Effect of surface treatments on the bond repair strength of resin composite to different artificial teeth

The purpose of this study was investigate the influence of different surface treatments on the shear bond strength of two different type of artificial resin teeth repaired with composite resin. Fifteen (15) artificial teeth of each material (CR-composite resin and AR-acrylic resin) were divided into four parts and then embedded in acrylic resin. After, the teeth were separated into eight groups according to the surface treatments prior to the repair: control group (c), adhesive application (a), sandblasting (S) and sandblasting followed by adhesive application (Sa). Next, a composite resin cylinder (Ø = 0.95 mm e h = 2 mm) simulating a repair was built onto each surface. The specimens were submitted to a microshear bond test after 24 h, using a universal testing machine (1 mm/min, 50 kgf) until fracture. The data was subjected to two-way analysis of variance (ANOVA) and Tukey test, with a significance level of 5%. ANOVA showed statistical difference for the interaction artificial teeth material* surface treatment (p = 0.001). CR teeth (29.79 ± 11.54 MPa) showed higher bond strength mean values than AR (18.48 ± 9.73 MPa). Regardless the artificial teeth material, Sa (36.92 ± 6.16 MPa) treatment showed the higher bond strength values. The highest bond strength value was found in CRSa (45.93 ± 7.13 MPa) and the lowest was found in ARc (5.38 ± 0.90 MPa). Based on the results, tooth material should be taken in account in order to choose the best surface treatment and achieve suitable bond strength values when a repair is necessary. For artificial teeth in acrylic resin, applying an adhesive system is the best procedure, with or without sandblasting the alumina particles. However, for artificial teeth in composite resin, an association of sandblasting followed by applying an adhesive system showed more promising bond strength values.