Antioxidant and pro-oxidant properties of chlorhexidine and its interaction with calcium hydroxide solutions.
OBJECTIVE
To evaluate the antioxidant and pro-oxidant properties of chlorhexidine (CHX).


METHODS
The scavenging and generation of reactive oxygen species (ROS) by CHX in the presence or absence of saturated Ca(OH)(2) solutions was evaluated. The reaction emitted chemiluminescence in the presence of lucigenin thus was determined by a luminometer to evaluate the levels of ROS production. Changes in DNA conformation were analysed by agarose gel electrophoresis. Paired Student's t-test was used to compare the difference between groups.


RESULTS
Chlorhexidine (0.00002-0.02%) effectively scavenged 56-88% of the superoxide radicals generated by the xanthine/xanthine oxidase reaction. Through analysis of PUC18 DNA conformation changes, CHX was shown to be a mild scavenger of hydroxyl radicals generated by H(2)O(2) plus FeCl(2). However, CHX (>0.083%) decreased the mobility of PUC18 plasmid DNA with potential production of DNA-DNA cross-link and severe DNA breaks (presence of DNA smear) at further higher concentrations. Furthermore, CHX induced ROS production including H(2)O(2) and superoxide radicals in 0.1N NaOH (pH = 12.76) or Ca(OH)(2) (pH = 12.5) solutions.


CONCLUSIONS
Chlorhexidine exhibited both antioxidant and pro-oxidant properties under different conditions. These events are possibly involved in the killing of root canal and periodontal microorganisms when CHX and Ca(OH)(2) were used in combination or separately. Potential genotoxicity and tissue damage when extruded into the periradicular tissue and at higher concentrations should be considered during periodontal and endodontic practice.
Yeung
S Y
SY
Department of Dentistry, Chang-Gung Memorial Hospital, Taipei, Taiwan.
Huang
C S
CS
Chan
C P
CP
Lin
C P
CP
Lin
H N
HN
Lee
P H
PH
Jia
H W
HW
Huang
S K
SK
Jeng
J H
JH
Chang
M C
MC
D002126:Calcium Hydroxide / Q000737:chemistry; D002710:Chlorhexidine / Q000737:chemistry* / Q000633:toxicity*; D004249:DNA Damage; D004347:Drug Interactions; D016166:Free Radical Scavengers / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D017382:Reactive Oxygen Species / Q000737:chemistry; D012388:Root Canal Irrigants / Q000737:chemistry* / Q000633:toxicity*; D012972:Sodium Hydroxide / Q000737:chemistry
D016166:Free Radical Scavengers; D017382:Reactive Oxygen Species; D012388:Root Canal Irrigants; D012972:Sodium Hydroxide; D006861:Hydrogen Peroxide; D002126:Calcium Hydroxide; D002710:Chlorhexidine