Researchers at the Oregon Health & Science University (OHSU) School of Dentistry have found the majority of patients with self-ligating orthodontic brackets retain fewer bacteria in plaque than patients with elastomeric orthodontic brackets. They also found that a biochemical technique measuring adenosine triphosphate (ATP)-driven bioluminescence could be a useful chairside tool in the rapid quantification of oral bacteria and in the assessment of oral hygiene during orthodontic treatment. The findings were published in the American Journal of Orthodontics and Dentofacial Orthopedics. The common problem of acid-producing bacteria that surround orthodontic appliances can lead to tooth enamel breakdown and potential discoloration of the tooth surface; these aesthetic changes can persist for many years after orthodontic treatment. Although the newer bonded brackets have many advantages over the old metal bands that were fitted around each tooth, they do impede good oral hygiene, resulting in plaque accumulation and increased tooth enamel breakdown. While several studies have investigated the effects of fixed orthodontic appliances on bacterial flora, few studies have compared the effects of bracket architecture, specifically the archwire ligation method, or have evaluated the accumulation of bacteria that occurs with the bonding of fixed appliances. The OHSU team’s randomized clinical study examined 14 patients aged 11 to 17 years. Each patient had both self-ligating and elastomeric orthodontic brackets on opposing sides of the mouth, at both one week and 5 weeks after bonding. The numbers of oral bacteria in plaque surrounding the brackets were evaluated at both appointments, in addition to a prebonding appointment, using both conventional plating techniques enumerating bacterial colony number and the ATP-driven bioluminescence technique. More bacteria, including oral streptococci, were retained at tooth surfaces in plaque in patients with elastomeric orthodontic brackets at both the one- and 5-week postbonding appointments, and bacterial levels were particularly high at the one-week visit. Higher ATP-driven bioluminescence levels were also observed in plaque surrounding the elastomeric orthodontic appliances.
