Individual seeds are sometimes chewed and used in much the same way as chewing gum. Beeswax is also a common ingredient of natural chewing gum. Rosin can be used as a glazing agent in medicines and chewing gum. Forms of chewing gums were also chewed in Ancient Greece. However, betel chewing damages the teeth and gums while teeth blackening does not. The mouth also helps in chewing and biting food. This finding suggests that the effect of chewing gum is domain specific. The polymers that make up the main component of chewing gum base are hydrophobic. Polymers, including elastomers, are responsible for the stretchy and sticky nature of chewing gum. In Singapore importing chewing gum is a criminal offense. This is a list of chewing gum brands in the world. A review about the cognitive advantages of chewing gum by Onyper et al. His cancer was attributed to his habit of chewing tobacco. Prevention includes stopping smoking or chewing tobacco. Premolars can be considered transitional teeth during chewing, or mastication.