A 180-day clinical investigation of the tooth whitening efficacy of a bleaching gel with added amorphous calcium phosphate.

Objective: The purpose of this study was to determine if there are any significant long-term clinical benefits, or side effects, caused by the addition of amorphous calcium phosphate (ACP) to a professional, 16% peroxide bleaching gel.

Methodology: This study examined the effect of bleaching gel with added ACP in a subset of subjects (n=27) from a previously published, short-term (n=50) study, in which two groups were assigned to use either an experimental ACP-containing gel or a similar "control" gel. Both groups used the product for four hours (or overnight) daily for 14 days. In the present study, the long-term ACP effects on tooth color, gingival health, and three measures of dentinal hypersensitivity at post-treatment days +90 and +180 were assessed.

Results: In the previously published study, at day +five, the difference in tooth whitening efficacy (relative to baseline) between the test group and the control group was only 0.19 shades and was not statistically significant. In the present study, at day +90, the differences between the groups had almost doubled, and were calculated to be 0.34 shades (statistically different; t-test p = 0.002). Furthermore, at day +180, the differences had more than doubled again, with the ACP group subjects' teeth being 0.78 shades lighter than the control group's teeth (statistically different; t-test p = 0.002). Considered as a percentage, at day +180 the ACP group had retained nearly 10% more of their original whitening treatment result compared to control. There were no other significant differences found between the two groups. Tooth sensitivity, soft tissue health, and gingival health remained similar to baseline levels.

Conclusions: This study demonstrated that the ACP product offers 10% better long-term (6-months) whitening efficacy than the traditional bleaching gel tested. The long-term safety of the product has also been demonstrated, as there were no adverse gingival or other effects seen at either day +90 or day +180.