Scandinavian multicenter study on the treatment of 168 patients with 230 intruded permanent teeth - a retrospective cohort study

Background/Aim: The aim of the study was to evaluate the survival of intruded permanent teeth related to treatment in a large number of patients, with special focus on development of pulp necrosis and replacement resorption (ankylosis-related resorption). Materials and Methods: The material consisted of 168 patients (mean age 9.6 years) with 230 intruded permanent teeth from dental trauma clinics in Copenhagen, Denmark, Stockholm, Sweden, and Oslo, Norway. The degree of intrusion was classified as mild (1-<3 mm), moderate (3-7 mm), and severe (>7 mm). Root development was categorized with respect to root formation and development of the apex into three groups of increasing tooth maturity: very immature, immature, and mature. Results: Awaiting reeruption was the treatment of choice in 107 teeth (47%), orthodontic repositioning in 28 (12%) and surgical repositioning in 95 (41%) teeth. Pulp necrosis was diagnosed in 173 teeth (75%), infection-related root resorption in 57 (25%) and replacement resorption in 50 teeth (22%). Very immature teeth, teeth diagnosed with mild intrusion, and teeth awaiting reeruption had significantly (P < 0.05) fewer complications. In a stepwise discriminant function analysis, choice of treatment, root development, and degree of intrusion were significantly (P < 0.05) associated with the development of replacement resorption. Root development and degree of intrusion were significantly (P < 0.05) associated with the development of pulp necrosis. Conclusion: This study indicates that root development and degree of intrusion may be important for the development of pulp necrosis as well as replacement resorption, whereas choice of treatment only seems to influence the development of replacement resorption in intruded permanent teeth. Awaiting re-eruption resulted in the lowest risk for developing replacement resorption.