Intracoronal Sealing Ability of Two Dental Cements John D. Wells, DDS, David H. Pashley, DMD, PhD, Robert J. Loushine, DDS, R. Norman Weller, DMD, MS, W. Frank Kimbrough, DDS, MS, and Patricia N. Pereira, DDS, PhD The purpose of this study was to compare the effi- cacy of sealing the coronal 2-mm of the root canals versus covering the entire pulpal floor with one of two dental-resin cements (Principle or C&B Meta- bond). Sixty-two molars with the occlusal half of the crowns and the apical half of the roots removed were used. Each canal was enlarged by using a #3 Gates Glidden bur and obturated with unsealed gutta-per- cha cones. The teeth were randomly assigned to four groups, each containing 15 teeth, plus a negative and a positive control. In group 1, 2 mm of Principle were placed over the entire pulpal floor. In group 2, Prin- ciple was placed 2 mm into each canal orifice. Groups 3 and 4 were the same as groups 1 and 2, except C&B Metabond cement was used. After the cement set, the gutta-percha was removed and the integrity of the seal was tested by fluid filtration at a pressure of 20 cm H 2 O at 1 h and at 1, 2, and 4 weeks. The data were analyzed by a three-way ANOVA and the Student-Newman-Keuls tests at   0.05. The controls behaved as expected. Results showed that there were no statistically significant differences among the materials used or the location (p > 0.05), but there was a significant difference with respect to time. Principle leaked significantly more than C&B Metabond at 1 h (p < 0.05), but the seal became tighter over time. C&B Metabond leaked less early (p < 0.05) but increased in leakage at 4 weeks. Both materials sealed well over the 4-week study. Princi- ple was easier to use, and sealing the entire pulpal floor was easier than sealing only the canal orifice. Although coronal leakage has recently received much attention as a cause of failure in endodontically treated teeth, the concept is not new. As early as 1961, Marshall and Massler (1) proposed that the prog- nosis for a root-filled tooth was good if there was an adequate coronal seal. Saunders and Saunders (2) implicated the fracture of a coronal restoration or delay in placing a permanent restoration as possible causes of coronal leakage. Webber et al. (3) demonstrated a decrease in the sealing ability of temporary restorations over time. Swanson and Madison (4) found that all teeth obturated by using gutta-percha and sealer, in the absence of a temporary restoration, showed leakage ranging from 79% to 85% of the root length within 56 days, when exposed to saliva. Torabinejad et al. (5) evaluated the leakage of root-filled teeth when exposed to bacteria and found that after 19 days, 50% of the filled roots were contaminated. From previous clinical studies, a number of conclusions concerning the importance of a coronal seal relative to prognosis have been drawn. Ray and Trope (6) stated that the technical quality of the coronal restoration may be significantly more important than the technical quality of the endodontic treatment for apical periodontal health. Rapp et al. (7) evaluated various factors as they relate to surgically treated endodontic cases. He found significantly better healing with teeth that were permanently restored after surgery. Fortunately, research has shown that a second barrier can slow or prevent coronal leakage. Carman and Wallace (8) restored the root canals and pulp chambers with various materials and showed that a coronal barrier of gutta-percha and sealer leaked signifi- cantly more than teeth restored with amalgam, composite resin, glass ionomer, or intermediate restorative material (IRM). Despite research supporting the effectiveness of coronal barriers, a univer- sally accepted protocol that incorporates a coronal barrier after root canal therapy is nonexistent. A material that takes minimal time to place, requires minimal armamentarium, and has a good long-term seal may be more appealing to the clinician than materials that require multistep procedures. Polyacid-modified resin composite (compomer) dental cements are potential coronal-barrier materials. They do not require placement of a primer, unlike dentin-bonding agents, and some have the advantage of being both self-cured and light-cured. These compomers showed good durability and mar- ginal bond strength, compared with resin-modified glass ionomers in vivo (9). In a dye leakage study, compomer cement proved superior to Super EBA in preventing leakage when used as a root-end filling (10). In another dye penetration study, compomers showed less microleakage in radicular dentin, compared with var- ious composite resins (11). The purpose of this study was to compare the efficacy of sealing the coronal 2-mm of the root canals versus covering the entire pulpal floor with one of two dental-resin cements by using a fluid filtration system. MATERIALS AND METHODS Sample Preparation Sixty-two extracted, human mandibular molars were used in this in vitro study. All specimens were free of restorations or had JOURNAL OF ENDODONTICS Printed in U.S.A. Copyright © 2002 by The American Association of Endodontists VOL. 28, NO. 6, JUNE 2002 443