When a restoration (filling) is placed into a tooth then one corner or more may move independently when biting on the tooth. Not very commonly, this also occurs in a tooth with no restorations. The common complaint is a sharp pain when biting on hard food. This pain usually lasts only when biting down or releasing the bite.
Sometimes a cracked tooth may cause irreversible pulpitis (an inflamed nerve) or even pulp necrosis (a dead nerve inside the roots). These cases with require either root canal treatment or extraction.