What is the most likely diagnosis for a child with facial pressure and upper molar tooth pain?

The most likely diagnosis for a child presenting with facial pressure and upper molar tooth pain is acute sinusitis. This condition often arises following a viral upper respiratory infection and can lead to inflammation and swelling of the sinuses. The maxillary sinus, located near the upper molars, can become involved, leading to referred pain in the teeth that can feel like dental pain despite there being no dental issue present.

In acute sinusitis, the child may also experience symptoms such as nasal congestion, purulent nasal discharge, fever, and sometimes cough, reinforcing the diagnosis. The combination of facial pressure and referred tooth pain is commonly associated with the involvement of the maxillary sinus due to its anatomical proximity to the upper molars.

Other options, while relevant in a broader context of upper respiratory issues, are less likely given the specific symptoms. For instance, an acute dental abscess would typically present with localized swelling, severe pain at the site, and possibly systemic symptoms like fever, but it would not usually cause significant facial pressure across the region. Chronic sinusitis generally leads to a more prolonged symptom pattern, while severe allergic rhinitis might cause nasal congestion and itching but usually wouldn’t result in significant facial pressure or tooth pain.