Lingual orthodontic treatment: what is the current evidence base?

As the number of adults that seek orthodontic treatment continues to grow, so too is the popularity of lingual fixed appliances. Although the aesthetic advantages associated with these systems are obvious, for some orthodontists, there has been a reluctance to offer lingual-based treatment to their patients. This is often based upon the perceived problems associated with lingual braces, relating to discomfort and difficulties with speech for the patient, and problems in using these appliances for the orthodontist. Although some of these factors have been investigated, the current evidence base is weak, possibly due to the fact that these are evolving appliance systems. Among the studies that have been carried out to date, pain and discomfort for the patient appears to be similar following the placement of labial or lingual appliances, although the onset can be earlier with lingual brackets and the location different, with the tongue more frequently being involved. Customized lingual brackets may be associated with less pain than pre-fabricated. In addition, patients do seem to be more likely to experience difficulties with speech and mastication when fitted with a lingual appliance. However, there is some evidence that the lingual surfaces of the teeth are more resistant to early demineralization and caries. Little data exist regarding treatment outcome and ease of use for the orthodontist, either between lingual or labial appliances or between different lingual systems. Further research is required to investigate the efficiency of lingual appliance systems, both for the patient and orthodontist.