One of the most important factors in tooth discoloration is daily habits. Substances like coffee, tea, cigarettes, and colored beverages adhere to tooth enamel, causing yellowing over time. In addition, poor oral hygiene can lead to plaque and tartar buildup, making teeth appear darker.
Thinning of tooth enamel with age is one of the natural causes of yellowing. As the enamel layer thins, the underlying yellowish dentin layer becomes more visible. In addition, some medications, genetic factors, and childhood illnesses can also affect tooth color.