This study looks at two new types of orthodontic brackets (metal squares of the brace) that have recently been released. Both types have been developed to allow the brackets to stick better to the tooth surface. The difference between the two groups is the adhesive ('glue') that is used. One uses a more conventional type of pre-coated adhesive (APC-II). The other type uses a new flash-free adhesive that does not require the excess to be removed once placed. It is claimed by the manufacturer that this new adhesive has a far lower failure rate than other types. However, there are very few studies that have looked into the bond failures of these adhesives comparatively, with most being lab-based studies outside of the mouth.

The purpose of this study is to investigate which of the two bracket types lasts longest when glued to teeth for brace treatment and if there are any particular reasons why they may fail. This in turn will provide good evidence and research for future use of different bracket types, with an aim to prevent brackets from coming loose as little as possible during treatment. This could potentially result in smoother treatment for the participants and fewer visits.

A total of 56 participants within the Orthodontic Department at Guy's Hospital London, shall be recruited to the trial and randomly placed into one of the two groups. The participants invited to take part in the trial will require fixed braces ('train-tracks') and meet the specific criteria that the investigators are looking for. Once the braces are fitted, regular appointments are made and participants are asked to return for emergency appointments if any of the brace comes loose. The total time for follow-up after the brace is fitted is a maximum of 3 months. The results shall then be analysed.

Inclusion Criteria:

• Patients requiring fixed appliances.
• Patients aged >8 years old

Exclusion Criteria:

• Orthognathic patients requiring bands on first permanent molar teeth.
• Patients with cleft lip/palate or any other craniofacial anomalies.
• Patients already in fixed appliances.
• Patients who have first permanent molars missing.
• Patients with hypoplastic first permanent molars/fluorotic first permanent molars.
• Patients with first permanent molars in crossbite with displacement.
• Patients requiring sectional fixed appliances (not including the molars).
• Patients requiring bands on first permanent molars for TPA, Quadhelix etc.
• Patients who have buccal restorations/crowned first permanent molars.
• Patients who do not speak English fluently or understand written English easily.