FESEM Analysis of a Lithium Disilicate Treated With Acidulated Phosphate Fluoride for Intra-oral Repair

Objectives: To compare the ultra-morphology of lithium disilicate treated with 1.23% acidulated phosphate fluoride (APF) for intra-oral bonding repair.
Methods: Lithium disilicate block (Rosseta SM, OdontoMega/Hass) was sectioned into slices of 1mm thick. Each slice was wet-polished up to 2000-grit SiC paper, cut into small squares (3x3mm) and cleaned ultrasonically (10min) before being fired following the manufacturer’s recommendations. Specimens were assigned into twelve groups (n=1), according to the type of etching: G1= 1.23% APF (Flúor gel, Nova DFL) for 1min; G2= 1.23% APF for 2min; G3= 1.23% APF for 3min; G4= 1.23% APF for 4min; G5= 1.23% APF for 5min; G6= 1.23% APF for 6min; G7= 1.23% APF for 7min; G8= 1.23% APF for 8min; G9= 1.23% APF for 9min; G10= 1.23% APF for 10min; G11= 5% HF (IPS Ceramic Etching Gel, Ivoclar Vivadent) for 20sec; G12= untreated (control). Specimens were ultrasonically cleaned (10min), air-dried, sputter-coated with gold-palladium, and observed under a FESEM (JEOL) at magnifications 5,000X-10,000X.
Results: G1 (1.23% APF for 1min) resulted in a non-uniform etched ceramic surface combining areas of well-defined etching pattern. G2 to G10 revealed some resistant areas unetched by the 1.23% APF. G11 (5% HF) resulted in a non-uniform etched ceramic surface combining areas of well-defined etching pattern and areas with surface similar to control.
Conclusions: For intra-oral repair of polished lithium disilicate surface, the application of 1.23% APF for 1min resulted in ceramic etching pattern similar to 5% HF applied for 20 sec.