Don’t over think it. Keep in mind your only concerned about the front surface of your teeth which means there is no need to waste whitening gel on the back side. With that in mind use the gel sparingly and only apply it to the portion of the whitening tray that comes in contact with the front surface of your teeth. If you look at the image below you will see I applied gel to the teeth whitening tray and the gel is highlighted in blue to ensure you can see it. The gel is 22% carbamide peroxide and has a sticky formula which means it holds to the tray with minimal slippage (running).
Once the gel has been applied to the whitening tray you should place the tray on your teeth, however keep in mind you want to avoid pushing the gel to the bottom of the tray. With that being said you want to drag your teeth along the back side of the tray so it presses forward onto the gel versus a downward drag. For an example refer to the image below.
If you apply too much gel it will overflow into the mouth and irritate the tissues. Keep in mind one gel syringe is good for about 4 full applications.
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