treatment objective over a certain period of time and therefore generates a high predictability of the definitive rehabilitation in terms of esthetics and function. CAD/CAM technology enables the use of prefabricated polymer materials, which are fabricated under industrial conditions to form a highly homogeneous structure compared with those of direct fabrication. This increases long-term stability, biocompatibility, and resistance to wear. Furthermore, they offer more suitable CAD/CAM processing characteristics and can be used in thinner thicknesses than ceramic restorative materials. Also, based on the improved long-term stability, the transfer into the definitive restoration can be divided into multiple treatment steps. This article presents different clinical cases with minimally invasive indications for CAD/CAM-fabricated temporary restorations for the pretreatment of complex cases.

CAD/CAM-generated high-density polymer restorations for the pretreatment of complex cases: a case report.

Purpose: All-ceramic abutments are employed increasingly often in implant dentistry for esthetic reasons In vitro stress testing is required to evaluate the suitability of these constructions, especially in load-bearing posterior regions The purpose of the study was to assess and compare the fatigue and fracture resistance of one- and two-piece computer-aided design/computer-assisted manufacture (CAD/CAM) zirconia implant abutments with an internal-hex connection and prefabricated commercially available zirconia stock abutments Materials and Methods: Twenty-one abutment-crown specimens were prepared for three test groups Control group 1 (SZ) included specimens with unprepared stock zirconia abutments, test group 2 (OP) included one-piece CAD/CAM zirconia abutments, and test group 3 (TP) included two-piece CAD/CAM zirconia abutments All 21 specimens underwent thermocycling and fatigue testing Finally, all specimens were tested for fracture resistance with a universal testing machine The maximum load was applied to the tapered occlusal area of each crown at a 30-degree angle and a crosshead speed of 05 mm/min until the implant–abutment connection failed Kolmogorov-Smirnov, Shapiro-Wilk, and post-hoc Scheffe tests were used for statistical analysis Results: All abutments in groups SZ and OP fractured into two or more pieces after fracture resistance testing None of the TP abutments displayed apparent disintegration, but failure was evidenced by bending of the retention screw OP abutments (2321 ± 298 N) and SZ abutments (2518 ± 232 N) showed lower fracture loads than the TP abutments (2914 ± 278 N) However, only the difference between the OP and TP groups was statistically significant Further load-displacement analyses corroborated the higher mechanical stability of the TP abutments Conclusion: Superior resistance was achieved for two-piece hybrid CAD/CAM zirconia abutments These abutments might be clinically beneficial in high-load areas, such as premolar and molar regions

/pdf/in-vitro-fatigue-and-fracture-resistance-of-one-and-two-2jzhbntvj1.pdf

Florian Beuer

Papers

10-year Survival Evaluation for Glass-fiber–supported Postendodontic Restoration: A Prospective Observational Clinical Study

Accuracy of five intraoral scanners compared to indirect digitalization.

Is adhesive cementation of endodontic posts necessary

CAD/CAM-generated high-density polymer restorations for the pretreatment of complex cases: a case report.

In vitro fatigue and fracture resistance of one- and two-piece CAD/CAM zirconia implant abutments.