Effect of glazing technique and firing on surface roughness and flexural strength of an advanced lithium disilicate

Y. Lu, A. M.O. Dal Piva*, I. Nedeljkovic, J. P.M. Tribst, A. J. Feilzer, C. J. Kleverlaan

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Objective: The objective of this study was to investigate the effects of glazing technique and firing on the surface roughness and flexural strength of an advanced lithium disilicate (ALD) and lithium disilicate (LD). Methods: Eight groups of bar-shaped specimens (1 mm × 1 mm × 12 mm, N=160, 20/group) were manufactured from ALD (CEREC Tessera, Dentsply Sirona) and LD (IPS e.max CAD, Ivoclar). The specimens were then submitted to various posttreatments: crystallization (c), crystallization followed by a second firing (c-r), crystallization with glaze in one step (cg), and crystallization followed by a glaze layer firing (c-g). Surface roughness was measured by means of a profilometer, and flexural strength was determined using a three-point bending test. Surface morphology, fractography, and crack healing analysis were conducted using scanning electron microscopy. Results: Refiring (c-r) did not affect the surface roughness (Ra) while applying glaze at both cg and c-g procedures increased the roughness. ALDc-g (442.3 ± 92.5 MPa) promoted higher strength than ALDcg (282.1 ± 64.4 MPa), whereas LDcg (402.9 ± 78.4 MPa) was stronger than LDc-g (255.5 ± 68.7 MPa). Refiring completely closed the crack in ALD, but it had a limited effect on LD. Conclusions: Two-step crystallization and glazing improved ALD strength compared to the one-step protocol. Refiring and one-step glazing do not increase LD’s strength, while two-step glazing has a negative effect. Clinical relevance: Besides both materials being lithium-disilicate glass ceramics, the glazing technique and firing protocol affected their roughness and flexural strength differently. A two-step crystallization and glazing should be the first choice for ALD, while for LD, glazing is optional and when necessary, should be applied in one-step.

Original languageEnglish
Pages (from-to)3917-3926
Number of pages10
JournalClinical Oral Investigations
Volume27
Issue number7
Early online date13 May 2023
DOIs
Publication statusPublished - Jul 2023

Bibliographical note

Funding Information:
Yuqing Lu appreciates China Scholarship Council (CSC) for her PhD grant (202006240085).

Publisher Copyright:
© 2023, The Author(s).

Funding

Yuqing Lu appreciates China Scholarship Council (CSC) for her PhD grant (202006240085).

Keywords

  • Ceramic
  • Dental finishing
  • Glass
  • Lithium disilicate
  • Scanning electron microscopy
  • Strength

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