Surface characterization of feldspathic ceramic using ATR FT-IR and ellipsometry after various silanization protocols.
OBJECTIVE
This study characterized the feldspathic ceramic surfaces after various silanization protocols.


METHODS
Ceramic bars (2 mm × 4 mm × 10 mm) (N = 18) of feldpathic ceramic (VM7, VITA Zahnfabrik) were manufactured and finished. Before silane application, the specimens were ultrasonically cleaned in distilled water for 10 min. The ceramic specimens were randomly divided into nine groups (N = 2 per group) and were treated with different silane protocols. MPS silane (ESPE-Sil, 3M ESPE) was applied to all specimens and left to react at 20°C for 2 min (G20). After drying, the specimens were subjected to heat treatment in an oven at 38°C (G38), 79°C (G79) or 100°C (G100) for 1 min. Half of the specimens of each group were rinsed with water at 80°C for 15s (G20B, G38B, G79B, G100B). The control group (GC) received no silane. Attenuated total reflection infrared Fourier transform analysis (ATR FT-IR) was performed using a spectrometer. Thickness of silane layer was measured using a spectroscopic ellipsometer working in the λ = 632.8 nm (He-Ne laser) at 70° incidence angle. Surface roughness was evaluated using an optical profilometer. Specimens were further analyzed under the Scanning Electron Microscopy (SEM) to observe the topographic patterns.


RESULTS
ATR FT-IR analysis showed changes in Si-O peaks with enlarged bands around 940 cm(-1). Ellipsometry measurements showed that all post-heat treatment actions reduced the silane film thickness (30.8-33.5 nm) compared to G20 (40 nm). The groups submitted to rinsing in hot water (B groups) showed thinner silane films (9.8-14.4 nm) than those of their corresponding groups (without washing) (30.8-40 nm). Profilometer analysis showed that heat treatments (Ra ≈ 0.10-0.19 μm; Rq ≈ 0.15-0.26 μm) provided a smoother surface than the control group (Ra ≈ 0.48 μm; Rq ≈ 0.65 μm). Similar patterns were also observed in SEM images.


CONCLUSIONS
Heat treatment after MPS silane application improved the silane layer network. Rinsing with boiling water eliminated the outmost unreacted regions of the silane yielding to thinner film thicknesses.
São Paulo State University, Department of Prosthodontics and Dental Materials, São José dos Campos, Brazil. joserenatocq@hotmail.com
José Renato Cavalcanti
JR
Queiroz
Paula
P
Benetti
Mutlu
M
Ozcan
Luiz Fernando Cappa
LF
de Oliveira
Alvaro
A
Della Bona
Fernando Eidi
FE
Takahashi
Marco Antonio
MA
Bottino
D000538:Aluminum Silicates / Q000737:chemistry*; D017554:Carbon Compounds, Inorganic / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry; D003775:Dental Polishing / Q000295:instrumentation; D003776:Dental Porcelain / Q000737:chemistry*; D006358:Hot Temperature; D006801:Humans; D006813:Humidity; D054020:Lasers, Gas; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D055620:Optical Phenomena; D017680:Potassium Compounds / Q000737:chemistry*; D012031:Refractometry; D012821:Silanes / Q000737:chemistry*; D017655:Silicon Compounds / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013057:Spectrum Analysis; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
D000538:Aluminum Silicates; D017554:Carbon Compounds, Inorganic; D008689:Methacrylates; D017680:Potassium Compounds; D012821:Silanes; D017655:Silicon Compounds; C556625:VITA VM7; D014867:Water; D003776:Dental Porcelain; C016447:feldspar; C017492:methacryloxypropyltrimethoxysilane; C022088:silicon carbide