International Endodontic Journal, 35, 22–29, 2002 © 2002 Blackwell Science Ltd 22 Blackwell Science, Ltd Occlusal loading of EBA and MTA root-end fillings in a computer-controlled masticator: a scanning electron microscopic study C. I. Peters & O. A. Peters Endodontic Division, Department of Preventive Dentistry, Cariology and Periodontology, University of Zurich, Zurich, Switzerland Abstract Peters CI, Peters OA. Occlusal loading of EBA and MTA root-end fillings in a computer-controlled masticator: a scanning electron microscopic study. International Endodontic Journal, 35, 22 – 29, 2002. Aim The aim of this investigation was to assess the marginal adaptation of Super-EBA (EBA) and Pro Root MTA (MTA) root-end fillings and the occurrence of microcracks in resected root-ends of extracted teeth before and after occlusal loading for a five-year equivalent period in a computer-controlled masticator. Methodology Twenty-four molar teeth were root- filled using lateral condensation and their root-ends resected. Root-end cavities were prepared and either EBA or MTA root-end fillings were placed. All surgical proce- dures were completed in vitro under an operating micro- scope. Replicas taken of the root-end fillings and resected root-ends were examined using an SEM before and after they were subjected to in vitro chewing cycles in a com- puter-controlled chewing simulator for the equivalent of 5 years. Marginal adaptation and integrity of the two root-end filling materials were evaluated and the pres- ence of microcracks recorded. Results Before loading, a continuous margin was observed with 99.4 ± 2.4% of EBA and 99.2 ± 1.6% of MTA root-end fillings. After loading, the percentage of continuous margin decreased to 93.1 ± 6.6% and 98.9 ± 3.2% for EBA and MTA, respectively. After occlusal loading, 39.5% of the EBA root-end fillings were over- filled, whilst 52.6% of the MTA root-end fillings were underfilled. In total, 12.5% of the resected root-end surfaces showed microcracking before loading and 25% after occlusal loading. Conclusions Both EBA and MTA displayed excellent marginal adaptation before masticatory loading. After loading, the amount of continuous margin for both root- end filling materials decreased slightly but was still high. Keywords: EBA, marginal adaptation, microcracks, MTA, root-end filling, root resection. Received 8 November 2000; accepted 12 February 2001 Introduction Endodontic surgery may be indicated in cases where posts cannot be removed, following recent prosthodontic treatment, where apical radiolucencies persist and when root canal systems are inaccessible (Sultan & Pitt Ford 1995). Failure of endodontic surgery may be a result of a poor seal with the root-end filling, difficulties encoun- tered during surgical procedures, untreated root canals and unsealed isthmus areas (Weller et al. 1995). To avoid leakage of pathogens and toxins from infected root canals, an apical seal is established by resecting approx- imately 3 mm of the root-end with no or a small bevel angle (Carr 1994, Gilheany et al. 1994), the preparation of a root-end cavity (Von Arx et al. 1998) and the place- ment of a root-end filling. Dye penetration studies have been undertaken to assess leakage of Super-EBA (EBA) (Saunders et al. 1994, Gagliani et al. 1998) and Mineral Trioxide Aggregate (MTA) (Torabinejad et al. 1993, Aqrabawi 2000), but this methodology is also known to have drawbacks (Sultan & Pitt Ford 1995). Air entrapment, use of pres- sure and the unsuitable molecular size of dyes can Correspondence: Dr. Christine Peters, Endodontic Division, Department of Preventive Dentistry, Cariology and Periodontology, University of Zurich, Plattenstrasse 11, CH-8028 Zurich, Switzerland, (fax: +41 1634 4307; e-mail: c.peters@zzmk.unizh.ch).