Apexification With MTA

When teeth with immature roots suffer pulpal necrosis, the formation of dentin stops and root development ceases. As a result, the canals remain wide with thin dentin walls and a large apical opening. Often, the root canal system has an inverse architecture with the apical diameter significantly wider than the coronal diameter.This blunderbuss shape creates a challenge to achieving effective cleaning and shaping of the canal. All our instruments have an apical-coronal taper of .02 or greater, so cleaning of the walls is difficult. Only a randomized envelope of motion with a pre-curved reamer – as described by Schilder – and copious irrigation with NaOCL will create enough wall contact to remove bacteria and debris.

Immature, necrotic teeth also present challenges to obtaining a secure apical stop. Without a good stop, the apical termination of the gutta percha is unpredictable, often resulting in poorly condensed or overfilled canal. Only a warm GP protocol such as vertical compaction of warm gutta percha (the Schilder technique) or the “squirting” of preheated GP from an Obtura gun can achieve a solidly compacted apical fill and apical seal. These warm techniques depend on having a conically-shaped root canal preparation, where the apical diameter is the smallest and canal diameters increase coronally to prevent overfills.Over the years, calcium hydroxide (CaOH) pastes have become the material of choice for creating an artificial apical barrier. CaOH promotes closure of the apex with calcified tissue at the apical interface (apexification). Despite its efficacy, CaOH has several deficiencies, such as long treatment times of up to one year or more, delayed restoration of traumatically damaged teeth in the esthetic zone, multiple appointments, and the resultant treatment costs.

Felippe et al, in the January 2006 issue of IEJ, looked at the ability of mineral trioxide aggregate (MTA) to induce apical closure and periapical healing. MTA has been used for over 15 years as a root end filling in apical surgery cases with excellent results. MTA, with sterile water, compacts like wet sand in the root canal, hardening within 4 hours. Thirteen immature Beagle dog teeth were cleaned, shaped, and the apical third densely packed with MTA. The teeth were blocked sectioned after 5 months and evaluated histologically.

The authors found that MTA resulted in significantly higher numbers of teeth with a complete boney barrier at the level of the apical foramen when compared with CaOH. Further, this was achieved with a one appointment technique.

The only challenge in my experience to using MTA as an apical barrier material is predictably controlling the apical placement and density of the MTA. Packing a resorbable barrier, such as Collacote into the boney crypt to the level of the foramen under high magnification, will create a backstop for the MTA placement. Ultrasonic vibration of the MTA will ensure a dense, gapless fill in the apical third of the canal which can be back packed with warm GP.

MTA barrier, B-bone, PL-periodontal ligament

ABOUT DR. HOWARD BITTNER

Dr. Bittner was born and raised in the Surrey/Langley area. Following his pre-dental training at Simon Fraser University, he received his Doctor of Dental Medicine from the University of British Columbia in 1982 and his Certificate in Advanced Graduate Studies in Endodontics from Boston University’s Goldman School of Dental Medicine in 1995.

Dr. Bittner was in private practice in general dentistry for 11 years in Langley prior to his endodontic specialty training. He has a wide background in all facets of general dentistry, with advanced dental training in prosthetic dentistry from respected educational facilities such as Creating Restorative Excellence in Tacoma, Washington, and The Pankey Institute in Miami, Florida. He has been practicing the dental specialty of Endodontics since 1995.

He is a past president of the British Columbia Society of Endodontists, the Dental Specialists Society of British Columbia, and the Concentric Endodontic Study Club. Dr. Bittner is also a guest lecturer in the Faculty of Dentistry at the University of British Columbia.

 

On November 30, 2010, posted in: News for Doctors by