FIGURE 105.2 A: Primary dentition lettering system, starting with letter A in the upper right proceeding across to J in the upper left, then continuing with K in the lower left to T in the lower right B: Permanent dentition number system, starting with number in the upper right across to 16 in the upper left, then 17 in the lower left through 32 in the lower right (Reprinted with permission from Lippincott Williams & Wilkins’ Comprehensive Dental Assisting Philadelphia, PA: Lippincott Williams & Wilkins; 2011.) A complicated tooth fracture involves not only the enamel and dentin but also the pulpal tissue, which is evident by a red area within the fracture site ( e-Fig 105.4 ) To best preserve the viability of that tooth, the exposed pulp should be treated as soon as possible Prognosis depends on the size of the exposure, the time interval between the trauma and therapy, and the maturity of the involved tooth Teeth with root fractures may present with mobility and/or crown displacement and can only be diagnosed with an intraoral dental radiograph Treatment involves reduction if the tooth segments are not aligned and splinting the affected tooth to the noninjured adjacent teeth Pulpal therapy often is necessary if physiologic healing of the fragments does not occur