ADC - Australian Dental Council Endodontic Principles and Procedures Questions and Answers — Questions and Answers
Question 1: A 25-year-old patient presents with a severe, spontaneous, throbbing pain in the mandibular right first molar (tooth 46) that worsens when lying down. Clinical examination reveals a deep carious lesion. The tooth is tender to percussion, and pulp vitality testing with a cold stimulus elicits a sharp, lingering pain. A periapical radiograph shows a widened periodontal ligament space around the mesial root apex. What is the most likely diagnosis for the pulp and periapical tissues?
- Reversible pulpitis with normal apical tissues
- Irreversible pulpitis with symptomatic apical periodontitis (Correct answer)
- Pulp necrosis with asymptomatic apical periodontitis
- Acute apical abscess with pulp necrosis
Correct answer: Irreversible pulpitis with symptomatic apical periodontitis
The patient's symptoms of spontaneous, severe, and lingering pain are classic signs of irreversible pulpitis. The tenderness to percussion and radiographic evidence of a widened PDL indicate that the inflammation has extended into the periapical tissues, leading to symptomatic apical periodontitis. Reversible pulpitis would present with sharp, non-lingering pain to a stimulus. Pulp necrosis would not respond to cold testing, and an acute apical abscess would typically present with more pronounced swelling.
Question 2: During root canal treatment, which of the following is the primary function of sodium hypochlorite (NaOCl) as an irrigant?
- Removal of the smear layer
- Dissolution of organic tissue and antimicrobial action (Correct answer)
- Chelation of inorganic dentine components
- Lubrication of endodontic files
Correct answer: Dissolution of organic tissue and antimicrobial action
Sodium hypochlorite's primary and most crucial roles in endodontics are its ability to dissolve necrotic and vital pulp tissue (organic components) and its potent broad-spectrum antimicrobial activity against bacteria and biofilms within the root canal system. While it has some lubricating effect, this is not its primary function. Removal of the smear layer (inorganic component) is primarily achieved by chelating agents like EDTA.
Question 3: A dentist is performing root canal treatment on a maxillary first molar. After creating the access cavity and beginning instrumentation, they notice a small, persistent hemorrhage from the pulpal floor, mesial to the main mesiobuccal canal orifice. Which of the following procedural errors is the most likely cause?
- Perforation into the furcation (Correct answer)
- A lateral perforation of the root
- Fracture of an endodontic instrument
- Missing the second mesiobuccal (MB2) canal
Correct answer: Perforation into the furcation
A perforation into the furcation area is a common procedural error during access cavity preparation in molars. It occurs when the bur is directed too deeply or at an incorrect angle, breaching the pulpal floor and entering the periodontal ligament space in the furcation. This typically results in persistent hemorrhage that is difficult to control. Missing a canal or a fractured instrument would not typically present with bleeding from the pulpal floor itself.
Question 4: A 10-year-old child presents to your clinic 45 minutes after avulsing their maxillary central incisor (tooth 11) during a sports accident. The tooth has been kept in a dry handkerchief. The child is medically fit. What is the most appropriate immediate management step?
- Gently rinse the tooth with saline, replant it immediately, and splint for 2 weeks. (Correct answer)
- Scrub the root surface to remove debris, soak in doxycycline, and then replant.
- Delay replantation and schedule an appointment with an endodontist for the next day.
- Initiate root canal treatment on the tooth extra-orally before replanting.
Correct answer: Gently rinse the tooth with saline, replant it immediately, and splint for 2 weeks.
According to the International Association of Dental Traumatology (IADT) guidelines, for an avulsed permanent tooth with an open or closed apex and an extra-oral dry time of less than 60 minutes, the tooth should be gently rinsed with a sterile solution like saline, replanted as soon as possible, and a flexible splint placed for up to 2 weeks. Scrubbing the root surface is contraindicated as it damages the periodontal ligament cells. Delaying replantation significantly worsens the prognosis. Extra-oral RCT is only considered if the extra-oral dry time is prolonged ( > 60 mins).
Question 5: Which of the following is a significant advantage of using bioceramic sealers (e.g., MTA-based sealers) for root canal obturation compared to traditional zinc oxide-eugenol (ZOE) based sealers?
- They are easier to remove for retreatment.
- They exhibit significant shrinkage upon setting.
- They are hydrophobic and repel moisture.
- They are bioactive and promote hard tissue formation. (Correct answer)
Correct answer: They are bioactive and promote hard tissue formation.
Bioceramic sealers are known for their biocompatibility and bioactivity. They can interact with periradicular tissues to promote the formation of cementum and bone, which is advantageous for healing. Unlike ZOE sealers, they are hydrophilic (set in the presence of moisture) and undergo slight expansion upon setting. A major disadvantage is that they are very difficult to remove, making retreatment challenging.
Question 6: When preparing an access cavity for a mandibular first molar with a vital pulp, the ideal outline form is typically:
- Circular and centred on the occlusal surface
- Triangular, with the base towards the mesial
- Oval, oriented in a mesio-distal direction
- Trapezoidal or rhomboidal, located in the mesial half of the tooth (Correct answer)
Correct answer: Trapezoidal or rhomboidal, located in the mesial half of the tooth
The ideal access cavity for a mandibular first molar is trapezoidal or rhomboidal in shape. This form reflects the underlying anatomy of the pulp chamber, which is wider mesially (to accommodate the mesiobuccal and mesiolingual canals) and narrower distally (for the distal canal(s)). The outline is confined to the mesial half of the occlusal surface to conserve tooth structure while providing straight-line access to the canals. A triangular shape is typical for maxillary incisors, while an oval shape is more common for premolars.
ADC - Australian Dental Council Endodontic Principles and Procedures Questions and Answers
A 25-year-old patient presents with a severe, spontaneous, throbbing pain in the mandibular right first molar (tooth 46) that worsens when lying down.
Clinical examination reveals a deep carious lesion.
The tooth is tender to percussion, and pulp vitality testing with a cold stimulus elicits a sharp, lingering pain.
A periapical radiograph shows a widened periodontal ligament space around the mesial root apex.
What is the most likely diagnosis for the pulp and periapical tissues?