[Dental injuries due to miniplate osteosynthesis. Classification, treatment management, complications, and prognosis].

Background: In spite of a monocortical design, miniplate osteosynthesis can injure dental roots directly as well as damage dental substance indirectly by interrupting the apical blood stream.
Purpose: The present retrospective study classifies different types of dental root trauma caused by monocortical screws, suggests therapeutic options based on diagnosis, and documents survival probability and prognosis after tooth trauma.
Patients and Methods: During a period of 11 years, 380 patients with permanent dentition underwent miniplate osteosynthesis for the treatment of mandibular fractures, 29 of whom sustained dental root trauma caused by drilling failure. These patients were clinically and radiographically examined for a follow-up time of not less than 38 months.
Results: The 29 patients could be classified into four different types of dental root trauma: 13 pulp injuries above the apical third of the root (type Ia), 6 pulp injuries in the apical third of the root or extradental lesions interrupting the apical blood stream (type Ib), 4 lesions to the central radicular dentin without pulp injury (type II), and 6 lesions to the peripheral radicular dentin and root cementum (type III). Of 13 type Ia injuries, 5 developed apical periodontitis and dilatation of the periodontal space. Therefore one root canal treatment and three apicoectomies were performed. One tooth had to be extracted. Three further type Ia injuries and two type Ib injuries showed root resorptions inducing two root canal treatments. One of six type Ib injuries required root canal treatment because of apical periodontitis. One of four type II injuries caused root resorption not requiring therapy. No relevant, pathological finding could be identified after type III injury.
Conclusions: The type of dental root trauma caused by miniplate osteosynthesis determines therapy, complication rate, and survival of the injured tooth.