Evaluation of Ultrasonically Placed MTA and Fracture Resistance with Intracanal Composite Resin in a Model of Apexification
The purpose of this study was to evaluate whether intracoronal delivery of an apical barrier of mineral trioxide aggregate (MTA) placed ultrasonically, non-ultrasonically, or ultrasonically with the addition of an intracanal composite resin provided a better seal against bacterial leakage. A second purpose was to determine whether intracanal composite resin or gutta-percha and sealer placed against an apical barrier of MTA provided greater resistance to root fracture. In a standardized in vitro open apex model, MTA was placed as an apical barrier at a thickness of 4 mm, with and without ultrasonic vibration. The barriers were challenged with bacteria exposure within a leakage model, and fracture resistance was assessed with increasing forces applied via an Instron machine. After 45 days, the addition of ultrasonics significantly improved the MTA seal, compared with the non-ultrasonics treatment (Kruskal Wallis nonparametric ANOVA with Dunn multiple comparison test p < 0.05). Bacterial leakage occurred in 6 (33%) of 18 in the non-ultrasonic MTA group, 2 (11%) of 18 in the ultrasonic MTA group, and 1 (6%) of 18 in the ultrasonic MTA-composite group. There were no significant differences at 90 days. A 4-mm thickness of MTA followed with an intracanal composite resin demonstrated a significantly greater resistance to root fracture than MTA followed with gutta-percha and sealer (one-way ANOVA with Newman-Keuls multiple comparison test, p < 0.01). The MTA–gutta-percha group was not significantly different than the MTA unrestored positive control.
Dr. Lawley is a resident, Department of Endodontics, Wilford Hall Medical Center, Lackland AFB, Texas; Dr. Schindler is a Clinical Professor, Department of Endodontics, University of Texas Health Science at San Antonio, Texas; Dr. Walker is a Clinical Professor, Department of Endodontics, University of Texas Health Science Center at San Antonio, Texas; Dr. Kolodrubetz is a Professor, Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, Texas.
Address requests for reprints to Dr. William G. Schindler, UTHSCSA, Department of Endodontics, Mail Code 7892, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900
This article is the work of the United States government and may be reprinted without permission. Dr. Lawley is an employee of the United States Air Force at Lackland Air Force Base, Texas. Opinions expressed therein, unless otherwise specifically indicated, are those of the authors. They do not purport to express the views of the Department of the Air Force or any other Department or Agency of the United States government.
The authors thankfully acknowledge Dr. Kenneth M. Hargreaves for academic and editorial assistance and statistical analysis and Alex Burgum for technical assistance with the PCR experiments. Materials for this study were donated by Dentsply Tulsa Dental, Bisco, and Centrix.
ABSTRACT