OBJECTIVETo evaluate the clinical efficacy of a combined in-office cold light bleaching and night-guard vital bleaching (NGVB) system for treating tetracycline stained teeth (TST).

METHODS90 patients with light, medium and heavy TST were randomly and evenly divided into 3 groups. 30 patients with 472 TST from the treatment group were treated with in-office cold light bleaching and NGVB, 30 patients with 466 TST from the control group 1 were treated with in-office cold light bleaching and 30 patients with 469 TST from control group 2 were treated with NGVB. At the time of treatment completion, after half a year and after one year, Vitalescence esthetic restorative masters shade guide was used to record the change of color. Bleaching efficacy and course of treatment were calculated, and lightening stability were evaluated.

RESULTS1) Three groups had satisfied lightening efficacy for light TST with 100% bleaching efficacy. The overall efficacy of treatment group and control group 2 were superior to the in-office cold light bleaching system (P < 0.05). Though there was no significant lightening efficacy difference between the treatment group and control group 2 (P > 0.05), the periods of treatment of the treatment group for light, medium and heavy TST were shortened by 43%, 46% and 49%, respectively, compared to the control group 2. 2) All three groups' treatment efficacy for light, medium and heavy TST became weaker progressively (P < 0.05). 3) For the treatment efficacy between the time of treatment completion and after half a year and one year, there was significant statistical difference (P < 0.01) for the control group 1, while there was no significant difference for both the treatment group and the control group 2 (P > 0.05). Both treatment group and control group 2 had better performance in treatment stability than control group 1.

CONCLUSIONIn treating the light and medium tetracycline stained teeth, the combined in-office cold light bleaching and NGVB system can achieve a more satisfied whitening result in much shorter period, and significantly enhance the long term whitening stability.