Peel strength and interfacial characterization of maxillofacial silicone elastomers bonded to titanium.
To investigate the effect of three adhesive primers on the morphology, chemistry and peel bond strength of two maxillofacial silicone elastomers with commercially pure titanium (cpTi).



The effect of three primers (PR2:A-304 Primer/A-320 Bonding Enhancer, PR3:Super Bond, and PR4:Super Glue) on cpTi morphology and chemistry were studied by reflected light polarized microscopy (RPOLM) and reflection Fourier-transform infrared microspectroscopy (RFTIRM). For testing the bond strength between two elastomers (EL1:MDX4-4210, EL2:A-2006) and primed cpTi surfaces, a 90° T peel test was performed (PBS), using as reference EL1, EL2 specimens bonded to heat-cured poly(methyl methacrylate) resin (PMMA) primed with A-330G primer (PR1). Failure modes were analyzed under a stereomicroscope, and the percentage of remaining silicone (RS%) on cpTi and PMMA were calculated by image analysis. Scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDX) was used to investigate representative failure patterns on cpTi. Data were analyzed with Weibull analysis, ANOVA plus post hoc tests, and Pearson correlation coefficient (a=0.05).



Thick-irregular (PR2), thin-smooth (PR3), and uniform-porous (PR4) films were identified on cpTi by RPOLM. RFTIRM revealed: a strong peak of Si-O-Si with a distribution following the outline of the image (PR2); COO-M groups developed, but unevenly distributed (PR3); and reduction in CC groups due to in situ polymerization (PR4). Following PBS, the ranking of the statistical significant differences in Weibull scale parameter (σ0) of the EL1 group was PMMA_PR1>cpTi_PR2,cpTi_PR3>cpTi_PR4, whereas for the EL2 group cpTi_PR2>PMMA_PR1>cpTi_PR4,cpTi_PR3. For RS%, the ranking in the EL1 group was: PMMA_PR1>cpTi_PR2>cpTi_PR3>cpTi_PR4, and in the EL2 cpTi_PR2>cpTi_PR3>cpTi_PR4,PMMA_PR1. There was no statistically significant correlation between PBS and RS%, with the exception of EL1_PMMA_PR1. In all groups mixed failure modes were found by SEM/EDX.



Although there is evidence of bonding with cpTi, there are important differences among the primer/elastomer combination that may affect the clinical performance of these materials.
Department of Prosthodontics, National and Kapodistrian University of Athens, School of Dentistry, Athens, Greece. Electronic address: iartopoulou@gmail.com.
Ioli Ioanna
II
Artopoulou
Section of Maxillofacial Prosthodontics and Oncologic Dentistry, Department of Head and Neck Surgery, Division of Surgery, The University of Texas MD Anderson Cancer Center, Houston, USA.
Mark S
MS
Chambers
Department of Biomaterials, National and Kapodistrian University of Athens, School of Dentistry, 2 Thivon Str., 11 527 Goudi, Athens, Greece.
Spiros
S
Zinelis
Department of Biomaterials, National and Kapodistrian University of Athens, School of Dentistry, 2 Thivon Str., 11 527 Goudi, Athens, Greece.
George
G
Eliades
D001840:Dental Bonding; D003738:Dental Cements; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D012826:Silicone Elastomers; D013499:Surface Properties; D013718:Tensile Strength; D014025:Titanium
D003738:Dental Cements; D012826:Silicone Elastomers; D014025:Titanium
Bond strength; FTIR; Maxillofacial silicone elastomer; SEM/EDX; cpTi