Home › Forums › Endodontics & conservative dentistry › DEALING WITH ENDODONTIC PROBLEMS
Welcome Dear Guest
To create a new topic please register on the forums. For help contact : discussdentistry@hotmail.com
- This topic has 2 replies, 2 voices, and was last updated 21/05/2011 at 3:49 pm by
Anonymous.
-
AuthorPosts
-
20/05/2011 at 3:27 pm #17225
Anonymous
This in vitro study used computed tomography (CT) to compare the occurrence of canal transportation in the apical third of mesiobuccal canals in maxillary molars instrumented with 3 techniques. Sixty teeth were assigned to 3 groups (n = 20), and the root canals were instrumented as follows: Group 1, hand instrumentation with K-files; Group 2, K-files coupled to an oscillatory system powered by an electric engine; Group 3, ProTaper NiTi rotary system powered by an electric engine. To compare the canal transportation produced by the different techniques, preinstrumentation and postinstrumentation 3-dimensional CT images were obtained from root cross-sections of the region located 3 mm short of the apical foramen of each root canal. The CT scans were exported to Adobe Photoshop software, and the initial and final images were superimposed to detect the root canal wall differences between them. Canal transportation was measured by the distance between the prepared canal center and the anatomic canal center. The manual technique produced lesser canal transportation (0.10 mm) than the oscillatory and rotary techniques (0.37 and 0.22 mm, respectively); this difference was statistically significant (P = .021). All studied techniques produced canal transportation.
21/05/2011 at 3:49 pm #17227NEGOTIATING TO THE APEX in order to gain a working measurement is not always an easy task. I often hear from dentists that the canal is “blocked” or “calcified,” and they ask what they can do to get the 08 or 10 instrument down to the apex for a measurement. In some instances, the canals are blocked with calcium, but most of the time the canal makes a sharp turn that makes it impossible for a straight instrument to get around or past that bend in the root. The answer is always the same: pre-bend the endodontic instrument. A bent instrument will never get you into trouble. A straight instrument in a curved canal can lead to several iatrogenic problems.
If the instrument has a bend at the apical tip, the instrument circumscribes a circle at the tip when you rotate it. As you rotate the circle around the canal wall, it will eventually drop into the curved part of the canal. You will then be able to go to the apex of the canal. If the instrument is straight, it will circumscribe a point at the apical tip when you turn it to find the bend in the canal. The point will not find or fall into a curved canal. In fact, if you work the instrument enough it will make a ledge in the canal. Ledge formation is iatrogenic and makes instrumentation harder to do; consequently, completing the root canal procedure will take longer.
The best way to avoid creating a ledge in the canal and to find the curved canal itself is to place a 45-degree bend in the endodontic instrument. As you place the endodontic instrument into the canal and rotate, it will eventually fall into the canal
At that point, you can gently use a “wrist watch” motion to get to the apex. The 45-degree bend is easy to make with any “College pliers” or locking pliers. Just grab the apical end of the endodontic instrument with the pliers and bend the end to approximately 45 degrees. In a stainless steel instrument, the bend will remain when you release the instrument
The bend will not remain in a NiTi instrument. Because NiTi instruments are super-elastic, they do not hold a bend; instead they return to their original shape once released from the pliers. -
AuthorPosts
- You must be logged in to reply to this topic.