Inclusion Criteria:  The age ranges from 13-18 years old. Good oral hygiene. Clinical gingival health on the intact periodontium. Permanent dentition. Moderate crowding. Non-extraction treatment plan. If extraction of teeth is required, the treatment plan should allow for postponing extraction after sample collection.  Exclusion Criteria:  Systemic diseases associated with loss of periodontal supporting tissues. Metabolic bone diseases and systemic medications affecting bone metabolism. Craniofacial anomalies such as cleft lip and/or palate. Xerostomia. Tobacco-related habits such as smoking, tobacco chewing, etc.