Yellowing, sensitivity above braces after three years of braces. could this be due to enamel loss? are there other possibilities?

Caries: It is extremely important to maintain excellent oral hygiene and oral habits while wearing braces since the irregular shape and flanges can trap many food debris. See your orthodontist right away to have this problem resolved before it gets worse and may cause permanent discoloration or need for crowns, fillings and root canals..

Oh my: Average time in braces done by a specialist Orthodontist is 18-24 months. Yellowing/sensitivity may be due to compromised Oral Hygiene. Please see your Orthodontist, or General Dentist, whichever is doing your braces treatment, and discuss your symptoms and also the reasons for your extended time in treatment.