Objectives: This in vitro study determined the effect of enamel pretreatment with
phosphoric acid and ethylenediaminetetraacetic acid (EDTA) on the bond strength of
strong, intermediary strong, and mild self-etching adhesive systems.
Methods: Ninety sound human premolars were used. Resin composite cylinders were bonded
to flat ground enamel surfaces using three self-etching adhesive systems: strong Adper
Prompt L-Pop (pH=0.9–1.0), intermediary strong AdheSE (pH=1.6–1.7), and mild Frog
(pH=2). Adhesive systems were applied either according to manufacturer instructions
(control) or after pretreatment with either phosphoric acid or EDTA (n=10). After
24 hours, shear bond strength was tested using a universal testing machine at a cross-head
speed of 0.5 mm/minute. Ultra-morphological characterization of the surface topography
and resin/enamel interfaces as well as representative fractured enamel specimens were
examined using scanning electron microscopy (SEM).
Results: Neither surface pretreatment statistically increased the mean shear bond
strength values of either the strong or the intermediary strong self-etching adhesive
systems. However, phosphoric acid pretreatment significantly increased the mean shear
bond strength values of the mild self-etching adhesive system. SEM examination of
enamel surface topography showed that phosphoric acid pretreatment deepened the same
etching pattern of the strong and intermediary strong adhesive systems but converted
the irregular etching pattern of the mild self-etching adhesive system to a regular
etching pattern. SEM examination of the resin/enamel interface revealed that deepening
of the etching pattern was consistent with increase in the length of resin tags. EDTA
pretreatment had a negligible effect on ultra-morphological features.
Conclusions: Use of phosphoric acid pretreatment can be beneficial with mild self-etching
adhesive systems for bonding to enamel. (Eur J Dent 2010;4:418-428)
Keywords
Self-etch adhesives - Ground enamel - Bonding - SEM - Phosphoric acid pretreatment
- EDTA pretreatment