NBDE Periodontics and Endodontics Questions and Answers

Question 1

A 45-year-old patient presents with a chief complaint of a "gummy smile." Clinical examination reveals probing depths of 2-3 mm, minimal bleeding on probing, and a gingival margin located significantly coronal to the CEJ.
Bone sounding reveals a distance of 5 mm from the gingival margin to the alveolar crest.
What is the most likely diagnosis?

Accepted Answer

Altered Passive Eruption

Answer

Chronic Periodontitis

Answer

Medication-induced Gingival Hyperplasia

Answer

Aggressive Periodontitis

Question 2

Which of the following is the primary purpose of using 17% Ethylenediaminetetraacetic acid (EDTA) as an irrigant during root canal therapy?

Accepted Answer

To remove the inorganic component of the smear layer.

Answer

To dissolve organic pulpal tissue remnants.

Answer

To provide broad-spectrum antimicrobial activity.

Answer

To act as a lubricant for rotary instruments.

Question 3

A clinician is evaluating a maxillary molar with a Nabers probe. The probe passes completely through the furcation from the buccal to the mesiopalatal aspect, and the entrance to the furcation is clinically visible due to significant gingival recession. According to Glickman's classification, what is the correct classification for this furcation involvement?

Accepted Answer

Class IV

Answer

Class II

Answer

Class I

Answer

Class III

Question 4

A 22-year-old patient reports sharp, lingering pain in tooth #30 that lasts for several minutes after a cold stimulus is removed. The pain also occurs spontaneously and has awakened the patient from sleep. Percussion and palpation tests are within normal limits. A periapical radiograph shows a deep composite restoration but no periapical radiolucency. Based on these findings, what are the most likely pulpal and periapical diagnoses?

Accepted Answer

Symptomatic Irreversible Pulpitis and Normal Apical Tissues

Answer

Reversible Pulpitis and Normal Apical Tissues

Answer

Symptomatic Irreversible Pulpitis and Symptomatic Apical Periodontitis

Answer

Necrotic Pulp and Asymptomatic Apical Periodontitis

Question 5

Which of the following clinical scenarios is most indicative of a primary periodontal lesion with secondary endodontic involvement?

Accepted Answer

A vital tooth with generalized severe bone loss and a wide, conical periodontal pocket.

Answer

A non-vital tooth with a deep, isolated, narrow periodontal pocket that traces to the apex.

Answer

A non-vital tooth with a small sinus tract that traces directly to the apex of the tooth.

Answer

A vital tooth with a history of trauma presenting with internal root resorption radiographically.

Question 6

A periodontist prescribes a subantimicrobial dose of doxycycline (20 mg twice daily) for a patient with chronic periodontitis as an adjunct to scaling and root planing. What is the primary mechanism of action for this specific therapy?

Accepted Answer

To inhibit the activity of host-derived collagenase (matrix metalloproteinases).

Answer

To exert a bactericidal effect on key periodontal pathogens.

Answer

To stimulate osteoblastic activity and promote alveolar bone formation.

Answer

To directly reduce the depth of periodontal pockets through epithelial reattachment.