Effect of water storage on the microtensile bond strength of composite resin to dentin using experimental rigid rod polymer modified primers.
OBJECTIVE
Rigid rod polymers (RRPs) can be used as reinforcing fillers, comparable to inorganic particulate fillers, with the exception that RRP fillers can be dissolved from the surface, thus potentially improving their adhesion to polymer matrix. This study evaluated the effect of water storage on the microtensile bond strength (μTBs) of composite resin to dentin using experimental RRP modified primers.


METHODS
Experimental primers were fabricated by dissolving RRP (Parmax, 1240, Mississippi PolymerTechnologies, USA) into dichloromethane (DCM) and mixing it with the monomers bis[2-(methacryloyloxy)- ethyl]phosphate (BMEP) and 3(methacryloyloxy)-propyltrimethoxysilane (MPS). Three experimental primers were prepared with different proportions for each dentin substrate. The same commercial etch-and-rinse adhesive was used with each group. Surfaces of human molars were wet ground occlusally. The experimental primers were applied onto dentin prior to light polymerization of the incremental composite resin buildup. Teeth were sectioned after 48 h, 6 months, or 12 months of water storage and then tested with the microtensile tester (Dillon Quantrol, Bisco).


RESULTS
ANOVA revealed that the solvent:monomer ratio and RRP had a significant effect (p < 0.05) on bond strength in 48-h groups (3-way ANOVA). Increasing the solvent:monomer ratio and addition of RRP into primers increased the μTBS values. However, long-term water storage decreased the μTBS values in the high solvent:monomer ratio group. In the other groups, water storage did not decrease the μTBS values.


CONCLUSIONS
One-year water storage lowered the dentin bond strength obtained using the primer with a high solvent:monomer ratio, whereas no decrease of bond strength was observed for the other study groups or for the control group.
Department of Biomaterials Science, University of Turku, Turku, Finland. anmavu@utu.fi
Anne-Maria
AM
Vuorinen
Scott R
SR
Dyer
Pekka K
PK
Vallittu
Lippo V
LV
Lassila
D000134:Acid Etching, Dental / Q000379:methods; D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D003188:Composite Resins; D001840:Dental Bonding / Q000379:methods*; D003799:Dental Stress Analysis; D003804:Dentin; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008422:Materials Testing; D008752:Methylene Chloride; D010755:Organophosphates / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D019279:Resin Cements / Q000737:chemistry*; D012821:Silanes / Q000737:chemistry; D012997:Solvents; D013718:Tensile Strength; D013997:Time Factors; D014867:Water; D055815:Young Adult
D003188:Composite Resins; D017220:Dentin-Bonding Agents; D010755:Organophosphates; D011108:Polymers; D019279:Resin Cements; D012821:Silanes; D012997:Solvents; C492568:propyltrimethoxysilane; D014867:Water; D008752:Methylene Chloride