What is the situation when the child grinds his teeth sometimes when he doesn't sleep during the day?

Patient's question:

Patient Age: Nine and a half months
Detailed Condition and Purpose of Consultation: My child is nine and a half months old. She has two teeth growing below and four teeth growing above. Currently, during the day (when she is awake), she sometimes grinds her teeth, making loud noises like "bang, bang." I initially thought it might be due to a deficiency and took her to the hospital for some tests. The results showed that her levels of toxic substances like lead and mercury were not elevated, and she was not deficient in trace elements or nutrients such as calcium. I would like to ask, what could be the reason for this, and how should we proceed?
Auxiliary Examinations: Levels of toxic substances like lead and mercury were not elevated, and she was not deficient in trace elements or nutrients such as calcium.

Doctor's answer:

Bruxism is caused by the repeated contraction of the jaw muscles, resulting in the clattering of upper and lower teeth. The contraction of the jaw muscles is controlled by the trigeminal nerve. When the trigeminal nerve is excited, it leads to the contraction of the jaw muscles, resulting in the occurrence of bruxism.