Silanizing Effectiveness on the Bond Strength of Aged Bulk-Fill Composite Repaired After Sandblasting or Bur Abrasion Treatments: An in vitro Study

Abstract

To measure the repair shear bond strength (SBS) of an aged bulk-fill composite after different mechanical (diamond bur vs sandblasting) and chemical (universal adhesive with or without a previous silanization) surface treatments. Materials and Methods: Bulk-fill composite (Filtek One Bulk Fill, 3M ESPE) was used to construct seventy-two specimens aged through 10,000 thermal cycles. The specimens were allocated into two groups (n = 36 each) according to the mechanical roughening: Db, treated with a diamond bur, and Sb, treated by sandblasting. Each group was further subdivided into three subgroups (n = 12 each) according to the chemical conditioning: Db-only and Sb-only, unconditioned specimens; Db-U and Sb-U, specimens were conditioned with silane-containing universal adhesive (Scotchbond Universal adhesive, 3M ESPE); and Db-S-U and Sb-S-U, specimens were conditioned with a silane agent (Prosil, FGM) before employing the universal adhesive. The same composite material was used for repair. An additional reference group was constructed to measure the cohesive strengths of the bulk-fill composite. SBS testing was performed using a universal testing machine at a crosshead speed of 1 mm/min, and the failure modes were evaluated by stereomicroscope. The surface topography of resin composite after roughening was assessed by scanning electron microscopy. SBS data were statistically analyzed by ANOVA, Tukey's test and independent t-test. Results: The significantly highest SBS was recorded in the reference group (P ≤ 0.05). Sb-only obtained significantly higher SBS than Db-only (P < 0.001). No significant difference in SBS was noted between Db-U and Sb-U or Db-S-U and Sb-S-U. Likewise, no significant difference was observed between the subgroups treated with or without silane (P > 0.05). Conclusion:The sandblasted specimens demonstrated a higher repair SBS than the diamond bur-treated specimens. The use of an additional silanizing step before applying silane-containing universal adhesive did not enhance the SBS of the repaired composite.

Repair of monolithic zirconia restorations with different direct resin composites: effect on the fatigue bonding and mechanical performance

“…Enhancing the bonding potential of zirconia is a constant challenge due to its polycrystalline microstructure and the almost total absence of silica content [ 8 ]. In this sense, the statement of a standard protocol of repair for this material is still lacking, and different resin-based materials have been suggested to repair zirconia crowns with a high and stable level of bonding, thus assuring longevity for repaired restorations [ 17 , 18 ]. The present study adopted the use of a 10-MDP containing primer, which was previously reported as an effective option due to the action of the phosphate monomer to increase the bonding potential of zirconia by a chemical mechanism, mainly when combined with mechanical interlocking promoted by air abrasion [ 34 , 35 ].…”

“…Attempting to improve the results for repairing procedures, alternative resin-based materials have been suggested, as the use of bulk-fill and even flowable resin composites [ 17 , 18 ]. The use of bulk-fill resin-based materials is increasing for restorative purposes as it makes the technique simpler by allowing the filling of larger cavities in a single increment (up to 4 mm) [ 19 , 20 ].…”