Calcium hydroxide is a widely used dental material, known for its beneficial properties. Its application has significantly contributed to preserving tooth health and promoting healing within the dental pulp. Its versatility and effectiveness ensure its continued importance in modern dental practices.
Understanding Calcium Hydroxide
Calcium hydroxide is a strong basic compound. In dentistry, it is commonly encountered in various forms, including a powder, a paste, or as a component in cavity liners. A pure calcium hydroxide paste typically exhibits a high pH, ranging from approximately 12.5 to 12.8. This alkaline nature is a fundamental property that underpins many of its therapeutic effects in dental applications. It achieves its actions through the dissociation of calcium (Ca²⁺) and hydroxyl (OH⁻) ions when it comes into contact with aqueous solutions.
Primary Dental Applications
Calcium hydroxide finds extensive use in several dental procedures.
Pulp Capping
One primary application is in pulp capping, which can be direct or indirect. In direct pulp capping, the material is placed directly over an exposed pulp to protect it and encourage healing, while indirect pulp capping involves placing it over a thin layer of remaining dentin to protect the pulp from further irritation. Its purpose is to create a protective barrier and stimulate new dentin formation.
Cavity Liner or Base
Another significant use is as a cavity liner or base beneath restorative materials. When placed in a prepared cavity, it acts as a protective layer for the pulp, shielding it from thermal changes, chemical irritation from restorative materials, and microbial ingress. This protective function also helps to promote reparative dentin formation.
Temporary Root Canal Filling
Calcium hydroxide is also widely employed as a temporary root canal filling, particularly as an intracanal medicament during endodontic procedures. Its presence within the root canal helps to disinfect the canal system between appointments, reducing bacterial load. This is valued for its antimicrobial properties against common endodontic pathogens.
How Calcium Hydroxide Promotes Healing
The effectiveness of calcium hydroxide in promoting healing stems largely from its high pH. This basic environment is hostile to most bacteria, as the hydroxyl ions released disrupt bacterial cytoplasmic membranes, denature proteins, and damage bacterial DNA. This strong antibacterial action helps to sterilize the affected area, reducing infection and allowing the tooth’s natural healing processes to begin.
Calcium hydroxide actively stimulates the formation of reparative dentin, known as a dentin bridge. The high pH irritates the pulp tissue, encouraging pulp cells to lay down new, protective dentin. This newly formed dentin acts as a barrier, further protecting the underlying pulp from external stimuli and bacterial invasion. The material also exhibits anti-inflammatory effects, calming irritated pulp tissue and facilitating a more favorable healing response.
Important Considerations for Its Use
Calcium hydroxide offers several advantages in dentistry, including its biocompatibility, cost-effectiveness, and ease of use. It is a material that the body generally tolerates well, making it a reliable choice for direct contact with living pulp tissue. Its economic nature also makes it widely accessible for various dental treatments.
Despite its benefits, calcium hydroxide does have limitations. It possesses relatively low mechanical strength, making it unsuitable as a permanent restorative material for chewing forces. Its solubility is another consideration, as it can dissolve over time, especially if exposed to oral fluids. This solubility can lead to marginal leakage when used as a sealer. While it stimulates dentin bridge formation, tunneling defects can occur within this new dentin. Therefore, calcium hydroxide is often used as an interim or foundational material, preparing the tooth for a more robust, permanent restoration.