(a) The attempt to bypass the fragment with a Hedstrom file , used in rotary motion, resulted in root perforation. (b) Etiology of a perforation during attempted bypassing of a fragment: the file is “directed” outward by the top of the fragment. Early radiographic control in some cases can help to avoid a perforation

(a) Fractured instrument in the apical part of the root canal. (b) Successful removal of the fragment. (c) The post-obturation control reveals substantial loss of dentine in the coronal and middle third of the root canal and a perforation at the furcational inner side of the curvature

(a) A maxillary second molar with a small fragment of a #30 Hedstrom file referred for endodontic treatment. (b) Lateral perforation was created at the apical third of the palatal root during efforts to remove the fragment, and thus 4 mm of the apical third including the perforation site were sealed with MTA. (c) The remaining palatal canal was obturated with injection of thermoplasticized gutta-percha and the buccal root canal with lateral compaction of gutta-percha and epoxy-resin sealer. (d–f) The scheduled clinical and radiographic recall examinations at 6 months, a year, and 2 years, respectively, revealed uneventful healing (Courtesy Dr. K. Kodonas)

(a) Clinical appearance of a mandibular canine with a fragment. (b–d) Excessive removal of tooth structure during fragment removal with ultrasonics. (e) Removed fragment

(a) Fractured instrument in the mesiolingual root canal. (b, c) Control radiograph following removal of the fragment. (d) The radiographic control reveals massive loss of dental hard tissue in the coronal part of the root canal

(a) Preoperative radiograph showing a fractured instrument in the mesiobuccal root canal of a maxillary molar. (b) During successful removal of the fragment, a second instrument (Hedstrom file) fractured. Despite this second fracture, the root canal could be prepared and obturated to its apical terminus

(a) Preoperative radiograph of a maxillary second left molar with inadequate root canal treatment and an instrument fragment approximately 5 mm long at the mesiobucall root canal. (b) Second fracture of the original fragment during efforts to retrieve it with ultrasonics under the dental operating microscope. Note the preparation of the canal up to the original site of the fragment

(a) Preoperative radiograph with a 2.5 mm fragment of Hedstrom file #30 in the mesial third of the mesiobuccal root canal of a mandibular second molar. (b) Preparation of a staging platform with a #2 Gates Glidden bur and removal of the fragment with an ultrasonic technique under the dental operating microscope. (c) Immediate post-obturation radiograph. Note the characteristic appearance of the ledge at the outer side of the curvature

(a) Fragment in the apical part of a mandibular canine. (b) Successfully removed fragment. (c) The control radiograph shows ledging at the outer side of the curvature, not allowing preparation and obturation to the apical terminus

(a) Preoperative radiograph. (b) Small ledge created during the attempt to bypass the fragment at the outer side of the curve. (c) Removal attempts were continued at the outer side of the curve, resulting in enlargement of the ledge and a small perforation

(a) Fractured instrument in the distobuccal root canal of a maxillary molar. (b) Following initial bypassing of the fragment, severe transportation of the root canal occurred

Transportation of a fragment deeper into the root canal. (a) Preoperative radiograph. A 6 mm fragment of a #25 Hedstrom file can be seen at the coronal third of the mesiobuccal canal of the first mandibular molar. During retrieval attempts, a 1.5 mm segment of the original fragment was broken and removed, but the remaining part was inadvertently pushed apically. (b) The remaining portion was eventually bypassed with the file bypass technique and the root canal was instrumented and obturated up to the apex incorporating the fragment in the mass of gutta-percha

(a) Preoperative radiograph showing a fragment in the coronal part of the mesial root canal. (b) The fragment has been removed but has been dislodged into the distal root canal. (c) Having no friction, the fragment could be removed using a moist paper point. (d) Removed fragment

(a) Preoperative radiograph. An approximately 4 mm long fragment of an SS file can be seen in the mesial root of an underobturated mandibular molar. (b–g) “Movement” of the fragment toward the apex and eventual extrusion into the periapex during efforts to bypass and retrieve it with the file bypass technique. (h) Immediate post-obturation radiograph. (i) One-year recall radiograph (Courtesy Dr. G. Alexandrou)