Longitudinal monitoring of demineralization peripheral to orthodontic brackets using cross polarization optical coherence tomography

Objectives: The aim of this study was to test the hypothesis that cross-polarization optical coherence tomography (CP-OCT) can be used to longitudinally monitor demineralization peripheral to orthodontic brackets in an extended clinical study. Methods: A high-speed CP-OCT system was used to acquire 3D volumetric images of the area at the base of orthodontic brackets over a period of 12 months after placement. The reflectivity was measured at 3-month intervals for 12 months to determine if there was increased demineralization. Two teeth were monitored on 20 test subjects and the brackets were bonded using two types of adhesives. This was a randomized controlled clinical study with a split mouth design such that each subject served as his or her own control. On one side, the control premolar was bonded with a bonding agent (Adper Scotchbond from 3 M ESPE, St. Paul, MN) and composite (Transbond XT from 3 M Unitek, Monrovia, CA) that lacked fluoride. On the other side, the experimental premolar was bonded with a fluoride releasing glass ionomer cement (GC Fuji Ortho LC from GC America, Alsip, IL). Results: There was a small but significant increase in the calculated lesion depth and integrated reflectivity over that depth (Delta R) for both adhesive types (p < 0.0001) indicating increasing demineralization with time. There was no significant difference in the lesion depth (p = 0.22) and Delta R (p = 0.91) between the groups with the fluoride releasing glass ionomer cement and the conventional composite. Conclusions: CP-OCT was able to measure a significant increase in demineralization (p < 0.0001) at the base of orthodontic brackets over a period of 12 months. (C) 2014 Elsevier Ltd. All rights reserved.