Effect of whitening toothpastes with different hydrogen peroxide concentrations: Penetration into the pulp chamber and color change

OBJECTIVES

This study evaluated the efficacy of simulated brushing with toothpastes containing different concentrations of hydrogen peroxide (HP) in pulp chamber penetration and color change. Also, physical-chemical properties (concentration, pH and viscosity) were evaluated.

METHODS

Forty-nine premolars were divided into seven groups (n = 7): untreated (control); whitening gel (White Class 6 %, 6 %BG) with one 90  min application (6 %BG 90  min) and 14 applications of 90  min (6 %BG 14×90 min); toothpastes (Colgate Luminous White Glow 3 %, 3 %TP; Crest 3D White Brilliance 4 %, 4 %TP; Colgate Optic White Pro-Series 5 %, 5 %TP) and 6 %BG toothbrushing for 14 applications of 90 s. HP penetration into the pulp chamber was measured through UV-Vis spectrophotometry and color change with a spectrophotometer (ΔEab, ΔE00, and ΔWID). Initial concentration, pH, and viscosity were measured through Titration, Digital pH-meter, and Rheometer, respectively. Statistical analysis used one-way ANOVA and Tukey's test (α = 0.05).

RESULTS

6 %BG (14×90 min) and 4 %TP groups showed acidic pH and higher concentrations of HP in the pulp chamber compared to the other groups (p < 0.05). On the other side, 3 %TP and 5 %TP groups showed alkaline pH, higher viscosity between the toothpastes and lower HP penetration (p < 0.05). The 6 %BG AH (14×90 min) group exhibited the most significant color change (ΔEab, ΔE00, and ΔWID) (p < 0.05).

CONCLUSIONS

Brushing with whitening toothpaste with an acidic pH leads to greater HP penetration into pulp chamber; but, even when a high concentrated HP whitening toothpaste was used, a lower whitening effect was observed when compared to a two-week at-home bleaching.

CLINICAL SIGNIFICANCE

Whitening toothpastes containing up to 5 % HP produced lower whitening effect than two-week at-home bleaching. Additionally, HP was detected within the pulp chamber which can potentially impact in tooth sensitivity.

A double-blind randomized clinical trial of two carbamide peroxide tooth bleaching agents: 2-year follow-up

OBJECTIVES

This double-blind randomized clinical trial aimed to evaluate the whitening effect of two at-home tooth bleaching agents and the effect of dietary habits after 2 years. The patients' view about bleaching longevity was also investigated.

METHODS

Ninety-two subjects with mean shade of C1 or darker for the six maxillary anterior teeth were randomized into two groups (n=46) according to the carbamide peroxide (CP) concentration: 10% (CP10) or 16% (CP16). The treatment was performed using the whitening agent in a tray for 2h/day during 3 weeks. Shade evaluations were done with a shade guide and a spectrophotometer at baseline, 1-month, 6-month, 1-year and 2-year post-bleaching.

RESULTS

Eighty-one (88%) of the original 92 subjects enrolled in the study were recalled at 2-year follow-up and, the tooth shade remained significantly lighter than at baseline, in both treatment groups, considering the tooth shade median values (p<0.001) or the color parameters: L*a* (p<0.001) for CP10 and, L*b* for CP16 group (p<0.001). Subjects from CP10 and CP16 reported a consumption of beverage and food stains as high as at 6-month and 1-year recalls and, more than 66% of the participants from each group reported a tooth shade relapse from mild to moderate (p=0.6).

SIGNIFICANCE

At 2-year post-bleaching, tooth shade remained lighter than at baseline for both CP concentrations tested. Tooth shade relapse associated to increasing of a* and b* color parameters were observed for both groups when compared to the end of the treatment (CEP # 37/05).