Missed Canals Additional canals in teeth can be missed in occasion. Canals commonly missed are additional canals in mesial root of maxillary molars, distal roots of mandibular molars. Second canal in lower incisors, second canals and bifurcated canals in lower premolars and third canal in upper premolar also can be missed. Always pay attention and expect extra canals. Use of water-cooled, smooth diamond bur can prevent this situation. And not forcing the bur into the restoration can also prevent such incidence.
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A deviation from the original canal curvature without communication with the periodontal ligament. Forms as a new pathway at a tangent to the true pathway of the root canal.
Inadequate access to the apical part of the root canal during access cavity prep. Complete loss of control of the instrument if the endodontic treatment is attempted via a proximal surface cavity or through a proximal restoration Incorrect assessment of the root canal direction Forcing and driving the instrument into the canal Using a noncurved stainless steel instrument that is too large for a curved canal Failing to use the instruments in sequential order.
B, The ledge may be removed with a severely curved file, rasping against the ledge arrows in the presence of sodium hypochlorite or a lubricant. To bypass the ledge, the tip of a correcting file should be severely curved to hug the inside wall of the curve. Recognition The instrument can no longer be inserted into the canal to full WL. Loss of normal tactile sensation of the tip of the instru binding in the lumen - instru point hitting against a solid wall.
When ledge formation is suspected, a radiograph of the tooth with the instrument in place will provide additional information. The central x-ray beam should be directed through the involved area. If the radiograph shows that the instrument point appears to be directed away from the lumen of the canal, completion of the canal preparation must include an effort to bypass the ledge formation. Preoperative evaluation - Accurate interpretation of diagnostic RG for curvature, length and initial size.
Knowledge and awareness of the typical rootcanal morphology and its variations. Access cavity preparation and WL determination Appropriate access cavity Adequate flaring of the coronal half of the canal Longer canals of small diameter are most prone to ledging Instrumentation Techniques and instrument modifications Precurving instruments and not forcing them is a sure preventive measure.
Using instruments with noncutting tips and NiTi files has been shown to be very beneficial in maintaining root canal curvatures. Laser irradiation techniques result in more ledge formation.
The modified-tip files tend to maintain the original canal curvature better and more frequently than unmodified-tip files - Flex-R files, Control Safe files, Anti-Ledging Tip files, and Safety Hedstrm files. The concept of use of these files is that the rounded tip does not cut into the wall but will slip alongside it.
Perforations Cervical perforations - locating and widening the orifice or inappropriate use of GG burs. Lateral perforations at midroot level occur mostly in curved canals, either as a result of perforating when a ledge has formed during initial instrumentation or along the inside curvature of the root as the canal is straightened out - stripping.
Old perforation previously not treated with likely bacterial infection, Questionable Prognosis. Small perforation smaller than 20 endodontic instrument mechanical damage to tissue is minimal with easy sealing opportunity, Good Prognosis. Large perforation done during post preparation, with significant tissue damage and obvious difficulty in providing an adequate seal, salivary contamination, or coronal leakage along temporary restoration, Questionable Prognosis.
Coronal perforation coronal to the level of crestal bone and epithelial attachment with minimal damage to the supporting tissues and easy access, Good Prognosis. Crestal perforation at the level of the epithelial attachment into the crestal bone, Questionable Prognosis.
Apical perforation apical to the crestal bone and the epithelial attachment, Good Prognosis. Rationale for treatment - prevention and treatment of periradicular inflammation. Achieved by measures aimed to control infection of the site and provide the best possible seal against penetration of bacterial elements. Subsequently, the perforation should be adequately sealed. The efficacy of a sealing material depends primarily on sealability and biocompatibility and ability to support osteogenesis and cementogenesis.
MTA - minimal or no inflammation and cementum repair occurred at the material interface. High surface pH supports repair and hard tissue formation in a similar to calcium hydroxide. Holland et al. No comparative human studies to demonstrate the superiority of MTA to other materials. Numerous case reports show excellent healing results. Treatment by a surgical approach Indications - large perforations, perforations as a result of resorption, failure of healing after non-surgical repair, nonsurgically inaccessible perforations, extensive coronal restorations, when concomitant management of the periodontium is indicated, and large overfilling of the defect.
Before corrective surgery, root canals must be properly treated and permanently filled. When surgical intervention is needed in an apical perforation, resection of the apical root to sound root structure with an adequate filling is recommended. A Class I cavity is prepared and the preferred filling material is placed. Guided tissue regeneration has been attempted to manage perforations and offer the possibility of successful repair in surgical treatments by serving as a barrier for apical migration of epithelium Intentional replantation may be considered when orthograde and surgical treatments are not possible, undesirable, or have already failed.
This procedure can be recommended as a substitute for surgical treatment when the perforation defect is too large for repair and when the perforation is inaccessible without excessive bone removal.
Endodontic Procedural Errors: Frequency, Type of Error, and the Most Frequently Treated Tooth
Table 2 Distribution of errors in right and left maxilla and mandible. The right permanent mandibular first molar was particularly prone to errors, showing a greater overall percentage of errors than any other tooth, and was the only tooth in which errors superseded the acceptable cases see Figure 6. Figure 6 Overall distribution of errors in individual teeth. Percentage of overfill and underfill in individual teeth has been elaborated in Figures 7 and 8.
Clinical negligence or endodontic mishaps: A surgeons dilemma
A deviation from the original canal curvature without communication with the periodontal ligament. Forms as a new pathway at a tangent to the true pathway of the root canal. Inadequate access to the apical part of the root canal during access cavity prep. Complete loss of control of the instrument if the endodontic treatment is attempted via a proximal surface cavity or through a proximal restoration Incorrect assessment of the root canal direction Forcing and driving the instrument into the canal Using a noncurved stainless steel instrument that is too large for a curved canal Failing to use the instruments in sequential order. B, The ledge may be removed with a severely curved file, rasping against the ledge arrows in the presence of sodium hypochlorite or a lubricant. To bypass the ledge, the tip of a correcting file should be severely curved to hug the inside wall of the curve. Recognition The instrument can no longer be inserted into the canal to full WL.
Endodontic Mishaps in detail
Endodontic mishaps: etiology, prevention, and management.