Type IIa GIC is used for:
Type I: Luting crowns, bridges, and orthodontic brackets.
Type IIa: Esthetic restorative cements.
Type IIb: Reinforced restorative cements.
Type III: Lining cements, base.
Ref: Phillip’s Science of Dental Materials ed 12 pg 320
Luting crowns, bridges and orthodontic brackets
Esthetic restorative cements
Reinforced restorative cements
Lining cements