Candidiasis is a fungal infection of the oral mucosa most commonly caused by the opportunistic yeast Candida albicans, arising when the mouth’s natural microbial balance is disturbed. Often called oral thrush, it is one of the most prevalent oral infections encountered in dental practice and presents across a broad clinical spectrum.

Common Causes and Risk Factors

Candida species are commensal organisms found in the mouths of healthy individuals; infection emerges only when host defenses are compromised or the local oral environment shifts unfavorably. Key predisposing factors include:

• Xerostomia — reduced salivary flow removes a critical antifungal barrier, placing dry-mouth patients at significantly elevated risk
• Prolonged use of broad-spectrum antibiotics or inhaled corticosteroids, which disrupt the oral microbiome
• Ill-fitting or poorly maintained dentures, a pattern closely associated with denture stomatitis
• Systemic immunosuppression from HIV/AIDS, uncontrolled diabetes, or cancer chemotherapy
• Smoking and inadequate oral hygiene

Clinical Forms

Oral candidiasis is not a single entity but a family of related presentations, each with distinct features:

• Pseudomembranous candidiasis (thrush) — creamy white, curd-like plaques on the tongue, palate, or buccal mucosa that wipe away to reveal an erythematous base
• Erythematous (atrophic) candidiasis — smooth red patches most often affecting the hard palate or dorsal tongue, commonly seen beneath maxillary dentures
• Angular cheilitis — fissuring and erythema at the labial commissures, frequently co-occurring with intraoral infection
• Chronic hyperplastic candidiasis — adherent white plaques that do not wipe off and require biopsy to exclude epithelial dysplasia

Diagnosis and Management

Diagnosis is primarily clinical but can be confirmed through cytological smear, culture, or incisional biopsy when the presentation is atypical or fails to respond to initial therapy. Antifungal treatment — typically topical nystatin or systemic fluconazole for resistant or severe cases — is highly effective. Equally important is correcting the underlying predisposing factor: optimizing denture hygiene, managing xerostomia, or coordinating with the patient’s physician to modify systemic medications where feasible. Because oral candidiasis can be the presenting sign of undiagnosed diabetes or significant immunosuppression, a thorough medical history and timely referral are essential parts of complete dental care.