What causes cavities on tooth and what's the solution. i regularly clean my teeth but still facing cavities problem .what could be future protection.

Several factors: Cavities are caused by bacteria that produce acids and this will decay the tooth. Diet low in sugar and acid is important to decrease the growth of cariogenic bacteria. Brushing at least twice a day and flossing once a day will remove the plaque that feed the bacteria. Fluoride will strengthen teeth. Some medication cause dry mouth which will increase cavities. Xylitol also fights decay.

Infection: Decay is an infection. By "cleaning" do you mean you brush? Proper daily flossing is necessary also. Use a Fluoride toothpaste and have Fluoride treatments at the dentists. Avoid between meal snacks with sugar in them. Avoid carbonated soft drinks and non-carbonated drinks with sugar in them between meals.

Other factors, maybe: Assuming you have great home care, you need a diet low in sugars, many of which are also abundant in unprocessed foods. Gerd or acid reflux could also contribute to the problem. You may have to go through some dental sleuthing once the usual suspects have been eliminated to really understand what is going on.

Bacteria + sugar: Cavities occur when bacteria turn sugars into acids, etching holes in the teeth. Talk to your dentist about diet, oral hygiene, fluorides, and so much more. You need exam to find out why and then what can be done to help. Lots of solutions available.