Radiological and histological signs of inflammation in human root-filled teeth

Objectives: The aim of this study was to assess the relationship between histological and radiological signs of inflammation in human root-filled teeth. Methods: Block-sections of root-filled teeth were gathered from 26 human cadavers which had been stored in formalin for various periods of time. The blocks were radiographically exposed, longitudinally sectioned (6-10µm) and HE-stained. 53 roots could be evaluated both radiographically and histologically. Histological sections were categorized into "inflamed" or "uniflamed". Apices from untreated non-carious teeth served as controls. The presence of accessory canals was recorded as well as their contents (empty/tissue/filling material). The radiographs were evaluated by two blinded experienced operators. In case of initial disagreement, discussion took place until agreement was achieved. Statistical analysis was performed with chi square test. Results: 100% of the roots had accessory canals, of which 12 showed tissue remnants, all other were empty. 49% of the cases were histologically uninflamed at the apex, 52% appeared radiographically intact. The odds ratio of finding a histologically inflamed root tip with radiologic lucency vs. if the apex was intact radiographically was 9.2 with a significance of p=0.002. The odds ratio of finding a histologically uninflamed apex with a radiologically tight coronal seal was 3.7 at p=0.053. Conclusions: It may be concluded that there are relationships between radiological and histological signs of inflammation in human root-canal treated teeth. There seems to be a strong tendency that the radiologically determined quality of the coronal seal has an impact on the histological state of the root filled tooth.