The clinical parameters do not allow to assess the state of suffering of the periodontium, especially alveolar bone remodeling during orthodontic treatment. Recent method to monitor effectiveness of orthodontic treatment and the response of the alveolar bone to orthodontic forces is the quantification of GCF constituents which may act as biomarker for same. So this book focuses on the constituents present in GCF which are biomarkers to quantify the tooth movement.