640 Efficacy of silane after thermal-fatigue on bond-strengths degradation to zirconia

Friday, March 23, 2012: 8 a.m. - 9:30 a.m.
Presentation Type: Oral Session
J. PHARK, Herman Ostrow School of Dentistry - Divison of Restorative Sciences, University of Southern California, Los Angeles, CA, N. SARTORI, Universidade Federal de Santa Catarina, Florianopolis, Santa Catarina, Brazil, L. DALMAGRO PERUCHI, University of Southern California, São José, Santa Catarina, Brazil, A. SADAN, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, and S. DUARTE, Division of Restorative Sciences, University of Southern California, Los Angeles, CA

Objectives : To evaluate the influence of artificial aging by thermocycling on deterioration of microtensile bond-strength (μTBS) to zirconia.

Methods: Pre-sintered zirconia blocks (e.max ZirCAD, Ivoclar) were cut (14.5x15.5x7 mm) and fully sintered according to manufacturer's instruction. After air-abrasion with Al2O3 particles, three different silanes were tested: 1. Clearfil Ceramic Primer (CLE; Kuraray); 2. Monobond Plus (MB; Ivoclar); 3. Z Prime Plus (ZP; Bisco), and control group (CO) without silane application. A dual-cure resin cement (Clearfil Esthetic, Kuraray) was standardized for all experimental groups. Each group was assigned into three subgroups subjected to different thermal fatigue as: 5,000 thermal cycles (5K), 20,000 thermal cycles (20K), or no thermal cycles (NA) of artificial aging. Thermocycling was performed at 5°C and 55°C (SD-Mechatronik). All specimens were sectioned with a precision saw and 0.64mm2 sticks obtained.  The sticks were tested for μTBS, using a universal testing machine (Instron) at a crosshead speed of 0.5 mm/min. The data were submitted to Kruskal-Wallis and Mann-Whitney Tests (α=0.05).

Results: (Pre-testing failure/number of specimens) Mean±SD in MPa

Artificial aging

No aging

5,000 cycles

20,000 cycles


(0/68) 52.47±11.1aA

(0/66) 24.54±5.3bA

(0/71) 24.19±4.9bA


(0/68) 43.94±13.9aB

(0/70) 26.43±6.4bA

(0/71) 22.82±6.3cA


(0/72) 20.13±7.1aC

(12/69) 4.88±3.6bB

(52/71) 1.00±2.0cB


(70/70) 0.00±0.0aD

(69/69) 0.00±0.0aC

(67/67) 0.00±0.0aB

Means with same lower-case letters, in the same row, are not statistically different. Means with same upper-case letters, in same column, are not statistically different.

Conclusions: Thermocycling significantly reduces μTBS to zirconia. CLE and MB were able to withstand intense thermal fatigue, without pre-testing failure. Silane is essential for stabile long-term bond-strength to zirconia.

Keywords: Adhesion, Cements, Ceramics and Dental materials