third molars - guidelines and indications for extraction

Question 1

Describe the anatomy of third molars including crown and root calcification

Answer 1

Third molars are the last set of molars that usually erupt between 18 and 24 years old
Crown calcification begins between 7 and 10 years and is complete by 18
Root calcification is complete between 18 and 25 years

Question 2

What is the most common reason for third molars to fail to erupt?

Answer 2

Impaction, where tooth eruption is blocked

Question 3

What are the consequences of impaction of third molars?

Answer 3

Caries
Periodontitis
Cyst formation

Question 4

Define pericoronitis

Answer 4

The inflammation around the crown of a partially erupted tooth.

Question 5

What are the nerves at risk during third molar surgery?

Answer 5

Inferior alveolar nerve
Lingual nerve
Nerve to mylohyoid
Long buccal nerve

Question 6

What are the 3 guidelines for third molars extraction?

Answer 6

1. NICE Guidelines on Extraction of Wisdom Teeth
2. SIGN Publication Number 43 - Management of Unerupted and Impacted Third Molar Teeth
3. FDS, RCS 2020 - Parameters of Care for patients undergoing mandibular third molar surgery.

Question 7

What are the therapeutic indications for extraction of third molars?

Answer 7

Infection (caries, pericoronitis, periodontal disease, or local bone infection)
Cysts
Tumors
External resorption of 7 or 8

Question 8

Describe the location of the lingual nerve during third molar surgery

Answer 8

The lingual nerve is close to the lingual plate in the mandibular and retromolar area
In 15-18% of cases, it can be at or above the level of the lingual plate, and it is typically located between 0-3.5mm medial to the mandible

Question 9

What causes pericoronitis?

Answer 9

When food and debris get trapped under the operculum of the partially erupted tooth

Question 10

Name 4 of the signs and symptoms of pericoronitis?

Answer 10

Pain
Swelling (intraoral or extraoral)
Bad taste
Pus discharge
Occlusal trauma to the operculum
Ulceration of the operculum
Evidence of cheek biting
Bad breath
Limited mouth opening
Dysphagia
Fever
Malaise
Regional lymphadenopathy

Question 11

How is pericoronitis treated?

Answer 11

Incision of localized pericoronal abscess if required
Irrigation with warm saline or chlorhexidine mouthwash
Extraction of the upper third molar if traumatizing the operculum
Frequent warm saline or chlorhexidine mouthwashes
Analgesia
Maintaining fluid intake and eating
Antibiotics only in severe cases or when the patient is systemically unwell or immunocompromised.

Question 12

What are the predisposing factors for pericoronitis?

Answer 12

Partial eruption and vertical or distoangular impaction
Opposing maxillary third molars or second molars causing mechanical trauma
Upper respiratory tract infections
Stress and fatigue
Poor oral hygiene
Insufficient space between the ascending ramus of the lower jaw and the distal aspect of the second molar
Being of white race with a full dentition