MJDF Part 1 - Membership of Joint Dental Faculties Endodontics and Pulp Therapy 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?

Accepted Answer

Hank's Balanced Salt Solution (HBSS) or milk

Answer

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?

Accepted Answer

Stop irrigation, reassure the patient, and irrigate the canal with copious sterile saline or water.

Answer

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'?

Accepted Answer

To prevent the blockage of the apical constriction with dentine debris during instrumentation.

Answer

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?

Accepted Answer

Mineral Trioxide Aggregate (MTA) or a calcium silicate-based cement (e.g., Biodentine)

Answer

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?

Accepted Answer

The quality and integrity of the coronal restoration.

Answer

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]

MJDF Part 1 Practice Test

MJDF Part 1 Practice Test

MJDF Part 1 - Membership of Joint Dental Faculties Endodontics and Pulp Therapy Questions and Answers