child's tooth

My son was complaining about something in his tooth. Upon further inspection with a flashlight it looks like half his tooth is GONE. And some grey discoloration. I noticed the other side of his teeth. Same thing is happening to the other tooth but not so bad yet. I don't know what happened? It is a baby molar tooth He said there is no pain though. A lil background on him He is a type 1 diabetic and he had sealants on his teeth quite a long time ago. Maybe even 8 yrs ago. Tweet