Apical & marginal periodontium

* Overfilling will of necessity sometimes occur.
* The apical periodontium is considered robust and adaptive to many insults.
Pain may be experienced after overfilling with many materials, but it is
unclear whether bacteria play a role in interappointment pain.
* Intense pain after irrigation with sodium hypochlorite is an extremely
seldom but dramatic occurrence.
* Local inflammatory reactions are seen after extrusion of material into
the periodontal ligament and/or the adjoining bone marrow spaces. These
reactions do not progress to create chronic apical periodontitis.
Marginal periodontium
* Etchants and necrotizing agents may adversely affect the marginal gingiva.
* Calcium hydroxide may burn through thin gingiva covering eg, perforation
exits.
* Formaldehyde- or arsenical-containing devitalization pastes may cause
extensive necrosis of gingiva and underlying bone