White spots are normal, ive used them for six days and have not had a problem and results are wonderful! You shouldn't brush your teeth at least 10 minutes before use as well as right after. Sometimes id put them in for about 60 minutes and theyve worked fine. Before i put them in i use my fingers to rub the excess gel out as well as all over the tray so it is evenly distributed. Also, after you put them in you can use a tissue or something to wipe around the gum area. I also use to wear braces and so i have a clear retainer and i would put the gel into the retainer and it would work ten times better, which might have been a disadvantage since my top teeth are now a little whiter than my bottom!!! Never had any problems with gums, no white spots on gums, no pain, etc.