Third molars Flashcards
- When does crown calcification begin and end?
- when does root calcification end?
- radiographically begins between 7 and 10 and ends by 18y
- 18-25y
- what are some of things mandibular molars be impacted with?
- what are some of the consequences of impacted M3M?
- adjacent teeth, alveolar bone, surrounding mucosal soft tissue or a combo of these
- caries, pericorinitis or cyst formation
- What are nerves at risk during 3rd molar surgery?
- what is lingual nerve a branch of and what is it’s location/
- inferior alveolar nerve
Lingual nerve (mandibular division of trigmenial nerve)
Nerve to mylohyoid
Long buccaneers nerve - 0-3.5mm medial to mandible
What is guidelines for 3rd molars?
- NICE, guidance on extraction of wisdom teeth 2000
SIGN publication number 43 - management of unerupted and impacted 3rd molar teeth 2000
FDS, RCS 2020 - parameters of care for patients undergoing mandibular 3rd molar surgery
- What are therapeutic indications for extraction?
- infection (caries, pericorinitis, perio or local bone infection) - most common
Cysts
Tumours
External resorption of 7 or 8
What is information for cysts and 3rd molars?
- more common in mandible than maxilla
Prophaylactic removal or coronetomy of diseased free lower 43rd molar would present development of cyst. Would be small so not an indication to remove
Apart from therapeutic types what other indications for removal of 3rd molars?
- surgical indications ie within surgical field (orthographic, fractured mandible, in resection of diseased tissue)
high risk of disease
Medication indications ie awaiting cardiac surgery, immunosuppressed or to prevent osteonecrosis before starting bisphosphonates
Accessibility - limited access
Patient age- complications and recovery time increase with age
Autotransplantation usually to a first molar
GA
- what is pericorinitis?
- what is only health condition related to it?
- Inflammation around the crown of a partially erupted tooth
The tooth is normally partially erupted and visible
Food & debris gets trapped under the operculum resulting in inflammation or infection
Usually transient and self-limiting
Usually occurs 20-40 years
General health not related to incidence of pericoronitis, except URTI
Second most common indication for M3M extraction
- what are signs and symptoms of pericorinitis?
- Pain
Swelling – Intra or extraoral
Bad taste
Pus discharge - from operculum
Occlusal trauma to operculum
Ulceration of operculum
Evidence of cheek biting
Foetor oris (halitosis)
Limited mouth opening
Dysphagia
Pyrexia
Malaise
Regional lymphadenopathy
what is treatment for pericorinitis?
- Incision of localised pericoronal abscess if required
+/- local anaesthetic (IDB) – depends on pain/patient
Irrigation with warm saline or chlorhexidine mouthwash (10-20ml syringe with blunt needle – under the operculum).
Extraction of upper third molar if traumatising the operculum
Patient instructed on frequent warm saline or chlorhexidine mouthwashes
what are POIG for pericorinitis?
- Advice regarding analgesia
Instruct patient to keep fluid levels up and keep eating (soft/liquid diet if necessary)
Generally do not prescribe antibiotics unless more severe pericoronitis, systemically unwell, extra-oral swelling, immunocompromised e.g. diabetic
If large extra-oral swelling, systemically unwell, trismus, dysphagia – refer to maxillofacial unit or A&E
what are predisposing factors to pericorinitis?
Partial eruption and vertical or distoangular impaction
Opposing maxillary M3M or M2M causing mechanical trauma contributing to recurrent infection
Upper respiratory tract infections as well as stress and fatigue pericoronitis
Poor oral hygiene
Insufficient space between the ascending ramus of the lower jaw and the distal aspect of the M2M
White race
A full dentition
during extra oral assessment if patient complains of problems with wisdom tooth when is it unlikely to be a wisdom tooth problem?
if 3rd molar unerupted no communication on distal of 2nd molar then more likely a tmj problem
during 3rd molar assessment what does an OPT determine?
Presence or absence of disease (in 3M or elsewhere)
Anatomy of 3M (crown size, shape, condition, root formation)
Depth of impaction
Orientation of impaction
Working distance (distal of lower 7 to ramus of mandible)
Follicular width
Periodontal status
The relationship or proximity of upper third molars to the maxillary antrum and of lower third molars to the inferior dental canal
Any other assoc pathology
what signs have been demonstrated to be associated with a significantly increased risk of nerve injury during third molar surgery
- diversion of the inferior dental canal
- darkening of the root where crossed by the canal
- interruption of the white lines of the canal
what is this?
Diversion/deflection of the inferior dental canal
what is this?
Darkening of the root where crossed by the canal
what is this?
Interruption of the white lines/lamina dura of the canal
what is this?
Deflection of root
what is this?
Narrowing of inferior dental canal
what is this?
Narrowing of the root
what is this?
Dark and bifid root
what is this?
Juxta apical area
- if suspect close relationship with IAN what do you take?
- what is angulation/orientation of wisdom teeth measured against?
cone beam CT
curve of spee
how is the 48 sitting?
transverse
what are the orientations of the wisom teeth here?
48 - lying mesially
38 - horizontal
what are the depth grades of bone removal and what are they related to?
Superficial – crown of 8 related to crown of 7
Moderate – crown of 8 related to crown and root of 7
Deep – crown of 8 related to root of 7
- how long does it take for sutures to usually dissolve?
- when is the risk of jaw fracture higher for mandibular wisdom tooth removal?
- 2-3 weeks
- large cystic lesion
- what are the post op complications
- what are the percentages for temp and permanent numbness?
- Pain
Swelling
Bruising
Jaw Stiffness/limited mouth opening
Bleeding
Infection
Dry Socket (localised osteitis)
Numbness (anaesthesia) or tingling (paraesthesia) of lower lip, chin, side of tongue
IDN (lower lip/chin):
Temporary 10-20 percent
Permanent <1%
Lingual Nerve (one side of tongue, taste)
Temporary – 0.25 – 23%
Permanent – 0.14 – 2%
- damage to what nerve causes altered taste and why?
- how long can it take for nerves to recover?
Altered taste (rare) (Revise Chorda Tympani - arises from Facial nerve, taste buds from anterior two thirds of tongue, carries fibres via Lingual nerve)
Dysaesthesia (rare) – painful, uncomfortable, unpleasant sensation of lower lip, chin, tongue; sometimes neuralgia type pain.
Also reduced sensation (hypoaesthesia) or heightened sensation (increased sensation).
- 18-24 months
if there is a close relationship to IAN what can you do?
- coronectomy and leave the root
what are steps of surgical removal
Anaesthesia
Access
Bone removal as necessary
Tooth division as necessary
Debridement
Suture
Achieve haemostasis
Post-operative instructions
- what is flap you do for a wisdom removal
- why is a lingual flap a risk?
- buccal mucoperiosteal flap +/- raising lingual flap
- risk of damaging lingual nerve
- what are the steps for reflection part of surgical removal?
- what are the most difficult reflection?
- what instruments do you use?
- Commence raising flap at base of relieving incision (already gaping / bone visible)
Undermine / free anterior papilla before proceeding with reflection distally (avoid tears)
Reflect with periosteal elevator firmly on bone
Avoid dissection occurring superficial to periosteum
Reduce soft tissue bruising / trauma
- Papilla
mucogingival junction - Mitchell’s trimmer
Howarth’s periosteal elevator
Ash Periosteal Elevator
Curved Warwick James elevator
what is this?
howarth elevator
what is this
mitchell trimmer
what is this?
ash elevator
what is this
rake retractor
what is this
Minnesota retractor
what are the steps of retraction for surgical removal
- Access to operative field
Protection of soft tissues
Flap design facilitates retraction
Howarth’s periosteal elevator, rake retractor or Minnesota retractor
Should be done with care
Atraumatic / passive retraction
Rest firmly on bone
Awareness of adjacent structures, e.g. mental nerve
- what is the steps for bone removal of surgical removal
- what can air driven handpieces cause
- Electrical straight handpiece with saline cooled bur
Round or fissure stainless steel & tungsten carbide burs
Protection of soft tissues
It is carried out on the buccal aspect of the tooth and onto the distal aspect of the impaction
The intention is to create a deep, narrow gutter around the crown of the wisdom tooth
Not a shallow, broad gutter
Bone should be removed to allow correct application of elevators on the mesial and buccal aspects of the tooth
- Air driven handpieces may lead to surgical emphysema
why do you start on distal for bone removal
start on distal then move round to mesial as starting from mesial creates risk of plunging into soft tissues
- how do you do a horizontal crown section?
- how do you section for a coronectomy?
- When sectioning to remove entire tooth section above the enamel – cementum junction. This leaves some crown behind and allows orientation and elevation.
Further Sectioning of roots after horizontal crown section if required. Then roots elevated individually.
- When carrying out coronectomy – section below enamel – cementum junction.
- how are tooth divided in surgical removal?
- Most commonly the crown of the tooth is sectioned from the roots and the crown and roots are elevated as individual items
Sometimes further separation of the roots with a bur is required following elevation of the crown, and each root is elevated as an individual item
- how do you do a vertical crown section?
- Where the roots are separate, the tooth may be sectioned longitudinally/vertically
This allows removal of the distal portion of the crown and distal root, followed by elevation of the mesial portion of the crown and mesial root
how do you do the debridement part of surgical removal?
Physical
Bone file or handpiece to remove sharp bony edges
Mitchell’s trimmer or Victoria curette to remove soft tissue debris
Irrigation
Sterile saline into socket and under flap
Suction
Aspirate under flap to remove debris
Check socket for retained apices etc
When the tooth is removed any debris must be cleaned out and any follicular tissue or granulation tissue from chronic infection should be curetted – especially that hidden behind the second molar
You must irrigate below the flap before you reposition it
- what are steps for suturing and what are aims?
Approximate tissues
Compress blood vessels
Aims
Reposition tissues
Cover bone
Prevent wound breakdown
Achieve haemostasis
what is this suture called
envelope
why is suture put here
if you feel papilla is free
what are complete steps of coronectomy?
Flap design as necessary to gain access to tooth. Generally – standard wisdom tooth flap designs
Transection of tooth 3-4mm below the enamel of the crown into dentine
Elevate/lever crown off without mobilising the roots
Pulp left in place – untreated
If necessary – further reduction of roots with a rose head bur to 3-4mm below alveolar crest (not always possible)
Socket irrigated
Flap replaced – some reposition flap leaving socket open, some close flap completely (primary closure with periosteal release if necessary)
Antibiotics not prescribed routinely
what is follow up for coronectomy?
Review 1-2 weeks
Further review 3-6 months then 1 year. Some review at 2 years but most discharge back to GDP after 6 months or 1 year review
Radiographic review – 6 months or 1 year; or both. Thereafter if symptomatic. Some take an immediate or 1 week post op radiograph
what must you warn patient about for coronectomy?
If the root is mobilised during crown removal the entire tooth must be removed (more likely with conical fused roots)
Leaving roots behind could result in infection (rarely seen)
Can get a slow healing/painful “socket”
The roots may migrate later and begin to erupt through the mucosa; and may require extraction
- when can upper third molars be difficult to remove?
- what must you support for upper third molars removal and what is there a risk of?
- dense bone or limited mouth opening
- Support the tuberosity with finger and thumb
If there is undue resistance to elevation/extraction then excessive force can fracture the tuberosity – the use of forceps and support to the tuberosity should reduce this risk in these circumstances
