Differential Diagnosis for Bump on Lower Gum

Single Most Likely Diagnosis

• Pericoronitis or residual inflammation: The patient had a wisdom tooth extraction a month ago, and the bump has been present since then. The pain on palpation and the location of the bump suggest that it could be related to the extraction site, possibly due to residual inflammation or a complication of the extraction process.

Other Likely Diagnoses

• Dental cyst or granuloma: These can form at the site of a extracted tooth, especially if the extraction was complicated or if there was incomplete healing.
• Irritation fibroma: A benign growth that can occur in response to chronic irritation, such as from a sharp tooth edge or a dental instrument.
• Mucosal abscess or localized infection: Although the dentist mentioned no signs of a dental abscess, a small, localized infection could still be present, causing the bump and pain.

Do Not Miss Diagnoses

• Osteomyelitis: A bone infection that can occur after a dental extraction, especially if there was significant trauma or contamination during the procedure. It's crucial to consider this diagnosis due to its potential severity and need for prompt treatment.
• Necrotic bone (osteonecrosis): This is a rare but serious condition where the bone tissue dies due to inadequate blood supply, which can be a complication of dental procedures.
• Malignancy (e.g., squamous cell carcinoma): Although extremely rare in an 18-year-old, any unexplained oral lesion or bump should be evaluated for the possibility of cancer to ensure early detection and treatment.

Rare Diagnoses

• Stafne bone cavity: A rare, benign condition where a cavity forms in the jawbone, which could potentially cause a bump on the gum.
• Giant cell granuloma: A rare, benign tumor that can occur in the jaw, potentially causing a bump or swelling on the gum.
• Eruption cyst: If the bump is associated with an unerupted tooth, it could be an eruption cyst, although this is less likely given the history of recent tooth extraction.

Starting antibiotics without a clear diagnosis of a bacterial infection might not be necessary. Further evaluation, possibly including imaging studies (like a panoramic radiograph) and a biopsy if the lesion persists or grows, would be more appropriate to determine the cause of the bump and guide treatment. Consultation with an oral surgeon or a specialist in oral pathology might also be beneficial for a definitive diagnosis and management plan.