Overinstrumentation: Etiology

Lack of or incorrect determination of canal length are obviously the most common reasons for overinstrumentation. Other causes may be attributed to incorrect positioning of the silicone stoppers and inadequate observation of the reference points.
In acute apical periodontitis, overinstrumentation (ca. 1 mm) with small files is sometimes intentionally carried out to permit drainage of pus from the periapical area via the root canal.