Matrix systems are bands, rings, and wedges used to recreate a tooth's proximal contour and contact point when placing direct composite or amalgam restorations in Class II and other multi-surface cavity preparations. Sectional matrix systems with separation rings help re-establish tight, anatomically correct proximal contacts, reducing the risk of food impaction and secondary caries, while circumferential matrix bands suit larger or full-crown-form restorations. Proper matrix selection and placement directly affects restoration contour, contact tightness, and marginal seal, making this category a routine consumable in direct restorative dentistry.