FREE NDEB Endodontics and Periodontics 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?

Accepted Answer

Primary endodontic lesion with secondary periodontal involvement; initiate endodontic therapy first, then re-evaluate periodontal status.

Answer

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?

Accepted Answer

Vertical root fracture

Answer

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?

Accepted Answer

A palatogingival groove

Answer

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?

Accepted Answer

Cone-shift technique (parallax)

Answer

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?

Accepted Answer

Vertical root fracture in an endodontically treated molar

Answer

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.

NDEB - National Dental Examining Board Practice Test

NDEB - National Dental Examining Board Practice Test

FREE NDEB Endodontics and Periodontics Questions and Answers