CLASS 5 LARGE DEFECT  

A large class 5 defect must consider increased composite shrinkage upon light curing, forces of abfraction and effects of contraction/expansion from hot and cold.  Thermal coefficient of expansion is different for composite when compared to tooth structure which results in stress at the restoration to tooth interface.  Large restorations require increased retention which is achieved by bonding to more enamel and creating mechanical retention with converging lateral, gingival and incisal walls.  Composite and bonding materials should have an increased modulus of elasticity to match tooth structure.

Undercuts on walls are created with small burs. Remaining tooth structure is prepared with diamond burs to increase surface area and eliminate poor quality dentin.  Bonding to enamel and dentin is completed.  Composite is added to wall areas in small increments and cured.  Small increments are added and cured to minimize shrinkage until complete contours are established.  Finishing is done with burs and polished with sandpaper disks, rubber wheels, cups, points and polishing pastes.