Effect of Arginine and nano-hydroxyapatite application on the hypersensitivity and color change of bleached enamel: A randomized controlled clinical trial

BACKGROUND: To evaluate the effect of 2.5% Arginine and nano-hydroxyapatite (nHA) application on the post-bleaching hypersensitivity (HS) and color change in a randomized controlled trial. MATERIAL AND METHODS: Sixty-four participants were randomly allocated to four groups (n=16) according to the investigated desensitizing agents (UltraEZ gel, experimental 2.5% Arginine, 2.5% nHA pastes and control (no treatment) groups). An in-office chemical bleaching agent (40% hydrogen peroxide) was used for vital bleaching of the anterior teeth. The desensitizing agents were applied to the assigned groups and left for 30 min then rinsed off the teeth. HS was evaluated using Visual Analogue Scale (VAS) from 0-10, immediate (after bleaching), first seven days, then every week for 3-w. Color change was evaluated using VITAPAN classical A1-D4 at baseline (before bleaching), immediate (after bleaching), and after 1,2, 3-w. RESULTS: HS results showed statistically insignificant difference between the tested groups at day-1 and -2. All groups showed no HS (0) at/and after day-3. There was a statistically significant color change between immediate, 1-w and 2-w and baseline results for investigated materials. No statistically significant difference was recorded between the baseline and 3-w for the investigated materials. Both Arginine and nHA groups showed a higher color change compared to UltraEZ group. CONCLUSIONS: Arginine and nHA present a potential treatment modality for the post-bleaching HS without jeopardizing the bleaching efficiency. Key words:Arginine, nano-hydroxyapatite, bleached enamel, hypersensitivity, color change, clinical trial.