Swift E J, May K N, Wilder A D, Heymann H O, Bayne S C
Department of Operative Dentistry, School of Dentistry, University of North Carolina at Chapel Hill, USA.
J Esthet Dent. 1999;11(1):36-42. doi: 10.1111/j.1708-8240.1999.tb00374.x.
The purpose of this study was to evaluate the 2-year effectiveness of a carbamide peroxide at-home bleaching gel used to provide tooth lightening treatment.
Twenty-nine patients participated in the original study, during which they treated their maxillary teeth with a 10% carbamide peroxide gel nightly for 2 weeks. Shades were determined before and after treatment by comparison with a Vita shade guide. Twenty-four patients (a recall rate of 83%) were recalled for evaluation 2 years after the initial bleaching treatment. The shade of the maxillary incisors was evaluated and compared with shades before, immediately after, and at 6 months and 2 years after initial treatment. Data were analyzed using a repeated-measures analysis of variance.
At 2 years after bleaching with a 10% carbamide peroxide gel, the median shade was D2, a six-increment difference from the baseline median of D3. Twenty of 24 patients (83.3%) had a shade change of two or more units, which is the threshold value for bleaching efficacy using American Dental Association guidelines. The lightening result remained statistically significant (p < .0001) at 2 years.
Although some reversal of the lightening effect occurs over time following the original bleaching treatment, loss of the lighter color appears to be gradual for most patients. Although the longevity of the lightening effect remains to be determined, this clinical trial indicates that the majority of patients have a satisfactory result 2 years after treatment.
本研究旨在评估一种用于牙齿美白治疗的家用过氧化脲漂白凝胶的两年有效性。
29名患者参与了最初的研究，在此期间他们每晚用上颌牙齿使用10%的过氧化脲凝胶，持续2周。治疗前后通过与Vita比色板对比确定牙齿颜色。24名患者（召回率83%）在初始漂白治疗2年后被召回进行评估。评估上颌切牙的颜色，并与初始治疗前、治疗后即刻、6个月和2年后的颜色进行比较。数据采用重复测量方差分析进行分析。
用10%的过氧化脲凝胶漂白2年后，中位色为D2，与基线中位色D3相差6个色阶。24名患者中有20名（83.3%）的色阶变化为两个或更多单位，这是根据美国牙科协会指南确定的漂白效果阈值。两年时美白效果在统计学上仍具有显著性（p <.0001）。
尽管在最初的漂白治疗后，随着时间的推移美白效果会出现一定程度的逆转，但对于大多数患者来说，较浅颜色的消退似乎是逐渐的。虽然美白效果的持久性仍有待确定，但该临床试验表明，大多数患者在治疗2年后有满意的结果。
