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Etching solution on Zirconia crowns Dr. Goran: Effects of acid treatment in conjunction with ultrasonic on resin zirconia bond strength

Dr Goran Prokic

MDT Angelo Di franco

By Dr Goran Prokic and MDT Angelo Di franco

T he following technique was developed in Seoul, Korea by S-D Dental Clinic, Yonsei University, Kyung Hee University and Eberhard-Karls University Tubingen, Germany. Until recently many surface roughening methods were developed for ZirconiumOxide restorations. But due to its resistance to conventional etching these were not e ective. However recently alternative etching techniques have been introduced. is can also be used to increase bond strength of resin cement. Dr Casucci found that this hot etching method increased the bond strength between Zr and resin. And mechanical properties of Zr were not e ected. Ultrasonic treatment plays an important role in molecular motion. Protons become iodised and more acidic outcomes. ereforeZr is easilydissolved inacidswithultrasonic treatment. is is best performed by the laboratory prior to sending case back to the dentist. Materials and Methods Zirconia corematerial (ACUCERA Inc., Korea) and two resincements were selected. Rely X Unicem U200 (3M Deutschland GmbH, Germany) and Multilink N (Ivoclar Vivadent AG, Liechtenstein) were used. Forty-eight Y-TZP (yttria-tetragonal zirconia polycrystals) discs (Diameter 15mm, Height 4mm) were produced and mirror like nished and polished. Y-TZP discs were randomly assigned to four groups (n=12 per group) according to the surface treatment and resin cement used. Four experimental groups were shown as follows: Multilink on acid-etched surface (M/E), Unicem on acid-etched surface (U/E), Multilink on polished surface (M/P), Unicem on polished surface (U/P). Half of the specimens were dipped in HF/HNO3 solution (ZIRCOS-E, Bioden co., Korea) and kept for 30 min with ultrasonic. After rinsing with distilled water and steam cleaning, annealing processes were subsequently conducted at 1150ºC. For the shear bond strength test resin cements (Diameter 6mm, Height 5mm) were bonded on the Y-TZP surface using putty index according to manufacturers’ recommendation.

Surface roughness of 3 specimens of each group was evaluated using a 3D optical analyzer (Burker, Daltonik, Germany), and microscope analysis was performed. Bonded specimens were subjected to shear bond strength (SBS) test at a crosshead speed of 1mm/min using a universal testing machine (Instron Model 3366, USA) After shear bond strength test, all fractured surfaces of specimens were examined to determine the failure pattern by a digital microscope using X10 magni cation. Fracture modes were classi ed as adhesive failure (fracture occurring at resin cement and zirconia interface), cohesive failure (fracture occurring within resin cement), or mixed failure (occurrence of both adhesive failure and cohesive failure). Statistical analyses were performed using the statistical software IBM SPSS Statistics 22. e Levene’s test was applied to ensure the normal distribution of data before the ANOVA (p.05). e one-way ANOVA was performed for each ZIRCOS-E, Bioden.co., Korea group to determine the di erence of shear bond strength values (p=0.05)

Angelo MDT: Based on my experiences with this new solution for dental aesthetics, these aremy general observations and possible solutions. e advent of zirconia in the global dental sector will turn out to be one of the historical events that have most transformed the way of working of operators in the sector. In the current state of things, some issues remain open, where there is a need for clarity and improvements: among these the precision and stability of the artifact, the link to the interface, the aging of the artifact, including its compatibility in the moist environment of the oral cavity. ese topics require further serious neutral scienti c investigation. I new and innovativemethods of constructing dental prosthetics using CAD/CAM has led to an ever-expanding search for new and

94 AUSTRALASIAN DENTIST