Problem solving endodontics – removal of a fractured instrument
John Rhodes describes the retreatment of a mandibular incisor in which a fractured instrument has to be removed.
Three basic steps
There are three basic steps when removing objects from the root canal; firstly there must be sufficient space coronally for unimpeded removal, secondly ultrasound is used on the lateral aspect to vibrate, dislodge or unscrew the object and finally a means of retrieval from the root canal system.
Figure 1 case study removal of a fractured instrument
In this retreatment case the entire working portion of an instrument has fractured and will need to be removed in order to disinfect the root canal. The presence of a periapical lesion indicates that the entire root canal is undoubtedly infected.Mandibular incisors can have complex root canal morphology and often more than one canal. The prevalence of two canals has been reported as between 12%-35%. Even when there are not two separate canals the root canal shape is ribbon-like with a narrow, thin cross section.Many difficulties when root filling mandibular incisor teeth occur as a result of inadequate access cavity preparation.
If the access is too small, angled incorrectly or placed too far lingually on the cingulum the lingual canal (if present) is easily missed. Working through such access cavities places increased stress on rotary or reciprocating instruments; the first danger zone occurs coronally as the instrument is contorted to gain access to the root canal, in this situation the entire working length of the file may fracture. Apical curvatures provide the second danger zone and potential fracture of an instrument tip, in this…
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