1. Dental Caries (Tooth Decay)

Dental caries is a microbial infection leading to demineralization of tooth structures.

- Enamel Caries (Initial Caries): Early lesion confined to the enamel, detected via radiography or visual inspection (e.g., white spot lesions).

- Dentin Caries: Progression into dentin, causing sensitivity. Classified as moderate (outer dentin) or advanced (deep dentin, risking pulp involvement).

- Pulp Exposure: Penetration into the pulp chamber, requiring endodontic intervention.

2. Pulp and Periapical Diseases

Pulpitis

Inflammation of the dental pulp, often caused by caries, trauma, or cracks:

- Acute Pulpitis: Severe spontaneous pain, thermal sensitivity, and nocturnal exacerbation.

- Chronic Pulpitis: Persistent dull pain or long-standing sensitivity, may progress to pulp necrosis.

Pulp Necrosis

Non-vital pulp tissue due to untreated infection or trauma, leading to:

- Periapical Periodontitis: Infection spreading to periapical tissues:

- Acute Periapical Abscess: Localized purulent inflammation, severe biting pain, and swelling.

- Chronic Periapical Lesions: Granuloma, cyst, or fibrous scar formation (asymptomatic until advanced).

3. Periodontal Diseases

Inflammatory conditions affecting tooth-supporting tissues:

Gingivitis

Plaque-induced inflammation of gingiva:

- Marginal Gingivitis: Redness, edema, and bleeding on probing (non-destructive to alveolar bone).

- Aggressive Gingivitis: Localized (e.g., around molars/anterior teeth) or generalized, linked to poor oral hygiene.

Periodontitis

Progressive destruction of periodontal ligament and alveolar bone:

- Chronic Periodontitis: Most common form, with periodontal pocket formation (≥3mm), attachment loss, and mobility.

- Aggressive Periodontitis: Rapid bone loss, often in young patients, associated with Aggregatibacter actinomycetemcomitans.

4. Oral Mucosal Disorders

Ulcerative Lesions

- Aphthous Ulcers (Canker Sores): Painful, oval ulcers with yellow fibrin coating and red halo; minor (≤10mm), major, or herpetiform.

- Traumatic Ulcers: Caused by denture irritation, sharp teeth, or self-inflicted trauma (non-regular shape, site-specific).

Infectious Diseases

- Oral Candidiasis: Fungal infection (Candida spp.), presenting as pseudomembranous (removable white plaques), erythematous (red mucosa), or denture-related stomatitis.

- Herpetic Stomatitis: Vesicular lesions from HSV-1, common in primary infection (gingivostomatitis) or recurrent (labial/herpal lesions).

Pre-Malignant/Malignant Lesions

- Leukoplakia: White, non-scrapable plaque; 2–6% malignant potential (histology: hyperkeratosis, dysplasia).

- Erythroplakia: Red, velvety patch with higher malignant risk (often severe dysplasia/carcinoma in situ).

5. Odontogenic Tumors and Cysts

Benign Tumors

- Ameloblastoma: Locally invasive epithelial tumor (multilocular radiolucency, jaw expansion, tooth displacement).

- Odontoma: Hamartomatous growth of dental tissues:

- Compound Odontoma: Contains small, well-formed tooth-like structures (common in anterior maxilla).

- Complex Odontoma: Disorganized mass of enamel/dentin (posterior jaws).

Cysts

- Radicular Cyst: Most common periapical cyst, arising from necrotic pulp (associated with non-vital tooth).

- Dentigerous Cyst: Associated with impacted teeth, enveloping crown (radiolucency around crown).