Zheng Chun-yan, Pan Jie, Wang Zu-hua, Wang Yang
Department of Cariology and Endodontology, Peking University School and Hospital of Stomatology, Beijing 100081, China.
Department of General Dentistry, Peking University School and Hospital of Stomatology, Beijing 100081, China.
Beijing Da Xue Xue Bao Yi Xue Ban. 2014 Feb 18;46(1):30-4.
To evaluate the effects of a commercial bleaching agent containing 35% (mass fraction) hydrogen peroxide on the growth of Streptococcus mutans biofilm on enamel disc surface.
A total of 20 enamel disks were made from human extracted teeth and the enamel surfaces were kept intact. The discs were autocalved and randomly divided into two groups: bleaching group and control group. Each group contained 10 discs. For bleaching group, the enamel discs were whitened by commercial 35% hydrogen peroxide according to the instruction (Beyond(TM) Professional Dental Whitening Kit, Beyond Technology, TX,USA ); no treatment for control group. All the discs were kept in sterile human saliva for 3.5 hours, and then the mixture of brain heart infusion broth (BHI) medium and Streptococcus mutans were added. The discs and Streptococcus mutans were incubated together in BHI medium with 5% CO(2) (volume fraction), at 37 °C. After 3, 7, 14, 21 and 28 d's incubation, two discs of each group were taken out and the biofilms on the enamel surfaces were evaluated by using conventional bacteria counts and confocal laser scanning microscope (CLSM). The bacteria in the biofilm on one disc enamel surface were analyzed by plating on BHIS agar and the colony-forming units were counted. The biofilm on the other disc surface was stained using a two-colour fluorescent dye kit (Bacerial Viability Kit L-7012) for CLSM.
The vital bacteria counts of vital cells in the 3, 7, and 14 d's biofilms of the bleaching group were significantly fewer than those of the control group. Especially in the 3 days' biofilm on the whitened surface, the vital bacteria counts [(3 595 ± 2 903) μm(2) vs. (89 155 ± 65 963) μm(2),t = 8.71,P = 0.00] and proportion of vital bacteria [(26.0% ± 16.4%) vs.(92.2% ± 10.9%), t = 19.93, P = 0.00] were significantly fewer than those of the control. While, for the 21d's biofilm, the vital bacteria counts and the percentage of the vital cells of the bleaching group were more than those of the control group significantly [(66 262 ± 23 772) μm(2) vs. (51 184 ± 20 502) μm(2), t = 2.59, P = 0.012].
The hydrogen peroxide-containing bleaching agent may inhibit the growth of Streptococcus mutans biofilm for about 3 weeks; but after 3 weeks, it seems that the bleached surface will increase the growth of biofilm. Whether the whitening therapy will increase caries susceptibility of the bleached surface needs further research.
评估一种含35%（质量分数）过氧化氢的商用漂白剂对牙釉质盘表面变形链球菌生物膜生长的影响。
从人类拔除的牙齿上制作20个牙釉质盘，保持牙釉质表面完整。将这些盘进行高压灭菌并随机分为两组：漂白组和对照组。每组包含10个盘。对于漂白组，按照说明书（Beyond(TM) Professional Dental Whitening Kit，Beyond Technology，TX，美国）用商用35%过氧化氢使牙釉质盘增白；对照组不做处理。所有盘在无菌人唾液中保存3.5小时，然后加入脑心浸液肉汤（BHI）培养基和变形链球菌的混合物。将盘和变形链球菌在含5% CO₂（体积分数）的BHI培养基中于37℃共同培养。培养3、7、14、21和28天后，每组取出两个盘，通过常规细菌计数和共聚焦激光扫描显微镜（CLSM）评估牙釉质表面的生物膜。在一个盘牙釉质表面生物膜中的细菌通过接种到BHIS琼脂平板上进行分析并计数菌落形成单位。另一个盘表面的生物膜用双色荧光染料试剂盒（Bacerial Viability Kit L - 7012）染色用于CLSM。
漂白组3、7和14天生物膜中活细菌数量显著少于对照组。特别是在增白表面3天的生物膜中，活细菌数量[（3595±2903）μm²对（89155±65963）μm²，t = 8.71，P = 0.00]和活细菌比例[（26.0%±16.4%）对（92.2%±10.9%），t = 19.93，P = 0.00]显著少于对照组。而对于21天的生物膜，漂白组的活细菌数量和活细胞百分比显著多于对照组[（66262±23772）μm²对（51184±20502）μm²，t = 2.59，P = 0.012]。
含过氧化氢的漂白剂可能在约3周内抑制变形链球菌生物膜的生长；但3周后，似乎增白表面会促进生物膜的生长。增白治疗是否会增加增白表面的龋齿易感性需要进一步研究。
