The mock-up stage involves transferring the diagnostic wax model prepared in the lab to the patient’s mouth using bis-acrylic temporary composite materials via a silicone key, and testing the final result live. The approximately 1% to 2% linear shrinkage rate exhibited by bis-acrylic materials during polymerization (hardening) can, if not properly managed, lead to problems such as slight openings at the marginal margins (gingival margins) or improper fit to the tooth surface. To ensure that this shrinkage does not mislead the aesthetic trial and the patient’s sensation, it is essential for the dentist to select premium bis-acrylic agents with extremely low shrinkage rates and high dimensional stability, to remove excess material with micro-burrs before hardening is complete, and to meticulously check the marginal fit for accurate occlusion and phonetic tests.