Complete class 1 using #330 bur
Extend occlusal outline to marginal ridge
Switch to #245 Bur - 3 mm length
Sweep bur buccolingually in a pendulum motion
and in a gingival direction.
Break contacts and check with explorer
Axial wall should follow external contour
Width of isthmus 1/2 of occlusal table
Proximal box widest at gingival margin
Rounded axiopulpal line angle
No bevel at the gingival margins