0099-2399/91/1711-0541/$03.00/0 JOURNAL OF ENDODONTICS Copyright 9 1991 by The American Association of Endodonti~s
Printed in U.S.A. VOL. 17, NO. 11, NOVEMBER1991
Long-Term Sealing Ability of a Calcium Hydroxide Sealer Frank Scott Sleder, DDS, Marvin O. Ludlow, DDS, MS, and Joseph Robert Bohacek, DDS
tion, control exudate in problem teeth, and stimulate development of root formation. New sealers are now available in which the zinc oxide and eugenol have been replaced with calcium hydroxide. It is postulated that the calcium hydroxide in the sealer may stimulate a sterile biological closure of the apical region, thus enhancing the seal and the success of the treatment. Sealapex is a calcium hydroxide type sealer, in use since the early 1980's. Several studies have been undertaken to examine its biological properties as well as to compare it with other well-established sealers in terms of sealability. Several studies examining toxicity (inflammatory response) (1-4) have been performed comparing Sealapex with some of the more commonly used sealers. These studies demonstrated generally a mild inflammatory reaction, with an influx of foreign body giant cells--a response no more severe and often less severe than that of other sealers. If calcium hydroxide is released continuously by Sealapex, the question of solubility of the product over an extended period of time is of concern. Barnett and Flax (2), using specimens of sealers implanted in dog mandibles, demonstrated that indeed there is a loss of Sealapex over time. Caicedo and von Fraunhofer (5) studied the properties of calcium hydroxide sealers and found that Sealapex showed a significant volumetric expansion during setting. They theorized that this was due to water absorption. This may also increase the solubility of Sealapex. As Tagger et al. (6) noted in their study, the pellets of set Sealapex placed in distilled water disintegrated after 75 min. With a number of studies indicating that Sealapex may have a much higher solubility than desired, Sealapex's sealability over an extended period of time must be questioned. If much less surface area of the sealer is exposed to tissue fluids, as in a properly filled tooth, will the solubility decrease or stop? One way to determine the answer was to compare Sealapex with a known acceptable sealer in a long-term in vitro study for the amount of leakage. With the controversy arising from the question of solubility versus sealability, it was obvious that there was a need for a long-term study.
A calcium hydroxide sealer (Sealapex) was compared with a zinc oxide and eugenol sealer (TubliSeal) over a 32-wk interval to examine solubility in an in vitro simulation. After obturation with guttapercha and the appropriate sealer, specimens were immediately immersed in a saline solution to challenge the sealers' solubility. The solutions were changed weekly to allow for a continued dissolution of the sealers and to prevent establishment of an equilibrium between the solution and the sealers. The 2- and 32-wk specimens were removed from the solutions, immersed in India ink for 3 days, and then made transparent by a clearing process. Microscopic examination was used to determine the linear penetration of the ink for each tooth. Results revealed that Sealapex statistically had no greater dissolution (based upon linear penetration) than Tubli-Seal at both 2 and 32 wk. It is suggested that Sealapex has a sealing ability comparable to Tubli-Seal and can withstand long-term exposure to tissue fluids without significant leakage. This may allow time for the biochemical action of the calcium hydroxide to stimulate physiological calcification of the apical foramen.
Throughout the years, root canal sealers based upon a mixture of zinc oxide and eugenol have been used to ensure adequate sealing of the root canal system. These sealers worked by (a) cementing the individual gutta-percha cones together, (b) cementing the gutta-percha to the dentinal wall, and (c) filling in any spaces surrounding and between the cones. By these actions, the sealers prevent communication between the apical tissues and the oral cavity fluids. The interface between the dentinal wall and the gutta-percha in the apical region is the most crucial area in preventing apical leakage. All sealers have some degree of solubility in tissue fluids. It is, therefore, this interface that may cause failure of treatment. Failure of the apical seal will necessitate reobturation of the entire canal or periapical surgery in order to correct the defect. Thus, it is critical to ensure that a proper, long-standing seal will remain. Calcium hydroxide has been used in endodontics for a number of years to repair root perforations, halt root resorp-
MATERIALS AND METHODS Endodontic treatment procedures routinely used at Creighton University School of Dentistry were used in this laboratory study. To help minimize experimental variables, one operator preformed all endodontic procedures.
541
542
Sleder et al.
Journal of Endodontics TABLE 1, Dye penetration (mm) for individual teeth 2 Weeks
32 Weeks Control
No. Tubli-Seal
Tubli-Seal Positive
1 2 3 4 5 6 7 8 9 10 11 12 Mean SD
Control
Sealapex
0.123 1.481 0.000 0.196 0.325 0.471 1.666 0,295 0,309 0,178 0,198 0.782
0.000 0.855 1.524 0.502 0.563 0.313 0.308 0.478 0.405 0.168 0.676 0.396
0.502 0.539
0.516 0.388
Sealapex
Negative
3.103
Fifty-two extracted, single-rooted, anterior teeth were placed in a solution of 2.5% sodium hypochlorite (Clorox Corp., Oakland, CA) for 24 h to remove any remaining soft tissue. The crowns were then removed to facilitate instrumentation of the canals. A # 15 endodontic file (Flexofile; L. D. Caulk Co., Division of Dentsply International, Milford, DE) was passed just through the apical foramen. One millimeter was then subtracted from this measured length to represent the working length. The canals then were enlarged to an appropriate master apical file size (#45 to 60) and flared using the stepback method. An irrigant of 2.5% NaOC1 was used between files. To ensure patency, the # 15 file was again passed through the apical foramen to remove debris that may have accumulated. Throughout the procedure the teeth were kept moist in saline-soaked gauze. The teeth were next randomly divided into three groups. Group 1 contained four teeth which served as controls. These teeth were obturated with gutta-percha, but without sealer. Group 2 contained 24 teeth which would be obturated with gutta-percha and Sealapex (Kerr Corp., Romulus, MI) as the sealer, while the remaining 24 teeth in group 3 would be obturated with gutta-percha and sealed using Tubli-Seal (Kerr Corp.). The canals of the teeth in groups 1 to 3 were dried using paper points. Gutta-percha master cones (Hygenic Corp., Akron, OH) were fitted so that the tip of the cone at the apex would develop slight resistance to withdrawal (tug-back). The appropriate sealer was then applied to the canal walls using the master apical file down to the level of 1 m m short of the working length. Next, the master cone, coated with sealer, was inserted and laterally condensed with a hand spreader (Hy-Friedy GP-2; Hy-Friedy Corp., Chicago, IL) as size medium-fine accessory cones (Hygenic Corp.) were added. Enough gutta-percha was then removed to allow a 4-mm thickness of Cavit (Premier Dental Products, Co., Norristown, PA) to seal the coronal access. The three groups were then immediately put into separate glass containers filled with saline, allowing the sealer to set completely in a fluid environment. The saline was changed weekly.
0.0
0.674 0.535 0.235 0.000 0.000 0.690 0.000 0.133 1.730 0.322 0.733 1.227
1.140 1.232 0.644 0.740 0.300 0.753 0.000 0.225 0.463 0.613 0.273 0,355
0.523 0.535
0.561 0.369
Positive
Negative
2.290
0.0
At the end of 2 weeks, one half of the teeth from each group was removed for initial analysis. Two teeth from group 1 served as positive and negative controls. One tooth had the entire surface covered with two coats of fingernail polish (including the apex), while the other tooth did not have the apex covered. Twelve teeth each from groups 2 and 3 were also covered with nail polish, except for 2 m m short of the apical foramen. All 26 teeth were then placed in an India ink solution (Waterproof Black India; Higgins Co., Fort Worth, TX) for approximately 72 h at 37~ The teeth were then rendered translucent by the procedure described by Yancich et al. (7). The teeth were removed from the ink and rinsed with tap water. Next, the nail polish was removed and the teeth were placed into a solution of 5% nitric acid, which was changed daily for 5 days. At the end of this time, the teeth were again washed under tap water for 10 min and then dehydrated by being placed in 100% methanol for 3 days, with the solution once again being changed daily. The teeth were then soaked in methyl salicylate until they were translucent. Using a stereomicroscope (Nikon SMZ-2T; Nikon Inc., Gordon City, NY) with a filar eyepiece and Digimatic micrometer head (Mitutoyo; MTI Corp., Paramus, N J), two observers measured the linear penetration of the ink as measured from the apical stop of the gutta-percha. These measurements were recorded for analysis (Table 1). For a period of 30 wk the remaining teeth were stored in covered glass containers filled with saline. The saline was replaced weekly so that dissolved sealer would not affect the dissolution of the remaining sealer. At the end of the 32-wk interval, the teeth were subjected to the same processes as described above. RESULTS Measurements for all specimens were determined from the apical tip of the gutta-percha come to as far coronally as the dye penetrated. Table 1 lists the raw data and the means for each group. The negative controls at both 2 and 32 wk showed no linear penetration of dye. The positive controls demon-
Vol. 17, No. 11, November 1991
strated leakage values of 3.103 m m at 2 wk and 2.290 m m at 32 wk. Using mean leakage (Table 1), it can be inferred that there is no great difference between Sealapex and Tubli-Seal at either 2 or 32 wk. This was verified by analysis of variance (p > 0.99 t) which showed no significant difference between the two sealers at either 2 or 32 wk or between the 2- or 32-wk groups of the same sealer.
Ca(OH)2-Based Sealer
543
Seal. It is hypothesized that, due to the limited surface area of the sealer which is exposed to the tissue fluids in the root canal, a negligible amount of dissolution is occurring. Further studies involving in vivo testing under these circumstances are necessary to evaluate fully this calcium hydroxide sealer as to all its potential benefits. This research was supported by the John C. Kenefick Faculty Development Award granted by the Health Future Foundation. The authors are grateful for the support from the Creighton University Center for Hard Tissue Research.
DISCUSSION The means for dye penetration of the Sealapex samples (0.516 m m at 2 wk and 0.561 mm at 32 wk) are similar to those obtained by Alexander and Gordon (8) (0.58 m m at 6 days) and Barkhordar et al. (9) (0.343 m m at 48 h). This is in contrast to Rothier et al. (10), who obtained a mean value of 1.282 m m which is more than twice as high. This difference may be accounted for by the fact that in the study of Rothier et al., penetration was measured from the apical foramen, not from the tip of the gutta-percha cone itself, as in this study. The results obtained in this study were consistent with the results of Zmener (1). He examined Tubli-Seal, CRCS, and Sealapex and found there was no statistical difference between the sealers. Zmener, however, stated that none of the materials provided an adequate seal and found an increase in leakage after 10 days. Hovland and Dumsha (11) on the other hand, found that all of the sealers they studied provided an adequate seal. Using Procosol, Tubli-Seal, and Sealapex, they demonstrated no significant difference in leakage between sealers even up to 30 days. Numerous other studies (8-10, 12-14) have compared Sealapex with the above-mentioned sealers as well as others and have consistently found no difference between the various sealers. In this study, even with the direct challenge of placing the unset sealers immediately into the saline solutions, both sealers provided adequate seals from dye penetration. A factor that could not be taken into account in this study was the effect of macrophages upon the seal. The importance of this one factor was noted in several toxicity and calcification studies (2, 4, 12, 15-17). These studies showed that the macrophages contained titanium dioxide particles. The particles have been identified as originating from the Sealapex sealer. It is not known whether ingestion occurs from a solution of the calcium hydroxide in tissue fluids or because of active ingestion from the set sealer. This study gives a better understanding of a characteristic of this calcium hydroxide sealer in an in vitro system. At 32 wk, examination has shown that Sealapex is no more soluble than other sealers and that its seal is comparable to Tubli-
Dr. Sleder is assistant professor, Dr. Ludlow is chairman, and Dr. Bohacek is assistant professor, Department of Endodontics, Creighton Dental School, Omaha, NE. Address requests for reprints to Dr. Marvin Ludlow, Department of Endodontics, Creighton University Dental School, 2802 Webster Plaza, Omaha, NE 68178.
References 1. Zmener O. Evaluation of the apical seal obtained with two calcium hydroxide-based endodontic sealers. Int Endod J 1987;20:87-90. 2. Barnett T, Flax M. Solubility and biocompatibility of calcium hydroxidecontaining root canal sealers. Endod Dent Traumatol 1988;4:152-9. 3. Yesilsoy C, Koren L, Morse D, Kobayashi C. A comparative tissue toxicity evaluation of established and new root canal sealers. Oral Surg 1988;65:45967. 4. Tagger M, Tagger E. Periapical reactions to calcium hydroxide-containing sealers and AH26 in monkeys. Endod Dent Traumato11989;5:139-46. 5. Caicedo R, von Fraunhofer J. The properties of endodontic sealer cements. J Endodon 1988;14:527-34. 6. Tagger M, Tagger E, Kfir A. A release of calcium and hydroxyl ions from set endodontic sealers containing calcium hydroxide. J Endodon 1988;14:58891. 7. Yancich P, Hartwell G, Portell F. A comparison of apical seal: chloroform versus eucalyptol-dipped gutta-percha obturation. J Endodon 1989;15:25760. 8. Alexander J, Gordon T. A comparison of the apical seal produced by two calcium hydroxide sealers and a Grossman-type sealer when used with laterally condensed gutta-percha. Quintessence Int 1985;9:615-21. 9. Barkhordar R, Bui T, Watanabe L. An evaluation of sealing ability of calcium hydroxide sealers. Oral Surg 1989;68:88-92. 10. Rothier A, Leonardo M, Bonettti I, Mendes A. Leakage evaluation in vitro of two calcium hydroxide and two zinc oxide-eugenol-based sealers. J Endodon 1987;13:336-8. 11. Hovland E, Dumsha T. Leakage evaluation in-vitro of the root canal sealer cement Sealapex. Int Endod J 1985; 18:179-82. 12. Barnett F, Trope M, Rooney J, Tronstad L. In-vivo sealing ability of calcium hydroxide-containing root canal sealers. Endod Dent Traumatol 1989;5:23-6. 13. Lim K, Tidmarsh B. The sealing ability of Sealapex compared with AH26. J Endodon 1986;12:564-6. 14. Jacobsen E, BeGole E, Vitkus D, Daniel J. An evaluation of two newly formulated calcium hydroxide cements: a leakage study. J Endodon 1987;13:164-9. 15. Holland R, de Souza V. Ability of a new calcium hydroxide root canal filling to induce hard tissue formation. J Endodon 1985;11:535-43. 16. Soares I, Goldberg F, Massone E, Soares IM. Periapical tissue response to two calcium hydroxide-containing endodontic sealers. J Endodon 1990;16:166-9. 17. Zmener O, Guglielmotti M, Cabrini R. Biocompatibility of two calcium hydroxide-based endodontic sealers: a quantitative study in the subcutaneous connective tissue of the rat. J Endodon 1988;14:229-35.
Printed in U.S.A. VOL. 17, NO. 11, NOVEMBER1991
Long-Term Sealing Ability of a Calcium Hydroxide Sealer Frank Scott Sleder, DDS, Marvin O. Ludlow, DDS, MS, and Joseph Robert Bohacek, DDS
tion, control exudate in problem teeth, and stimulate development of root formation. New sealers are now available in which the zinc oxide and eugenol have been replaced with calcium hydroxide. It is postulated that the calcium hydroxide in the sealer may stimulate a sterile biological closure of the apical region, thus enhancing the seal and the success of the treatment. Sealapex is a calcium hydroxide type sealer, in use since the early 1980's. Several studies have been undertaken to examine its biological properties as well as to compare it with other well-established sealers in terms of sealability. Several studies examining toxicity (inflammatory response) (1-4) have been performed comparing Sealapex with some of the more commonly used sealers. These studies demonstrated generally a mild inflammatory reaction, with an influx of foreign body giant cells--a response no more severe and often less severe than that of other sealers. If calcium hydroxide is released continuously by Sealapex, the question of solubility of the product over an extended period of time is of concern. Barnett and Flax (2), using specimens of sealers implanted in dog mandibles, demonstrated that indeed there is a loss of Sealapex over time. Caicedo and von Fraunhofer (5) studied the properties of calcium hydroxide sealers and found that Sealapex showed a significant volumetric expansion during setting. They theorized that this was due to water absorption. This may also increase the solubility of Sealapex. As Tagger et al. (6) noted in their study, the pellets of set Sealapex placed in distilled water disintegrated after 75 min. With a number of studies indicating that Sealapex may have a much higher solubility than desired, Sealapex's sealability over an extended period of time must be questioned. If much less surface area of the sealer is exposed to tissue fluids, as in a properly filled tooth, will the solubility decrease or stop? One way to determine the answer was to compare Sealapex with a known acceptable sealer in a long-term in vitro study for the amount of leakage. With the controversy arising from the question of solubility versus sealability, it was obvious that there was a need for a long-term study.
A calcium hydroxide sealer (Sealapex) was compared with a zinc oxide and eugenol sealer (TubliSeal) over a 32-wk interval to examine solubility in an in vitro simulation. After obturation with guttapercha and the appropriate sealer, specimens were immediately immersed in a saline solution to challenge the sealers' solubility. The solutions were changed weekly to allow for a continued dissolution of the sealers and to prevent establishment of an equilibrium between the solution and the sealers. The 2- and 32-wk specimens were removed from the solutions, immersed in India ink for 3 days, and then made transparent by a clearing process. Microscopic examination was used to determine the linear penetration of the ink for each tooth. Results revealed that Sealapex statistically had no greater dissolution (based upon linear penetration) than Tubli-Seal at both 2 and 32 wk. It is suggested that Sealapex has a sealing ability comparable to Tubli-Seal and can withstand long-term exposure to tissue fluids without significant leakage. This may allow time for the biochemical action of the calcium hydroxide to stimulate physiological calcification of the apical foramen.
Throughout the years, root canal sealers based upon a mixture of zinc oxide and eugenol have been used to ensure adequate sealing of the root canal system. These sealers worked by (a) cementing the individual gutta-percha cones together, (b) cementing the gutta-percha to the dentinal wall, and (c) filling in any spaces surrounding and between the cones. By these actions, the sealers prevent communication between the apical tissues and the oral cavity fluids. The interface between the dentinal wall and the gutta-percha in the apical region is the most crucial area in preventing apical leakage. All sealers have some degree of solubility in tissue fluids. It is, therefore, this interface that may cause failure of treatment. Failure of the apical seal will necessitate reobturation of the entire canal or periapical surgery in order to correct the defect. Thus, it is critical to ensure that a proper, long-standing seal will remain. Calcium hydroxide has been used in endodontics for a number of years to repair root perforations, halt root resorp-
MATERIALS AND METHODS Endodontic treatment procedures routinely used at Creighton University School of Dentistry were used in this laboratory study. To help minimize experimental variables, one operator preformed all endodontic procedures.
541
542
Sleder et al.
Journal of Endodontics TABLE 1, Dye penetration (mm) for individual teeth 2 Weeks
32 Weeks Control
No. Tubli-Seal
Tubli-Seal Positive
1 2 3 4 5 6 7 8 9 10 11 12 Mean SD
Control
Sealapex
0.123 1.481 0.000 0.196 0.325 0.471 1.666 0,295 0,309 0,178 0,198 0.782
0.000 0.855 1.524 0.502 0.563 0.313 0.308 0.478 0.405 0.168 0.676 0.396
0.502 0.539
0.516 0.388
Sealapex
Negative
3.103
Fifty-two extracted, single-rooted, anterior teeth were placed in a solution of 2.5% sodium hypochlorite (Clorox Corp., Oakland, CA) for 24 h to remove any remaining soft tissue. The crowns were then removed to facilitate instrumentation of the canals. A # 15 endodontic file (Flexofile; L. D. Caulk Co., Division of Dentsply International, Milford, DE) was passed just through the apical foramen. One millimeter was then subtracted from this measured length to represent the working length. The canals then were enlarged to an appropriate master apical file size (#45 to 60) and flared using the stepback method. An irrigant of 2.5% NaOC1 was used between files. To ensure patency, the # 15 file was again passed through the apical foramen to remove debris that may have accumulated. Throughout the procedure the teeth were kept moist in saline-soaked gauze. The teeth were next randomly divided into three groups. Group 1 contained four teeth which served as controls. These teeth were obturated with gutta-percha, but without sealer. Group 2 contained 24 teeth which would be obturated with gutta-percha and Sealapex (Kerr Corp., Romulus, MI) as the sealer, while the remaining 24 teeth in group 3 would be obturated with gutta-percha and sealed using Tubli-Seal (Kerr Corp.). The canals of the teeth in groups 1 to 3 were dried using paper points. Gutta-percha master cones (Hygenic Corp., Akron, OH) were fitted so that the tip of the cone at the apex would develop slight resistance to withdrawal (tug-back). The appropriate sealer was then applied to the canal walls using the master apical file down to the level of 1 m m short of the working length. Next, the master cone, coated with sealer, was inserted and laterally condensed with a hand spreader (Hy-Friedy GP-2; Hy-Friedy Corp., Chicago, IL) as size medium-fine accessory cones (Hygenic Corp.) were added. Enough gutta-percha was then removed to allow a 4-mm thickness of Cavit (Premier Dental Products, Co., Norristown, PA) to seal the coronal access. The three groups were then immediately put into separate glass containers filled with saline, allowing the sealer to set completely in a fluid environment. The saline was changed weekly.
0.0
0.674 0.535 0.235 0.000 0.000 0.690 0.000 0.133 1.730 0.322 0.733 1.227
1.140 1.232 0.644 0.740 0.300 0.753 0.000 0.225 0.463 0.613 0.273 0,355
0.523 0.535
0.561 0.369
Positive
Negative
2.290
0.0
At the end of 2 weeks, one half of the teeth from each group was removed for initial analysis. Two teeth from group 1 served as positive and negative controls. One tooth had the entire surface covered with two coats of fingernail polish (including the apex), while the other tooth did not have the apex covered. Twelve teeth each from groups 2 and 3 were also covered with nail polish, except for 2 m m short of the apical foramen. All 26 teeth were then placed in an India ink solution (Waterproof Black India; Higgins Co., Fort Worth, TX) for approximately 72 h at 37~ The teeth were then rendered translucent by the procedure described by Yancich et al. (7). The teeth were removed from the ink and rinsed with tap water. Next, the nail polish was removed and the teeth were placed into a solution of 5% nitric acid, which was changed daily for 5 days. At the end of this time, the teeth were again washed under tap water for 10 min and then dehydrated by being placed in 100% methanol for 3 days, with the solution once again being changed daily. The teeth were then soaked in methyl salicylate until they were translucent. Using a stereomicroscope (Nikon SMZ-2T; Nikon Inc., Gordon City, NY) with a filar eyepiece and Digimatic micrometer head (Mitutoyo; MTI Corp., Paramus, N J), two observers measured the linear penetration of the ink as measured from the apical stop of the gutta-percha. These measurements were recorded for analysis (Table 1). For a period of 30 wk the remaining teeth were stored in covered glass containers filled with saline. The saline was replaced weekly so that dissolved sealer would not affect the dissolution of the remaining sealer. At the end of the 32-wk interval, the teeth were subjected to the same processes as described above. RESULTS Measurements for all specimens were determined from the apical tip of the gutta-percha come to as far coronally as the dye penetrated. Table 1 lists the raw data and the means for each group. The negative controls at both 2 and 32 wk showed no linear penetration of dye. The positive controls demon-
Vol. 17, No. 11, November 1991
strated leakage values of 3.103 m m at 2 wk and 2.290 m m at 32 wk. Using mean leakage (Table 1), it can be inferred that there is no great difference between Sealapex and Tubli-Seal at either 2 or 32 wk. This was verified by analysis of variance (p > 0.99 t) which showed no significant difference between the two sealers at either 2 or 32 wk or between the 2- or 32-wk groups of the same sealer.
Ca(OH)2-Based Sealer
543
Seal. It is hypothesized that, due to the limited surface area of the sealer which is exposed to the tissue fluids in the root canal, a negligible amount of dissolution is occurring. Further studies involving in vivo testing under these circumstances are necessary to evaluate fully this calcium hydroxide sealer as to all its potential benefits. This research was supported by the John C. Kenefick Faculty Development Award granted by the Health Future Foundation. The authors are grateful for the support from the Creighton University Center for Hard Tissue Research.
DISCUSSION The means for dye penetration of the Sealapex samples (0.516 m m at 2 wk and 0.561 mm at 32 wk) are similar to those obtained by Alexander and Gordon (8) (0.58 m m at 6 days) and Barkhordar et al. (9) (0.343 m m at 48 h). This is in contrast to Rothier et al. (10), who obtained a mean value of 1.282 m m which is more than twice as high. This difference may be accounted for by the fact that in the study of Rothier et al., penetration was measured from the apical foramen, not from the tip of the gutta-percha cone itself, as in this study. The results obtained in this study were consistent with the results of Zmener (1). He examined Tubli-Seal, CRCS, and Sealapex and found there was no statistical difference between the sealers. Zmener, however, stated that none of the materials provided an adequate seal and found an increase in leakage after 10 days. Hovland and Dumsha (11) on the other hand, found that all of the sealers they studied provided an adequate seal. Using Procosol, Tubli-Seal, and Sealapex, they demonstrated no significant difference in leakage between sealers even up to 30 days. Numerous other studies (8-10, 12-14) have compared Sealapex with the above-mentioned sealers as well as others and have consistently found no difference between the various sealers. In this study, even with the direct challenge of placing the unset sealers immediately into the saline solutions, both sealers provided adequate seals from dye penetration. A factor that could not be taken into account in this study was the effect of macrophages upon the seal. The importance of this one factor was noted in several toxicity and calcification studies (2, 4, 12, 15-17). These studies showed that the macrophages contained titanium dioxide particles. The particles have been identified as originating from the Sealapex sealer. It is not known whether ingestion occurs from a solution of the calcium hydroxide in tissue fluids or because of active ingestion from the set sealer. This study gives a better understanding of a characteristic of this calcium hydroxide sealer in an in vitro system. At 32 wk, examination has shown that Sealapex is no more soluble than other sealers and that its seal is comparable to Tubli-
Dr. Sleder is assistant professor, Dr. Ludlow is chairman, and Dr. Bohacek is assistant professor, Department of Endodontics, Creighton Dental School, Omaha, NE. Address requests for reprints to Dr. Marvin Ludlow, Department of Endodontics, Creighton University Dental School, 2802 Webster Plaza, Omaha, NE 68178.
References 1. Zmener O. Evaluation of the apical seal obtained with two calcium hydroxide-based endodontic sealers. Int Endod J 1987;20:87-90. 2. Barnett T, Flax M. Solubility and biocompatibility of calcium hydroxidecontaining root canal sealers. Endod Dent Traumatol 1988;4:152-9. 3. Yesilsoy C, Koren L, Morse D, Kobayashi C. A comparative tissue toxicity evaluation of established and new root canal sealers. Oral Surg 1988;65:45967. 4. Tagger M, Tagger E. Periapical reactions to calcium hydroxide-containing sealers and AH26 in monkeys. Endod Dent Traumato11989;5:139-46. 5. Caicedo R, von Fraunhofer J. The properties of endodontic sealer cements. J Endodon 1988;14:527-34. 6. Tagger M, Tagger E, Kfir A. A release of calcium and hydroxyl ions from set endodontic sealers containing calcium hydroxide. J Endodon 1988;14:58891. 7. Yancich P, Hartwell G, Portell F. A comparison of apical seal: chloroform versus eucalyptol-dipped gutta-percha obturation. J Endodon 1989;15:25760. 8. Alexander J, Gordon T. A comparison of the apical seal produced by two calcium hydroxide sealers and a Grossman-type sealer when used with laterally condensed gutta-percha. Quintessence Int 1985;9:615-21. 9. Barkhordar R, Bui T, Watanabe L. An evaluation of sealing ability of calcium hydroxide sealers. Oral Surg 1989;68:88-92. 10. Rothier A, Leonardo M, Bonettti I, Mendes A. Leakage evaluation in vitro of two calcium hydroxide and two zinc oxide-eugenol-based sealers. J Endodon 1987;13:336-8. 11. Hovland E, Dumsha T. Leakage evaluation in-vitro of the root canal sealer cement Sealapex. Int Endod J 1985; 18:179-82. 12. Barnett F, Trope M, Rooney J, Tronstad L. In-vivo sealing ability of calcium hydroxide-containing root canal sealers. Endod Dent Traumatol 1989;5:23-6. 13. Lim K, Tidmarsh B. The sealing ability of Sealapex compared with AH26. J Endodon 1986;12:564-6. 14. Jacobsen E, BeGole E, Vitkus D, Daniel J. An evaluation of two newly formulated calcium hydroxide cements: a leakage study. J Endodon 1987;13:164-9. 15. Holland R, de Souza V. Ability of a new calcium hydroxide root canal filling to induce hard tissue formation. J Endodon 1985;11:535-43. 16. Soares I, Goldberg F, Massone E, Soares IM. Periapical tissue response to two calcium hydroxide-containing endodontic sealers. J Endodon 1990;16:166-9. 17. Zmener O, Guglielmotti M, Cabrini R. Biocompatibility of two calcium hydroxide-based endodontic sealers: a quantitative study in the subcutaneous connective tissue of the rat. J Endodon 1988;14:229-35.
