Text: This is why your dentist hectors you to rubber-tip your gums, brush with a superconcentrated fluoride toothpaste, and wear a night guard to control your bruxing (which loosens teeth, opening pockets between teeth and gum, etc.).
Entailment: This is why your dentist gives you advice about how to look after your teeth which seems overzealous.
Contradiction: That is the reason why your dentist dismisses night guards and special toothpastes as needless.