Microshear Bond Strength of Different Ceramic Repair Strategies

Objectives: the aim of this study was to evaluate the microshear bond strength of composite resin to ceramic using different ceramic repair approaches.

Methods: Twenty-two ceramic discs (IPS Empress Esthetic) were fabricated, polished and divided into eleven repair strategy groups before the application of an adhesive agent (Scotchbond Multipurpose Adhesive: Hidrofluoric acid etching for 60 seconds (HF); Application of Clearfil Silane Kit (CSK); Application of RelyX Ceramic Primer (RCP); Sandblasting with 50µm Al2O3 particles (SAND); Sandblasting with 30µm Cojet® particles (COJ); HF + CSK (HFCSK); HF + RCP (HFRCP); SAND + RCP (SANDRCP); COJ + RCP (COJRCP); SAND + CSK (SANDCSK) and; COJ + RCP (COJCSK). Silicon Tygon tubes of 1,1mm diameter (0,95mm² of area) and 2mm high were used to produce twenty composite (Z250) specimens per group. After 24h in water at 37°C the resin cilinders were subjected to the microshear test at a crosshead speed of 0,5mm/min using an Ultradent testing device.

Results: Highly significant differences (p<0.001) were detected through a Mann-Whitney U-test. The highest microshear bond strength was obtained for COJCSK and decreased as following: COJCSK (38.2 ± 10.4 MPa)^ab > HFCSK (34.4 ± 6.8)^abc > SANDCSK (33.1 ± 9.2)^abc > SANDRCP (32.1 ± 9.4)^abc > COJRCP (31.4 ± 8.1)^abc > HFRCP (30.0 ± 5.8)^bc > RCP (19.0 ± 4.9)^d > HF (17.2 ± 4.9)^de > CSK (15.4 ± 3.3)^e > COJ (10.1 ± 4.1)^f > SAND (9.3 ± 3.2)^f. Means with different letters are statistically different (p<0.05).

Conclusion: Sandblasting fractured ceramic surfaces before the application of a silane coupling agent may account as a substitute approach for intraoral etching with HF, avoiding its harmful potential.