Pain or discomfort is most commonly reported during the initial days of wearing a new set of clear aligners. This is primarily due to the pressure exerted on the teeth to initiate their movement, which leads to temporary soreness or tenderness. The underlying mechanism involves the application of controlled, gradual force by the aligners on the teeth, which stimulates the periodontal ligament and initiates bone remodeling—a critical process necessary for orthodontic tooth movement. Supporting this, a randomized clinical trial by White et al. (2017) found that mild to moderate discomfort is typically experienced within the first 2–3 days after inserting a new aligner set, with symptoms generally subsiding thereafter (White DW, Julien KC, Jacob H, Campbell PM, Buschang PH. Discomfort associated with Invisalign and traditional brackets: a randomized clinical trial. Angle Orthod. 2017;87(6):801-808).