233 Effect of Air-abrasion and Thermocycling on Flexural Strength of Zirconia

Thursday, March 22, 2012: 2 p.m. - 3:15 p.m.
Presentation Type: Poster Session
F.O. ABI-RACHED1, C.G. GUEDES2, R. DEL CASTILLO-SALMERÓN3, J.I. ROSALES-LEAL3, J.G.S.P. ALMEIDA2, and R.G. FONSECA1, 1Department of Dental Materials and Prosthodontics, Araraquara Dental School, Univ Estadual Paulista - UNESP, Araraquara - São Paulo, Brazil, 2Department of Dentistry, School of Health Sciences, University of Brasília - UnB, Brasília - Distrito Federal, Brazil, 3Department of Stomatology, School of Dentistry, University of Granada, Granada, Spain
Objective: To evaluate the influence of air-abrasion and thermocycling on the flexural strength of a commercially available zirconia (Y-TZP).   

Method: Bar-shaped specimens were made from Cercon (Dentsply) and received one of the following air-abrasion conditions (n=20): (1) as-sintered (control); (2) 50 µm Al2O3 particles; (3) 125 µm Al2O3 particles; (4) 250 µm Al2O3 particles and (5) 110 µm silica-modified Al2O3 particles (Rocatec Plus - 3M ESPE). Half of the specimens were submitted to the mechanical testing after thermocycling (10,000 cycles, 5-55 ºC). Three-point flexural strength test was conducted using a mechanical testing machine (1.0 mm/min). Data were analyzed by 2-way ANOVA and Tukey HSD post hoc tests (α=.05).

Result: The Y-TZP flexural strength was affected (P<.01) by air-abrasion condition and thermocycling (Table 1).

Table 1. Flexural strength mean values (MPa), standard deviations (±) and statistical results


No thermocycling



1084.7 ± 159.0 Aa

863.1 ± 173.9 Ab

50 µm Al2O3

1126.3 ± 284.5 Aa 

892.6 ± 145.5 Ab 

125 µm Al2O3

1167.6 ± 199.8 Aa

911.2 ± 246.1 Ab

250 µm Al2O3

634.4 ± 113.6 Ba

774.8 ± 189.6 Aa

Rocatec Plus

1210.9 ± 238.7 Aa

967.6 ± 183.5 Ab

Different uppercase superscripted letters indicate significant differences in columns (P<.05)

Different lowercase superscripted letters indicate significant differences in rows (P<.05)

Conclusion: Flexural strength of zirconia (Y-TZP) was affected only by air-abrasion with larger Al2O3 particles (250 µm) in the non-thermocycled group. Except for the group abraded with 250 µm Al2Oparticles, thermocycling significantly decreased the flexural strength of all groups.

Keywords: Aging, Ceramics and flexural strength