By nature our mouth, jaw and our body has developed together over a million of years. All our body parts are designed to operate together at peak efficiency. When we lose any of our tooth, the efficiency decreases and function suffers at the missing or lost tooth space side.
When we lose a tooth, we lose some ability to chew food properly from the affected side. This may mean that you either place more stress on the other teeth in order to chew all the food you eat, or you do not chew well enough and what is swallowed is not quite ready to be digested. This can lead to digestive difficulty. You might have to eliminate certain favorite foods because you cannot chew them thoroughly.
For each missing tooth, you lose approximately 10 to 15 % of your remaining ability to chew food.
Other problems also occur. The teeth adjacent to the space left by the missing tooth will eventually shift. If for example, a lower tooth is extracted, the opposing tooth in the upper jaw will grow slowly (or sometimes quickly) longer in a downward direction into the missing tooth space. This is called extrusion or super-eruption. Here is an example: