Single Application of Antimicrobial Quaternary Ammonium K21 Reduces Plaque Cariogenicity

Objectives: K21, an antimicrobial quaternary ammonium compound may aid in oral hygiene practice of the orthodontic patient. We hypothesized that a single application of K21 on smooth surfaces will reduce the development and cariogenicity of the biofilm around orthodontic brackets.
Methods: After consenting, 32 participants were recruited from the Orthodontic Clinic of the University of Colorado SODM. Pre-treatment plaque disclosure (for plaque maturity) using GC Tri-Plaque ID Gel^TM was completed and photographs taken for later grading. Using a split-mouth design, one quadrant per arch was randomly assigned to receive the experimental compound, K21, and the opposite side received placebo. Participants were brought back between 4 and 6 weeks later; disclosure and photographs were completed again. Photographs were scored (0=none, 1=immature, 2=non-cariogenic, and 3=cariogenic plaque) by two separate, calibrated examiners. Chi² was used to assess the significance in the frequency change in the plaque scores. A total of 1536 surfaces were graded by each examiner.
Results: There was no significant difference between the placebo and K21 groups at the initial time point in the plaque scores (p=0.8457), indicating that baseline distributions were not statistically different. Post-treatment, the K21 scores were significantly less than the placebo scores (p=0.0035). There was a reduction of scores from 3 (cariogenic) towards 0 (no plaque) in the placebo group confirming the importance of intra-treatment prophylaxis.
Conclusions: Our hypothesis is supported: the use of K21 resulted in a significant reduction in plaque maturity scores compared to placebo. Thus, a single application of K21 significantly reduces plaque index scores over a 4-to-6-week period.