Dentaltown March 2013 - (Page 84)

endodontics feature by Kenneth Koch, DMD, and Ali Nasseh, DDS, MMSc Endodontics has been, and continues to be, all about the preservation of the natural dentition. In the clinical practice of endodontics, once proper straight line access has been created, the next task is the cleaning and shaping of the root canal system. However, the real challenge is to accomplish this in a consistent and predictable manner. The first question we must ask ourselves is, “Why do we shape a root canal?” The answer is clear. We shape a root canal 1) to allow our irrigation agent (sodium hypochlorite) to work in the most effective manner possible and 2) to expedite obturation. The next question is the issue of taper and a comparison must be made between a variable taper preparation and a constant taper preparation. Presently, in endodontics, we have two methods of root canal instrumentation: variable taper or constant taper. Both of these methods can do a good job of cleaning the root canal system. However, there are some profound differences. A variable taper method uses rotary files that have the same common apical tip size but vary in their tapers. For example, one may use a variable taper technique that employs a .25 apical tip size and utilizes variable tapers in the range of .12, .10, .08, .06, .04 and .02. While a variable taper sequence tends to promote disengagement of the instruments, what is sacrificed is the predictability of shape commonly associated with a constant taper preparation. Due to their lack of a constant, reproducible shape, most variable taper methods are associated with thermoplastic obturation. Furthermore, with large variable taper sizes such as .12, .10 and .08 there is the serious concern of coring out the orifice and removing an excessive amount of tooth structure in the critical coronal third of the canal. Consequently, while a variable taper technique may facilitate the insertion of carrierbased obturation methods, or thermoplastic techniques, extreme caution must be used not to remove excessive tooth structure and thereby compromise the long-term retention of the tooth. This is a very key point. A constant taper preparation, on the other hand, is generally more conservative in the coronal third of the radicular dentin. 84 MARCH 2013 » dentaltown.com http://www.dentaltown.com

Table of Contents for the Digital Edition of Dentaltown March 2013

Dentaltown.com Highlights
Howard Speaks: Dentistry Could Come Back with a Vengeance
Professional Courtesy: I’m No Anti-Dentite
Continuing Education Update
Second Opinion: Should Endodontists Place Implants?
Needle Stick Question
Am I the Only One Who Didn’t Know How to Use My Loupes?
The Patient Blames Me for Cracking His Tooth
Corporate Profile: {KöR}
CAD/CAM Materials
Dentaltown Research: Cosmetic Dentistry
Do-it-Yourself Finance, Part IV: Savings and Investing
Product Profile: Centrix
Keep Them Coming Back
You Should Know: Likeable Dentists
Multimodality Endodontics
Endodontics for the Recent Graduate: Instrumentation
Continuing Education Porcelain Veneers: From Case Selection to Cementation
8½ Tips for Dental Safety Checklists
How Prepared Are You For a Medical Emergency?
Dental Stem Cell Preservation and the Dawning of Regenerative Oral Medicine
Product Profile: Ivoclar EvoCerem
Narrow Diameter Implant Overdentures with Locator Attachments
In This Issue: Zeroing in on Xerostomia
Perio Reports
Ad Index
Profile in Oral Health: Substances for Targeting Xerostomia
Dentally Incorrect

Dentaltown March 2013