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