The objectives of this study were to evaluate the cytotoxicity and sealing properties of four classes of endodontic sealers (PCS/Kerr, RoekoSeal/Roeko, TopSeal/Dentsply, and EndoREZ/Ultradent). For cytotoxicity testing (MTT method), the materials were either placed immediately in contact with cultured cells or 24 h after setting, then evaluated at three subsequent time points (24 h, 48 h, or 1 wk). For the leakage study, extracted human roots were obturated with acrylic cones and sealers and immersed for 48 h into rhodamine‐labeled lipopolysaccharide. The roots were then observed under a confocal laser scanning microscope to estimate (semiquantitatively) the presence of the rhodamine‐lipopolysaccharide (LPS) inside the canal. The results showed that cytotoxicity generally increased with time, and that most materials pose significant cytotoxic risks, particularly in the freshly mixed condition. Further, all materials showed significant leakage although there was large variation among teeth. Overall, the silicon‐based material (Roeko Seal) was less cytotoxic and more effective in sealing root canals against LPS leakage than other materials.

FCOD may rarely affect only one tooth, resembling a periapical granuloma or cyst. Careful diagnosis is of paramount importance in cases of questionable periapical lesions affecting normal-looking teeth, before beginning treatment. FCOD generally requires no treatment. Biopsy is warranted in case of doubt.

Periapical giant cell lesions may be unilocular and therefore misdiagnosed as an endodontic lesion because of their radiographic similarity to an inflammatory periradicular lesion, especially if the teeth have been root filled or if the vitality is negative or doubtful. It is important to follow up the healing process of a periapical radiolucency related to a root filled tooth and, in case of persistence, to perform surgery and to submit the specimen for histological examination.

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