the aim of this in vitro study was to evaluate the effect of different bur types and acid etching protocols on the shear bond
strength (SBS) of a resin modified glass ionomer cement (RM-GIC) to primary dentin. Forty-eight clinically sound human
primary molars were selected and randomly assigned to four groups (n=12). In G1, the lingual surface of the teeth was cut with
a carbide bur until a 2.0-mm-diameter dentin area was exposed, followed by the application of RM-GIC (Vitremer – 3M/ESPE)
prepared according to the manufacturer’s instructions. The specimens of G2, received the same treatment of G1, however the
dentin was conditioned with phosphoric acid. In groups G3 and G4 the same procedures of G1 and G2 were conducted
respectively, nevertheless dentin cutting was made with a diamond bur. The specimens were stored in distilled water at 37o
C for
24h, and then tested in a universal testing machine. SBS. data were submitted to 2-way ANOVA (= 5%) and indicated that SBS
values of RM-GIC bonded to primary dentin cut with different burs were not statistically different, but the specimens that were
conditioned with phosphoric acid presented SBS values significantly higher that those without conditioning. To observe
micromorphologic characteristics of the effects of dentin surface cut by diamond or carbide rotary instruments and conditioners
treatment, some specimens were examined by scanning electron microscopy. Smear layer was present in all specimens regardless
of the type of rotary instrument used for dentin cutting, and specimens etched with phosphoric acid presented more effective
removal of smear layer. It was concluded that SBS of a RM-GIC to primary dentin was affected by the acid conditioning but the
bur type had no influence.