A histomorphometric and radiographic study of replanted human premolars

The purpose of this study was to investigate time-related dental tissue reactions to tooth replantation in mature and immature human premolars by histomorphometric and radiographic methods.

Sixty premolars were extracted, immediately replanted (T0), and left without intervention for 1, 2, 3, 6, 12, and 24 weeks before re-extraction (T1). Periapical radiographs were taken at T0 and T1 in all groups except for the 24 week group. Paraffin-embedded teeth were sectioned buccolingually at 5 µm, stained with haematoxylin-eosin, and prepared for histological analysis. Root resorption, tertiary dentine, and root and crown length were recorded and compared on both radiographs and paraffin sections.

Initial degeneration of the odontoblast layer and disturbance of vasculature and normal architecture of the pulp were seen in both mature and immature teeth within the first 3 weeks. Revascularization and tertiary dentine formation was visible on histological sections in immature teeth at 6 weeks. After 24 weeks, most immature teeth had pulps partly or completely obliterated. Abundant tertiary dentine observed on histological slides was not easily seen on periapical radiographs. Likewise, surface root resorption found in both immature and mature teeth was not visible on the radiographs up to 6 weeks after replantation.

Within the limits of this study it can be concluded that the dental pulp of immature teeth has the ability to regenerate and produce tertiary dentine after replantation. Root resorptions and tertiary dentine seen on histological sections are not visible on corresponding radiographs 6 and 12 weeks after replantation.