God has been extremely kind to us by giving two sets of teeth, namely - milk and permanent. Each set has its own importance and functions. To take it further, each tooth is uniquely designed so as to be most efficient while mastication.
There are 32 permanent teeth. So, we take them for granted and many a times do not bother to replace missing teeth. These leads to uneven wearing of teeth. As shown in image, it also produces unwanted movement of opposing tooth leading to disturbance with the neighboring teeth. This produces tooth decay and gum problems.
For longevity and good dental health, we should always replace missing teeth. This can be done either by Implants or fixed tooth colored bridge.