The evaluation of four conditioners for glass ionomer cements using field-emission scanning electron microscopy.
OBJECTIVE
The purpose of this study was to evaluate the GIC-dentine interface morphology using FE-SEM after four different conditioners (Ketac Conditioner, Dentin Conditioner, Cavity Conditioner, and an experimental conditioner K-930), used with two RM-GICs and one self-cured GIC, and to observe the effect with an AFM of the four different conditioners on the surface of polished human dentine.


METHODS
SAMPLE PREPARATION FOR FE-SEM: Twenty-four 1-mm thick dentine discs were obtained from superficial occlusal dentine of extracted human third molars, and finished with wet 600-grit SiC paper. The discs were treated for each of the GICs using the conditioners according to the manufacturers' instructions. The specimens were kept in tap water for 24 h at 37 degrees C, and then assigned for one of two observational techniques; a fractured technique and an acid-base technique. Specimens were mounted on aluminium stubs, gold sputter-coated and observed using a FE-SEM. SAMPLE PREPARATION FOR AFM: Four rectangular dentine blocks approximately 2mm(3) were prepared from two extracted human third molars, polished and finished with diamond paste down to 0.25 microm particle size. One half of each sample was treated with one of the conditioners according to the manufacturers' instructions, and the other half was not conditioned. The samples were stored in distilled water prior to AFM contact mode observation.


RESULTS
FE-SEM: All specimens of all materials demonstrated good adaptation to the underlying dentine. However, the specimens conditioned with K-930 showed increased demineralization and a thicker acid-base resistant layer (2.8-3.4 microm) compared with the others (1-2 microm). AFM: The images of conditioned specimens showed demineralization of peritubular dentine. Funneling of dentinal tubule orifices of specimens conditioned with K-930 was observed, and was also seen for the FE-SEM specimens.


CONCLUSIONS
The use of surface conditioners resulted in similar adaptation to the non-conditioned specimens at the GIC-dentine interface. All of the GICs demonstrated intimate adaptation to the dentine surface whether it was conditioned or not.
Tanumiharja
M
M
School of Dental Science, The University of Melbourne, 711 Elizabeth Street, Melbourne 3000, Victoria, Australia.
Burrow
M F
MF
Cimmino
A
A
Tyas
M J
MJ
D000134:Acid Etching, Dental; D000180:Acrylic Resins / Q000494:pharmacology; D019343:Citric Acid / Q000494:pharmacology; D001840:Dental Bonding; D003804:Dentin / Q000187:drug effects*; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning / Q000379:methods; D016369:Smear Layer; D013499:Surface Properties / Q000187:drug effects; D013501:Surface-Active Agents / Q000494:pharmacology
D000180:Acrylic Resins; D005899:Glass Ionomer Cements; D013501:Surface-Active Agents; D019343:Citric Acid; C006903:carbopol 940