Use the 44% whitening gel the same way you used the original whitening gel included with your kit: Apply a thin, even line of gel to the upper and lower sections of the mouth tray, taking care not to overfill it.

Since the 44% gel is more concentrated, it's important to make sure the gel stays on the surface of your teeth and doesn't spread onto your gums, as this may cause temporary gum irritation or sensitivity. If you notice any excess gel after inserting the tray, simply wipe it away with a q-tip or tissue before beginning your whitening session.