0099-2399184/1007-030415020010 JOURNAL OF ENDODONTIC$ Copyright 9 1984bytheAmedcan AssooationofEndodont~sts
Printed in U S A MOL. 10, NO. 7, JULY 1984
Isopropyl Cyanoacrylate as a Root Canal Sealer Cianocrilato Isopropilico como un Sellador de Conductos Mahmoud Torabinejad, DMD, MSD, Henry Kahn, DDS, and Donna Bankes, DDS
Isopropyl cyanoacrylate was evaluated as a root canl sealer by comparing it with three commercial sealers. Six groups of 20 teeth were studied: a negative control group in which apical openings were plugged with wax; a positive control group in which canals were filled with gutta-percha without any sealer; and four experimental groups in which the canals were filled with gutta-percha along with either Hydron, AH-26, Grossman, or isopropyl cyanoacrylate as root canal sealers, respectively. After obturation, the roots were immersed in India ink for 24 h. The extent of leakage through the apical openings was measured. Canals filled with guttapercha in conjunction with isopropyl cyanoacrylate did not differ significantly from those in the waxplugged control group in the extent of leakage. In contrast, canals obturated with commercial sealers showed significantly more leakage (p < 0.01).
The Washington study (1) showed that 58.6% of endodontic failures were caused by the incomplete obturation of root canals. Based on this and other investigations (2-8), obtaining a fluid-tight seal has become a major objective of root canal therapy. Solid-core filling materials, such as gutta-percha or silver points, do not adhere to the walls of root canals and need a root canal sealer to prevent apical leakage. However, commonly used root canal sealers are not completely impermeable to dyes or radioisotopes (2-4, 6, 9-12). The fact that root canal sealers do not seal completely indicates that the ideal sealer has yet to be found. Cyanoacrylates have been used in medicine and dentistry for a number of years. Many investigators have shown that these materials are relatively biocompatible (13-20). As a result of its bonding characteristics and biocompatibility, we chose to evaluate isopropyl cyanoacrylate as a root canal sealer, by comparing it with Grossman, AH-26, and Hydron root canal sealers.
El cianocrilato isopropilico fue evaluado como un sellador de conductos comparandolo con tres selladores comerciales. Fueron estudiados seis grupos de 20 dientes: un grupo negativo de control en el cual el ~,pice abierto rue obturado con cera, un grupo positivo de control en los cuales los conductos fueron obturados con gutapercha sin ningt~n sellador; y cuatro grupos experimentales en los cuales los conductos fueron obturados con gutapercha ya sea con cualquiera de los siguientes selladores: Hydron, AH-26, Grossman o cianocrilato isopropilico respectivamente. Despues de la obturacion, las raices fueron sumergidas en tinta de la India por 24 hs. Fue medida la extension de la filtracion a trav(~s del apice. Los conductos obturados con gutapercha en conjuncion con cianocrilato isopropilico no difirieron significativamente en la extension de la filtracion de aqu(~llos del grupo de control atacados con cera. En contraste los r tos obturados con selladores comerciales, mostraron significativamente m~,s filtracion (p < 0.01).
MATERIALS AND METHODS
One-hundred twenty single-rooted human maxillary and mandibular teeth were used in this study. In order to keep the teeth moist and their attached soft tissues fixed, they had been stored in 10% formalin after extraction. They were radiographed to confirm root canal patency and closure of the apex, then soaked in 2.25% sodium hypochlorite for 1 wk to remove soft tissues from the root surfaces. The crowns were removed at the cementoenamel junction using high-speed fissure burs. Each canal was cleaned and shaped to the apical foramen to a size 50 K file. The rest of each canal was flared by the stepback filing technique described by Weine (21). After flaring, the patency of the apical opening was checked with a #50 K file. The canals were irrigated with a 2.25% solution of sodium hypochIorite during cleaning and shaping. The roots were then stored in distilled water. The roots were randomly assigned to one of six groups of 20 roots each. The apical openings of the root canals in group 1, the negative control group, were 304
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plugged with 1 to 2 mm of wax using no other filling material. The coronal openings were filled with 2 to 3 mm of Cavit. In group 2, the positive control group, the canals were filled with gutta-percha without any root canal sealer. Groups 3, 4, and 5 consisted of roots in which the canals were filled with gutta-percha along with either Hydron, AH-26, or Grossman root canal sealer, respectively. Gutta-percha cones were fitted with good tugback to within 1 to 1.5 mm of the apical opening of each root canal. Hydron, AH-26, and Grossman sealers were mixed to the consistency recommended by their manufacturers. Each root canal was coated twice and the assigned sealer applied with a 45 K file. Before final seating, the apical 2 to 3 mm of the master gutta-percha cone was dipped in chloroform for 1 to 2 s before being placed into the root canal. After placing the master gutta-percha point, the rest of the canal was filled with gutta-percha using the lateral condensation technique. In group 6, isopropyl cyanoacrylate (IPCA-40; Pacer Technology & Resources, Inc., Campbell, CA) was deposited into the canals through a 30-gauge needle, and the canals were filled with gutta-percha as before. Obturation was evaluated with buccolingual and mesiodistal radiographs. Canals incompletely filled were reobturated. After obturation, 2 to 3 mm of gutta-percha were removed from the coronal opening of each canal with warm pluggers and the resulting space was filled with Cavit. Each root was then placed in a capped vial containing 2 • 2 gauze pads saturated with water, and the sealer was allowed to set at room temperature for 48 h. The roots, except for the apical 2 mm, were coated with two layers of nail polish. They were then immersed in India ink for 24 h. After this, the roots were placed in acetone to remove the nail polish, then decalcified in 20% formic acid at room temperature for 7 to 10 days. Decalcification was considered to be complete when the roots were soft and the radiographs showed no signs of calcified tissue. The decalcified roots were rinsed in running tap water and dehydrated in a series of alcohol rinses. After soaking overnight in 85% ethyl alcohol, they were rinsed twice in each of three ethyl alcohol solutions (90, 95, and 100%) for 1 h per rinse. The roots were then placed in methyl salicylate from 2 to 3 h to make them transparent. The leakage of ink into the canals was measured with a millimeter ruler under a dissecting microscope. An analysis of variance tested for statistical differences among the groups. Furthermore, a q test (22) determined the significance of these differences between all possible pairs of means for all of the groups.
of only 2 root canals in the wax-plugged, negative control group, and in all 20 teeth in the positive control group in which the canals were filled without any sealer (Fig. 1). Among the experimental groups, canals sealed with cyanoacrylate allowed the least amount of leakage (Fig. 2); those sealed with Hydron, AH-26, and Grossman root canal sealers allowed much more (Fig. 3). TABLE 1. Frequency and extent of apical leakage into the canals
No. of Teeth Average With Leakage Leakage (mm)
(n = 20) 1: Canals plugged with apical wax (negative control group) 2: Canals with gutta-percha and without sealer (positive control group) 3: Canals with gutta-percha and Hydron 4: Canals with gutta-percha and AH-26 5: Canals with gutta-percha and Grossman sealer 6: Canals with gutta-percha and cyanoacrylate
The mean values and standard deviations of the measurements of leakage in all groups are shown in Table 1. The ink penetrated through the apical openings
FIG I. Positive control tooth shows penetration of India ink into the root canal. Leakage extends 5.9 mm into the canal from the root tip. Original magnification x l 0 .
Torabinejad et al.
FIG 2. Root canal filled with gutta-percha points in conjunction with isopropyl cyanoacrylate as a root canal sealer shows 0.5 mm of penetration of India ink. Original magnification x l 0.
One-way analysis of variance showed statistical differences between the means of the groups. The q test showed that the mean leakage of the cyanoacrylate group did not differ significantly from that of the waxplugged control group. In contrast, the means of all other groups did differ significantly from those of the wax-filled control group and the cyanoacrylate group (Table 2). DISCUSSION
Results from the wax-plugged control group showed that two coats of nail polish prevented India ink from penetrating into the root canals. The absence of a significant amount of leakage in this group indicates that penetration of ink into the root canals in other groups was through the apical openings. The differences in leakage between the canals filled with guttapercha without sealer and the canals sealed with guttapercha and commercial sealers support the recommendation to use a root canal sealer with solid-core filling materials (2-8). Results from the experimental groups show that isopropyl cyanoacrylate seals apical openings significantly better than any of the other sealers studied and
Journal of Endodontics
FIG 3. Root canal filled with gutta-percha points along with AH-26 as a root canal sealer shows 1.4 mm of penetration of India ink. Original magnification x l 0, TABLE 2. Statistical significance of differences between the mean values of leakage of all pairs of groups Not Significant
95% Significant (p < 0.05)
99% Significant (p < 0.01)
1 versus 6 4 versus 5 2 versus 3
2 versus 4 and 5 3 versus 4 and 5 4 versus 6
6 versus 2, 3, and 5 1 versus 2, 3, 4, and 5
that Grossman and AH-26 root canal sealers are significantly more effective than Hydron. Isopropyl cyanoacrylate was injected into the root canals whereas other sealers were applied to the root canal walls with a #45 K file. The difference in the methods of application of sealers can lead to a discrepancy in the quantity and dispersion of various sealers. This could affect the relative evaluation of the results, but would not alter the fact that isopropyl cyanoacrylate seals the root canals adequately. Director et al. (9) also showed significantly greater apical leakage in canals sealed with Hydron compared with canals sealed with gutta-percha and Grossman sealer using the lateral and vertical condensation methods. Our results, and theirs, conflict with those reported by Spradling and Senia (10), who showed that root canals sealed with Hydron and kept at 100% humidity
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at 37 ~ for 1 wk prevented leakage better than PCA sealer, ZOE paste, Endo fill, and gutta-percha with Roth's 801 or Tancredi sealers using the lateral condensation technique. They attributed the differences between their findings and those of Director et al. (9) to the bench-curing of Hydron. In the present study, the teeth were stored in 100% humidity for 48 h after obturation. The difference between our results and those of Spradling and Senia (10) could be the result of differences in the duration of curing the Hydron (1 wk versus 48 h), the thickness of Hydron at the apical openings, and the methods of applying Hydron. Antioniazzi et al. (11 ) found AH-26 less permeable to dye penetration than zinc oxide and eugenol paste. Fogel (12) evaluated the suitability of Adaptic, AH-26, ZOE, B & T, Cavit, and Durelon as root canal fillers. His findings, and ours, show no significant differences in the degree of dye penetration between AH-26 and ZOE-based root canal sealers, such as Grossman's. Grossman (23) states that the ideal root canal sealer should: be tacky enough to adhere to root canal walls; seal the canal completely; be radiopaque; mix easily with cement; not shrink when it sets; not stain teeth; be bacteriostatic; set slowly; be insoluble in tissue fluids; be biocompatible; and be soluble in common solvents if removal of filling materials becomes necessary. By these criteria, isopropyl cyanoacrylate has potential as a root canal sealer. It is biocompatible (1320) and bacteriostatic (24-26). It adheres to root canal walls, and our study demonstrated that it can seal the canal against dye penetration. Studies are in progress to evaluate other properties of cyanoacrylate as a root canal sealer. This study was supported by the Graduate Endodontic Fund of Loma Linda University. Dr. Torabineiad is professor of endodontics and director of graduate endodontic research at Loma Linda University, School of Dentistry. Dr. Kahn is professor emeritus of endodontics, Loyola University, School of Dentistry, and professor of endodontics, Loma Linda University. School of Dentistry. Dr. Bankes is in private practice in Sacramento, CA. Address requests for reprints to Dr. Torabinejad, Department of Endodontics, School of Dentistry, Loma Linda University, Loma Linda, CA 92350.
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