Bond Strength of Composite Resin to Preveneered Stainless Steel Crowns

Objectives: To determine shear forces required to dislodge a flowable composite resin from anterior Stainless Steel Crowns (SSCs).

Methods: Forty preveneered incisor SSCs (NuSmile® Primary Crowns, Houston, Texas) were used in this study. Crowns were embedded in self-cure acrylic resin with their labial surface parallel flat to the floor and randomly divided according to the surface treatment into five groups of eight each. Group 1 served as control with no surface treatment, groups 2 and 3 were treated with self-etch (Adper™ Prompt™ L-Pop™) and total etch (35% phosphoric acid gel + Adper™ Scotchbond™ Multi-Purpose Plus) adhesives respectively. Groups 4 and 5 were treated with diamond bur before application of dental adhesives similar to groups 2 and 3. All specimens were mounted in an assembly apparatus and a flowable composite (Filtek™ Supreme Plus) was applied to the opening in a split Teflon mold and light cured. A shear load was applied to the repair material/crown interface at a crosshead speed of 0.5 mm/min using a universal testing machine. Failure mode was assessed using an x 10 stereomicroscope. Results were analyzed using one-way analysis of variance, and Tukey's HSD test was used to determine the significantly different groups (p≤0.05).

Results: One-way ANOVA revealed statistically significant differences between the groups. (p≤0.00001). The highest bond force was achieved with the use of diamond bur and total etch adhesive while the lowest bond force was recorded for the control group. Control group showed mainly adhesive failure of the repairing material while cohesive failure was not recorded for any group. More adhesive/cohesive failure of the original veneer resin was recoded with the use of diamond bur.

Conclusions: Flowable composite can be bonded to preveneered SSCs using self-etch or total etch adhesive. The use of diamond bur increased bond forces of flowable composite to preveneered SSCs.