Impacted teeth - 3rd molars Flashcards
When do you need to surgically remove a tooth?
when you cannot remove/extract a tooth conventionally:
- Gross caries so unable to use forceps and no application point for elevators
- Complex root morphology even if the crown is intact
- Retained roots below the alveolar bone so no point of application for elevators
- Impacted teeth
- Displaced teeth
- Ectopic teeth
- Pathology
What is impaction?
- occurs when there is prevention of complete eruption into a normal functional position due to lack of space or development in an abnormal position. This predisposes to pathological changes.
- this can involve only soft tissues or hard and soft tissues.
What is an ectopic tooth?
malpositioned due to congenital factors
What is a displaced tooth?
malpositioned due to presence of pathology
What is a completely unerupted tooth?
entirely covered by soft tissue and also partially/totally covered in alveolar bone
What is an ankylosed tooth?
fused with the alveolar bone, rare with 8s, occurs after middle age, tooth may not erupt at all
Generally, why do teeth become impacted?
lack of space in the arch as a consequence of evolutionary changes and lack of an abrasive diet
What are the most commonly impacted teeth?
the teeth which erupt latest:
- mandibular third molars
- maxillary canines
- mandibular premolars/canines
- maxillary incisors
- maxillary third molars
What does this radiograph show?
horizontally impacted partially erupted tooth 48 (LR8)
When do mandibular third molars emerge?
between 18-24 years but can be out with this range
How common is it for mandibular third molars to fail to develop?
fail to develop in 1:4 adults
What % of mandibular third molars are impacted?
72%
In the UK what guidelines are referred to for knowing when to refer a pt for third molar removal?
NICE (2000)
What is the most common indication for removal of mandibular third molars?
pericoronitis
What tooth has the most common incidence of caries due to an impacted mandibular third molar?
mandibular second molars with the third molar impacted against it, particualrly if it is mesioangularly impacted
What are some common indications for mandibular third molar removal?
- pericoronitis
- unrestorable caries
- cellulitis/osteomyelitis
- periodontal disease - particularly if over 30 years of age
- orthodontic reasons particularly if distalising maxillary buccal segments, inconclusive what contribution mandibular 8s make to crowding
What are some uncommon indications for mandibular third molar removal?
- prophylactic removal in medically/surgically compromised patients
- obscure pain
- tooth in line of fracture
- disease of follicle e.g. cyst, tumour
- orthognathic surgery
- transplant donor to another site in mouth
What does this radiograph show?
- horizontally impacted lower right 8
- extensive distal caries of lower right 7, unrestorable
What does this radiograph show?
cyst-like radiolucency on the whole corner of the mandible
What are the relative contraindications for the removal of impacted third molars?
- weigh up all variables
- asymptomatic teeth
- non-compliant patients - patients must be given all the information, document this in the notes
- overt nerve involvement
What is pericoronitis?
inflammation of the tissues around the crown of any partially erupted/impacted tooth
When is pericoronitis a reason to refer a pt for removal of a third molar?
when the patient has had 2 or more episodes of pericoronitis
What are the features of pericoronitis?
- trismus, pain, dysphagia, malaise, bad taste
- signs of inflammation of the pericoronal tissues, with frank pus from under the operculum
- cheek biting and cuspal indentations on the operculum
- halitosis, food packing
- can progress with systemic symptoms and spread to adjacent tissue spaces
What does this photo show?
pericoronitis
- third molar under the pad of soft tissue (operculum)
What does this photo show? How might you manage this?
a more extreme example of pericoronitis with signs of trauma on the soft tissues caused by being bitten on by the upper molar
may grind cusps of opposing tooth or if the opposing tooth is an upper 8 then may extract this
What does this photo show? How would this be treated?
extreme pericoronitis, operculum is very large and seems hyperplastic
treat with removal of upper 8 to remove trauma and then once the tissues around the lower 8 have improved arrange for extraction
How is pericoronitis treated?
local measures:
- irrigation, oral hygiene measures
- remove trauma, i.e. extract upper 8 or grind down cusps
general measures
- analgesics, antibiotics if systemically unwell/immunocompromised
- admission in severe airway threatening cases of cellulitis
What bacteria are commonly involved in periodontitis?
predominantly anaerobic
- Streptococci , Actinomyces, Propionibacterium, a beta-lactamase producing Prevotella, Bacteroides, Fusobacterium, Capnocytophaga and Staphylococci
What bacteria have been related to periodontal pocket deepening between the 2nd and 3rd molars?
Prevotella intermedia and Campylobacter rectus
When would antibiotics be prescribed in pericoronitis?
- antibiotics should only be prescribed when surgical removal of the cause or drainage of the infection under local anaesthesia is impossible (e.g. trismus, patient compliance).
- antibiotics are required if there is evidence of a systemic spreading infection necessitating urgent referral for hospitalisation.
What is involved in a mandibular third molar assessment appointment?
- history, examination, investiagtions
- balance between symptoms and need for removal and risks associated with removal or observation
- treatment choices are:
- conservative - monitor, regular x-rays etc
- operculectomy = NOT RECOMMENDED!
- removal
- coronectomy
What factors influence the decision of mandibular third molar removal?
- systemic disease, age
- anatomical position of tooth and root morphology, adjacent structures and teeth
- limited access
- patient compliance
- quantity, quality of bone, ankylosis
- presence of infection, periodontal disease, associated pathology, fractures
- history of TMJ problems
What is involved in the radiographical assessment of an impacted third molar?
- ideally an OPG (PA can sometimes show the root apices and relation to the IDC)
- visualise all the tooth and adjacent structures including bone, tooth morphology and number and shape of the roots, hypercementosis
- depth of bone around tooth
- follicular pathology
- external root resorption
- caries in the distal of the second molar
What 3 things must be commented on during radiographically assessment of an impacted mandibular third molar?
- relation to the 7 - crown, ACJ, or roots
- angulation to the adjacent teeth - vertical, mesio angular, disto angular, horizontal, transverse, aberrant
- proximity to the IDN - IDC-narrowing/darkening of canal as nerve crosses root, loss of white lines, deflection or deviation of IDC, dilaceration or bifid roots, change in colour of roots when crossed by nerve so that the area appears darker
What are the 3 Winter’s Lines?
white - occlusal plane
amber - bone margins
red - drawn from white line to mesio-buccal of amber line - indicates point of application of elevator
What are the 3 Winter’s Lines?
white - occlusal plane
amber - bone margins
red - drawn from white line to mesio-buccal of amber line - indicates point of application of elevator
What are the 4 descriptions for angle of impaction and how common are each?
- Vertical – around 30-38% of impacted 3rd molars
- Mesial – around 40%
- Distal – around 6-15%
- Horizontal – around 3-15%
Describe vertical impaction
3rd molar is sitting in the correct position in relation to the 2nd molar but has run out of space, may be impacted in soft or hard tissue
Describe mesioangular/mesial impaction
in relation to the 2nd molar the 3rd molar is tilted forward, the crown is inclined mesially to the vertical position it should be in. can’t clean between the contact point making the 2nd molar more prone to caries
Describe distoangular impaction
opposite to mesioangular, the crown of the 3rd molar is tilted distal in relation to the 2nds molar. the roots of the 3rd molar may be very close to the 2nd molar making getting an application point quite challenging
Describe horizontal impaction
like extreme mesioangular impaction, crown of the 3rd molar is 90 degrees to the 2nd molar
What does this radiograph show?
mesioangularly impacted lower right 8
What are the radiographic signs of a close relationship between the lower third molar and the IDC?
- Diversion of IDC
- Darkening of root as it is crossed by the IDC
- Loss of Lamina Dura of IDC
- Narrowing of IDC
- Deflection of roots of lower third molar as they approach the IDC
- Juxta apical area
What is a juxta apical area?
where there appears to be a free floating apex on one side of the canal which seems to be independent of the rest of the root on the other side of the canal
What does this illustration show/suggest?
Canal and roots superimposed but not close together
What does this illustration show/suggest?
Loss of lamina dura, no surrounding wall between contents of the canal and the roots
What does this illustration show/suggest?
lamina dura of canals lost, as canal crosses the roots there is a change in relative radiolucency of the roots (darkens where canal crosses) suggesting there is less mineralised tissue so either the canal is sitting in a groove in the roots or perforates through the roots itself, also has juxta apices.
high risk
What does this radiograph indicate about the relationship of the LR8 to the IDC?
canal narrowing, indicates close relationship of roots to IDC
What does this radiograph indicate about the relationship of the LL8 to the IDC?
could be superimposition but not clear cut, IDC bundle could be sitting on a groove on the tooth root
What does this radiograph indicate about the relationship of the LL8 to the IDC?
appears to be high risk as apex darker in relation to the rest of the root
What can CBCT imaging tell us about 3rd molar/IDC relationship that DPT can’t?
3D image, will tell you exactly where the IDC sits in relation to the roots, shows us another dimension
What does this CBCT tell us?
Bundle contents sitting on the lingual aspect of the 8, not as high risk as the 2D image suggests
Where do the majority of IDCs sit in relation to the 3rd molar?
lingual aspect (up to 70%)
What % of IDCs radiographically sit below the apices of all teeth?
67.7% (~2/3)
What % of IDCs radiographically sit only 2mm below the apices of the premolars?
15.6%
What % of IDCs radiographically sit only 2mm above the lower border of the mandible?
5.2%
What % of IDCs are partially or totally absent on radiographs?
11.5%
What are the % incidences of post operative alteration in sensation to the lower lip and tongue (short term and long term)?
Lower lip
- Short term – 5%
- Long term – less than1%
Tongue
- Short term – 10%
- Long term - less than1%
- Taste – can be affected
Why is altered sensation in the tongue more common than in the lip?
previously thought to be surgical technique and lingual extraction such as seen in this photo
What is a coronectomy?
remove the crown and leave the roots in place
What may occur during a coronectomy?
if the roots are mobile at the time of coronectomy you must remove them, therefore when consenting the patient state that the plan is to coronect the tooth but removal may be unavoidable
What may happen after a coronectomy?
Post-operatively there is a risk if infection of the roots and a risk of migration of the roots upwards into the mouth
What does this radiograph show?
post-coronectomy of lower 8s
What does this radiograph show?
post-coronected retained roots which have migrated into the mouth, need another surgery to remove this but is at lower risk of damage to the IAN now
What happens if enamel is left behind after a coronectomy?
bone will not form on/around enamel so will cause problems
When should CBCTs be carried out?
when the findings are expected to alter management decisions
For third molar removal, what is planned from the radiograph (DPT)?
5 points planned from radiograph (DPT)
- what would be the path of eruption
- extrinsic/ intrinsic obstacles to removal
- required bone removal
- point of application
- flap design
(plan in reverse order from the order of the surgery e.g. plan the flap last)
What do each of the markings on this radiograph indicate in terms of surgical planning?
blue arrow - path pf withdrawal
green crosses - extrinsic obstacles
blue dotted line - level of bone removal
red - point of application for elevator
What flap is usually used when removing a 3rd molar?
3-sides/triangular flap - distal relieving incision up the ascending ramus, around the crown of the 3M, include the papilla between the 3M and 2M and mesial relieving incision
What does this show?
a triangular flap
What are 1, 2 and 3 labelling?
1 = distal relieving incision, 1 crown length long, landmark= ascending ramus
2 = perio-coronal incision cutting through the alveolar crest fibres includes the papilla between the 3M and 2M
3 = mesial relieving incision down from the 2M to the depth of the sulcus
What is an envelope flap?
doesn’t have a mesial relief inscision, extends pericoronally around the 2nd molar
How is bone removed during a surgical extraction?
using burs
- saline irrigation
- to relieve impaction
- create point of application
- remove bone with round bur to create a narrow gutter mesio buccally avoiding adjacent roots then switch to fissure bur to create deep gutter
During a surgical extraction when is the crown divided?
either horizontally or axially
- horizontal impactions
- distoangular to avoid excessive bone removal but ensuring a good application point is retained
When would roots be divided for removal?
pincer (convergent) roots, divergent roots (differing paths of withdrawal)
What would be needed to remove this 3rd molar?
need to section crown off
- bone removal to level of ACJ
- drill 2/3 of way through the crown and remove using elevator
- elevate roots
Describe what would be done to remove this 3rd molar
- triangular flap
- bone removal
- crown sections at level of ACJ
- division of furcation/roots
- elevations of roots
- debridement of cavity
- suture flap back in place
Describe would be done to remove this third molar
- triangular flap
- remove bone
- section crown at level of ACJ
- division of furcation/roots
- elevation of roots
- debride socket
- suture flap back in place
Why are convergent or divergent roots intrinsic obstacles?
differing paths of withdrawal, requires sectioning of furcation
What should be done or not done when using elevators?
- different types of elevators and the indications for use
- minimal force using an application point, never use adjacent tooth as fulcrum point , avoid levering
- avoid unfavourable rotation of apex into IDB
- always support mandible whilst using elevators
What are the key points about flap suturing after a surgical?
- when planning the flap design it was essential that after surgery the flap would rest on bone to avoid wound breakdown
- the most important suture is the one placed from the buccal tissues to the lingual tissues immediately distal to the second molar tooth to encourage good periodontal health
- the fewer sutures placed the better to secure primary closure and haemostasis
- materials 3/0 vicryl rapide
What is anatomical closure?
realigning the flap exactly where it started, which means you don’t have full closure of the wound
What is the post operative regime for a 3rd molar removal?
- analgesics (+/- antiobiotics if risk of infection e.g. immunocompromised)
- HSMW
- soft diet
- topical ice packs
- suture removal at one week if not resorbable
- arrange follow up for difficulty cases or immunocompromised patients, or if high risk for altered sensation
What are the complications associated with the surgical removal of impacted 3rd molars?
- haemorrhage - primary or secondary
- loose teeth or damage to adjacent
- fractured mandible
- dry socket (1-5%) or infection with purulent discharge
- sensory deficit - IDB = 5% temp, lingual temp = 10%, perm = <1%
- complications generally associated with any extraction
How are maxillary 3rd molars classified?
in the same way as mandibular 3rd molars
- majority mesioangular or vertically impacted
Compared to mandibular 3rd molars what makes extraction of maxillary 3rd molars less complicated?
- thin cortical bone
- short single root in 74% cases
What are the difficulties when extracting maxillary 3rd molars?
- access difficult due to position behind second molars, malar buttress and buccal position therefore oral hygiene problematic when erupted
- unerupted teeth may cause resorption of the second molar , associated pathology
If a pt is undergoing GA for removal of symptomatic mandibular 3rd molars, what is often recommended to them?
simultaneous removal of maxillary 3rd molars, for convenience
How are erupted maxillary 3rd molars removed?
elevation or forceps extraction
How are unerupted maxillary 3rd molars removed?
- raise buccal flap, thin friable bone removed with couplands and elevator used to move the tooth down, back and buccally
- one suture to reposition flap
When removed upper 3rd molars why should excessive upwards force be avoided?
due to possible displacement into antrum
Summary of impacted 3rd molar treatment lecture
