Abstract
Dental resin composites are commonly used in the restorative management
of teeth via adhesive bonding, which has evolved significantly over
the past few decades. Although current self-etch bonding systems
decrease the number of clinical steps, the acidic functional monomers
employed exhibit a limited extent of demineralization of enamel in
comparison to phosphoric acid etchants, and the resultant superficial
ionic interactions are prone to hydrolysis. This study evaluates the
etching of primers constituted with bis[2-(methacryloyloxy) ethyl]
phosphate (BMEP) of dental hard tissue, interfacial characteristics,
and inhibition of endogenous enzymes. We examine the incorporation of
2 concentrations of BMEP in the formulation of experimental primers
used with a hydrophobic adhesive to constitute a 2-step self-etching
bonding system and compare to a commercial 10–methacryloyloxydecyl
dihydrogen phosphate (10-MDP)–containing system. The interaction of
the primer with enamel and dentine was characterized using scanning
electron, confocal laser scanning, and Raman microscopy while the
polymerization reaction between the BMEP primers and hydroxyapatite
was evaluated by Fourier-transform infrared spectroscopy. The
inhibitory effect against matrix metalloproteinase (MMP) enzymes of
these primers was studied and percentage of inhibition analyzed using
1-way analysis of variance and Tukey’s post hoc test
(
P
< 0.05). Results of the scanning electron
microscopy micrographs demonstrated potent etching of both enamel and
dentine with the formation of longer resin tags with BMEP primers
compared to the 10-MDP–based system. The BMEP polymerized on
interaction with pure hydroxyapatite in the dark, while the 10-MDP
primer exhibited the formation of salts. Furthermore, BMEP primers
were able to inhibit MMP activity in a dose-dependent manner. BMEP
could be used as a self-etching primer on enamel and dentine, and the
high degree of polymerization in the presence of hydroxyapatite can
contribute to an increased quality of the resin polymer network,
prompting resistance to gelatinolytic and collagenolytic
degradation.