Please choose the correct ending to complete the given sentence: Health: [header] How to protect gums during teeth whitening [title] Make an appointment for a dental exam and cleaning. [step] Before you start any whitening treatments, you should see your dentist. They can take x-rays, give you an exam, and treat any dental issues you have.

Ending1: Make sure to keep yourself clean, and make sure you don't eat junk before you have your dental and scheduled appointment. [substeps] You can put your teeth at night and eat something after that. Ending2: You should also get your teeth cleaned, as whitening treatments will be more effective and even on clean teeth. [substeps] For instance, you should get cavities filled before whitening your teeth to prevent compounded problems and pain from the bleach. Ending3: Ask your dentist any questions you have and be as honest as possible when your dentist hears about how well you are doing. [title] Trim your teeth every three to four months. Ending4: They will also make sure that your teeth are clean and that you are eating the right foods before and during the procedure. Be sure to shower before and after you go to the dentist to protect against any human skin bacteria and the dangers of periodontitis.

Answer format: ending1/ending2/ending3/ending4