MJDF Part 1 - Membership of Joint Dental Faculties Endodontics and Pulp Therapy Questions and Answers — Questions and Answers
Question 1: A 9-year-old child presents with a traumatically avulsed maxillary permanent central incisor (UR1) that has been out of the mouth for 45 minutes. The tooth was kept in the patient's mouth (in their saliva). According to the International Association of Dental Traumatology (IADT) guidelines, which are standard practice in the UK, what is the most appropriate storage medium if immediate replantation is not possible upon arrival at the clinic?
- Tap water
- Hank's Balanced Salt Solution (HBSS) or milk (Correct answer)
- A dry tissue
- The patient's saliva in a container
Correct answer: Hank's Balanced Salt Solution (HBSS) or milk
The IADT guidelines, followed in the UK, state that the best storage medium for an avulsed tooth is one with physiological osmolality and pH. Hank's Balanced Salt Solution (HBSS) is considered the ideal medium. [8] If HBSS is not available, cold milk is the next best alternative as it is readily available and maintains periodontal ligament cell viability for a reasonable period. [4, 7, 10] Tap water is hypotonic and damages cells, a dry environment is the worst option, and saliva, while better than dry storage, has poor osmolality and high bacterial content making it suboptimal. [7]
Question 2: A 28-year-old patient presents with symptoms of irreversible pulpitis in a mandibular first molar (LR6). During root canal irrigation with sodium hypochlorite (NaOCl), the patient suddenly experiences severe, sharp pain, followed by rapid swelling of the cheek. Which of the following is the most critical immediate action?
- Complete the obturation of the canals immediately to seal the apex.
- Prescribe a course of systemic antibiotics and discharge the patient.
- Stop irrigation, reassure the patient, and irrigate the canal with copious sterile saline or water. (Correct answer)
- Administer an intramuscular injection of a corticosteroid to manage the inflammation.
Correct answer: Stop irrigation, reassure the patient, and irrigate the canal with copious sterile saline or water.
This scenario describes a sodium hypochlorite accident where the irrigant has been extruded beyond the apex. The immediate priority is to stop the procedure and dilute the extruded NaOCl by flushing the canal with a neutral solution like sterile saline or water. [15, 33] This helps to limit further tissue damage. Reassurance and pain management (e.g., long-acting local anaesthetic) are also vital. [15, 29] Completing obturation is contraindicated, and while antibiotics may be prescribed later to prevent secondary infection, it is not the first action. [15] Corticosteroids are part of management but diluting the chemical irritant is the most critical first step.
Question 3: In endodontic treatment, what is the primary purpose of establishing and maintaining 'apical patency'?
- To intentionally enlarge the apical foramen to create an apical 'blunderbuss'.
- To ensure the final obturation material extrudes slightly, forming an apical puff.
- To prevent the blockage of the apical constriction with dentine debris during instrumentation. (Correct answer)
- To remove the smear layer from the entire canal wall using a large file.
Correct answer: To prevent the blockage of the apical constriction with dentine debris during instrumentation.
Apical patency is defined as keeping the apical portion of the canal free of debris by passing a small, flexible file (e.g., a size 10 K-file) slightly beyond the working length. [3, 12, 19] Its main purpose is to prevent dentine shavings and necrotic tissue from being compacted at the apex, which could cause a blockage, loss of working length, or procedural errors like ledging. [3, 13] It does not aim to enlarge the foramen but to keep it clear, which also enhances irrigant delivery to the apical third. [3, 13]
Question 4: A 22-year-old patient has a carious pulp exposure in a vital maxillary second premolar (UR5) with symptoms of reversible pulpitis. A direct pulp cap is planned. According to contemporary UK practice and evidence, which material offers the highest success rates for this procedure in permanent teeth?
- Calcium hydroxide cement
- Glass ionomer cement
- Zinc oxide eugenol
- Mineral Trioxide Aggregate (MTA) or a calcium silicate-based cement (e.g., Biodentine) (Correct answer)
Correct answer: Mineral Trioxide Aggregate (MTA) or a calcium silicate-based cement (e.g., Biodentine)
Modern evidence strongly supports the use of bioactive calcium silicate-based cements like Mineral Trioxide Aggregate (MTA) and Biodentine for vital pulp therapy, including direct pulp capping. [5, 17, 23] These materials have demonstrated significantly higher long-term success rates compared to the traditional material, calcium hydroxide, due to their superior sealing ability, biocompatibility, and ability to stimulate higher quality reparative dentine bridge formation. [5, 16] Glass ionomer and zinc oxide eugenol are not appropriate materials for direct contact with exposed pulp tissue.
Question 5: Following the completion of root canal treatment, which factor is considered to be of at least equal importance to the quality of the obturation for long-term endodontic success?
- The type of intracanal medicament used between appointments.
- The brand of gutta-percha used for obturation.
- The quality and integrity of the coronal restoration. (Correct answer)
- The use of a patency file during instrumentation.
Correct answer: The quality and integrity of the coronal restoration.
Numerous studies have shown that the long-term success of endodontic treatment is dependent on both a well-executed root filling and a high-quality, well-sealed coronal restoration. [2, 11, 20, 37] A leaking or deficient coronal restoration allows for the ingress of oral bacteria and their by-products, which can lead to the re-infection of the root canal system and subsequent failure of the treatment, regardless of how well the canals were initially filled. [14, 20, 43]
Question 6: A 45-year-old patient is diagnosed with symptomatic irreversible pulpitis and apical periodontitis in a mandibular molar (LL6). A full pulpotomy is being considered as a vital pulp therapy option. Which finding would be a definitive contraindication for proceeding with a full pulpotomy?
- The tooth has a mature, closed apex.
- The patient reports spontaneous, lingering pain.
- The pulp tissue continues to bleed uncontrollably after coronal pulp removal. (Correct answer)
- A periapical radiograph shows slight widening of the periodontal ligament space.
Correct answer: The pulp tissue continues to bleed uncontrollably after coronal pulp removal.
The success of vital pulp therapy, including pulpotomy, relies on removing the inflamed coronal tissue and placing a biomaterial onto healthy, vital radicular pulp tissue. [21, 28] The ability to achieve haemostasis (i.e., stop the bleeding) after a reasonable time (e.g., 5-10 minutes) is a key clinical indicator that the underlying radicular pulp is healthy enough to be preserved. [27, 28] Uncontrollable bleeding suggests that inflammation extends deep into the radicular pulp, making pulpotomy unlikely to succeed and indicating the need for a full pulpectomy (conventional root canal treatment). [27]
MJDF Part 1 - Membership of Joint Dental Faculties Endodontics and Pulp Therapy Questions and Answers
A 9-year-old child presents with a traumatically avulsed maxillary permanent central incisor (UR1) that has been out of the mouth for 45 minutes.
The tooth was kept in the patient's mouth (in their saliva).
According to the International Association of Dental Traumatology (IADT) guidelines, which are standard practice in the UK, what is the most appropriate storage medium if immediate replantation is not possible upon arrival at the clinic?