Effects of the initial stage of active fixed orthodontic treatment and sex on dental plaque accumulation: A preliminary prospective cohort study

Objectives: The aim of this pilot study was to assess the effect of orthodontic treatment and gender on plaque index.

Materials and methods: In this prospective cohort study, the O’Leary plaque index of 25 orthodontic patients was clinically examined before the beginning of treatment (as control) and after the leveling stage (as treatment group). The role of treatment and gender was assessed using two-way repeated-measure ANOVA, paired and independent-sample t-tests, and Pearson correlation coefficient (α = 0.05, β ⩽ 0.1).

Results: ANOVA showed a significant increase in plaque index after treatment (P = 0.000), but without any difference between the genders (P = 0.997) or any interaction between the variables gender and treatment (P = 0.796). There were significant post-treatment increases in plaque index in males (paired t-test’s P = 0.018) and females (P = 0.000). The plaque indices were not different between males and females, either before leveling (independent-sample t-test’s P = 0.785) or after it (P = 0.880). There were no correlations between patients’ gender and either of pre- or post-treatment PI levels (both r statistics < 0.06, both P values > 0.83). However, the correlation between pre- and post-treatment plaque indices was significant (r = 0.623, P = 0.001).

Conclusion: Initial stage of active fixed orthodontic treatment can cause considerable dental plaque accumulation, similarly in men and women.