Free NDEB Endodontics and Periodontics Questions and Answers — Questions and Answers
Question 1: A patient presents with a deep, isolated 8mm periodontal pocket on the mesial aspect of a mandibular first molar, which has a necrotic pulp. Radiographically, a periapical radiolucency is evident. According to Simon's classification, what is the diagnosis and the correct initial treatment sequence?
- Primary periodontal lesion; initiate periodontal debridement immediately.
- True combined lesion; perform periodontal and endodontic therapy concurrently.
- Primary endodontic lesion with secondary periodontal involvement; initiate endodontic therapy first, then re-evaluate periodontal status. (Correct answer)
- Concomitant pulpal and periodontal lesion; extract the tooth.
Correct answer: Primary endodontic lesion with secondary periodontal involvement; initiate endodontic therapy first, then re-evaluate periodontal status.
The lesion originates from the necrotic pulp (primary endodontic) and drains coronally through the periodontal ligament space, creating a deep pocket that can subsequently become colonized by plaque and calculus (secondary periodontal involvement). The correct protocol is to address the primary source of infection—the necrotic pulp—by performing root canal therapy first. Periodontal status is then re-evaluated after 2-3 months to determine if the pocket has resolved or if subsequent periodontal therapy is required.
Question 2: A patient complains of a dull, persistent ache and discomfort on biting from an endodontically treated maxillary premolar. Probing reveals a deep, narrow pocket on the buccal aspect. A periapical radiograph shows a 'J-shaped' or 'halo' radiolucency extending from the apex along the side of the root. What is the most probable diagnosis?
- Condensing osteitis
- Vertical root fracture (Correct answer)
- Failed endodontic treatment due to a missed canal
- Chronic apical periodontitis
Correct answer: Vertical root fracture
The combination of a deep, isolated probing defect and a 'J-shaped' or 'halo' radiolucency on an endodontically treated tooth is pathognomonic for a vertical root fracture (VRF). These signs indicate a communication between the root canal system and the periodontium along the fracture line, leading to extensive, characteristic bone loss. The prognosis for a tooth with a VRF is typically hopeless, leading to extraction.
Question 3: A 22-year-old patient presents for a routine check-up. A deep, narrow probing defect is found on the palatal aspect of the maxillary right lateral incisor. The tooth is vital, non-carious, and has no history of trauma. A radiograph reveals a faint, dark line running parallel to the root canal. Which of the following is the most likely cause of this localized periodontal defect?
- Aggressive periodontitis
- Trauma from occlusion
- A palatogingival groove (Correct answer)
- An early primary endodontic lesion
Correct answer: A palatogingival groove
A palatogingival groove is a developmental anomaly that acts as a plaque-retentive area, allowing bacteria to migrate apically and cause a deep, isolated periodontal pocket. The tooth typically remains vital unless the lesion progresses to involve the pulp via lateral canals or the apical foramen. Its radiographic appearance as a 'parapulpal line' and the specific clinical presentation on a vital maxillary lateral incisor are classic diagnostic features.
Question 4: During a radiographic examination, a well-defined, oval radiolucency is seen within the confines of the root canal of a maxillary central incisor. The outline of the root canal appears ballooned and distorted, but the periodontal ligament space around the root is intact. What radiographic technique is most definitive in confirming the diagnosis?
- Bitewing radiograph
- Occlusal radiograph
- Cone-beam computed tomography (CBCT)
- Cone-shift technique (parallax) (Correct answer)
Correct answer: Cone-shift technique (parallax)
This presentation is characteristic of internal root resorption. The cone-shift (parallax) technique is a key method to differentiate internal from external resorption. With internal resorption, the lesion is part of the canal, so its position remains centered within the canal regardless of the horizontal angle of the x-ray beam. In external resorption, the lesion is on the root surface and will appear to shift its position relative to the canal when the beam angle is changed.
Question 5: Which of the following scenarios has the poorest long-term prognosis, typically resulting in tooth extraction?
- Primary endodontic lesion with a draining sinus tract
- Primary periodontal lesion with secondary endodontic involvement
- Vertical root fracture in an endodontically treated molar (Correct answer)
- Class II furcation involvement on a vital molar
Correct answer: Vertical root fracture in an endodontically treated molar
A vertical root fracture (VRF) almost universally carries a hopeless prognosis, leading to extraction. The fracture line allows for persistent microbial leakage along the length of the root, making it impossible to seal and leading to progressive bone loss. The other options, while serious, can often be managed with a combination of endodontic and/or periodontal therapies with a more favorable long-term prognosis.
Question 6: A patient requires treatment for a mandibular molar with a Class II furcation involvement and a concomitant diagnosis of pulpal necrosis. What is the most appropriate sequence of treatment to ensure the best possible outcome?
- Periodontal surgery first, followed by endodontic treatment after 3 months.
- Concurrent endodontic and periodontal surgical treatment.
- Extraction is the only predictable option.
- Complete endodontic therapy, wait 2-3 months for initial healing, then perform periodontal surgery. (Correct answer)
Correct answer: Complete endodontic therapy, wait 2-3 months for initial healing, then perform periodontal surgery.
The primary etiology of the apical and potentially some of the furcal bone loss is the necrotic pulp. Therefore, endodontic therapy must be completed first to eliminate the source of infection from within the tooth. After a healing period of 2-3 months, the periodontal condition is re-evaluated. The Class II furcation, being a distinct periodontal defect, will not resolve with endodontic therapy alone and will then require surgical periodontal management, such as guided tissue regeneration or furcation plasty.
Free NDEB Endodontics and Periodontics Questions and Answers
A patient presents with a deep, isolated 8mm periodontal pocket on the mesial aspect of a mandibular first molar, which has a necrotic pulp.
Radiographically, a periapical radiolucency is evident.
According to Simon's classification, what is the diagnosis and the correct initial treatment sequence?