Not all custom whitening trays are the same quality. They might be made of similar materials, but there are small differences that can make them more comfortable and effective.
First you want your whitening trays to have reservoirs. Reservoirs are small pockets that are on the whitening trays on the front of the tooth’s surface. These reservoirs allow for more room for the whitening gel to come in contact with the teeth. Whitening gel will naturally expand as it whitens the teeth. The reservoirs allow for the expansion of the whitening gel without the trays pulling away from your teeth.
If a low quality material is used to create the whitening trays then your trays can yellow quickly. All materials will yellow in time, but low quality material will yellow quicker. You want to use a good cleaning product like fresh guard by efferdent to prevent your whitening trays from yellowing.
The way the whitening trays are trimmed affect the comfort or the whitening trays. If the whitening trays are just trimmed straight across and don’t follow the contours of the teeth iy allows the bleaching gel to come in contact with the gums. You can experience a burning sensation of the gums and less of the gel will come in contact with the teeth lowering the effectiveness.