Dear Readers,
The use of calcium hydroxide as a root canal medicament is common place, especially with its many advantages. One important fact that is overlooked is its mode of administration.
Although available as a plain powder, the commercial products may be aqueous, viscous, or oil based; fast setting, slow setting, or controlled setting. While the pastes are used as intracanal medicaments, setting formulations are used as cavity liners or endodontic sealers.[1] Besides the antimicrobial activity, it is important to understand the benefit of using a particular formulation.[2,3]
The aqueous versions consist of calcium hydroxide mixed with either water, saline, anesthetic solution, Ringer's solution, an aqueous suspension of methyl cellulose, or carboxy methyl cellulose or anionic detergent solutions. The aqueous combinations release calcium and hydroxyl ions rapidly and have a high degree of solubility. As a result, the root canal dressing needs to be changed several times increasing the number of appointments.[4]
In a viscous preparation, the vehicles used are glycerin, polyethylene glycol, or propylene glycol with the calcium hydroxide. These mixtures release calcium and hydroxyl ions slowly, have a low solubility, and remain in the root canal for a longer time interval, hence reducing the number of sittings.[5] This results in better antimicrobial actions with better performance and biocompatibility.
The oil-based blends have calcium hydroxide in combination with olive oil, silicone oil, camphorated monochlorophenol CMCP, fatty acids, eugenol, or metacresylacetate. These mixes have a low solubility and remain in the root canal for a prolonged time.[6]
In summary, the indications of calcium hydroxide as per vehicle types can be:
For clinical situations that require a rapid ionic liberation at the beginning of the treatment, an aqueous vehicle containing calcium hydroxide paste is indicated
While in clinical situations that require a gradual and uniform ionic liberation, a viscous vehicle containing calcium hydroxide pastes is used
Pastes containing oily vehicles have restricted use and are only employed in those clinical situations that require a very slow ionic dissociation.
Thus, it is of utmost importance that the clinician understands the chemistry and clinical outcomes related with the use of various vehicles for calcium hydroxide in intracanal medication.
REFERENCES
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