Hello and thank you for your questions.
First cavities are caused by bacterial infections in your teeth. The bacteria produce acids that eat away at the outer surface of your teeth (enamel) and then spread to the inside of your teeth.
Cavities are prevented by:
-decreasing frequency of sugar intake, especially sticky, tacky snacks
-avoiding beverages high in caffeine, sugar and acids: coffee, energy drinks, fruit drinks, sports drinks
-following the 3-2-1 rule: brush 3 times a day, floss 2 times and gargle with Listerine
1 time daily
-do not sip on soda pops or fruit drinks, drink them and then switch to water, the longer you spend sipping on a soda the more exposure you have to acids that eat away at your teeth.
-go to the dentist
annually and have a cleaning twice a year.
-if you have cavities get them fixed right away before they progress and become worse.
The hole in your tooth is called a cavity. The gums growing into the hole is called hyperplastic overgrowth. You are having an irritation in the area, the gums are swelling and growing due to this issue and filling in the void of your tooth.
If the cavity is in the top of the tooth, you may actually have hyperplastic pulp also known as a pulp polyp.
You need to have the cavity filled, possibly a root canal
and crown, or an extraction of the tooth depending on how bad the hole is.
This is not necessarily dangerous, but could lead to more discomfort and a more severe infection down the road. Don't sit on this until it becomes painful, have it repaired and addressed as soon as you can.
Best wished and good health