Final answer:
Line angles are important in wax-ups because they determine the shape, contour, and esthetics of the restoration.
Step-by-step explanation:
Line angles are important in wax-ups because they determine the shape and contour of the tooth restoration. They help in creating the correct anatomy and functional occlusion.
Line angles also influence the aesthetics of the restoration by determining the position and length of cusps and incisal edges.
For example, in posterior teeth, the line angle between the occlusal and buccal or lingual surfaces helps in shaping cusps. In anterior teeth, line angles affect the overall shape of the incisal edge and the embrasures between the teeth.