Hi Dear, Welcome to Health Care Magic Team. Understanding your concern about health. As you describe in your query the white bump on your gum is pointing towards a condition called canker sore or aphthous ulcer .canker sore can occur due ti several reasons like minor injury due to vigorous brushing and braces , sensitivity from the food having high acidic content and certain detergent ingredients of tooth paste like ,infection,stress ,deficiency of vitamin b12 and folic acid . It could be also because of gum disease like gingivitis in thicase your dentist can remove plaque from your teeth and prescribe you some antibiotics. Usually canker sores go away by there own in few days .If the persist ,I would suggest you to avoid irritants and allergens like food and toothpaste containing sodium laurly sulfate , add vitamin supplements to your diet ,maintain oral hygiene as you already doing, avoid smoking if you have smoking habit , Do not break or squeeze sore on gum this can make it further complicated . If the white bump persists for a week consult dentist who can prescribe you some oral or topical antibiotics and anti inflammatory. Hope your concern has bern resolved. Get Well Soon. Best Wishes, Dr. Harry Maheshwari