Optimized Zirconia 3D Printing Using Digital Light Processing with Continuous Film Supply and Recyclable Slurry System

High-Performance Polymer-derived Ceramics in LCD 3D Printing

This study demonstrates the fabrication of high-strength, lightweight polymer-derived ceramics (PDCs) using silicon oxycarbide (SiOC)-precursor formulations with liquid crystal display (LCD) vat photopolymerization (VPP) technology. Complex geometries, such as gyroids and stochastic lattices, are successfully 3D-printed and evaluated under varying feature thicknesses and pyrolysis temperatures (800 °C and 1200 °C). Photorheology and thermogravimetric analysis (TGA) validated the efficient curing and pyrolysis characteristics of a printable precursor formulation based on vinyl methoxysiloxane homopolymer (VMM-010), which demonstrated rapid curing, low viscosity, and compatibility with LCD 3D printing, ensuring precise layering and efficient resin removal. Micro-CT scans confirmed its structural integrity and absence of voids, even in relatively thick components (≈3 mm). The VMM-based PDC lattices achieved specific compressive strengths up to 9.4 MPa g⁻¹ cm3, a 50-fold improvement over comparable lattices produced with a high-porosity SiOC PDC, and exceptional high-temperature stability, maintaining structural integrity after 2 h at 1500 °C. Compositional analysis revealed lower free carbon content and improved ceramic phase formation, driving the enhanced mechanical and thermal performance of the VMM-based ceramic. These findings underscore the scalability, reliability, and superior performance of VMM formulations for LCD 3D printing, offering new possibilities for high-performance ceramic applications in aerospace, automotive, and biomedical industries.

Accuracy and adaptation of 3D printed zirconia crowns: A review of current methodologies

STATEMENT OF PROBLEM

The 3-dimensional (3D) printing of polymers and metals is a reality in dentistry; however, despite the advances, the printing of ceramic crowns is still in its infancy.

PURPOSE

The purpose of this review was to examine studies that evaluated the accuracy and adaptation of zirconia crowns produced by additive manufacturing with an emphasis on 3D printing.

MATERIAL AND METHODS

Electronic databases (Embase, PubMed, SCOPUS, Web of Science, and Google Scholar) were searched between February and March 2024 using the keywords zirconium, zirconium oxide, crowns, 3D printing, additive manufacturing, stereolithography, vat polymerization, digital light processing, nanoparticle jetting, lithography-based ceramic manufacturing, accuracy, trueness, and precision, augmented by manual searches. The eligibility criteria included articles only in English and published in peer-reviewed journals.

RESULTS

The database search resulted in 136 articles, reduced to 52 after duplicates were eliminated. After abstract reading and the application of the exclusion criteria, 14 articles remained to be read in full. All studies showed a low risk of bias.

CONCLUSIONS

The main printing techniques for zirconia crowns include material jetting and vat polymerization, which generally allow crown manufacture with accuracy and marginal adaptation within the clinically accepted range and close to that of milled crowns.

Environmental sustainability related to dental materials and procedures in prosthodontics: A critical review

This article aims to review the status, challenges, and directions of environmentally sustainable oral healthcare by focusing on the dental materials and procedures used in prosthodontics. Sustainable development is a global priority and requires a systemic, integrative approach from all sectors of society. The oral healthcare sector is responsible for substantial greenhouse emissions throughout its value chain, including raw material extraction, industrial production, supply distribution, clinical practice, and management of waste. Of all dental specialties, prosthodontics has been one of the main generators of carbon emissions by fabricating a single product such as dentures or crowns in multiple steps. Dental prosthetic procedures involve chemicals and materials such as polymers, ceramics, metals, gypsum, and wax, which are often used in large quantities and for a single use. Thus, environmental risks and socioeconomic burdens can result from residuals and improper disposal, as well as waste and the embedded costs of unused materials retained by manufacturers, retail suppliers, dental laboratories, and dental clinics. To mitigate the environmental impact generated by conventional prosthodontics, we urge awareness and the adoption of sustainable good practices in the daily routine of dental clinics and laboratories. Capacity building and investment in a circular economy and digital technology can reduce the carbon footprint of prosthetic dentistry and improve the quality of life for present and future generations.

Fracture toughness and hardness of in-office, 3D-printed ceramic brackets

OBJECTIVES

Three-dimensional (3D) printing technology is a promising manufacturing technique for fabricating ceramic brackets. The aim of this research was to assess fundamental mechanical properties of in-office, 3D printed ceramic brackets.

MATERIALS AND METHODS

3D-printed zirconia brackets, commercially available polycrystalline alumina ceramic brackets (Clarity, 3 M St. Paul, MN) and 3D-printed customized polycrystalline alumina ceramic ones (LightForce™, Burlington, Massachusetts) were included in this study. Seven 3D printed zirconia brackets and equal number of ceramic ones from each manufacturer underwent metallographic grinding and polishing followed by Vickers indentation testing. Hardness (HV) and fracture toughness (K1c) were estimated by measuring impression average diagonal length and crack length, respectively. After descriptive statistics calculation, group differences were analysed with 1 Way ANOVA and Holm Sidak post hoc multiple comparison test at significance level α = .05.

RESULTS

Statistically significant differences were found among the materials tested with respect to hardness and fracture toughness. The 3D-printed zirconia proved to be less hard (1261 ± 39 vs 2000 ± 49 vs 1840 ± 38) but more resistant to crack propagation (K1c = 6.62 ± 0.61 vs 5.30 ± 0.48 vs 4.44 ± 0.30 MPa m^1/2 ) than the alumina brackets (Clarity and Light Force respectivelty). Significant differences were observed between the 3D printed and the commercially available polycrystalline alumina ceramic brackets but to a lesser extent.

CONCLUSIONS

Under the limitations of this study, the 3D printed zirconia bracket tested is characterized by mechanical properties associated with advantageous orthodontic fixed appliances traits regarding clinically relevant parameters.

Digital Light Processing of Zirconia Suspensions Containing Photocurable Monomer/Camphor Vehicle for Dental Applications

This study reports the utility of solid camphor as a novel diluent in photocurable hexanediol diacrylate (HDDA) monomer to manufacture 4 mol% yttria partially stabilized zirconia (4Y-PSZ) components for dental applications by digital light processing (DLP). The use of a 65 wt% HDDA-35 wt% camphor solution allowed 4Y-PSZ suspensions to have reasonably low viscosities (1399 ± 55.8 mPa·s at a shear rate of 75 s-1), measured by a cone/plate viscometer, at a high solid loading of 48 vol%, where 4Y-PSZ particles prepared by calcination of as-received 4Y-PSZ granules, followed by a ball-milling process, were used with assistance of a dispersant. These 4Y-PSZ suspensions could be successfully applied to our custom-made DLP machine for manufacturing 4Y-PSZ components. To this end, several processing parameters, including layer thickness of 4Y-PSZ suspension, UV illumination time for layer-by-layer photocuring process, and initial dimensions of 4Y-PSZ objects, were tightly controlled. As sintering temperature increased from 1300 °C to 1500 °C, relative density and grain size of 4Y-PSZ objects increased, and cubic phase content also increased. Thus, after sintering at the highest temperature of 1500 °C for 3 h, high mechanical properties (biaxial flexural strength = 911 ± 40.7 MPa, hardness = 1371 ± 14.4 Hv) and reasonably high optical transmittance (translucency parameter = 7.77 ± 0.32, contrast ratio = 0.809 ± 0.007), evaluated by a spectrophotometer, were obtained due to a high relative density (97.2 ± 1.38%), which would be useful for dental applications.