**Core Concept:** Chronic maxillary sinusitis is a condition characterized by inflammation of the maxillary sinus lasting for more than 12 weeks. The treatment options include both medical and surgical management.

**Why the Correct Answer is Right:** The correct answer is **C:** Endoscopic sinus surgery (ESS), also known as functional endoscopic sinus surgery (FESS), is the most effective surgical treatment for chronic maxillary sinusitis.

During ESS, the surgeon uses an endoscope to visualize the sinus cavities and remove the obstructing tissue, polyps, or bone, thereby restoring the normal sinus drainage pathways. This procedure helps to relieve the symptoms and improve the quality of life of patients suffering from chronic maxillary sinusitis.

**Why Each Wrong Option is Incorrect:**

A. **Medical management alone (Option A)**: While medical treatment, including antibiotics, steroids, and mucolytics, can provide symptomatic relief, it does not address the structural abnormalities that lead to sinus obstruction and recurring inflammation. As a result, the condition remains untreated, leading to poor outcomes.

B. **Only Antibiotics (Option B)**: Antibiotics are essential in treating acute sinusitis but are insufficient for chronic sinusitis. Chronic inflammation involves both bacterial and non-bacterial components, making antibiotics insufficient as a sole treatment modality.

D. **Medical management followed by Endoscopic sinus surgery (Option D)**: Medical management improves the overall condition but may not always result in full resolution of symptoms, especially in cases of severe or refractory chronic sinusitis. ESS is necessary to address the structural abnormalities and restore sinus drainage pathways.

Essential clinical pearl: In cases of chronic maxillary sinusitis, addressing both the medical and surgical aspects of treatment (Option C) provides the best overall outcome, improving symptoms, and preventing recurrences.