Introduction
After obturation the root canal filling is checked to confirm that the canal system is sealed along its whole length and in three dimensions, with no material in the periapical tissues. Its quality largely decides whether apical periodontitis heals or develops, so it is judged on a control radiograph at once and again at review. Materials and techniques: topics 46–47.
Methods of evaluation
- Control (post-operative) periapical radiograph – taken immediately after obturation with the paralleling technique (film holder, beam perpendicular to the film and to the long axis of the tooth). It must show the whole root filling and the bone around the apex.
- Angled (eccentric) view for multi-rooted teeth and two-canal premolars: the tube is shifted horizontally by about 20° to separate superimposed canals; by the SLOB rule (same lingual, opposite buccal) the lingual canal moves with the tube.
- Master-cone radiograph – before sealer and compaction, to check the cone's length while it can still be corrected.
- Clinical examination at review: pain, swelling, tenderness to percussion and palpation, sinus tract, mobility, probing depths (a deep isolated pocket suggests root fracture) and the state of the coronal restoration.
- CBCT – not routine; limited field of view, only when periapical radiographs are inconclusive and the result would change treatment (e.g. persistent symptoms without a visible lesion, suspected missed canal or root fracture). Gutta-percha causes streak artefacts, so CBCT judges filling density poorly.