Towards a better understanding of the adhesion mechanism of resin-modified glass-ionomers by bonding to differently prepared dentin.
OBJECTIVE
The purpose of this study was to evaluate the bonding effectiveness of a resin-modified glass-ionomer (RMGI) to differently prepared dentin and how this restorative material interacts with these distinct substrates. Also the potential adhesion-promoting role of a polyalkenoic-acid conditioner was assessed.


METHODS
Forty-eight dentin surfaces were prepared from sound human molars and randomly distributed among 6 experimental groups. Fuji II LC (GC) was applied on bur-cut (100 μm diamond), fractured and Er:YAG laser-irradiated (200mJ, 10Hz, 31.4J/cm(2)) dentin with or without the beforehand application of the aqueous polyalkenoic-acid conditioner, Cavity Conditioner (GC). After 7 days of storage in water at 37 °C, specimens were prepared for microtensile bond strength testing (μTBS), as well as for TEM characterization of the resultant RMGI-dentin interface. Statistical analysis of the μTBS results was performed using ANOVA and Tukey's test (p<0.05).


RESULTS
The use of conditioner resulted in a significantly higher bond strength only when dentin was prepared by diamond bur (p<0.05). Laser irradiation induced micro-cracks on the dentin surface and led to the lowest bond strength, irrespective of the use of conditioner (p<0.05). Fuji II LC was able to partially demineralise (up to 2.0μm) and infiltrate bur-cut and fractured dentin, but no evident interaction was observed at the interface between the RMGI and laser-irradiated dentin.


CONCLUSIONS
Laser-induced surface modifications impaired the interaction of the RMGI with dentin, thereby negatively influencing its bonding effectiveness. The use of a polyalkenoic-acid conditioner remains crucial for the RMGI to bond effectively to bur-cut dentin.
Cardoso
Marcio Vivan
MV
Catholic University of Leuven, School of Dentistry, Oral Pathology and Maxillo-facial Surgery, Department of Conservative Dentistry, Leuven BIOMAT Research Cluster, Kapucijnenvoer, 7, B-3000 Leuven, Belgium.
Delmé
Katleen I M
KI
Mine
Atsushi
A
Neves
Aline de Almeida
Ade A
Coutinho
Eduardo
E
De Moor
Roeland J G
RJ
Van Meerbeek
Bart
B
D000180:Acrylic Resins / Q000737:chemistry; D000268:Adhesiveness; D001840:Dental Bonding; D003754:Dental High-Speed Equipment; D003799:Dental Stress Analysis / Q000295:instrumentation; D003804:Dentin / Q000293:injuries / Q000528:radiation effects / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry; D018130:Diamond / Q000737:chemistry; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006801:Humans; D053844:Lasers, Solid-State; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D019279:Resin Cements / Q000737:chemistry*; D012117:Resins, Synthetic / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013718:Tensile Strength; D013997:Time Factors; D014082:Tooth Fractures / Q000473:pathology; D019246:Tooth Preparation / Q000295:instrumentation / Q000379:methods*; D014867:Water / Q000737:chemistry
D000180:Acrylic Resins; D017220:Dentin-Bonding Agents; C079765:Fuji II LC cement; D005899:Glass Ionomer Cements; D019279:Resin Cements; D012117:Resins, Synthetic; D014867:Water; C006903:carbopol 940; D018130:Diamond