Instrument separation during root canal treatment is relatively common and is a complication of root canal treatment. The most conventional treatment after instrument separation is to remove the broken needle as far as possible. If the broken pin is too deep and too costly to remove, which may lead to lateral penetration or root fracture of the root, it can be left out for the time being and treated with plastination or conventional root canal filling. Broken pins located in the apical 1/3 of the root are not easy to remove, but in most cases this location does not cause much inflammation after root canal treatment. Broken pins that have gone beyond the root apex must be removed in a timely manner because they are a foreign body that can irritate the bone of the root apex, resulting in granulomas or abscesses at the root apex. Broken pins that have broken off in the root should also be removed as much as possible to avoid imperfect root canal treatment.