Clear aligners often feel tight, especially when switching to a new set, because they are designed to apply controlled pressure to your teeth to move them gradually into the desired alignment. This sensation is a direct result of biomechanical forces acting on the periodontal ligament and surrounding bone, initiating a biological response called bone remodeling (Rossini et al., 2015). The tightness typically reflects that the aligners are actively working—engaging the teeth in the necessary movement. This process can lead to temporary discomfort or soreness, especially in the first 2–3 days of a new aligner tray, but it usually subsides as the teeth adjust (White et al., 2017). This tight feeling is normal and should not be mistaken for an ill-fitting appliance unless it persists or causes significant pain, in which case a dental consultation is recommended. References: Rossini, G., Parrini, S., Castroflorio, T., Deregibus, A., & Debernardi, C. (2015). Efficacy of clear aligners in controlling orthodontic tooth movement: A systematic review. Angle Orthodontist, 85(5), 881–889. https://doi.org/10.2319/061614-436.1 White, D. W., Julien, K. C., Jacob, H. B., Campbell, P. M., Buschang, P. H. (2017). Discomfort associated with Invisalign and traditional brackets: A randomized clinical trial. Angle Orthodontist, 87(6), 801–808. https://doi.org/10.2319/012417-62.1