This white paper examines the mechanisms, implications, and management of discoloration in direct-printed 4D aligners. Unlike conventional thermoformed aligners, 4D aligners exhibit a chromatic shift during intraoral wear that is strongly associated with biofilm colonization and bacterial metabolites. Rather than being an esthetic drawback, this discoloration can function as a visual hygiene indicator, providing early warning of microbial activity. Supported by Scanning Electron Microscope (SEM) imaging and spectrophotometric data, the root cause is primarily the adsorption of bacterial chromophores onto the surface of the polar material, aided by layered surface microtextures. Effective strategies, including oxygen-powered mouthwashes for prevention and cleansing tablets for reversal, ensure that discoloration remains manageable and reinforce its value as functional biofeedback.