Understanding the biological events during fixed orthodontic treatment is essential for optimizing treatment strategies, predicting patient response, and minimizing adverse effects. Most studies on bone remodeling have used invasive sampling methods such as tissue biopsies or serum collection; these methods cannot be used for routine clinical monitoring. Saliva is a simple medium that can reflect changes in local periodontal and bone conditions, it is also non-invasive and cheap. There is little evidence about the temporal expression of genes related to bone metabolism (RANKL, OPG, ALP, TRAP, RUNX2) in saliva during orthodontic therapy. This study will help advance the understanding of biological responses during orthodontic tooth movement and explore whether saliva can be an appropriate diagnostic medium for monitoring bone remodeling in orthodontic patients

Inclusion criteria:

1.15 to 25 years of age 2.moderate crowding (3-6 mm) 3.generally good health with no systemic conditions that could influence bone metabolism 4. no recent use of medications known to affect bone metabolism (such as bisphosphonates and corticosteroids) or any other NSAIDs.

Exclusion criteria:

1. periodontal disease
2. smoking or any form of tobacco use
3. pregnancy or lactation
4. prior orthodontic treatment
5. craniofacial syndromes
6. The use of antibiotics within 3 months before the study. -

Twenty-four patients (mean age 18.5 ± 3.2 years) who were receiving fixed orthodontic care were enrolled in this investigation.