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Evaluation of pH and Calcium Ion Release of Three Root Canal Sealers
ENWD~MICS Copyright 0 2000 by The American Association of Endodontists
Printed in U S A . VOL. 26, No. 7, JULV2000
JOURNAL OF
Evaluation of pH and Calcium Ion Release of Three Root Canal Sealers Marco Antonio Hungaro Duarte, MD, Ana Claudia Cardoso de Oliveira Demarchi, MD, Marcelo Henrique Giaxa, Milton Carlos Kuga, DDS, Sylvio de Campos Fraga, DDS, and Luiz Carlos Duarte de Souza, DDS
Apexit and Sealer 26, the latter developed on the basis of Berbert's observation (2) in 1978. However, it should be pointed out that sealers containing calcium hydroxide in their composition will only perform their biological and microbiological action if calcium ion and hydroxyl release occur (5, 6). The purpose of the present study was to assess the pH and calcium ion release provided by calcium hydroxide-containing sealers.
The pH and calcium ion release of three root canal sealers-Sealapex, Sealer 26, and Apexit-were assessed at 24 and 48 hr, and at 7 and 30 days after spatulation. After manipulation, the sealers were placed in 1-cm-long tubes measuring 4 mm in diameter and immersed in a glass flask containing 10 ml of deionized water, which was hermetically sealed and stored at 37°C. The tubes were removed at the scheduled times and the water in which they were immersed was tested for pH with a pHmeter and for released calcium by atomic absorption spectrophotometry. Starting 48 hr after immersion, Selapex produced an alkaline pH and released significantly higher calcium amounts compared with the other two sealers, with even more pronounced results after 30 days. On the basis of the results obtained, we conclude that Sealapex presented the highest calcium and hydroxyl release, especially after longer time intervals, whereas Sealer 26 showed highest release during the initial periods (i.e. during its setting time). Apexit presented the least satisfactory results.
MATERIALS AND METHODS The materials assessed are described herein. Sealer 26 (Dentsply Ind. Co., Petr6polis, Brazil) consists of powder containing calcium hydroxide and epoxy resin as the fluid. The sealer is spatulated at a proportion of 2 g of powdedl.1 g of resin, as recommended by de Moraes (7). Sealapex (Kerr Co., Romulus, MI) consists of two pastes: the base paste containing calcium oxide and the catalyzer paste. The two pastes are mixed in equal proportions. Apexit (IvoclarNivadent, Schaan, Liechtenstein) consists of two pastes: the base paste containing calcium oxide and calcium hydroxide, and the catalyzer paste. The two pastes are mixed in equal proportions.
pH Analysis The materials were manipulated at the proportions indicated herein and then placed in 1-cm-long plastic tubes measuring 4 mm in diameter. Each tube was placed in a glass flask containing 10 ml of distilled water that was hermetically sealed after sample immersion. pH was determined with a pHmeter (Micronal Ind. Ltd., Piracicaba, Brazil) 24 and 48 hr, and 7 and 30 days after spatulation. At each time interval, the tubes were returned to glass flasks containing fresh solutions, and the pH of the previous solution was determined. A total of five samples were used for each sealer.
A root canal sealer must have ideal properties to be used for root canal filling. Antimicrobial action and biocompatibility are fundamental to promote antisepsis in the root canal and to favor apical and periapical tissue repair (1). Concerned mainly about the need for biological action, Berbert (2) proposed a combination of calcium hydroxide with AH26 cement and observed better biocompatibility with the use of this material. Some years later, root canal sealers with calcium hydroxide in their composition became available on the market, with Sealapex and CRCS (Calciobiotic Root Canal Sealer) being the first ones to be developed. Investigations (3, 4) assessing the biological response of calcium hydroxide-containingsealers, especially Sealapex, have supported the advantages of the presence of this substance in their composition. Other sealers became available later, among them
Analysis of Calcium Ion Release The procedure used to measure calcium ion release was the same as that for pH analysis. Tubes of the same diameter and length were immersed in 10 ml of distilled water and evaluated for 389
.
390
Journal of Endodontics
Duarte et al. TABLE1. Mean pH values obtained after different periods of time
Sealer Sealapex Apexit
24 Hr
48 Hr
7 Davs
30 Davs
9.84 9.72 8.85
9.02 9.46 8.6
9.45 9.51 9.11
9.74 10.99 9.18
TABLE 2. Mean calcium ion release (mg/lOO ml) at different periods of time
Sealer 26 Sealapex Apexit
24 Hr
48Hr
7 Days
30 Days
3.84 5.84 0.86
4.77 1.96 0.43
1.31 2.56 0.65
3.7 58.74 2.72
calcium ion release at the same time intervals, and then returned to flasks containing fresh solutions. Calcium release was measured with an atomic absorption spectrophotometer model AA12/1475 (Varian, S5o Paulo, Brazil). To prevent the possible interference of alkaline phosphates and metals, the samples and standards were diluted in 10% EDTA (1 M), and the glass flasks were washed with 5% nitric acid. A standard stock solution of 10 mg/100 ml of calcium was diluted in 10% EDTA (1 M) to obtain concentrations of 0.025, 0.05,0.1, and 0.3 mg/100 ml. The samples studied were diluted as needed and 10% EDTA (1 M ) was used as the blank to calibrate the apparatus to zero. Data were calculated by comparison to the standard curve. Statistical analysis was performed by ANOVA for each time interval studied, and individual comparisons were performed by the Tukey-Kramer test.
RESULTS Data concerning mean pH and calcium ion release are shown in Tables 1 and 2, respectively.
DISCUSSION Calcium release and an alkaline pH for a material that contains calcium hydroxide or oxide in its composition are extremely important for good biological and microbiologicalperformance of the material. Calcium participates in the activation of calcium-dependent ATPase (8) and reacts with tissue carbon dioxide, forming calcium carbonate crystals that favor mineralization (6, 9). Microbiologically, calcium reacts with carbon dioxide, reducing the source of respiration for anaerobic bacteria (10). Concerning pH, if the material releases hydroxyl ion, thus favoring alkalinity, it will also favor repair and promote an antimicrobial action (5, 6). The results show that at 24 hr, 7 days, and 30 days after spatulation, Sealapex presented the highest calcium release, with a significant difference from Sealer 26 and Apexit at 30 days. With respect to pH, Sealapex presented the highest values at 48 hr, 7 days, and 30 days, differing significantly from Apexit at all times and from Sealer 26 at 30 days. These results c o n f i i the good performance of Sealapex in terms of the physicochemical properties studied, as also reported by others (11, 12).
Sealer 26 is an AH26 derivative with calcium hydroxide added. The results for Sealer 26 were satisfactory, also in agreement with previous reports (13, 14), and were superior to those obtained with Apexit at all times and slightly superior to those obtained with Sealapex during the early periods of evaluation. This differs to some degree from the results reported by da Silva et al. (11). In our study, the sealers were inserted into tubes and immersed in distilled water immediately after spatulation, whereas in the study by da Silva et al. (1 l), the materials were immersed after setting. We observed that Sealapex started to present better values than Sealer 26 after 48 hr (i.e. after the setting time of the material), which occurs within this period of time. This is due to the fact that Sealapex is highly soluble after setting, whereas Sealer 26 is not (15). These results explain the better biological results obtained with Sealapex (3, 4). On the basis of the results obtained, we conclude that Sealapex gave the highest calcium and hydroxyl release, especially after longer time intervals, whereas Sealer 26 showed the highest release during the initial periods (i.e. during its setting time). Apexit presented the least satisfactory results. This research was supported by CNPq and the Vbritas Foundation. Drs. Duarte, Cardoso de Oliveira Demarchi, Kuga, de Campos Fraga, Duarte de Souza, and Mr. Giaxa are affiliated with the University of Sagrado Coraqlo, Bauru, Brazil. Address requests for reprints to Dr. Marco Antonio Hungaro Duarte, R. Antonio Alves, 25-60, Apt. 84, Bauru, SP, Brazil C.E.P. 17043-060.
References 1. Grossman LI, Oliet S, DelRio C. Endodontic practice. 11th ed. Philadelphia: Lea & Febiger, 1988:242. 2. Berbert A. Comportamento dos tecidos apicais e periapicais ap5s biopulpectomia e obturaqlo do canal com AH26, hidr6xido de cklcio ou mistura de ambos. Estudo histolbgico em dentes de c8es. Ph.D. Thesis. Bauru, Brazil: University of S o Paulo, 1978. 3. Holland R, De Souza V. Ability of a new calcium hydroxide filling material to induce hard tissue formation. J Endodon 1985;11:535-43. 4. Tagger M, Tagger E. Periapical reactions to calcium hydroxide-containing sealers and AH26 in monkeys. Endod Dent Traumatol 1989;5:139-46. 5. Estrela C, Sydney GB, Bammann LL, Felippe 0 Jr. Estudo do efeito biol6gico do pH na atividade enzimktica de bactbrias anaer6bias. Rev Fac Odontol Baum 1994;2:31-8. 6. Estrela C, Sydney GB, Bammann LL, Felippe0 Jr. Mechanismof action of calcium and hydroxyl ions of calcium hydroxide on tissue and bacteria. Brazil Dent J 1995;6:85-90. 7. De Moraes IG. Propriedades fisicas de cimentos ep6xicos experimentais para obtura@es de canais radiculares, baseados no AH26. Ph.D. Thesis. Bauru, Brazil: University of Slo Paulo. 1984. 8. Abiko Y. Studies on calcium-stimulated adenosine triphosphatase in the albino rabbit dental pulp. Its subcellular distribution and properties. J Dent Res 1977;56:1558-68. 9. Seux D, Couble ML, Hartmann DJ, Gauthier JP. Magloire H. Odontoblast-like cytodifferentiation of human dental pulp cells in vitro in the presence of calcium hydroxide cement. Arch Oral Biol 1991;36:117-28. 10. Kontakiotis G, Nakou M, Georgopoulou M. In vitro studies of the indirect action of calcium hydroxide on the anaerobic flora of root canal. Int Endod J 1995;28:285-9. 11. Da Silva LAB, Leonard0 MR, Da Silva RS, Assed S, Guimaraes LFL. Calcium hydroxide root canal sealers: evaluation of pH, calcium ion concentration and conductivity. Int Endod J 1997;30:205-9. 12. Tagger M. Tagger E, Kfir A. Release of calcium and hydroxyl ions from set endodontic sealers containing calcium hydroxide. J Endodon 198834: 588-91. 13. Duarte MAH. Avaliaqao in vitro do poder anti-Gptico e pH de cimentos e pastas empregados na prktica endod8ntica. Master’s Thesis. Bauru, Brazil: University of S o Paulo, 1996. 14. Siqueira JF Jr, Fraga RC, Garcia PF. Evaluation of sealing ability, pH and flow rate of three calcium hydroxide-based sealers. Endod Dent Traumatol 1995;11:225-8. 15. Fidel RAS, Span6 JCE, Barbin EL, Silva RG. PQora JD. Estudoin vitro sobre a solubilidade e a desintegraqlo de alguns cimentos endodbnticos que contbm hidr6xido de c8lcio. Rev Odontol Univ S o Paulo 1994;8:217-20.
Printed in U S A . VOL. 26, No. 7, JULV2000
JOURNAL OF
Evaluation of pH and Calcium Ion Release of Three Root Canal Sealers Marco Antonio Hungaro Duarte, MD, Ana Claudia Cardoso de Oliveira Demarchi, MD, Marcelo Henrique Giaxa, Milton Carlos Kuga, DDS, Sylvio de Campos Fraga, DDS, and Luiz Carlos Duarte de Souza, DDS
Apexit and Sealer 26, the latter developed on the basis of Berbert's observation (2) in 1978. However, it should be pointed out that sealers containing calcium hydroxide in their composition will only perform their biological and microbiological action if calcium ion and hydroxyl release occur (5, 6). The purpose of the present study was to assess the pH and calcium ion release provided by calcium hydroxide-containing sealers.
The pH and calcium ion release of three root canal sealers-Sealapex, Sealer 26, and Apexit-were assessed at 24 and 48 hr, and at 7 and 30 days after spatulation. After manipulation, the sealers were placed in 1-cm-long tubes measuring 4 mm in diameter and immersed in a glass flask containing 10 ml of deionized water, which was hermetically sealed and stored at 37°C. The tubes were removed at the scheduled times and the water in which they were immersed was tested for pH with a pHmeter and for released calcium by atomic absorption spectrophotometry. Starting 48 hr after immersion, Selapex produced an alkaline pH and released significantly higher calcium amounts compared with the other two sealers, with even more pronounced results after 30 days. On the basis of the results obtained, we conclude that Sealapex presented the highest calcium and hydroxyl release, especially after longer time intervals, whereas Sealer 26 showed highest release during the initial periods (i.e. during its setting time). Apexit presented the least satisfactory results.
MATERIALS AND METHODS The materials assessed are described herein. Sealer 26 (Dentsply Ind. Co., Petr6polis, Brazil) consists of powder containing calcium hydroxide and epoxy resin as the fluid. The sealer is spatulated at a proportion of 2 g of powdedl.1 g of resin, as recommended by de Moraes (7). Sealapex (Kerr Co., Romulus, MI) consists of two pastes: the base paste containing calcium oxide and the catalyzer paste. The two pastes are mixed in equal proportions. Apexit (IvoclarNivadent, Schaan, Liechtenstein) consists of two pastes: the base paste containing calcium oxide and calcium hydroxide, and the catalyzer paste. The two pastes are mixed in equal proportions.
pH Analysis The materials were manipulated at the proportions indicated herein and then placed in 1-cm-long plastic tubes measuring 4 mm in diameter. Each tube was placed in a glass flask containing 10 ml of distilled water that was hermetically sealed after sample immersion. pH was determined with a pHmeter (Micronal Ind. Ltd., Piracicaba, Brazil) 24 and 48 hr, and 7 and 30 days after spatulation. At each time interval, the tubes were returned to glass flasks containing fresh solutions, and the pH of the previous solution was determined. A total of five samples were used for each sealer.
A root canal sealer must have ideal properties to be used for root canal filling. Antimicrobial action and biocompatibility are fundamental to promote antisepsis in the root canal and to favor apical and periapical tissue repair (1). Concerned mainly about the need for biological action, Berbert (2) proposed a combination of calcium hydroxide with AH26 cement and observed better biocompatibility with the use of this material. Some years later, root canal sealers with calcium hydroxide in their composition became available on the market, with Sealapex and CRCS (Calciobiotic Root Canal Sealer) being the first ones to be developed. Investigations (3, 4) assessing the biological response of calcium hydroxide-containingsealers, especially Sealapex, have supported the advantages of the presence of this substance in their composition. Other sealers became available later, among them
Analysis of Calcium Ion Release The procedure used to measure calcium ion release was the same as that for pH analysis. Tubes of the same diameter and length were immersed in 10 ml of distilled water and evaluated for 389
.
390
Journal of Endodontics
Duarte et al. TABLE1. Mean pH values obtained after different periods of time
Sealer Sealapex Apexit
24 Hr
48 Hr
7 Davs
30 Davs
9.84 9.72 8.85
9.02 9.46 8.6
9.45 9.51 9.11
9.74 10.99 9.18
TABLE 2. Mean calcium ion release (mg/lOO ml) at different periods of time
Sealer 26 Sealapex Apexit
24 Hr
48Hr
7 Days
30 Days
3.84 5.84 0.86
4.77 1.96 0.43
1.31 2.56 0.65
3.7 58.74 2.72
calcium ion release at the same time intervals, and then returned to flasks containing fresh solutions. Calcium release was measured with an atomic absorption spectrophotometer model AA12/1475 (Varian, S5o Paulo, Brazil). To prevent the possible interference of alkaline phosphates and metals, the samples and standards were diluted in 10% EDTA (1 M), and the glass flasks were washed with 5% nitric acid. A standard stock solution of 10 mg/100 ml of calcium was diluted in 10% EDTA (1 M) to obtain concentrations of 0.025, 0.05,0.1, and 0.3 mg/100 ml. The samples studied were diluted as needed and 10% EDTA (1 M ) was used as the blank to calibrate the apparatus to zero. Data were calculated by comparison to the standard curve. Statistical analysis was performed by ANOVA for each time interval studied, and individual comparisons were performed by the Tukey-Kramer test.
RESULTS Data concerning mean pH and calcium ion release are shown in Tables 1 and 2, respectively.
DISCUSSION Calcium release and an alkaline pH for a material that contains calcium hydroxide or oxide in its composition are extremely important for good biological and microbiologicalperformance of the material. Calcium participates in the activation of calcium-dependent ATPase (8) and reacts with tissue carbon dioxide, forming calcium carbonate crystals that favor mineralization (6, 9). Microbiologically, calcium reacts with carbon dioxide, reducing the source of respiration for anaerobic bacteria (10). Concerning pH, if the material releases hydroxyl ion, thus favoring alkalinity, it will also favor repair and promote an antimicrobial action (5, 6). The results show that at 24 hr, 7 days, and 30 days after spatulation, Sealapex presented the highest calcium release, with a significant difference from Sealer 26 and Apexit at 30 days. With respect to pH, Sealapex presented the highest values at 48 hr, 7 days, and 30 days, differing significantly from Apexit at all times and from Sealer 26 at 30 days. These results c o n f i i the good performance of Sealapex in terms of the physicochemical properties studied, as also reported by others (11, 12).
Sealer 26 is an AH26 derivative with calcium hydroxide added. The results for Sealer 26 were satisfactory, also in agreement with previous reports (13, 14), and were superior to those obtained with Apexit at all times and slightly superior to those obtained with Sealapex during the early periods of evaluation. This differs to some degree from the results reported by da Silva et al. (11). In our study, the sealers were inserted into tubes and immersed in distilled water immediately after spatulation, whereas in the study by da Silva et al. (1 l), the materials were immersed after setting. We observed that Sealapex started to present better values than Sealer 26 after 48 hr (i.e. after the setting time of the material), which occurs within this period of time. This is due to the fact that Sealapex is highly soluble after setting, whereas Sealer 26 is not (15). These results explain the better biological results obtained with Sealapex (3, 4). On the basis of the results obtained, we conclude that Sealapex gave the highest calcium and hydroxyl release, especially after longer time intervals, whereas Sealer 26 showed the highest release during the initial periods (i.e. during its setting time). Apexit presented the least satisfactory results. This research was supported by CNPq and the Vbritas Foundation. Drs. Duarte, Cardoso de Oliveira Demarchi, Kuga, de Campos Fraga, Duarte de Souza, and Mr. Giaxa are affiliated with the University of Sagrado Coraqlo, Bauru, Brazil. Address requests for reprints to Dr. Marco Antonio Hungaro Duarte, R. Antonio Alves, 25-60, Apt. 84, Bauru, SP, Brazil C.E.P. 17043-060.
References 1. Grossman LI, Oliet S, DelRio C. Endodontic practice. 11th ed. Philadelphia: Lea & Febiger, 1988:242. 2. Berbert A. Comportamento dos tecidos apicais e periapicais ap5s biopulpectomia e obturaqlo do canal com AH26, hidr6xido de cklcio ou mistura de ambos. Estudo histolbgico em dentes de c8es. Ph.D. Thesis. Bauru, Brazil: University of S o Paulo, 1978. 3. Holland R, De Souza V. Ability of a new calcium hydroxide filling material to induce hard tissue formation. J Endodon 1985;11:535-43. 4. Tagger M, Tagger E. Periapical reactions to calcium hydroxide-containing sealers and AH26 in monkeys. Endod Dent Traumatol 1989;5:139-46. 5. Estrela C, Sydney GB, Bammann LL, Felippe 0 Jr. Estudo do efeito biol6gico do pH na atividade enzimktica de bactbrias anaer6bias. Rev Fac Odontol Baum 1994;2:31-8. 6. Estrela C, Sydney GB, Bammann LL, Felippe0 Jr. Mechanismof action of calcium and hydroxyl ions of calcium hydroxide on tissue and bacteria. Brazil Dent J 1995;6:85-90. 7. De Moraes IG. Propriedades fisicas de cimentos ep6xicos experimentais para obtura@es de canais radiculares, baseados no AH26. Ph.D. Thesis. Bauru, Brazil: University of Slo Paulo. 1984. 8. Abiko Y. Studies on calcium-stimulated adenosine triphosphatase in the albino rabbit dental pulp. Its subcellular distribution and properties. J Dent Res 1977;56:1558-68. 9. Seux D, Couble ML, Hartmann DJ, Gauthier JP. Magloire H. Odontoblast-like cytodifferentiation of human dental pulp cells in vitro in the presence of calcium hydroxide cement. Arch Oral Biol 1991;36:117-28. 10. Kontakiotis G, Nakou M, Georgopoulou M. In vitro studies of the indirect action of calcium hydroxide on the anaerobic flora of root canal. Int Endod J 1995;28:285-9. 11. Da Silva LAB, Leonard0 MR, Da Silva RS, Assed S, Guimaraes LFL. Calcium hydroxide root canal sealers: evaluation of pH, calcium ion concentration and conductivity. Int Endod J 1997;30:205-9. 12. Tagger M. Tagger E, Kfir A. Release of calcium and hydroxyl ions from set endodontic sealers containing calcium hydroxide. J Endodon 198834: 588-91. 13. Duarte MAH. Avaliaqao in vitro do poder anti-Gptico e pH de cimentos e pastas empregados na prktica endod8ntica. Master’s Thesis. Bauru, Brazil: University of S o Paulo, 1996. 14. Siqueira JF Jr, Fraga RC, Garcia PF. Evaluation of sealing ability, pH and flow rate of three calcium hydroxide-based sealers. Endod Dent Traumatol 1995;11:225-8. 15. Fidel RAS, Span6 JCE, Barbin EL, Silva RG. PQora JD. Estudoin vitro sobre a solubilidade e a desintegraqlo de alguns cimentos endodbnticos que contbm hidr6xido de c8lcio. Rev Odontol Univ S o Paulo 1994;8:217-20.