Wednesday, November 21, 2012
Recently, I received this email from a friend who is an endodontist:
“A referring dentist called me, very upset at his new XXX rotary system. He said he is separating files right and left and has gone back to hand files only, it is so bad. He has been in practice for 10 years and likes endo. He has used the “YYY" system with no problems several years ago (probably YYY files). He works for a dentist who has gone with XXX. Your thoughts please.”
Optimizing endodontic results requires the clinician prevent iatrogenic events such as those referenced above, and simultaneously to utilize proven treatment strategies following basic principles. Such principles require adherence, irrespective of which file system the clinician uses to achieve these goals.
I believe the skills of the clinician and adherence to time honored endodontic principles are more important than the instruments or technique used to obtain the result. Rotary nickel titanium (RNT) files systems are no exception to this rule.
RNT files will fracture if used improperly. While I have not interviewed or watched the doctor above, and noting that some systems are inherently “safer” than others, I am familiar with the systems mentioned in the email (which have been left nameless), and I believe it is ultimately the clinician, not the system, creating the fractures.
Both in dental trade magazines and refereed journals much has been written about the science of RNT fracture and clinical strategies to prevent fracture. Ideally, every effort should be made to avoid iatrogenic events rather than trying to correct a misadventure after it has occurred.
The above notwithstanding, RNT separation remains a vexing problem, especially for novice clinicians, or even for experience clinicians while learning a new system.
When separation occurs, I believe the clinician has an obligation to refer the patient to an endodontist for at least an evaluation, and if possible file removal, and if indicated, surgical correction.
This two-part article was written to look at a case with a separated RNT file, discuss what may have created the separation and also what was done to remove the fragment.
Figure 1: Separated File in the mesial root of tooth #30 as referred.
The Clinical Case
The patient presented with a separated RNT file in the mesial root of tooth #30. The patient was ASA 2. Medically and dentally there were no contraindications to treatment. The tooth was asymptomatic and percussion, palpation, mobility and probing were all within normal limits.
Consent to treatment was obtained. Consent was detailed, one part of which was to inform the patient that the existing crown may fracture upon access and might need replacement.
Figure 2: File fragment bypassed.
Crown fracture is a risk because access will require a larger occlusal opening to allow straight-line access of the ultrasonic instruments needed to reach and hopefully remove the fragment.
Another issue discussed during the informed consent was the risk of a possible iatrogenic event in removal and/or that the fragment may not be retrievable. Appreciating the risk of perforation will go far towards preventing this iatrogenic misadventure. Removal of a file fragment should only be attempted by those with the lighting, magnification and training to do so, generally an endodontist.
Assessment of RNT fracture requires the clinician evaluate the following (among other issues):
- The type of file that fractured
- The taper and tip size of the fractured segment
- Fracture location and specifically, how much of the file is above and below the point of greatest curvature of the root—The more coronal the segment, the greater the chance of file retrieval
- Whether fracture was the result of cyclic fatigue or torque failure—The type of failure influences the removal technique
- The experience of the clinician and the equipment and supplies at hand
- Tooth position in the arch
- Rotation and/or tipping
- Co-morbidities present, secondary perforation, canal blockages, canal transportations, a second separated file, etc.
- Restorability
- Coexisting resorption and anatomical anomalies
- Periodontal status
- Limited opening, gagging, etc.
- The patient’s risk tolerance for retreatment
Figure 3: Canal obstruction removed.
Part 2 of the article will describe the means used to remove the file—a combination of expanded access, ultrasonics to uncover the file, K and safe ended Mani SEC O K hand files to bypass and reciprocate past the fragment and irrigate the fragment out of the canal.
I welcome your feedback.