Denture Creams such as Super Poligrip, Fixodent and Others, May be Associated With Numbness, Tingling, Muscle Weakness and Other Neurological Issues.
Sometimes nerve damage suffered from Zinc poisoning is permanent.
So you should relate his problems and symptoms
If he using a cane is for old age and as a support and he did not develop any symptoms what i mentioned in the first lines then there is less likelihood that they are connected.
So visit a neurologist and consult to come to a conclusion,
Take care!