Peroxides present in oral healthcare products generally exert favourable protective activities against the development and progression of tooth decay, plaque,
gingivitis, and
halitosis, etc. However, despite the high level of research focus on
hydrogen and
carbamide peroxides as therapeutically active (and
tooth-whitening) agents, to date the use of alternative chemical forms of
peroxides such as peroxoborates for these purposes has received only scant attention. Intriguingly, peroxoborate and its
esters with polyols, such as
glycerol, have a very diverse chemistry/biochemistry in aqueous
solution, for which there is an increasing amount of evidence that it remains distinctive from that of
hydrogen peroxide; such properties include self-associative and hydrolytic equilibria, and their abilities to participate in electrophile- or nucleophile-scavenging,
metal ion-complexing, redox and
free radical reactions, for example. Therefore, the purpose of this detailed commentary is to evaluate both differences and similarities between the molecular/biomolecular reactivities of peroxoborate species and
hydrogen peroxide in vitro, ex-vivo and in vivo. It encompasses brief sectional accounts regarding the molecular heterogeneity of peroxoborates, the release of bioactive agents therefrom, and their oxidative attack on oral cavity biomolecules (the nucleophilic or electrophilic character of these oxidations are discussed). Further areas explored are the abilities of
borates and peroxoborates to enhance the solubility of
iron ions in aqueous
solution, their involvements in
free radical biochemistry (particularly the complexation of
oxygen radical-promoting transition
metal ions by, and
antioxidant properties of, peroxoborate-
polyol ester adducts), and the specific inhibition of
protease enzymes. Further aspects focus on the
tooth-whitening, oral malodor neutralizing, and potential mutagenic and genotoxic properties of peroxoborates, along with possible mechanisms for these processes. The abilities of peroxoborates, and
peroxides in general, to modulate the activities of inflammatory mediators and
vitamins,
antioxidant or otherwise, are also explored.