Purpose: Evaluation of a new surface treatment method to obtain a good bond strength between a luting composite and (1) a light-cured, (2) a heat-cured and (3) a thermoplastic resin.
Materials and methods: Specimens were prepared and tests conducted according to ISO 10477, Amend. 1. The surfaces of Targis (light cured), SR Isosit (heat cured), and Dental D (thermoplastic) were ground under water cooling with 400-grit grinding paper, polished with 800-grit paper and air dried. Each resin material was divided into 3 groups of 10 specimens each. Group 1 was flame treated with a PyrosilPen for 5 s/2 cm2, group 2 for 10 s/2 cm2, and group 3 for 20 s/2 cm2. Subsequently, a methacryl silane was applied, followed by a luting composite. Prior to measuring shear bond strength, the specimens were thermocycled 5000 times in a water bath between 5 degrees C and 55 degrees C. SEM, FTIR investigations, and fracture analysis were also done. Etched and silanized Empress II - the gold standard - was used as a control.
Results: The following shear bond strengths were found: treatment time 5 s/2 cm2, Targis 25 (+/- 12) MPa, SR Isosit 17 (+/- 11) MPa; treatment time 10 s/2 cm2, Targis 23 (+/- 12) MPa, SR Isosit 26 (+/- 8) MPa; treatment time 20 s/2 cm2, Targis 29 (+/- 5) MPa, SR Isosit 26 (+/- 9) MPa. All Dental D specimens failed completely so that shear bond strength could not be measured. The control achieved 27 (+/- 6) MPa. No significant differences were found between the materials or the flaming times. On all flamed surfaces, Si was detected by FTIR. SEM showed that no heat destruction occurred at a flaming time of 5 s/2 cm2, a slight change at 10 s/2 cm2, and a significant change at 20 s/2 cm2.
Conclusion: This new bonding technology is an effective method for surface-treating polymerized composite resin materials to obtain good bonding to luting composites. The method fails on thermoplastic resins.