Can polyneuropathy cause your face to become numb (including your teeth) on one side?

Perhaps: By definition, polyneuropathy is symmetrical -- meaning that you should expect it to be on both sides. However, unilateral neuropathy is possible and could affect the trigeminal nerve which can affect the face and teeth, particularly if it targets the main nerve tract before it splits into 3 branches. This is trigeminal neuralgia. See your Neurologist for evaluation and tx options. Good Luck.

Definitions: Polyneuropathy by definition is symmetrical and bilateral. A mononeuropathy affecting a branch of the trigeminal nerve could be causing your facial problem, and advise you seek a dentist to evaluate, and if appropriate, a neurologist to proceed further.