Trueness and precision of 3D-printed versus milled monolithic zirconia crowns: An in vitro study

Henriette Lerner; Katalin Nagy; Nicola Pranno; Fernando Zarone; Oleg Admakin; Francesco Mangano

doi:10.1016/j.jdent.2021.103792

Trueness and precision of 3D-printed versus milled monolithic zirconia crowns: An in vitro study

J Dent. 2021 Oct:113:103792. doi: 10.1016/j.jdent.2021.103792. Epub 2021 Sep 2.

Authors

Henriette Lerner¹, Katalin Nagy², Nicola Pranno³, Fernando Zarone⁴, Oleg Admakin⁵, Francesco Mangano⁶

Affiliations

¹ Department of Oral Surgery, University of Szeged, Szeged, Hungary. Electronic address: h-lerner@web.de.
² Department of Oral Surgery, University of Szeged, Szeged, Hungary. Electronic address: katalin.nagy@universityszeged.com.
³ Department of Oral and Maxillofacial Sciences, Sapienza University, Rome, Italy. Electronic address: nicola.pranno@uniroma1.it.
⁴ Department of Neurosciences, Reproductive and Odontostomatological Sciences, University Federico II, Naples, Italy. Electronic address: fernandozarone@mac.com.
⁵ Department of Pediatric, Preventive Dentistry and Orthodontics, Sechenov First State Medical University, Moscow, Russia. Electronic address: admakin1966@mail.ru.
⁶ Department of Pediatric, Preventive Dentistry and Orthodontics, Sechenov First State Medical University, Moscow, Russia. Electronic address: francescoguidomangano@gmail.com.

PMID: 34481929
DOI: 10.1016/j.jdent.2021.103792

Abstract

Purpose: To compare the trueness and precision of 3D-printed versus milled monolithic zirconia crowns (MZCs).

Methods: A model of a maxilla with a prepared premolar was scanned with an industrial scanner (ATOSQ®, Gom) and an MZC was designed in computer-assisted-design (CAD) software (DentalCad®, Exocad). From that standard tessellation language (STL) file, 10 MZCs (test) were 3D-printed with a Lithography-based Ceramic Manufacturing (LCM) printer (CerafabS65®, Lithoz) and 10 MZCs (control) were milled using a 5-axis machine (DWX-52D®, DGShape). All MZCs were sintered and scanned with the aforementioned scanner. The surface data of each sample (overall crown, marginal area, occlusal surface) were superimposed to the original CAD file (ControlX®, Geomagic) to evaluate trueness: (90-10)/2, absolute average (ABS AVG) and root mean square (RMS) values were obtained for test and control groups (MathLab®, Mathworks) and used for analysis. Finally, the clinical precision (marginal adaptation, interproximal contacts) of test and control MZCs was investigated on a split-cast model printed (Solflex350®, Voco) from the CAD project, and compared.

Results: The milled MZCs had a significantly higher trueness than the 3D-printed ones, overall [(90-10)/2 printed 37.8 µm vs milled 21.2 µm; ABS AVG printed 27.2 µm vs milled 15.1 µm; RMS printed 33.2 µm vs milled 20.5 µm; p = 0.000005], at the margins [(90-10)/2 printed 25.6 µm vs milled 12.4 µm; ABS AVG printed 17.8 µm vs milled 9.4 µm; RMS printed 22.8 µm vs milled 15.6 µm; p= 0.000011] and at the occlusal level [(90-10)/2 printed 50.4 µm vs milled 21.9 µm; ABS AVG printed 29.6 µm vs milled 14.7 µm; RMS printed 38.9 µm vs milled 22.5 µm; p = 0.000005]. However, with regard to precision, both test and control groups scored highly, with no significant difference either in the quality of interproximal contact points (p = 0.355) or marginal closure (p = 0.355).

Conclusions: Milled MZCs had a statistically higher trueness than 3D-printed ones; all crowns, however, showed high precision, compatible with the clinical use.

Clinical significance: Although milled MZCs remain more accurate than 3D-printed ones, the LCM technique seems able to guarantee the production of clinically precise zirconia crowns.

Keywords: 3D printing; Clinical precision; Milling; Monolithic zirconia crowns; Trueness.

MeSH terms

Computer-Aided Design
Crowns*
Dental Prosthesis Design
Printing, Three-Dimensional
Zirconium*

Substances

Zirconium
zirconium oxide