I suddenly started feeling sensitivity to air that I inhale on my front tooth. Sensitivity (and slight pain) origins from the gum line (I personally feel so). Hot drinks don't pain or feel sensitive, cold drink does but very little. No visible sign of decay, tartar or caries. What's wrong? I have a sudden sensitivity to cold drinks a month after I had a cavity filled that I was told by the dentist wasn't very deep. Why the sensitivity?