Comparison of wear and fracture resistance of additively and subtractively manufactured screw-retained, implant-supported crowns

Almira Ada Diken Türksayar; Münir Demirel; Mustafa Borga Donmez; Emin Orkun Olcay; Tan Fırat Eyüboğlu; Mutlu Özcan

doi:10.1016/j.prosdent.2023.06.017

Comparison of wear and fracture resistance of additively and subtractively manufactured screw-retained, implant-supported crowns

J Prosthet Dent. 2023 Jul 19:S0022-3913(23)00418-3. doi: 10.1016/j.prosdent.2023.06.017. Online ahead of print.

Authors

Almira Ada Diken Türksayar¹, Münir Demirel², Mustafa Borga Donmez³, Emin Orkun Olcay⁴, Tan Fırat Eyüboğlu⁵, Mutlu Özcan⁶

Affiliations

¹ Assistant Professor, Department of Prosthodontics, Faculty of Dentistry, Biruni University, Istanbul, Turkey; and Guest Researcher, ADMiRE Research Center-Additive Manufacturing, Intelligent Robotics, Sensors and Engineering, School of Engineering and IT, Carinthia University of Applied Sciences, Villach, Austria.
² Assistant Professor, Oral and Dental Health, Vocational School, Biruni University, Istanbul, Turkey.
³ Associate Professor, Department of Prosthodontics, Faculty of Dentistry, Istinye University, Istanbul, Turkey; and Visiting Researcher, Department of Reconstructive Dentistry and Gerodontology, School of Dental Medicine, University of Bern, Bern, Switzerland. Electronic address: mustafa-borga.doenmez@unibe.ch.
⁴ Assistant Professor, Department of Prosthodontics, Faculty of Dentistry, Istinye University, Istanbul, Turkey.
⁵ Associate Professor, Department of Endodontics, Istanbul Medipol University, Faculty of Dentistry, Istanbul, Turkey.
⁶ Professor and Head, Clinic of Masticatory Disorders and Dental Biomaterials, Center for Dental Medicine, University of Zurich, Zurich, Switzerland.

PMID: 37479623
DOI: 10.1016/j.prosdent.2023.06.017

Abstract

Statement of problem: Additively manufactured resins indicated for fixed definitive prostheses have been recently marketed. However, knowledge on their wear and fracture resistance when fabricated as screw-retained, implant-supported crowns and subjected to artificial aging is limited.

Purpose: The purpose of this in vitro study was to evaluate the volume loss, maximum wear depth, and fracture resistance of screw-retained implant-supported crowns after thermomechanical aging when fabricated using additively and subtractively manufactured materials.

Material and methods: Two additively manufactured composite resins (Crowntec [CT] and VarseoSmile Crown Plus [VS]) and 2 subtractively manufactured materials (1 reinforced composite resin, Brilliant Crios [BC] and 1 polymer-infiltrated ceramic network, Vita Enamic [EN]) were used to fabricate standardized screw-retained, implant-supported crowns. After fabrication, the crowns were cemented on titanium base abutments and then tightened to implants embedded in acrylic resin. A laser scanner with a triangular displacement sensor (LAS-20) was used to digitize the preaging state of the crowns. Then, all crowns were subjected to thermomechanical aging (1.2 million cycles under 50 N) and rescanned. A metrology-grade analysis software program (Geomagic Control X 2020.1) was used to superimpose postaging scans over preaging scans to calculate the volume loss (mm³) and maximum wear depth (mm). Finally, all crowns were subjected to a fracture resistance test. Fracture resistance and volume loss were evaluated by using 1-way analysis of variance and Tukey Honestly significant difference (HSD) tests, whereas the Kruskal-Wallis and Dunn tests were used to analyze maximum wear depth. Chi-square tests were used to evaluate the Weibull modulus and characteristic strength data (α=.05).

Results: Material type affected the tested parameters (P<.001). CT and VS had higher volume loss and maximum wear depth than BC and EN (P<.001). EN had the highest fracture resistance among tested materials (P<.001), whereas BC had higher fracture resistance than CT (P=.011). The differences among tested materials were not significant when the Weibull modulus was considered (P=.199); however, VE had the highest characteristic strength (P<.001).

Conclusions: Additively manufactured screw-retained, implant-supported crowns had higher volume loss and maximum wear depth. All materials had fracture resistance values higher than the previously reported masticatory forces of the premolar region; however, the higher characteristic strength of the subtractively manufactured polymer-infiltrated ceramic network may indicate its resistance to mechanical complications.