For decades, calcium hydroxide–based materials played a central role in endodontics due to their antimicrobial properties and biological compatibility. However, advances in biomechanical preparation, three-dimensional obturation, and material science have redefined the requirements of an ideal endodontic sealer.
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✅ Calcium Hydroxide Sealers: Historical Perspective
Calcium hydroxide sealers were originally adopted because of their:
▪️ High alkalinity, promoting antibacterial effects
▪️ Ability to stimulate hard tissue formation
▪️ Relative ease of handling
Despite these advantages, their use as permanent sealers has increasingly been questioned as treatment goals shifted toward predictable, long-term apical sealing and structural integrity.
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Modern endodontics demands materials that maintain dimensional stability, resist dissolution, and provide a fluid-tight seal under functional stresses. Evidence shows that calcium hydroxide sealers exhibit:
▪️ High solubility over time, leading to leakage
▪️ Poor adhesion to dentin and gutta-percha
▪️ Inability to support monoblock concepts
▪️ Reduced performance in warm vertical compaction techniques
These deficiencies directly compromise the biomechanical integrity of the root canal system.
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Multiple in vitro and clinical studies confirm that calcium hydroxide sealers demonstrate inferior sealing ability compared with epoxy resin–based and bioceramic sealers. Progressive dissolution allows bacterial penetration, undermining long-term endodontic success.
Importantly, antibacterial activity does not compensate for inadequate sealing, as persistent microleakage remains the primary cause of post-treatment disease.
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Contemporary sealers—such as epoxy resin, calcium silicate–based (bioceramic), and MTA-derived materials—offer:
▪️ Low solubility
▪️ Superior dentinal adaptation
▪️ Chemical bonding or bioactivity
▪️ Compatibility with modern obturation techniques
These properties align with current biomechanical and biological principles of root canal therapy.
📊 Comparative Table: Calcium Hydroxide Sealers vs Modern Endodontic Sealers
| Aspect | Advantages | Limitations |
|---|---|---|
| Antibacterial activity | High initial pH with antimicrobial effect | Effect decreases over time and does not prevent leakage |
| Sealing ability | Easy placement in the canal | Inferior apical and coronal seal compared to resin and bioceramic sealers |
| Solubility | Gradual release of calcium ions | High long-term solubility leading to voids and microleakage |
| Biomechanical compatibility | Biocompatible with periapical tissues | Fails to reinforce root structure or support monoblock obturation |
While calcium hydroxide remains valuable as an intracanal medicament, its role as a definitive endodontic sealer is scientifically outdated. Current evidence underscores that long-term success depends more on durable sealing and biomechanical stability than on transient antimicrobial effects. The persistence of calcium hydroxide sealers in some clinical settings reflects habit rather than evidence-based practice.
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▪️ Avoid the use of calcium hydroxide–based sealers as permanent obturation materials
▪️ Prefer epoxy resin or bioceramic sealers for long-term sealing
▪️ Reserve calcium hydroxide for short-term intracanal medication
▪️ Align material selection with modern obturation techniques and biomechanical principles
▪️ Update clinical protocols according to current endodontic evidence
✍️ Conclusion
Calcium hydroxide as a long-term endodontic sealer no longer meets modern biomechanical standards due to its high solubility, inadequate sealing ability, and incompatibility with contemporary obturation concepts. Advances in material science have produced superior alternatives that ensure predictable, durable, and biologically sound outcomes, making the routine use of calcium hydroxide sealers as definitive materials unjustifiable in modern endodontic practice.
📚 References
✔ Ørstavik, D., Kerekes, K., & Eriksen, H. M. (2001). The quality of root canal fillings and the incidence of apical periodontitis. International Endodontic Journal, 34(7), 527–536. https://doi.org/10.1046/j.1365-2591.2001.00415.x
✔ Siqueira, J. F., & Rôças, I. N. (2008). Clinical implications and microbiology of bacterial persistence after treatment procedures. Journal of Endodontics, 34(11), 1291–1301. https://doi.org/10.1016/j.joen.2008.07.028
✔ Viapiana, R., Guerreiro-Tanomaru, J. M., Tanomaru-Filho, M., Camilleri, J. (2014). Physicochemical properties of epoxy resin-based and calcium silicate-based endodontic sealers. International Endodontic Journal, 47(3), 262–271. https://doi.org/10.1111/iej.12154
✔ Zhang, W., Li, Z., & Peng, B. (2009). Assessment of a new root canal sealer’s apical sealing ability. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 107(6), e79–e82. https://doi.org/10.1016/j.tripleo.2009.02.024
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