The objective of this observational study is to investigate the long-term stability of treatment with the Twin block appliance in a patient group previously treated with a Twin block appliance. The main questions it aims to answer are:
1. Does treatment with the Twin block appliance give a lasting treatment result or does the bite relapse over time due to different factors such as short treatment time, compliance or the patient's natural growth pattern?
2. How many patients that had received treatment with Twin block appliance required additional treatment with fixed appliances and for what reason?
Researchers will compare the patients present bite at (T2) by using study casts and cephalometric x-rays and compare this data with previous registrations made pre- (T0) and post-treatment (T1). Additional factors, such as how much relapse a patient has on average, will also be investigated.