A 45 years old male presents with complain of black spots on his tooth surface. He gives a history of multiple gold restorations and insists on getting the same for this tooth.The intraoral examination reveals pit and fissure caries in relation to 16. Which of the following features will be preferred for retention of the restoration in this case?
Skirts are preparation features used in cast gold restorations that extend the preparation around some, if not all, of the line angles of the tooth. When properly prepared, skirts provide additional, opposing vertical walls that increase retention of the restoration. The placement of skirts also enables increased resistance to fracture by allowing the envelopment of the remaining compromised tooth structure with the restorative material.
Sturdevant operative dentistry 7th Edition, Page No:131
Vertically  oriented  grooves
Horizontally oriented grooves
Coves
Skirts