Orthodontic bonding refers to the process of attaching fixed appliances (braces) to the teeth. The process has experienced many advances since the turn of the century, progressing from brittle plastic brackets applied using messy, weak and odiferous liquid or powder cements, to sturdy appliances bonded using durable and strong adhesives.
Orthodontist Jonathan Alexander-Abt co-published a paper in 2019 studying the results of a randomised controlled trial comparing two types of orthodontic bonding: light-cured composite and light-cured resin-modified glass ionomer cement.
The multicentre trial took place across four specialist orthodontic practices and two teaching centres. Patients from the age of 11 were randomly divided into two groups and allocated one of the two substances for bonding brackets as they started their fixed orthodontic treatment.
Pre-Treatment and Assessment
Digital photographic images were taken at the pre-treatment stage and the day of debonding, which were analysed by assessors, who were masked in terms of the allocation of groups. Up to three lay assessors and five clinical assessors formed the team that examined the images to determine whether new demineralised lesions were present and what the aesthetic impact was. There were 210 patients included in the study initially, with 197 completing the trial.
Of the 197 patients who completed the trial, complete digital images for before and after were available for 173. The results showed that 24% showed evidence of new demineralised legions, although only 9% had an aesthetic impact. Statistically, there was no significant difference to be found in the results for each group of patients for lesions or for first-time bracket failure.
The conclusion was therefore that using light-cured resin-modified glass ionomer cement has no benefits over using light-cured composite in terms of either bond failure or demineralised lesions. There may be other reasons why glass ionomer cement is preferable for use over composite.
Composite resin is considered to be the gold standard in orthodontic bonding. However, its use can be challenging under certain circumstances, such as where the enamel of the tooth is defective or where the braces need to be bonded to a surface other than enamel. These types of surfaces may include gold, porcelain, composite, amalgam and acrylic. Other bonding modalities therefore exist for when these types of situation arise.