Study Design: A randomized controlled trial with two parallel arms and an allocation ratio of 1:1.
Setting: The study will be conducted in the orthodontic department of Riyadh Elm University hospitals in Riyadh City, Saudi Arabia.
Participants: Patients undergoing fixed or clear aligner orthodontic treatment referred to REU dental hospital will be randomly allocated to either the clear aligner group or the fixed orthodontic appliance group.
Intervention: Prior to orthodontic treatment, all patients will receive phase I periodontal therapy and oral hygiene instructions. Fixed orthodontic appliances will be bonded using metallic brackets with a 0.022-inch slot and 0.014-inch NiTi archwires. Clear aligner patients will receive Invisalign® treatment.
Outcomes and Saliva Collection: Salivary samples will be collected using the spitting method at baseline (T0) and follow-up time points according to the study protocol. Salivary flow rate, pH, and buffering capacity will be assessed as described in the proposal.
Randomization and Blinding: Randomization will be performed using a random number generator with allocation concealment via opaque envelopes. The investigators involved in outcome assessment and data analysis will be blinded.
Ethical Considerations: The study will be submitted to the Institutional Review Board at Riyadh Elm University and conducted in accordance with IRB policies.