Dr Christian Day BOSF Grant 2004

The effects of different orthodontic appliances upon microbial communities

BOSF Grant 2004

Primary investigator

Christian Day (pictured), Jonathan Sandy, Nigel Harradine, Tony Ireland, David Dymock


The aim of this prospective randomised trial was to analyse changes in the oral microflora. To track these during a full course of orthodontic treatment and  up to 1 year post debond and also to relate any microflora changes to differing conditions (e.g. bands vs. bonds, elastomeric vs. self-ligating,  periodontal and enamel states).

Subjects and settings

Laboratory study with sampling from 24 orthodontic patients aged 11-14 years who were bonded/banded, elastomeric/ no-elastomeric, with a cross mouth study protocol.


24 patients undergoing full upper and lower fixed appliance therapy were recruited into this prospective randomised trial. For each patient, bonded molar tubes and molar bands were fitted to contra lateral quadrants of the mouth, with random assignment using sealed envelopes to ensure equal numbers in each group. For all of the remaining teeth, self-ligating brackets were fitted and cross mouth randomisation was also used to determine which self-ligating bracket (left or right) on the upper lateral incisor teeth would also have an elastomeric ligature fitted. Since all the ligation slides were closed, the treatment mechanics were identical on both lateral incisors and the only experimental variable was the presence or absence of elastomeric ligatures.  Clinical assessments were performed using gingival and plaque indices (5-│-5) and the enamel quality of 2│2 was assessed using a decalcification index. We also analysed the supragingival flora associated with the bands and bonds on the first molar teeth and 2|2 using DGGE and microarray analyses.


Plaque populations changed within 3 months of commencing treatment at all sites. The greatest differences in plaque composition were seen with self-ligating brackets with an elastomeric ligature. Post-treatment plaque associated with both types of molar attachment contained increased levels of periodontal pathogens P. gingivalis, T. forsythia and E. nodatum, while C. rectus, P. micra, and A. odontolyticus were also elevated with bonds. This study also demonstrated that not only are there progressive shifts in dental plaque composition during orthodontic treatment, but that there is no indication of restoration to pre-treatment microbiota, even 1yr after cessation of treatment. This is the only full year follow-up study to date showing potential longer term changes in microbial community structure.
The results suggest that molar bonds are more likely to elicit changes in the normal plaque microbiota towards a microbiota with raised disease potential. There were sustained increases in levels of microbial species not present at the start of treatment, and not present in plaque associated with molar bands. Although these results do not necessarily indicate that subjects may be more prone to gingivitis or periodontal diseases later in life, there should be concern over the potential for extended-term clinical effects associated with these microbiological changes.


The effects of different orthodontic appliances upon microbial communities. AJ Ireland, V Soro, SV Sprague, NWT Harradine, C Day, S Al-Anezi, HF Jenkinson, M Sherriff, D Dymock, JR Sandy. Orthodontics and Craniofacial Research 2014; 17 (2):115 – 123

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