Most people think that chewing gums are only used to freshen the breath.
Sugar-free chewing gums if used after eating help in reducing dental decay by stimulating the production of saliva and by clearing away food particles from the tooth surfaces. Increased salivary flow reduces the formation of acids in the mouth that lead to tooth decay.
Chewing gums do not replace the need to brush/floss, they are adjuncts in helping to decrease/prevent dental caries.
Some chewing gums containing an ingredient called as casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) is said to remineralize and harden tooth enamel, making your teeth stronger and less likely to suffer from tooth decay.