*Carlos Rocha Gomes Torres, DDS, PhD, associate professor, Department of Restorative Dentistry, Institute of Science and Technology, Sao Paulo State University - UNESP, Sao Jose dos Campos, SP, Brazil.
Sabrina Elise Moecke, DDS, MS, Department of Restorative Dentistry, Institute of Science and Technology, Sao Paulo State University - UNESP, Sao Jose dos Campos, SP, Brazil.
Oper Dent. 2022 May 1;47(3):E119-E130. doi: 10.2341/20-309-L.
This study investigated the influence of the viscosity and kind of thickener of 35% hydrogen peroxide bleaching gels on the tooth (color change, demineralization of enamel, and permeation) and on the gel [reactive oxygen species (ROS), pH, and peroxide concentration].
Two hundred forty specimens were divided into groups of bleaching gels with different thickeners (CAR, carbomer; ASE, alkali swellable emulsion; MSA, modified sulfonic acid polymer; SSP, semisynthetic polysaccharide; PAC, particulate colloids) in three viscosities (low: 50,000 cP; medium: 250,000 cP; high: 1,000,000 cP). Color change (ΔEab), demineralization of enamel by Knoop microhardness (KHN) reduction analysis, and peroxide permeation (PP) were analyzed in the specimens, while pH, peroxide concentration (PC), and ROS were evaluated in the gels. Data were analyzed by two-way ANOVA (α=0.05).
The higher viscosity gels reduced ΔEab, PP, enamel softening, and ROS in relation to the lower viscosity gels. However, the drop in pH and PC were higher in the more viscous gels. Gels with MSA produced higher ΔEab compared with SSP and ASE. The PP was higher for PAC, and smaller for SSP and CAR. The KHN reduction was higher for CAR and smaller for PAC. The higher pH reduction was seen for ASE and CAR, and the smaller for SSP. The PC reduction was higher for SSP and smaller for CAR. More ROS were observed for MSA and fewer for ASE.
Increased gel viscosity was associated with reduced color change, permeation, demineralization of enamel, and ROS, and led to increased peroxide decomposition and pH alteration during the treatment. The kind of thickener significantly interfered with the treatment effects.
本研究调查了 35%过氧化氢漂白凝胶的粘度和稠度剂种类对牙齿（颜色变化、釉质脱矿和渗透）以及凝胶[活性氧（ROS）、pH 值和过氧化物浓度]的影响。
将 240 个样本分为三组，分别使用不同稠度剂（CAR，Carbomer；ASE，碱膨胀乳液；MSA，改性磺酸聚合物；SSP，半合成多糖；PAC，颗粒胶体）的漂白凝胶，三种粘度（低：50,000 cP；中：250,000 cP；高：1,000,000 cP）。分析样本的颜色变化（ΔEab）、釉质脱矿的 Knoop 显微硬度（KHN）降低分析和过氧化物渗透（PP），同时分析凝胶的 pH 值、过氧化物浓度（PC）和 ROS。数据采用双因素方差分析（α=0.05）进行分析。
高粘度凝胶降低了与低粘度凝胶相比的ΔEab、PP、釉质软化和 ROS。然而，高粘度凝胶的 pH 值和 PC 下降幅度更大。MSA 产生的 ΔEab 高于 SSP 和 ASE。PAC 的 PP 较高，SSP 和 CAR 的 PP 较低。CAR 的 KHN 降低较高，PAC 的 KHN 降低较小。ASE 和 CAR 的 pH 值降低较大，SSP 的 pH 值降低较小。SSP 的 PC 降低较高，CAR 的 PC 降低较小。MSA 的 ROS 较多，ASE 的 ROS 较少。
凝胶粘度的增加与颜色变化、渗透、釉质脱矿和 ROS 的减少有关，并导致治疗过程中过氧化物分解和 pH 值变化增加。稠度剂的种类对治疗效果有显著影响。
