近幾年來，許多關於10% carbamide peroxide漂白藥劑對於牙釉質影響的實驗持續進行著，研究結果顯示出漂白藥劑的確會造成牙釉質表面型態不同程度的改變以及表面孔洞的增加。另一方面，漂白治療中可能引起的牙齒敏感現象也一直備受注目。一項研究顯示當10% carbamide peroxide漂白藥劑添加硝酸鉀與氟化物後，可降低牙齒敏感的發生且所能達到的漂白的效應並未減少。本實驗目的即主要為評估當硝酸鉀與氟離子添加至10% carbamide peroxide漂白藥劑所引發的效應。評估的項目包括了牙釉質表面型態與機械性質的改變。
　　本實驗共採用75顆牛牙，在每顆牛牙切緣三分之一的牙釉質處以先行打洞的膠帶將切緣端平均分配出三個等面積的圓形區域，並分別隨機選擇塗上選用的藥劑或不塗以任何藥劑 (作為控制組)並依照藥劑作用時間之不同分為三大組；實驗選用藥劑分別如下：1. 10% carbamide peroxide漂白劑，2. 3% (wt/vol)硝酸鉀與0.11% (wt/vol)氟離子的10% carbamide peroxide漂白劑。在經過56小時、112小時與168小時藥劑作用時間處理完畢後，取每一大組的10顆牙齒以掃瞄式電子顯微鏡來觀察，每一大組中的其餘15顆牙齒則是以原子力學顯微鏡從3D立體方向偵測牙釉質結構的改變並將所得之表面平均粗糙度做一統計分析；此15顆牙於原子力學顯微鏡後繼之以微硬度之測試。
　　在10% carbamide peroxide漂白藥劑中添加入硝酸鉀與氟離子，由掃描式電子顯微鏡與原子力學顯微鏡兩項儀器來評估，與單純的10% carbamide peroxide漂白藥劑作用相較，可觀察到的蝕刻效應較為輕微但平均表面粗糙度卻相對較高；而至於微硬度測試方面，則無任何具有統計意義之差異。

　　Numerous studies evaluated the effects of carbamide peroxide-containing bleaching agents on tooth hard tissues and showed significant changes of the enamel including increased porosity, non-uniform changes and the morphological alteration of the surface enamel. Also, tooth sensitivity is a common side effect of tooth bleaching. A study has demonstrated that the addition of potassium nitrate and fluoride produced less tooth sensitivity and resulted in no significant difference in the degree of perceived whitening. The aim of this study is to assess the effects of potassium nitrate and fluoride when they were incorporated in a 10% carbamide peroxide bleaching gel for whitening. Changes in superficial morphology and mechanical properties of the enamel will be evaluated in this study.
　　Seventy-five bovine teeth are used and their incisal-third enamel surfaces are divided into three round areas with preformed tape. Every round area is randomly treated in one of the following ways: untreated (employed as the media for comparison), treated with 10% carbamide peroxide gel or 10% carbamide peroxide gel containing 3% (wt/vol) potassium nitrate and 0.11 (wt/vol) fluoride. The bleaching period are 56 hours, 112 hours and 168 hours. Ten teeth in various time-period groups will be inspected with scanning electron microscope (SEM) and fifteen teeth of each group will be assessed using an atomic force microscope (AFM).
　　Microhardness test was following AFM evaluation with the same specimens. All the data of average surface roughness from AFM evaluation and microhardness test were analyzed statistically.
The addition of 3% (wt/vol) potassium nitrate and 0.11% (wt/vol) fluoride into 10% carbamide peroxide bleaching causes enamel surface less erosion effect with SEM evaluation, but more value of average surface roughness under AFM analysis when compared with 10% carbamide peroxide bleaching after 56-hours, 112-hours and 168-hours period. As for as microhardness test, there is not any statistically significant differences among unbleached and bleached enamel.

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