I live in ROI (Republic of Ireland) and h2o2 like many other seemingly harmless herbs or medicines available in the US or UK are completely unavailable here. My teeth really became yellow over the years as a result of high carb consumption as well as a poor hygiene during a period of depression in my teens and although I've improved, my self esteem is still quite low from my teeth.
So far I can only find those "effective tooth whiteners" in Boots, McCabes etc.. which are overpriced and don't state the concentration of hydrogen peroxide that make me think they might be advertising gimmicks.
I know the discouragement you read online as well as from dentists about using any kind of teeth bleaching products yourself but here its so freaking expensive to get it done as well as the fact that I'm saving for something else.
I know one male friend in the US who bought a high concentration shipped from eBay and simply dapped his toothbrush in it for two weeks. It worked but his gums and teeth are now sensitive so he has to avoid any mildly acidic foods or anything too hot or cold.
Any suggestions? I definitely think Irish customs will stop me from buying it on eBay even from England. Would I have a better chance if I went up to N.I?