Biaxial flexural strength of various CAD-CAM glass-ceramic materials

Layali Alakkad; Aikaterini Kostagianni; Matthew Finkelman; Ahmed Maawadh; Ala Ali; Aikaterini Papathanasiou

Biaxial flexural strength of various CAD-CAM glass-ceramic materials

Am J Dent. 2021 Apr;34(2):91-96.

Authors

Layali Alakkad¹, Aikaterini Kostagianni², Matthew Finkelman³, Ahmed Maawadh⁴, Ala Ali², Aikaterini Papathanasiou⁵

Affiliations

¹ King Fahad Hospital, Ministry of Health, Saudi Arabia.
² Advanced Education in Esthetic and Operative Dentistry Program, Department of Prosthodontics, School of Dental Medicine, Tufts University, Boston, Massachusetts, USA.
³ Division of Biostatistics and Experimental Design, School of Dental Medicine, Tufts University, Boston, Massachusetts, USA.
⁴ Department of Restorative Dental Science, College of Dentistry, King Saud University, Riyadh, Saudi Arabia.
⁵ Advanced Education in Esthetic and Operative Dentistry Program, Department of Prosthodontics, School of Dental Medicine, Tufts University, Boston, Massachusetts, USA, Aikaterini.Papathanasiou@tufts.edu.

PMID: 33940666

Abstract

Purpose: To evaluate and compare the flexural strength of three CAD-CAM glass-ceramic materials and to investigate the effect of various surface treatments on their flexural strength.

Methods: 120 rectangular specimens were fabricated from three different types of CAD-CAM ceramic blocks and were divided into three groups: zirconia-reinforced lithium silicate (Celtra Duo, Group 1), leucite-reinforced glass-ceramic (IPS Empress CAD, Group 2), and lithium disilicate ceramic (IPS e.max CAD, Group 3). Dimensions of the specimens were standardized to 14.5x12.5 mm and 1.5 mm thickness. Specimens in each group were randomized into four subgroups. The first subgroup (NS) did not undergo any surface treatment; the second subgroup (P) underwent polishing only; the third subgroup (G) underwent glazing only; and the fourth subgroup (PG) underwent both polishing and glazing surface treatments. Biaxial flexural strength (FS) testing was performed until fracture occurred; FS was calculated in MPa. All analyses were performed using SPSS version 24.

Results: Group NS2 showed the lowest FS (89.34 ± 25.30 MPa). Group PG3 showed a significantly higher FS (365.38 ± 52.52 MPa) than Group P3 (268.15 ± 48.34). There was a statistically significant difference among the material groups for each surface treatment: IPS e.max CAD showed the highest FS, which was significantly greater than that of both Celtra Duo and IPS Empress CAD. The combination of polishing and glazing surface treatment resulted in significantly higher flexural strength than polishing alone for all three materials tested. For each material, no significant difference was found between the following surface treatments: control and polishing-only surface treatments; glazing-alone and the combination of polishing and glazing surface treatments. For each surface treatment, Celtra Duo showed significantly lower flexural strength than IPS e.max CAD. However, it displayed higher flexural strength than IPS Empress CAD, although the difference was only significant for glazing and the combination of polishing and glazing.

Clinical significance: This study provides the clinician with an estimate of the flexural strength of glass-ceramic materials and shows how various surface treatments affect their strength.

MeSH terms

Ceramics*
Computer-Aided Design
Flexural Strength*
Materials Testing
Surface Properties