Free DMD Periodontics and Endodontics Questions and Answers — Questions and Answers
Question 1: A 22-year-old systemically healthy female presents with severe, angular bone loss localized to the maxillary first molars and mandibular incisors, discovered on routine radiographs. Clinical examination reveals 7-8 mm probing depths in these areas, but surprisingly minimal plaque and calculus accumulation. What is the most likely diagnosis?
- Chronic Periodontitis
- Localized Aggressive Periodontitis (Correct answer)
- Necrotizing Ulcerative Periodontitis (NUP)
- Periodontitis as a manifestation of systemic disease
Correct answer: Localized Aggressive Periodontitis
Localized Aggressive Periodontitis (LAP) is characterized by rapid, severe attachment loss typically affecting a younger population (often around puberty), with a classic presentation involving the first molars and incisors. A key diagnostic feature is the inconsistency between the minimal amounts of plaque/calculus and the severity of periodontal destruction.
Question 2: A patient presents with a deep, isolated 9mm periodontal pocket on the facial aspect of tooth #22. Pulp vitality testing reveals no response to cold or electric stimuli. A radiograph shows a J-shaped radiolucency extending from the apex to the mid-root. Based on Simon's classification, what is the most likely diagnosis?
- Primary periodontal lesion with secondary endodontic involvement
- True combined endo-perio lesion
- Primary endodontic lesion with secondary periodontal involvement (Correct answer)
- Vertical root fracture
Correct answer: Primary endodontic lesion with secondary periodontal involvement
The diagnosis is guided by the non-vital pulp status, which indicates the infection originated from within the tooth (primary endodontic). The infection likely drained coronally through the periodontal ligament, creating a sinus tract that mimics a deep periodontal pocket. Over time, this tract can become contaminated with oral bacteria, leading to secondary periodontal inflammation.
Question 3: The primary principle of Guided Tissue Regeneration (GTR) using a barrier membrane in treating an intrabony periodontal defect is to:
- Provide a scaffold for bone graft material to enhance stability.
- Deliver concentrated growth factors to the surgical site.
- Prevent the apical migration of the junctional epithelium.
- Exclude gingival epithelium and connective tissue from the root surface to allow for repopulation by PDL and bone cells. (Correct answer)
Correct answer: Exclude gingival epithelium and connective tissue from the root surface to allow for repopulation by PDL and bone cells.
The core principle of GTR is cell exclusion. Gingival epithelial and connective tissue cells proliferate much faster than periodontal ligament (PDL) and bone cells. The barrier membrane physically blocks these faster-growing tissues from contacting the root surface, creating a protected space for the slower-growing, desired cell types (PDL and bone cells) to regenerate the lost periodontal attachment apparatus.
Question 4: A patient complains of a sharp pain on tooth #14, specifically upon releasing pressure after biting down on something hard. The pain is momentary and difficult to pinpoint. Probing depths are within normal limits, and the tooth responds normally to thermal pulp testing. Which diagnosis is most probable?
- Reversible Pulpitis
- Vertical Root Fracture
- Cracked Tooth Syndrome (Correct answer)
- Acute Apical Periodontitis
Correct answer: Cracked Tooth Syndrome
Cracked tooth syndrome is classically characterized by a sharp, fleeting pain upon biting and, more specifically, upon the release of biting pressure. This 'rebound pain' occurs as the fractured segments of the tooth move and then snap back together, stimulating fluid movement within the dentinal tubules and irritating the pulp. In early stages, probing depths and vitality tests are often normal.
Question 5: Mineral Trioxide Aggregate (MTA) is a biocompatible material frequently used for perforation repairs and apexification. What is its primary chemical component, which is also found in Portland cement?
- Calcium hydroxide
- Bismuth oxide
- Tricalcium silicate (Correct answer)
- Zinc oxide
Correct answer: Tricalcium silicate
MTA is primarily composed of tricalcium silicate, along with dicalcium silicate and tricalcium aluminate. Bismuth oxide is added for radiopacity, and calcium hydroxide is a byproduct of the hydration (setting) reaction, contributing to MTA's high pH and bioactivity.
Question 6: Which of the following represents the primary therapeutic goal of non-surgical periodontal therapy, also known as Phase I therapy?
- To regenerate lost alveolar bone and cementum.
- To perform definitive occlusal adjustments.
- To remove microbial biofilm and calculus to reduce inflammation. (Correct answer)
- To prepare teeth for final prosthetic restorations.
Correct answer: To remove microbial biofilm and calculus to reduce inflammation.
The fundamental objective of non-surgical periodontal therapy (Phase I), which includes scaling and root planing, is to eliminate the primary etiological factors of periodontal disease—bacterial biofilm and calculus. This mechanical debridement reduces the bacterial load, resolves gingival inflammation, and creates a root surface that is biologically compatible with healing.
