What are the disadvantages of dental fixed appliances?

Generally, children or adults in permanent dentition are mostly in the process of orthodontic treatment, but it has its own shortcomings. First, when wearing fixed appliances, the patient's oral hygiene is not good to maintain, brushing is not easy to be in place, so it is easy to cause gingivitis. Second, fixed appliances will cause adverse reactions, is the decalcification of teeth, and finally may develop into caries.