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PRC Dentist Licensure study materials
PRC Dentist Licensure study resources

PRC Dentist Licensure: Oral and Maxillofacial Internal Medicine: Endodontics, Periodontics, Oral Mucosal Diseases

PRC Dentist Licensure · Work through your exam, one topic at a time.

All guide sections

Oral and Maxillofacial Internal Medicine: Endodontics, Periodontics, Oral Mucosal Diseases

This domain bundles endodontics, periodontics and oral mucosal disease - the diagnostic core of the exam, where one lesion may be benign, premalignant or infectious.

Endodontics

  • Working length sits 0.5–1.0 mm short of the radiographic apex; apex locators are unreliable with pus or blood in the canal.
  • Sodium hypochlorite 0.5–5.25% dissolves organic tissue and is antimicrobial; 17% EDTA removes the smear layer; chlorhexidine is a final rinse but must never be mixed with hypochlorite (brown precipitate).
  • Hypochlorite extrusion causes sudden pain, swelling and possible airway compromise - stop, irrigate with saline, monitor.
  • Single- versus multiple-visit treatment depends on infection status, not convenience.

Periodontics

Probing depth is not attachment loss: CAL = PD + recession. The 2018 classification stages severity (I–IV) and grades progression (A–C). Scaling and root planing is the foundation; adjunctive systemic antibiotics are reserved for specific aggressive or necrotising cases.

Mucosal disease

  • Leukoplakia is a diagnosis of exclusion with roughly 1% malignant transformation; biopsy is mandatory.
  • Oral lichen planus shows bilateral Wickham striae, typically on buccal mucosa; erosive forms need biopsy and follow-up.
  • Pemphigus vulgaris: suprabasal intraepithelial split with intercellular IgG. Mucous membrane pemphigoid: subepithelial split with linear IgG/C3 at the basement membrane.
  • Pseudomembranous candidiasis wipes off leaving erythema; denture stomatitis and angular cheilitis are common variants.

Worked example

A 50-year-old smoker has a painless 2 cm red-and-white, non-homogeneous lesion on the lateral tongue present for three months. The lateral tongue is the highest-risk site, non-homogeneous leukoplakia and erythroplakia carry high dysplasia risk, and smoking multiplies it. Correct action is incisional biopsy with referral - not observation and not an antifungal trial.

Traps

Calling every white patch candidiasis; treating erosive lichen planus with antibiotics; forgetting that erythroplakia transforms more often than homogeneous leukoplakia.