Evaluation of Shear Bond Strength of Methacrylate- and Silorane-Based Composite Resin Bonded To Resin-Modified Glass-Ionomer Containing Micro- and Nano-Hydroxyapatite

Statement of the problem: the adhesion of resin-modified glass-ionomer (rmgi) to composite resin has a very important role in the durability of sandwich restorations. hydroxyapatite is an excellent candidate as a filler material for improving the mechanical properties of glass ionomer cement. purpose: the aim of this study was to assess the effect of adding micro- and nanohydroxyapatite (ha) powder to rmgi on the shear bond strength (sbs) of nanofilled and silorane-based composite resins bonded to rmgi containing micro- and nano-ha. materials and method: sixty cylindrical acrylic blocks containing a hole of 5.5×2.5 mm (diameter × height) were prepared and randomly divided into 6 groups as group 1 with rmgi (fuji ii lc) plus adper single bond/z350 composite resin (5.5×3.5 mm diameter × height); group 2 with rmgi containing 25 wt% of micro-ha plus adper single bond/z350 composite resin; group3 with rmgi containing 25 wt% of nano- ha plus adper single bond/z350 composite resin; group 4 with rmgi plus p90 system adhesive/p90 filtek composite resin (5.5×3.5 mm diameter × height); group 5 with rmgi containing 25 wt% of micro-ha plus p90 system adhesive/p90filtek composite resin; and group 6 with rmgi containing 25 wt% of nano-ha plus p90 system adhesive/p90 filtek composite resin. the specimens were stored in water (37° c, 1 week) and subjected to 1000 thermal cycles (5°c/55°c). sbs test was performed by using a universal testing machine at a crosshead speed of 1 mm/min. data were analyzed by two-way anova and tukey test (p< 0.05). results: there were significant differences between groups 1 and 4 (rmgi groups, p= 0.025), and groups 3 and 6 (rmgi+ nano-ha groups, p= 0.012). however, among z350 and p90 specimens, no statistically significant difference was detected in the sbs values (p= 0.19, p= 0.083, respectively). conclusion: rmgi containing ha can improve the bond strength to methacrylatebased in comparison to silorane-based composite resins. meanwhile, rmgi without ha has the best bond strength to silorane-based composite resins.