Final answer:
A rough appearance assures a tooth has been properly etched.
Step-by-step explanation:
A rough appearance assures a tooth has been properly etched. When a tooth is being prepared for dental treatment such as a filling or crown, it needs to be etched with an acid solution to create a surface that will bond well with the filling material. The rough appearance created by the etching allows the filling material to adhere to the tooth securely.