en
Scientific article
Open access
English

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

Published inJournal of dentistry, vol. 124, 104221
Publication date2022-09
First online date2022-07-09
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.

eng
Keywords
  • 3D-printing
  • Milling
  • Resin pattern
  • Trueness
  • Computer-Aided Design
  • Crowns
  • Dental Marginal Adaptation
  • Dental Prosthesis Design / methods
  • Molar
Citation (ISO format)
ÇAKMAK, Gülce et al. Additive or subtractive manufacturing of crown patterns used for pressing or casting: a trueness analysis. In: Journal of dentistry, 2022, vol. 124, p. 104221. doi: 10.1016/j.jdent.2022.104221
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ISSN of the journal0300-5712
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