Oral Disease and Pathology

Oral Disease and Pathology

A critical role of the dental team is diagnosing and managing oral diseases. Recognizing the signs, symptoms, and etiology of common oral conditions allows for timely intervention and improved patient outcomes.

Dental Caries

Dental Caries (tooth decay) is an infectious, transmissible bacterial disease resulting in the localized destruction of tooth hard tissues. The disease process is driven by the interaction between cariogenic bacteria, fermentable carbohydrates, and a susceptible tooth surface over time.

When Non-Milk Extrinsic Sugars are consumed, cariogenic bacteria (such as Streptococcus mutans and Lactobacillus) in the dental plaque metabolize these sugars, producing organic acids (primarily lactic acid). This rapid drop in plaque pH triggers the Stephan Curve effect, where the pH falls below the critical level of 5.5, leading to the Demineralization of tooth enamel.

If the frequency of sugar intake is low, saliva can buffer these acids and facilitate Remineralization by depositing calcium, phosphate, and fluoride back into the enamel. However, if the frequency of sugar attacks is high, demineralization outpaces remineralization, leading to a carious lesion or 'cavity'.

Periodontal Disease

Periodontal diseases encompass a range of inflammatory conditions affecting the supporting structures of the teeth (the periodontium). They are primarily initiated by the accumulation of dental plaque biofilm at and below the gingival margin.

• Gingivitis: An early, reversible stage of periodontal disease. It is characterized by inflammation of the gingiva (gums) without the loss of bone or connective tissue attachment. Clinical signs include redness, swelling, and bleeding upon probing or brushing. If plaque is effectively removed through improved oral hygiene, the gingiva can return to a completely healthy state.
• Periodontitis: If gingivitis is left untreated in susceptible individuals, it can progress to periodontitis. This is an irreversible, chronic inflammatory disease that destroys the periodontal ligament and alveolar bone supporting the teeth. It is characterized by the formation of deep periodontal pockets, gingival recession, tooth mobility, and eventually, tooth loss. Smoking and poorly controlled diabetes are major risk factors for periodontitis.

The etiology of periodontal disease is deeply connected to the shift in the oral microbiome. While gingivitis is often associated with non-specific plaque accumulation, the progression to periodontitis involves a shift towards highly virulent, anaerobic, Gram-negative bacteria, such as Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia (the 'red complex' bacteria). These pathogens release destructive toxins and enzymes that not only directly damage the tissues but also provoke a hyper-inflammatory host immune response. This host response is responsible for the majority of the tissue destruction.

Tooth Wear (Non-Carious Cervical Lesions)

Tooth surface loss can occur independently of dental caries and is categorized into several types:

• Erosion: The chemical dissolution of tooth structure by non-bacterial acids. This can be extrinsic (dietary acids from carbonated drinks, citrus fruits) or intrinsic (gastric acid from conditions like gastroesophageal reflux disease (GERD) or bulimia). It typically leaves a smooth, cupped-out, glossy appearance on the tooth surface.
• Attrition: The physiological mechanical wear of teeth against each other. This is often associated with bruxism (grinding and clenching of teeth) and presents as flattened incisal or occlusal surfaces matching the opposing teeth.
• Abrasion: The mechanical wear of tooth structure caused by external objects, most commonly from over-vigorous or incorrect toothbrushing using an abrasive toothpaste. It typically presents as a V-shaped or U-shaped notch at the cervical margin (gumline) of the tooth.
• Abfraction: The loss of tooth structure at the cervical margin caused by biomechanical loading forces (flexure) during heavy biting or grinding, leading to microfractures in the enamel.

Oral Cancer

Oral Squamous Cell Carcinoma (OSCC) accounts for over 90% of oral malignancies. Early detection is paramount for a favorable prognosis, making regular oral cancer screenings a vital part of every routine dental examination. The primary risk factors are tobacco use (smoking and smokeless tobacco) and heavy alcohol consumption, which act synergistically. The Human Papillomavirus (HPV), particularly HPV-16, is increasingly implicated in oropharyngeal cancers.

During a routine dental examination, the clinician performs a comprehensive extra-oral and intra-oral soft tissue assessment. Extra-orally, this involves palpating the major lymph node chains of the head and neck to check for lymphadenopathy, which can indicate infection or malignancy. Intra-orally, the clinician visually inspects and palpates the tongue, floor of the mouth, buccal mucosa, and palate. The lateral borders of the tongue and the floor of the mouth are high-risk sites.

Key signs and symptoms to look out for include:

• A persistent ulcer that fails to heal within 2-3 weeks.
• Unexplained red patches (Erythroplakia) or white patches (Leukoplakia) on the oral mucosa.
• An unexplained lump, thickening, or induration in the mouth, lips, or neck.
• Unexplained tooth mobility not associated with periodontal disease.
• Difficulty or pain when swallowing (dysphagia).

Oral Candidiasis

Oral Candidiasis, commonly known as oral thrush, is an opportunistic fungal infection caused predominantly by Candida albicans. While Candida is a normal commensal organism in the mouth, it can overgrow and cause infection when the host's local or systemic defenses are compromised.

Predisposing factors include the use of broad-spectrum antibiotics, inhaled corticosteroids (often used for asthma), poorly fitting or inadequately cleaned dentures, dry mouth (xerostomia), and systemic conditions such as diabetes or immunosuppression (e.g., HIV/AIDS). It commonly presents as white, wipeable plaques on a red, erythematous base, often accompanied by a burning sensation.