Brief Answer:
Can be healing fever and fever due to infection

Detailed Answer:
Hello

Thanks for asking on this platform.I can understand your concern.
Fever following minor oral procedures can be due to the inflammation caused by minor injuries(release of chemical in response to injuries causing fever)or due to the infection acquired during/after the procedure.
During first few days it is very difficult to differentiate between these two.
If fever is mild,responds well to anti inflammatory medications and subsides within a day or two,it is more likely to be due to the inflammation.
In case fever of very high grade,non responsive to anti inflammatory medication,its persistence beyond 48 hours or any worsening in swelling or discharge from the gums,there is a high chance of infection.
Allergic reaction following braces are very rare but the possibility can not be ruled out.
I would like to continue the anti inflammatory medication like ibuprofen(it will take care of fever too) along with antiallergic like cetrizine.Monitor the temperature and if fever persists or condition worsens the braces may need to be removed and/or antibiotic treatment has to be started.
I suggest you to consult your dentist for clinical evaluation to rule out infection or any intra oral swelling and to discuss about the need of above mentioned medications.

I hope this helps.
Please let me know if you have any more doubts.
Wishing for your baby's good health.
Regards

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