My wisdom teeth are all fully erupted I heard it is advisable to have them extracted? Is this true?

This will depend on the clinical circumstances which are unique to each individual. Your dentist will advise specifically for you. If your 4 wisdom teeth are fully erupted into good positions and your oral hygiene is good around these teeth you may be advised to retain them. However, if you have poor oral hygiene, signs of gum disease , established dental decay or poor function you may be advised to have them removed. The purpose of this will be to maintain the oral health of the remaining teeth as access will be greatly improved for cleaning the remaining teeth. Wisdom teeth do not normally provide any function in an otherwise healthy mouth. In fact they may act as a reservoir for gum disease and dental decay causing both to spread to neighboring teeth and gums.