Final answer:
A dental assistant must replace an instrument package if there is a tear to ensure that sterile conditions are maintained and risk of infection is minimized.
Step-by-step explanation:
When a tear in an instrument package is noticed, the dental assistant must replace the instrument package. The integrity of the sterile packaging is compromised when there is a tear, which could lead to contamination of the instruments and increase the risk of infection for patients. Therefore, it is not sufficient to repair the tear or dispose of the instruments, and while consultation with a supervisor is always advisable for procedural questions, the immediate action is to replace the torn package with one that is intact and sterile.