Endodontic Considerations in Dental Trauma

PULP AND PERIODONTAL LIGAMENT PATHOSIS FOLLOWING DENTAL CARIES AND DENTAL TRAUMA

There appears to be major differences in etiology and pathogenesis of pulp pathosis related to caries progression and dental trauma._188,189 The main therapeutic problem in caries-related infected pulp necrosis appears to be control of bacteria in the pulp canal. Obturation of the root canal is for the most part an uncomplicated procedure in teeth with fully developed roots. In cases of trauma-related pulp necrosis (see page 22), which frequently occur in developing teeth with open apices, problems in root canal obturation, however, are often encountered. Furthermore, infection-related external root resorption (see page 24) cannot be arrested without proper disinfection of the root canal and dentinal tubules. Finally, due to its remodeling character, ankylosis can expose dentinal tubules, resulting in direct or indirect exposure of the potentially contaminated root canal content.

PROBLEMS OF PULP NECROSIS AND DEVELOPING ROOT FORMATION: TREATMENT OBJECTIVES

An open apex represents a major obstacle in disinfecting and obturating the root canal. Experimental and clinical studies have shown that bacteria are located in the necrotic pulp and surrounding dentinal tubules (Figure A). Removal of necrotic pulp tissue and disinfection of the root canal will lead to healing processes that in most cases result in closure of the apical area by a hard tissue barrier formed by cementoblasts. In rare cases where the Hertwig’s epithelial root sheath has survived, dentin and cementum may be formed resulting in additional root length (apexogenesis). Due to the frequently weakened structure of the immature root, treatment approaches should be selected which do not further weaken the tooth (i.e. extensive root canal filing or extensive chemical treatment of the canal [e.g. prolonged treatment with calcium hydroxide]), which can lead to spontaneous cervical root fracture.

PROBLEMS WITH INFECTION-RELATED ROOT RESORPTION

The presence of infection-related root resorption cavities on the root surface represents a significant threat to the prognosis of the endodontic procedure (Figure B). Unless all bacteria are permanently removed or inactivated in the root canal as well as the dentinal tubules, resorption may progress. If, however, bacteria are removed or inactivated, healing will take place with a new periodontal ligament inserted into newly formed cementum, or an ankylosis (in case of extensive resorption cavities).

PROBLEMS OF ANKYLOSIS-RELATED RESORPTION

Due to the inherently progressive nature of the ankylotic process (see page 25), where dentinal tubules may be exposed by osteoclastic activity, effective root canal obturation is essential. Furthermore, a bacteria-tight seal must be created at the entrance of the root canal. Unless these steps are taken, a slowly progressive ankylosis-related resorption may change to a rapidly invading infection-related resorption.

TIME RELATION OF VARIOUS PROPERTIES OF CALCIUM HYDROXIDE

For decades, calcium hydroxide has been known to be a very effective medication in the treatment of pulpal and periodontal complications following injury. This is primarily related to simultaneous disinfection of pulp tissue and the capacity to initiate hard tissue healing. Knowledge about the time relationship of these effects is necessary for its proper use. Calcium hydroxide is known to have a strong proteolytic effect.¹⁹⁰ Thus, most pulp remnants will be completely dissolved within 1 week. However, the same proteolytic effect apparently also affects the circumpulpal dentin, resultin/>