Shear Bond Strength of Molar Tubes to Enamel Using an Orthodontic Resin-Modified Glass Ionomer Cement Modified with Amorphous Calcium Phosphate

This study aimed to assess the shear bond strength (SBS) of molar tubes to the enamel surface of molar teeth using a resin-modified glass ionomer (RMGI) cement modified with amorphous calcium phosphate (ACP).

In this in-vitro study, 60 extracted human third molars were randomly divided into four groups for bonding of molar tubes to the enamel surface. Fuji Ortho LC and Fuji Ortho LC modified with ACP (1.55 wt%) were used in groups 1 and 2, respectively. In group 3, the enamel surface was sandblasted, and bonding was then performed using Fuji Ortho LC glass ionomer modified with ACP. In group 4, molar tubes were conventionally bonded using Transbond XT composite. The SBS was measured using a universal testing machine.

The mean SBS of groups 1 to 4 was 10.22, 6.88, 9.4, and 13.68 MPa, respectively. Only the SBS of group 1 was not significantly different from that of groups 3 and 4 (P>0.05). Comparison of adhesive remnant index (ARI) scores of the groups revealed significant differences only between groups 1 and 4 (P<0.001) and between groups 1 and 2 (P=0.002).

The results revealed that the addition of ACP to Fuji Ortho LC significantly decreased the SBS of molar tubes bonded to enamel compared to the conventional resin bonding system. Sandblasting of the enamel surface significantly increased the bond strength. Fuji Ortho LC modified with ACP is recommended for bonding of molar tubes to posterior teeth considering its cariostatic property.