A patient presented in my office complaining of pain in a tooth in the upper right quadrant of his mouth. Several weeks earlier, he had been playing with his five year old son when the child jumped up at the same time that dad bent down. The child butted his head into dad’s chin forcing his jaw to close in an eccentric position. The patient felt immediate pain and noted that a lower tooth had broken. He assumed that the lower tooth was the source of his pain, however, over the course of the next several days, the lower tooth ceased to hurt, and the patient noted pain when pressure was applied to the molar in the upper jaw. The pain was fairly low grade at first, but it became progressively more severe over the course of several weeks.
The image above shows shows an obvious vertical crack extending up the buccal (facing the cheek) developmental groove to some point under the gum line. Obvious to any dental professional, but probably not so obvious to the casual reader is the parulis (gum boil) seen in the gingiva immediately above the crown of the tooth. The crack also extends on the occlusal (top) of the tooth toward the distal (back), isolating the distal buccal cusp. The obviously separated fragment was only very slightly mobile indicating that the crack extended well into the bone.
Natural grooves in a tooth are also natural cleavage lines, and before the advent of modern air driven handpieces (drills), dentists made use of these when extracting teeth. It is often advantageous to break teeth into smaller pieces when extracting them from under dense bone or from tightly crowded dentitions. Dentists in those days were trained in the positions of these cleavage lines. The dentist would use a hammer and a chisel to cleave the tooth into pieces while removing it.
The two x-rays above show the tooth from different angles. The image on the left is a periapical film, taken from a high angle. It shows the tips of the roots. The one on the right is a bite-wing radiograph taken from an angle which does not distort the shape of the crowns of the teeth. The actual crack shows up on both of the films, but it shows up much better on the bite-wing. The periapical film shows radiolucent lesions (the dark “balloons”) about the root tips of the first molar. The bite wing also shows the damage done to the lower molar during the accident.
The patient was anesthetized and the tooth was extracted. As it happened, the tooth came out without further damage, and the result is seen in the image above. Note the pink “balloons” at the tips of all three roots. These are made of soft, floppy granulation tissue, and are called granulomas. Their presence accounts for the radiolucencies seen on the radiographs above. The crack extends from the crown of the tooth into the furcation (where the roots split off from the main body of the tooth), and in fact, the tooth came out of its socket as if it were a single entity instead of the two separate fragments it really was. The image below shows the tooth laid out and the loose fragment separated from the main body of the tooth.
Upper first molars generally have three roots. The fracture through the furcation split the tooth into two segments. The main body of the tooth contains both the palatal root (the larger one) and the distal-buccal root. The smaller segment contained the mesial buccal cusp along with the entire mesial buccal root. The darkness seen in the broken part of the crown is not decay. It is simply stain from food accumulated in the crack during the time the tooth was fractured and remained in the mouth. The granulomas formed in response to the dead nerve, which died as a result of the trauma suffered by the tooth during the accident