Influence of ceramic surface conditioning and resin cements on microtensile bond strength to a glass ceramic.
BACKGROUND
It is not clear how different glass ceramic surface pretreatments influence the bonding capacity of various luting agents to these surfaces.


OBJECTIVE
The purpose of this study was to evaluate the microtensile bond strength (microTBS) of 3 resin cements to a lithia disilicate-based ceramic submitted to 2 surface conditioning treatments.


METHODS
Eighteen 5 x 6 x 8-mm ceramic (IPS Empress 2) blocks were fabricated according to manufacturer's instructions and duplicated in composite resin (Tetric Ceram). Ceramic blocks were polished and divided into 2 groups (n=9/treatment): no conditioning (no-conditioning/control), or 5% hydrofluoric acid etching for 20 seconds and silanization for 1 minute (HF + SIL). Ceramic blocks were cemented to the composite resin blocks with 1 self-adhesive universal resin cement (RelyX Unicem) or 1 of 2 resin-based luting agents (Multilink or Panavia F), according to the manufacturer's instructions. The composite resin-ceramic blocks were stored in humidity at 37 degrees C for 7 days and serially sectioned to produce 25 beam specimens per group with a 1.0-mm(2) cross-sectional area. Specimens were thermal cycled (5000 cycles, 5 degrees C-55 degrees C) and tested in tension at 1 mm/min. Microtensile bond strength data (MPa) were analyzed by 2-way analysis of variance and Tukey multiple comparisons tests (alpha=.05). Fractured specimens were examined with a stereomicroscope (x40) and classified as adhesive, mixed, or cohesive.


RESULTS
The surface conditioning factor was significant (HF+SIL > no-conditioning) (P<.0001). Considering the unconditioned groups, the microTBS of RelyX Unicem was significantly higher (9.6 +/- 1.9) than that of Multilink (6.2 +/- 1.2) and Panavia F (7.4 +/- 1.9). Previous etching and silanization yielded statistically higher microTBS values for RelyX Unicem (18.8 +/- 3.5) and Multilink (17.4 +/- 3.0) when compared to Panavia F (15.7 +/- 3.8). Spontaneous debonding after thermal cycling was detected when luting agents were applied to untreated ceramic surfaces.


CONCLUSIONS
Etching and silanization treatments appear to be crucial for resin bonding to a lithia disilicate-based ceramic, regardless of the resin cement used.
Pisani-Proenca
Jatyr
J
Department of Dental Materials, School of Dentistry, University of Granada, Granada, Spain.
Erhardt
Maria Carolina G
MC
Valandro
Luiz Felipe
LF
Gutierrez-Aceves
Guillermo
G
Bolanos-Carmona
Maria Victoria
MV
Del Castillo-Salmeron
Ramon
R
Bottino
Marco Antonio
MA
D002516:Ceramics / Q000737:chemistry*; D001840:Dental Bonding / Q000379:methods; D006858:Hydrofluoric Acid / Q000008:administration & dosage*; D019279:Resin Cements / Q000737:chemistry*; D012821:Silanes / Q000008:administration & dosage*; D013499:Surface Properties; D013718:Tensile Strength
D019279:Resin Cements; D012821:Silanes; C023506:Glass ceramics; D006858:Hydrofluoric Acid