Effect of different metal surface treatments on microleakage of the two types of acrylic resin : heat cure and light cure at Co Cr interface

الملخص EN

Background : The microleakage (M.

L) at the metal-resin interface in a removable partial denture may results in discoloration, fluid percolation, and acrylic resin deterioration.

Enhancing resistance to microleakage at this interface may improve the long-term union between the two materials (alloy and acrylic resin).

The aim of this study was to determine the effect of various metal surface treatments on microleakage and bonding between the metal alloy and acrylic resin used in the fabrication of a removable partial denture.

Materials and Methods : Sixty rectangular Co / Cr samples (50 mm x 25 mm x 1 mm) were prepared and they had a grid pattern, which formed 50 squares which then divided into 2 groups according to the type of acrylic resin received each one 30 samples {A- for heat cure resin (HCR), B- for visible light cure resin (VLCR)} which were subdivided according to the type of surface treatments into 3 subgroups each one 10 samples (A1 B1 for Air Abrasion -- A2 B2 for Metal Prime II (MP II) application -- A3 B3 for combination of Air Abrasion and Metal Primer II application).

Each sample was divided into experimental half (treated) and a control half (untreated).

The samples were thermocycled (3000 cycles, 5 °C to 50 °C with a dwell time of 1 minute) after application of resin, and placed in sodium fluorescein (0.2 g / 1000 mL) dye solution (Uranine dye, BDH chemicals Ltd Poole, England) for 48 hours.

If the penetration of the dye was not more than half of the square it was recorded half square and if it was more than half it was recorded as one square.

Results : The results showed that the subgroup that received Air Abrasion + Metal Primer II surface treatments for both types of resins HC and VLC (A3 and B3) had the least M.

L values, followed by the Air Abrasion subgroup (A1 and B1).

Subgroups that received Metal Primer II alone (A2 and B2) showed the highest M.

L value than the other subgroups.

All Co / Cr samples with VLCR showed less dye penetration than that of HCR whether with surface treatment or without suggesting higher binding of resin with the Co / Cr surface.

Conclusion : A combination of air abrasion and MP II for light cure samples showed the highest reduction in M.

L compared to all other types of surface treatments and to HCR.

MP II alone was less effective in reduction of M.

L than other surface treatments.

The use of VLCR with different metal surface treatments revealed greater reduction in M.

L than that when used HCR even when there is no surface treatment.