Potassium Oxalate Monohydrate: Versatile Salt

Potassium oxalate monohydrate (POM) is a potassium salt of oxalic acid. Its crystal structure has been investigated by three-dimensional neutron diffraction studies. POM may be used in the preparation of SBA-15 (Santa Barbara Amoprhous-15)- catalyst. Besides, this material may be used in the synthesis of bis(2,2"-bipyridine) (oxalato-O,O′)nickel(ii) tetrahydrate, a mononuclear mixed-ligand complex.

Potassium oxalate monohydrate mouthrinse reduces dentinal hypersensitivity

Cervical dentinal hypersensitivity is a condition characterized by sharp pain associated with thermal, evaporative, tactile, osmotic, or chemical stimuli. Investigators have described this condition clinically as an exaggerated response to nonnoxious stimuli that is dependent on dentin exposure and the lack of obstruction of the dentinal tubules. More than 90% of hypersensitive tooth surfaces are at the cervical margin on the facial aspects of the teeth. The cause of dentinal hypersensitivity can be the result of dentinal tubules exposure because of loss of enamel or gingival recession. The prevalence of dentinal hypersensitivity varies from 4% through 57% in the general population studied. In our study, we evaluated the potential of a Potassium oxalate monohydrate (KO) mouthrinse formulation to reduce and control dentinal hypersensitivity compared with a placebo control mouthrinse. In particular, Super Seal (Bisco) was designed specifically as an in-office, topical, single-use product for exposed dentinal surfaces. The Potassium oxalate monohydrate mouthrinse in this study is intended as an over-the-counter product used as a twice-daily mouthrinse to reduce and control dentinal hypersensitivity. The FDA clearance, coupled with prior clinical experience with KO mouthrinse and risk assessment, shows that Potassium oxalate monohydrate can be used in humans without causing harm and that twice-daily use (up to 20 milliliters per day, maximum dose) does not pose significant risk, although we did not include people prone to developing kidney stones in this study.[1]

For mean cold air stimulus VAS score at week 4, the KO mouthrinse provided a statistically significant improvement relative to placebo mouthrinse (estimated difference, −14.27 mm; 95% CI, −18.68 to −9.87; 35.6% improvement; P < .001). For the mean tactile sensitivity with the Yeaple probe assessment at week 4, Potassium oxalate monohydrate mouthrinse provided a statistically significant improvement relative to placebo mouthrinse (estimate difference, 13.45 g; 95% CI, 9.83 to 17.08; 88.0% improvement; P < .001). Finally, for the week 2 mean cold air stimulus VAS score and the mean Yeaple probe assessment, the KO mouthrinse showed statistically significant improvements relative to placebo mouthrinse for both measurements. To summarize, in this study, we demonstrated the superiority of Potassium oxalate monohydrate mouthrinse over placebo mouthrinse. We did so for both the primary and the 4 key secondary efficacy end points, controlling the overall, familywise error rate at 5%. Fifteen participants experienced at least 1 AE during the study: 8 participants in the placebo group and 7 in the KO group. The investigators classified 9 of these AEs as probably or very likely related to study treatment. The investigators documented all AEs and followed them to resolution. Treatment-related AEs included oral mucosal exfoliation (5 in the Potassium oxalate monohydrate group; 1 in the placebo group) and gingival ulceration (3 in the placebo group).

The placebo success rate, although significantly lower than the Potassium oxalate monohydrate success rate, was also in the 30% or greater range for decreased sensitivity. This finding was not unexpected because investigators often see effects from placebo in pain studies, and the KO mouthrinse, even with the placebo effect, exceeded the 20% criterion of pain reduction compared with placebo. The difference in the magnitude of treatment differences between the 2 study centers also was not unexpected, given that there were 2 examiners. Nevertheless, we observed higher success rates for the Potassium oxalate monohydrate mouthrinse at both sites. Other than a few incidents of transient, superficial mucosal irritation and exfoliation in a small number of participants, the participants tolerated the mouthrinses in this study well. Our study’s results demonstrated that the experimental Potassium oxalate monohydrate mouthrinse used twice daily as an adjunct to toothbrushing provided statistically significant and clinically relevant reduction in and control of dentinal hypersensitivity compared with results with a placebo mouthrinse.

Dynamics of the water molecule in potassium oxalate monohydrate

Scientists have measured the inelastic neutron scattering spectra for a powder sample and three differently oriented single crystals of Potassium oxalate monohydrate on the TFXA spectrometer at the ISIS facility. The crystal structure consists of oxalate ions hydrogen-bonded by the water molecules into infinite linear chains, which are held together by electrostatic interactions with the K⁺ ions. The H₂O molecules are isolated from each other. The vibrations can then be separated into internal and external vibrations. The single crystals were cut and oriented so as to separate the rocking, twisting and wagging modes as much as possible. The rocking mode appears at 656 cm^-1 (overtone at 1278 cm^-1). A band at 746 cm^-1 with strong overtones at 1448 and 2099 cm-1 is assigned to the overlapping twisting and wagging modes. The translational modes are found at 97, 210 and 215 cm^-1.[2]

References

[1]Lynch, M. C., Perfect, R., McGuire, J. A., Milleman, J., Gallob, J., Amini, P., & Milleman, K. (2018). Potassium oxalate mouthrinse reduces dentinal hypersensitivity: A randomized controlled clinical study. Journal of the American Dental Association, 149(7), 608–618.

[2]Delaplane, R., Küppers, H., Noreland, J., & Parker, S. (2002). Dynamics of the water molecule in potassium oxalate monohydrate as studied by single crystal inelastic neutron scattering . Applied Physics A, 44 1, s1366–s1367. https://doi.org/10.1007/S003390201807

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