Potassium oxalate oral rinses for long-term relief from dentinal hypersensitivity: Three randomised controlled studies

Abstract Objectives To evaluate effectiveness of oral rinses containing dipotassium oxalate monohydrate (KOX) in relieving dentinal hypersensitivity (DH) after 8 w use adjunctive to brushing. Methods Three 8-week, randomised, controlled, double-blind, parallel-group, single-centre studies were conducted in adults with DH. In each study, participants were randomised to one of two experimental rinses or a placebo in a matrix design, such that each experimental rinse was evaluated in two studies. Rinses A (pH 4.5) and B (pH 7.0) contained 1.5% KOX and were fluoride-free; Rinse C (pH 4.5) contained 2.0% KOX and 45 ppm fluoride as NaF; the placebo rinse (pH 4.5) did not contain KOX or fluoride. Participants brushed with a fluoride dentifrice for 1 min, briefly rinsed with water, then rinsed with their assigned oral rinse for 1 min twice daily for 8 w. DH was assessed at baseline and following 4 and 8 w use by response to an evaporative (air) stimulus (evaluated by Schiff sensitivity score and a 10-point visual rating scale) and a tactile stimulus (Yeaple probe). Results All rinses in each study were associated with statistically significant improvements from baseline in measures of DH after 4 and 8 w treatment. However, between-treatment comparisons were inconsistent across the studies, with only Study 3 demonstrating a significant difference between the experimental (Rinses B and C) and placebo rinses. A number of treatment-related adverse events (all mild) were reported. Conclusions Rinses containing 1.5–2.0% KOX did not consistently demonstrate a benefit over placebo in relieving DH after 8 w use. Clinical significance While favourable results were found in one of the investigations, this suite of studies shows that the possibility of inconsistent results exists even with the best designed and executed trials.