What is the primary psychoactive compound in marijuana (Cannabis sativa)?

Delta-9-tetrahydrocannabinol (THC) is the primary psychoactive constituent of Cannabis sativa. THC binds to cannabinoid receptors (CB1 and CB2) in the brain and peripheral tissues, producing euphoria, altered perception, relaxation, and impaired coordination. In dentistry, heavy marijuana use is associated with xerostomia, increased caries risk, cannabis stomatitis, periodontal disease, and potential drug interactions (e.g., with epinephrine-containing local anesthetics due to sympathomimetic effects). CBD (cannabidiol) is non-psychoactive and is used therapeutically. Terpenes are aromatic compounds in cannabis responsible for scent, not psychoactivity.