Bonding is a cosmetic procedure that is more often carried out on the upper teeth, but it can also be done on the lower teeth. The difference between the two lies in how the material is built up and how much of the tooth surface is covered.
On the upper teeth, it is often enough to restore just the biting edge, without covering the whole surface of the tooth.
On the lower teeth, however, it is advisable to add material over a larger part of the tooth to ensure a stronger bond. This is due to the anatomical difference between the two jaws:
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The upper jaw is fixed, and its front teeth mainly hold the food when you bite.
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The lower jaw moves, and its front teeth do the main work of cutting through the food.
Because the lower teeth take more load during chewing and biting, the build-up on them needs to be more stable and durable than on the upper teeth.
This answer is for general information. Your own case needs an examination by an orthodontist.