Additive or subtractive manufacturing of crown patterns used for pressing or casting: A trueness analysis

Gülce Çakmak; Mustafa Borga Donmez; Alfonso Rodrigues Cuellar; Çiğdem Kahveci; Martin Schimmel; Burak Yilmaz

doi:10.1016/j.jdent.2022.104221

Additive or subtractive manufacturing of crown patterns used for pressing or casting: A trueness analysis

J Dent. 2022 Sep:124:104221. doi: 10.1016/j.jdent.2022.104221. Epub 2022 Jul 9.

Authors

Gülce Çakmak¹, Mustafa Borga Donmez², Alfonso Rodrigues Cuellar³, Çiğdem Kahveci⁴, Martin Schimmel⁵, Burak Yilmaz⁶

Affiliations

¹ Department of Reconstructive Dentistry and Gerodontology, School of Dental Medicine, University of Bern, Freiburgstrasse 7, Bern 3007, Switzerland. Electronic address: guelce.cakmak@unibe.ch.
² Department of Prosthodontics, Istinye University Faculty of Dentistry, Istanbul, Turkey; Department of Reconstructive Dentistry and Gerodontology, School of Dental Medicine, University of Bern, Bern, Switzerland.
³ Periodontist, Private Practice, Mexico City, Mexico.
⁴ Department of Prosthodontics, Giresun University Faculty of Dentistry, Giresun, Turkey.
⁵ Department of Reconstructive Dentistry and Gerodontology, School of Dental Medicine, University of Bern, Bern, Switzerland; Privat-Docent extra muros, Division of Gerodontology and Removable Prosthodontics, University Clinics of Dental Medicine, University of Geneva, Geneva, Switzerland.
⁶ Department of Reconstructive Dentistry and Gerodontology, School of Dental Medicine, University of Bern, Bern, Switzerland; Department of Restorative, Preventive and Pediatric Dentistry, School of Dental Medicine, University of Bern, Bern, Switzerland; Division of Restorative and Prosthetic Dentistry, The Ohio State University College of Dentistry, OH, USA.

PMID: 35820503
DOI: 10.1016/j.jdent.2022.104221

Abstract

Objectives: To investigate the effect of subtractive and additive manufacturing techniques on the trueness of crown patterns used for pressing or casting.

Material and methods: A complete-coverage mandibular right first molar crown was designed in standard tessellation language (STL) format. This STL served as the control (C-STL) and was used to fabricate 30 crown patterns in 3D-printed resin (PR, ProArt Print Wax), millable wax suitable for casting (BW, ProArt CAD Wax Blue), and millable wax suitable for pressing (YW, ProArt CAD Wax Yellow) (n = 10). Subtractively manufactured patterns were fabricated by using a 5-axis milling unit (PrograMill PM7), while 3D-printed patterns were fabricated by using a digital light processing-based 3D printer (PrograPrint PR5; Ivoclar Vivadent, Schaan, Liechtenstein). All fabricated patterns were digitized by using an intraoral scanner (CEREC Primescan SW 5.2) to generate test-STLs. C-STL and test-STLs were transferred into a 3D analysis software (Medit Link v 2.4.4). Trueness evaluation was performed at 4 different surfaces (external, intaglio with margin, marginal, and intaglio without margin) and for complete scan meshes (overall) by using the root mean square (RMS) method. Data were analyzed with Kruskal-Wallis and Mann-Whitney U tests (α = .05).

Results: RMS values varied significantly at all surfaces (P < .001), except for marginal surface (P = .151). PR had the highest RMS values at external surface (P ≤ .007), intaglio surfaces (with (P ≤ .003) and without margin (P ≤ .005)), and overall (P ≤ .01). No significant differences were observed between YW and BW (P ≥ .223).

Conclusion: Patterns fabricated by using subtractive manufacturing exhibited high trueness. The deviation values, in general, were small, particularly at intaglio and marginal surfaces; thus, clinical difference in crown-fit may be negligible using additive or subtractive technique.

Clinical significance: The fit of definitive crowns may be similar when tested crown patterns are additively or subtractively manufactured. However, crowns fabricated by using tested 3D-printed resin patterns may require more chairside adjustments compared with those fabricated by using subtractively manufactured wax patterns.

Keywords: 3D-printing; Milling; Resin pattern; Trueness.

MeSH terms

Computer-Aided Design
Crowns
Dental Marginal Adaptation*
Dental Prosthesis Design* / methods
Molar