The time is important which we give to the bacteria to organise their lines and launch the attack. The composition of the plaque which causes the inflammation of the gums differs from the composition of the material which causes caries. Probably that is why we can see that some people are more likely to have caries, while others tend to have tooth bed illnesses more often, which depends mostly from the composition of the oral flora (all the microorganisms in the mouth).
The composition of the plaque piled up near the gums slowly changes till it will predominantly contain bacteria that are able to cause gingivitis. The tooth bed -first the gums- reacts with an inflammation to the bacterial infection, the first consequence of which is that the gums will be swollen and sensitive, and they will be likely to bleed. The natural direct contact between the gums and the teeth will end, and the sensitive crown part of the teeth will loose its isolation.
Thus the tooth will be sensitive for cold and warm things, sweet or salty meals, tooth-cleaning, etc., and this will lead us to neglect tooth-cleaning more often. It is a shame because the thorough cleaning applied during tooth-cleaning can cease the inflammation within 2-3 days. In this case we suggest you to use a soft tooth brush because it does not irritate the teeth and the gums so much. The cleaning effect of a soft tooth brush is shorter so the cleaning time must be increased.