Detection of white spot lesions around orthodontic brackets using polarization-sensitive optical coherence tomography

Abstract

Introduction: The main purpose of this study was to determine whether a light detection system, polarization-sensitive optical coherence tomography (PS-OCT), can accurately track the initiation and progression of early demineralized lesions around orthodontic bracket bases. Another goal of the study was to analyze the protective effects of different fluoride modalities in preventing decay around bracket bases. Methods: Sixty human molar samples used for this in-vitro study were divided into 4 groups of 15. The groups consisted of the control (Ormco Enlight adhesive, no fluoride), fluoride in solution (2 ppm fluoride), fluoride sealant (Reliance Proseal), and glass ionomer adhesive (Fuji Ortho LC). Each section was mounted in acrylic and then scanned with the PS-OCT system at time 0 (before and after bracket placement), and subsequently at days 3, 6, 9, 12, and 15. Results: Quantitative analysis demonstrated that PS-OCT was effective in showing nondestructively that the various fluoride modalities significantly reduced the severity of the lesions (P <.001). The fluoride sealant group was significantly more effective than the fluoride in solution group and the glass ionomer group. Digital microradiography was completed as the gold standard with which the PS-OCT measurements were compared to verify accuracy of detection. Polarized light microscopy (PLM) was used to examine lesion depth. Microradiography and polarized light microscopy verified the presence of the lesions depicted by OCT, and PLM verified the depth of the lesions. Conclusions: This study demonstrated that PS-OCT can be used in the orthodontic clinical setting to monitor the severity of demineralization and the efficacy of intervention with fluoride-based therapeutic agents.