Dissolution of porcine incisor pulps in sodium hypochlorite solutions of varying compositions and concentrations.
BACKGROUND
The solubility of dental pulp tissue in sodium hypochlorite has been extensively investigated but results have been inconsistent; due most likely to variations in experimental design, the volume and/or rate of replenishment of the solutions used and the nature of the tissues assessed. Traditionally, the sodium hypochlorite solutions used for endodontic irrigation in Australia have been either Milton or commercial bleach, with Milton being the most common. Recently, a range of Therapeutic Goods Administration (TGA) approved proprietary sodium hypochlorite solutions, which contain surfactant, has become available. Some domestic chlorine bleaches now also contain surfactants. The purpose of this study was to perform new solubility assessments, comparing Milton with new TGA approved products, Hypochlor 1% and Hypochlor 4% forte, and with a domestic bleach containing surfactant (White King).


METHODS
Ten randomly assigned pulp samples of porcine dental pulp of approximately equal dimensions were immersed in the above solutions, as well as representative concentrations of sodium hydroxide. Time to complete dissolution was measured and assessed statistically.


RESULTS
White King 4% showed the shortest dissolution time, closely followed by Hypochlor 4% forte. White King 1% and Hypochlor 1% each took around three times as long to completely dissolve the samples of pulp as their respective 4% concentrations, while Milton took nearly 10 times as long. The sodium hydroxide solutions showed no noticeable dissolution of the pulp samples.


CONCLUSIONS
The composition and content of sodium hypochlorite solutions had a profound effect on the ability of these solutions to dissolve pulp tissue in vitro. Greater concentrations provided more rapid dissolution of tissue. One per cent solutions with added surfactant and which contained higher concentrations of sodium hydroxide were significantly more effective in dissolution of pulp tissue than Milton.
Clarkson
R M
RM
rogercla@ozemail.com.au
Moule
A J
AJ
Podlich
H
H
Kellaway
R
R
Macfarlane
R
R
Lewis
D
D
Rowell
J
J
D000818:Animals; D002424:Caustics / Q000008:administration & dosage / Q000494:pharmacology; D002626:Chemistry, Pharmaceutical; D003782:Dental Pulp / Q000187:drug effects*; D004202:Disinfectants / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D011897:Random Allocation; D012388:Root Canal Irrigants / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D012972:Sodium Hydroxide / Q000008:administration & dosage / Q000494:pharmacology; D012973:Sodium Hypochlorite / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D012995:Solubility / Q000187:drug effects; D013501:Surface-Active Agents / Q000737:chemistry; D013552:Swine; D013997:Time Factors
D002424:Caustics; D004202:Disinfectants; D012388:Root Canal Irrigants; D013501:Surface-Active Agents; D012972:Sodium Hydroxide; D012973:Sodium Hypochlorite