OS- Wisdom teeth Flashcards
When do wisdom teeth normally erupt
18-24
When does the calcification of the crowns of 8s start?
uppers 7-9. Lowers 8-10 years.
When is root calcification complete in wisdom teeth?
18-25
What is third molar agenesis?
When there is no third molar as it has not formed.
Where is third molar agenesis more common?
Maxilla. and in females
What is the rule of thumb for third molar agenesis?
If the 8 is not visible in a radiograph by 14- 8 will fail to develop.
What is the most common cause of failed eruption of third molars
Impaction
What is impaction?
The blocking of eruption of the tooth by (alveolar bone/other teeth/ surrounding mucosal soft tissue)
Compare unerupted/partially erupted and fully erupted third molars.
Unerupted- contained in the bone.
Partially erupted- some of the tooth has erupted into the oral cavity.
Fully erupted- whole occlusal surface is through the mucosa and exposed.
List the consequences of wisdom tooth impaction?
Caries
Pericoronitis
Cysts.
What nerves are at risk during a third molar surgery.
Lingual nerve
Inferior alveolar nerve
Nerve to mylohyoid.
Long buccal nerve .
Discuss the location of the lingual nerve.
Close to the lingual plate in the mandibular and retromolar region
Name the current guidelines followed for extraction of wisdom teeth
Faculty of dental surgery (FDS) parameters of care.
List indications for extraction of 8s
- infection (caries/pericoronitis/periodontal disease/ local bone infection
- Cysts
- Tumours located close to the molar
- External resorption of 7/8
- in the way of a surgical
- High risk of disease
- Medical indications (e.g. MRONJ)
What 8s would have a higher risk of caries?
A mesial angle or horizontally impacted 8
What is pericoronitis?
Inflammation around the crown of a partially erupted tooth. This causes food and debris to get trapped under the operculum (flap of gum) resulting in inflammation/infection (it is difficult to keep clean)
How can we tell clinically that a tooth is partially erupted?
If we find a communication when Probing distal to the 7
What is the normal age of patients presenting with pericoronitis?
20-40
Give signs and symptoms of pericoronitis?
- Pain
- swelling
- pus (causing bad taste)
- Bad breath
- Trauma to the operculum.
- Cheek biting
- Limited mouth opening
- Regional lymphadenopathy
- Dysphagia
- Pyrexia
How do we treat pericoronitis?
Incise the abcess
LA (dependent on patient and pain)
Irrigate the area with warm saline or chlorhexidine mouthwash (10-20ml syringe with blunt needle – under the operculum).
How does a patient presenting with ulceration of the operculum influence treatment?
The upper 3rd molar should be extracted as it is traumatising the operculum.
What patient instructions do we give to someone with pericoronitis?
Frequent mouthwash (warm saline or chlorohexidine)
Analgesia
Keep fluid levels up and keep eating (soft/liquid diet if neccessary)
When do we prescribe antibiotics for pericoronitis and what do we prescribe?
Extra-oral swelling.
Systemically unwell.
Immunocompromised
Metrondiazole.
How does pericoronitis presentation impact extraction of 8s
You need to wait for the resolution of the pericoronitis before extacting the 8s.
List some predisposing factors to pericoronitis?
Partial eruption and vertical/ distoangular impaction.
Opposing maxillary molars causing trauma & recurrent infection
Poor oral hygiene.
When asking the history of presenting complaint what else do we want to know about wisdom teeth patients?
Has it flared up before and have you had any previous antibiotic treatment.
Why are TMJ tests important in e/o for wisdom tooth asessment?
So we can rule out TMJD causing the pain
What is the working space and why is this important in the i/o examination of 8s.
The distance from the distal of the 2nd molar to the ascending ramus of the mandible.
This gives us the space we must work in to get the 3rd molar out.
What are when checking when looking at the occlusion in an i/o exam of 8s?
are the upper 7s and 8s occluding on the operculum. Are there any other 8s impacted or causing problems ?
What are we looking for an in OPT for patients presenting with wisdom tooth problems.
- presence/absence of disease
- Anatomy of the 3m (Crown size/shape/condition/ root number/morphology)
- Depth of impaction
- Orientation of impaction
- Working distance
- Follicular width (radiolucency around crown of unerupted molars
- Periodontal status
- Relationship/proximity of 3rd molars to maxillary antrum/ inferior dental canal.
What follicular width would we be concerned about?
> 2.5-3mm
What relationship with the inferior alveolar canal is shown here?
Diversion or deflection of the inferior dental canal
(the canal loops around the root)
What relationship with the inferior alveolar canal is shown here?
Darkening of the root where it is crossed by the canal
(dark band is crossing the root)
What relationship with the inferior alveolar canal is shown here?
Interuption of the white lines/lamina dura of the canal (we lose the white line then pick it up at the other side)
What relationship with the inferior alveolar canal is shown here?
Deflection of the root
What relationship with the inferior alveolar canal is shown here?
Narrowing of the inferior dental canal
(it gets narrower at the apex of the roots and then goes back to normal)
What relationship with the inferior alveolar canal is shown here?
Narrowing of the roots where they meet the canal
What relationship with the inferior alveolar canal is shown here?
Dark and bifid root (the root appears to split/divide over the canal)
What relationship with the inferior alveolar canal is shown here?
Juxta apical area- a well defined area lateral to the tooth (check this is not related to a non-vital tooth)
What radiographic appearances of wisdom teeth have significantly increased risk according to the SIGN guidelines?
Darkening of root.
Interuption of the white lines of the canal
Diversion of inferior dental canal.
Describe the orientation of this impacted wisdom tooth
Vertical impaction (both teeth are following the same course)
Describe the orientation of this impacted wisdom tooth
Mesioangular (Crown tilts towards the adjacent tooth(
Describe the orientation of this impacted wisdom tooth
Distoangular- crown tilts away from the adjacent tooth
Describe the orientation of this impacted wisdom tooth?
Horizontal
Compare the incidence of the orientations of impacted wisdom teeth?
Vertical 30-38%
Mesial 40%
Distal 6-15%
Horizontal 3-15%
Describe the orientation of this impacted wisdom tooth?
Transverse- crown and root of tooth is across the buccal/lingual
Name and describe the wisdom tooth shown in this radiograph
Aberrant wisdom tooth (tooth is positioned in the wrong place)
Why are distally impacted 3rd molars more difficult to remove?
May need to remove bone distal of the 3rd molar.
Roots of the 8 are very close to the roots of the 7 (risk of damaging 7)
How do we measure the depth of impaction?
What does it indicate?
Indicates- how much bone needs to be removed.
Looking at the relationship of the third molar to the second molar
Compare the different descriptions used for the depths of impaction?
superficial- Crown of 8 sitting at the same height as crown of 7
Moderate- crown of 8 related to crown and root of 7.
Deep-crown of 8 at the same height as root of 7.
What are the treatment options for an impacted 8?
- Refer
- Monitor
- Extract
- coronectomy
Describe a coronectomy and when would it be indicated?
Crown of the impacted tooth is surgically removed but the root is left.
If there is a close relationship with the canal and minimal/no caries.
Compare the active surveillance and a clinical review of the 8?
Active surveillance- monitoring with radiographs.
Clinical review- monitoring patient signs and symptoms.
What is the treatment plan for patients with Asymptomatic 3rd molar but high risk/diseased.
Surgical intervention or active surveillance until symptoms develop or disease progresses.
What is the treatment plan for patients with a symptomatic third molar and high risk/diseased.
Extraction
What is the treatment plan for patients with asymptomatic third molar and no disease/low risk
Clinical review
What is the treatment plan for patients with symptomatic third molar with non disease/ low risk?
Leave impacted molar & manage other diagnoses that could be causing the pain.
How would you explain the 3rd molar extraction procedure to a patient?
It is a surgical procedure- may need:
* a flap (cut in the gum but the patient will not feel it)
* Possible drilling
* Stitches- to help the gum heal.
There are risks: Damage to the adjacent teeth/ jaw fracture/ Pain/ infection/ bleeding/ bruising/ stiffness/ swelling/dry socket/ nerve damage.
How do we explain the sectioning of a tooth surgically?
The tooth may need to be cut into smaller pieces to be removed.
What is the risk of temporary nerve damage to the IDN?
10-20%
What is the risk of permanent nerve damage to the IDN?
<1%
What is the risk of temporary nerve damage to the lingual nerve ?
0.25-0.35%
What is the risk of permanent nerve damage to the lingual nerve?
0.14-2%
When is surgical removal of a tooth required?
When the tooth can’t be removed with forceps alone.
Why is LA placed independent of the type of sedation selected?
For local pain relief and haemostasis.
List the steps for sugical removal of third molars
- LA
- Access (flap)
- (if bone removal is needed)
- Check socket
- Debridement
- Suture
- Haemostasis & post operative instructions
How do we gain surgical access to a 3rd molar?
Lifting a buccal muco-periosteal flap (and sometimes a lingual flap)
What is the risk associated with raising a lingual mucoperiosteal flap?
The risk of the lingual flap damaging the lingual nerve.
List the steps for raising a buccal mucoperiosteal flap.
- Use a scapel in 1 continuous stroke around the neck of the tooth.
- Start at the base of the relieving incision to raise the flap from bone.
- Then reflect distally.
What instrument do we use to reflect the tissue of a flap and why?
Ash’s periosteal elevator firmly on bone to avoid disection and trauma to the tissues.
What instruments are used for retraction of a flap?
Minnesota retractor
Rake retractor
Ash’s periosteal elevator.
You have lifted a flap but further access is needed, what do you do?
Remove bone by cutting a buccal gutter.
What type of handpeice is used for surgical bone removal.
An electric straight handpeice with a saline cooled bur.
What is the buccal gutter and how do we produce it?
This is a narrow area of bone removal around the tooth to provide a point of application for placement of elevators.
To produce we keep a round bur in contact with the tooth the full way round the tooth from distal to mesial to ensure it is as narrow as possible.
When would we divide the tooth in the surgical extraction?
When after bone removal it is still not possible to remove the tooth with elevators and forceps .
How can we divide the tooth?
Split the crown and the root.
If still no space…
Split the distal and mesial (removing distal gives space to remove the mesial)
How do we debride the socket after extraction?
Physical debridement-
Remove sharp bony edges using bone file or handpiece.
Soft tissue debris- using mitchell’s trimmer or victoria curette.
Irrigation-Apply sterile saline into the socket and under the flap
Suction- Aspirate under the flap to remove debris & check socket for retained apices etc
Describe the incisions made for a 3 sided flap.
Distal relieving incision.
Incision at the neck of the tooth.
Mesial relieving incision
Describe the incisions made for an envelope (2 sided flap)
Distal relieving incision
Incision around the neck of tooth.
What sutures are used to close a 3 sided flap?
Suture at:
* Distal relieving incision
* mesial relieving incision
If you still see a gap/bone after placing the mesial incision you can place another suture.
If the papillae is free, you may chose to put a suture over the papillae.
What sutures are used to close a 2 sided flap?
1 distal relieving incision
1 interproximally between the 7 and the 8.
What Post-operative instructions is specific to wisdom teeth?
Your jaw may hurt for 2-3 weeks (this is expected due to location of wisdom teeth. )
If there is continued numbness in one area come back and see us.
What is a coronectomy and when do select it as a treatment option?
When we remove the crown of the tooth and leave the root in the mouth
When there is a risk of IADN damage with removal of the wisdom tooth.
Compare a coronectomy and decoronating a tooth?
We remove all the enamel in a coronectomy.
When we decoronate a tooth (for tooth division) we leave a little bit of enamel to help us elevate and orientate the roots.
Describe a coronectomy?
- lift flap.
- Transect the tooth 3-4mm below the enamel of the crown.
- Leave the pulp untreated (to heal over)
- Irrigate the socket with saline
- Replace the flap.
What are the risks associated with a coronectomy?
- Roots become mobile during procedure (roots need to be removed due to risk of infection)
- Roots becoming infected
- A slow healing (and painful socket)
- Continued eruption of the roots requiring extraction.
Why is essential to get a radiograph prior to upper third molar extraction
Root morphology of 3rd molar teeth is so variable (No of roots/shape of root/divergent root/ curved roots)
