Effect of temperature and storage time on dental bleaching effectiveness.

OBJECTIVE

To evaluate the effect of storage time and temperature on the effectiveness of bleaching agents.

METHODS

Enamel slabs were randomly allocated according to the concentration of carbamide peroxide (CP): 10% (CP10) and 16% (CP16). Shade evaluations were conducted at baseline and then after 3 and 12 months of storage at 3 different temperatures: 10°C (±2°C), 25°C (±2°C), and 35°C (±2°C). Objective color evaluation was performed (spectrophotometer CIELab* system and CIEDE2000) to calculate the color change (ΔE ). Subjective evaluation was performed using the VITA classical shade guide followed by shade variation (ΔS).

RESULTS

The bleaching effect of different CP concentrations (10% and 16%) at baseline showed no differences with regard to objective (ΔE ) and subjective parameters (ΔS) (P > .05). No differences were observed between CP concentrations stored for the same length of time and at the same temperature for either parameter (P > .05). In terms of objective measurement (ΔE ), a reduction in the bleaching effect was shown for both CP concentrations (10% and 16%) when stored for 12 months at 35°C, and compared with the baseline (P < .05). As regards the subjective parameters (ΔS), after 12 months, both CP concentrations (10% and 16%) stored at 35°C showed a decrease in bleaching capacity compared to baseline (P < .05). CP10 and CP16 stored at 10°C and 25°C did not suffer any loss in bleaching ability, even after 12 months (P > .05).

CONCLUSIONS

The storage of bleaching agents for long periods at high temperatures can reduce the bleaching effectiveness of CP at 10% and 16%.

CLINICAL SIGNIFICANCE

Clinicians must be made aware that they should store their bleaching products under proper temperature conditions and use them within an appropriate time frame; otherwise, the bleaching effect could be lost.