Root fractures of posterior teeth. which are defined as fractures involving
cementum, dentin, and pulp, are relatively uncommon among dental traumas.
This study describes an unusual horizontal fracture of a mandibular second
premolar. The tooth was asymptomatic and the fracture unnoticed until the c
rown broke off completely. The patient had no recollection of a causative e
vent nor was there any evidence of previous physical trauma. The tooth was
extracted, embedded in resin, sliced, and examined with different light mic
roscopes. It was concluded that the tooth had been damaged previously but n
ot to the extent that the pulp was seriously damaged. Resorption over a per
iod of time eventually caused the final fracture.