A new three-component formulation for the efficient whitening of teeth (Carbamide Plus).
OBJECTIVE
This study aimed to develop and characterise a new three-component dental whitening formulation which is as effective as the currently used carbamide peroxide but at significantly lower hydrogen peroxide concentrations.


METHODS
The new formulation (Carbamide Plus) was prepared containing hydrogen peroxide, urea, and sodium tripolyphosphate and compared directly with carbamide peroxide (containing just hydrogen peroxide and urea). To evaluate the clinical effectiveness of 5% Carbamide Plus, a randomised double-blind placebo-controlled clinical trial was conducted comparing the tooth colour of 33 patients using L*a*b* scores at baseline and after a 2-week whitening treatment. The behaviour of the three components in solution was determined by (1)H and (31)P NMR spectroscopy and pH dilution experiments.


RESULTS
This clinical trial revealed that 5% whitening gels containing Carbamide Plus were as effective as those containing 10% carbamide peroxide. (1)H and (31)P NMR spectroscopy revealed strong intermolecular interactions between hydrogen peroxide and both urea and sodium tripolyphosphate (STPP) with little apparent interaction between urea and STPP.


CONCLUSIONS
In this manuscript, we postulate that this increased whitening efficiency is due to a marked increase in local pH upon dilution which destabilises the hydrogen peroxide and expedites the whitening process. We postulate Carbamide Plus to be a three-component adduct with two molecules of carbamide peroxide binding to a central STPP unit with no direct interaction between STPP and urea. There were no statistically significant differences between Carbamide Plus and 10% carbamide peroxide in tooth-whitening achieved at 2 weeks. These results were recorded following 2 weeks of 2-h daily wear of at-home trays.


CONCLUSIONS
Carbamide Plus offers the potential of using significantly lower levels of hydrogen peroxide concentration to achieve similar dental whitening effects.
School of Pharmacy and Pharmaceutical Sciences, University of Ulster, Coleraine, Northern Ireland, BT52 1SA, UK.
Barry W
BW
Hyland
Ailbhe
A
McDonald
Nicholas
N
Lewis
Christopher
C
Tredwin
Aviva
A
Petrie
Sean
S
Hall
Chris
C
Todd
Bridgeen
B
McCaughan
John F
JF
Callan
D000077463:Carbamide Peroxide; D004311:Double-Blind Method; D004338:Drug Combinations; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D010545:Peroxides / Q000737:chemistry*; D011122:Polyphosphates / Q000737:chemistry; D014073:Tooth Bleaching / Q000379:methods*; D014508:Urea / Q000031:analogs & derivatives* / Q000737:chemistry
C000626064:Carbamide Plus; D004338:Drug Combinations; D010545:Peroxides; D011122:Polyphosphates; D000077463:Carbamide Peroxide; D014508:Urea; D006861:Hydrogen Peroxide; C005692:triphosphoric acid