Concussion and subluxation injuries to permanent teeth lead to obliteration of the pulp canal space in 3% to 11% of cases, depending on the severity of the injury and the developmental stage of the tooth. Obliteration of the pulp canal space may make root canal treatment necessary because of the development of apical periodontitis or for cosmetic reasons. If carefully executed, root canal treatment in teeth with an obliterated pulp canal space is highly successful and may act as a basis for internal bleaching.