Zaid A. Al Jeaidi 3 BDS, AEGD, SBARD
OBJECTIVE: To evaluate the influence of post hydrofluoric acid (HF acid) etch crystalline residue on the bond strength of lithium disilicate (LD) glass ceramics by means of microtensile bond strength (μ-tbs) testing.
METHODOLOGY: Thirty blocks (4x6x8mm) of LD ceramic were made with pressing furnace utilizing the lost wax technique. Out of these 20 ceramic blocks were subjected to edHF acid (9.5% for 90 sec)and rinsed with water (20 sec). The remaining 10 ceramic blocks were left un-etched to be used as negative controls (group A). Half (n=10) of the etched blocks were only rinsed with water (group B) and the other half (n=10) received post etch cleaning (PEC) (37.5% Phosphoric acid for 1 min, rinse with water for 20 seconds and ultrasonic bath immersion) (group C) of the surface. Silane was applied (5 mins) to all specimens. Ceramic and composite resin blocks were bonded using an adhesive resin and light cured restorative composite as a luting agent, under standard conditions. A total of 360 specimen sticks (8 x 1mm²) were subjected to micro-tensile testing. The means of micro-tensile bond strength (µ-tbs) were analyzed with ANOVA. RESULTS: The lowest and highest bind value was shown by group A (10.81±3.02) Mpa and group C (39.94±2.58) respectively. Post-etch cleaning of the residue formed on ceramic surface showed significant improvements in μ-tbs value (p=0.01) when compared to un-etched and etched ceramic specimens.
CONCLUSIONS: The presence of surface residue and crystalline salts produced after HF acid etch, significantly compromised the microtensile bond strength of LD ceramic to resin. Post etch cleaning of lithium disilicate ceramics significantly improved their microtensile bond strength to resin.
KEYWORDS: Ceramic, Lithium disilicate, Post-etch cleaning, microtensile bond strength, HF acid etch.
HOW TO CITE: Al-Jeaidi ZA. Influence of Post- Etch Crystalline Residue on the Bond Strength of Lithium Disilicate Ceramic An in vitro Study. J Pak Dent Assoc 2016; 25(2): 74-77
Received : 1 May 2016, Accepted: 30 June 2016