My teeth are looking transperent, what causes this?

Wear: Are your teeth looking shorter too? Usually when the enamel starts to thin out because of excess wear either due to grinding or abrasion teeth start to look transparent .Without seeing your teeth impossible to diagnose correctly but this is a guess based on your description. See a dentist for diagnosis and treatment. Bonding can make the enamel thicker and less translucent.

Varies: If you are not whitening your teeth, the first thing to consider is wear. If the edge of the tooth is thin, it becomes more transparent. Best to check with your dentist to make sure the wear is not excessive or damaging in nature.