Repair Success of Two Innovative Hybrid Materials as a Function of Different Surface Treatments.

PURPOSE: To evaluate surface treatments for chipping in order to avoid bonding problems between hybrid materials and composite resin and to determine the optimal surface treatment method during intraoral repair of restorations to achieve clinical success. MATERIALS AND METHODS: A total of 96 samples were prepared from computer-aided design/computer-assisted manufactured (CAD/CAM) blocks: 48 polymer-infiltrated ceramic (PIC) and 48 resin nano-ceramic (RNC). Prior to application of the surface treatments, the two test groups were each divided into four subgroups: control group; hydrofluoric acid group; hydrofluoric acid with silane group; and air-abraded with silica-coated aluminum oxide (Al2O3) sand with silane group. Each subgroup contained 12 samples. A shear bond strength (SBS) test was performed after artificial aging (5,000 cycles, 5°C to 55°C). RESULTS: For both types of ceramic used, all subgroups showed significantly higher SBS values than the control groups (P < .05). The highest SBS values for both types of ceramic were observed in the air-abraded with silica-coated Al2O3 particles group. CONCLUSION: Each of the surface treatment methods increased the SBS, with the most effective method being air abrasion with silica-coated Al2O3.

The effect of amine-free initiator system and the polymerization type on color stability of resin cements.

We investigated the short-term (4 weeks) color stability of light-cure and dual-cure resin cements. Sixty disk-shaped test specimens of adhesive resin cement (10 × 1 mm) were prepared. One feldspathic porcelain test specimen (12 × 14 × 0.8 mm) was prepared from a prefabricated ceramic block. The feldspathic sample was placed on the resin cement disk and all the measurements were performed without cementation. Specific color coordinate differences (ΔL, Δa, and Δb), and the total color differences (ΔE) were calculated after immersion in distilled water for different periods. Data were compared using one-way analysis of variance (ANOVA) (α = 0.05). The test results revealed that different chemical structures and curing modes affected the ΔE values (P < 0.05). The highest ΔE values were obtained for RelyX Unicem dual-cure cement (2.14 ± 0.40), and the lowest for NX3 light-cure cement (0.78 ± 0.34). Third generation adhesive resin cement free of tertiary amines and benzoyl peroxide showed relatively slight color change in both test groups (light-cure and dual-cure resin cement). (J Oral Sci 58, 157-161, 2016).

Effects of Er:YAG Laser Pretreatment with Different Energy Levels on Bond Strength of Repairing Composite Materials.

OBJECTIVE: The purpose of this study was to investigate the effects of Erbium-doped: yttrium-aluminum-garnet (Er:YAG) laser pretreatment with different energy levels on the shear bond strength (SBS) of repairing composite materials. BACKGROUND DATA: After long-term usage of composite resins in the mouth, they can need some repair. Repairing composite bonding so it attaches to the old restoration is important for clinical success. METHODS: Sixty composite resin materials were used in this study. The aging procedure was performed with 6000 thermocycles in water from 5°C to 55°C. Different surface pretreatment methods [control (no surface treatment), sandblasting, laser treatment (energy level 75, 100, 200, and 300 mJ)] were employed, for a total of six groups. Composite resins of the same kind as their substrates were adhered onto the conditioned substrates. The SBS test was used to assess the durability of all groups. Scanning electron microscopy (SEM) analysis was performed on a representative specimen in each group. RESULTS: Among six surface-treated groups the lowest bond strength was observed in Group C (9.41 MPa) (p<0.001). Group S exhibited the highest bond strength among all groups and showed significant difference from all other groups (33.41 MPa) (p<0.001). In the Er:YAG test groups, bonding values showed varying results from 15.27±0.58 (Group L300) to 25.98±1.08 (Group L75) and showed significant increase when compared with control group (p<0.05). CONCLUSIONS: Altough the sandblasted group exhibited the highest test values, Er:YAG laser treatment on repair composite bonding to old composite may become an alternative to other surface treatment methods.