3 - Dentoalveolar

Question 2

3rd Molar Classification

Answer 2

• Descriptive
  
  • Lower Third Molars
  • Winters Angulation Classification
    
    • Mesio - 45%
    • Vertical - 40%
    • Horizontal - 10%
    • Distoangular - 5%
    • Buccoangular
    • Linguoangular
    • Inverted
  • Upper Third Molars
  • Archer Classification
    
    • 1 - Mesio
    • 2 - Disto
    • 3 - Vertical
    • 4 - Horizontal
    • 5 - Buccal
    • 6 - Palatal
    • 7 - Inverted
      ​
• Assessment of Difficulty
  
  • WHARFE
    Maximum Score 16
    
    • Winter’s Angulation Classification
    • Height of mandible
    • Angulation of 2nd Molar
    • Root morphology
    • Follicle size
    • Exit pathway
      ​
  • Pell and Gregory
    
    • Ramus assessment - Roman Numerals
      
      • I - Anterior to ramus
      • II - 50% within ramus
      • III - completely within ramus
    • Occlusal plane
      
      • A - At occlusal plane
      • B - Between occlusal plane and CEJ
      • C - Below CEJ
        ​
  • Winter’s Line
    
    • White Line - Occlusal place
    • Amber Line - Bone level
    • Red Line - Perpendicular to occlusal plane to elevation point
      Distance between Amber line to point of elevation is measured
    • Interpretation
      
      • <5mm - LA
      • >5mm - GA
      • Every 1mm increases difficulty by 3x
        ​
  • Pedersen Classification
    
    • Pell and Gregory + Winters angulation
      ​
  • Lim Classification (Upper wisdom teeth)
    
    • Archer + Relationship to the sinus and 7s

Question 3

3rd Molar complications

Answer 3

• General risks with surgery
• Specific risks
  
  • Nerve
    
    • IAN
      
      • Nguyen 2014
    • Lingual
      
      • Pichler 2001
        
        • Temp 2% (7% with retraction)
        • Perm 0.5%
  • Infection
    
    • Ren 2007
      
      • 4% - Abx
      • 6% - No Abx
  • Dry socket
    
    • Ren 2007
      
      • 6% - Abx
      • 14% - No Abx
  • Fracture
    
    • 1 in 25 000

Question 4

3rd Molar Difficulty Assessment

Answer 4

*

Question 5

3rd Molar Epidemiology and Overview

Answer 5

• Carter and Worthington 2016
  
  • Impaction rate 25% of population
  • 75% have 4 wisdom teeth
  • 25% have 0-3 wisdom teeth
    ​
• Impaction theory
  
  • Differential rate of growth of mesial and distal roots
  • Inadequate arch space
  • Tooth developmental lags behind jaw growth so can’t influence it
  • Processed diet, better hygiene -> less dental loss -> inadequate space
    ​

Question 6

3rd Molar Indications and Contraindications

Answer 6

Indications

• Pathology - NICE 2000
  
  • Periodontal
  • Caries
  • Infective
    
    • Periapical
    • Abscess
  • Neoplastic
  • Fracture
  • Resorption 2nd Molar
• Prophylactic Removal
  
  • AAMOS 2014
    
    • Perio pocketing >5mm on 7s or in general
    • Orthodontic or orthognathic interference
    • Prosthodontics - Denture interference
    • Symptomatic
      
      • Food impaction
    • Medical
      
      • Immune suppression - Organ transplant
      • Radiotherapy and Chemotherapy
      • Implants - Joint prosthesis or other alloplastic implant
      • Occupational
        Prevention of mandible fracture - 2.8x Zhou
        
        • Military
        • Professional contact sport
  • Hyam 2018
    
    • Disease negative, Symptom negative
      
      • Patient
        
        • Med Hx
        • Finances
        • Social
        • Occupational/Hobbies
      • Dental
        
        • Difficulty
        • Proximity to nerve & Risk of complications
      • Surgeon
        
        • Experience
          ​

Contraindications

• <12 yrs old - Unable to predict whether tooth will erupt
• >40 yrs old - Risk potentially outweigh benefits
• Medically compromised and unfit for surgery
• Limited MO
• Unable to accept IAN risk
• Surgeon experience

Question 7

ww.3rd Molar Nerve Injury

Answer 7

• AAOMS 2014
  
  • 1% to 5% IAN (Temp + Permanant)
    0-0.9% IAN (Permanant)
  • 0.4 - 1.5% Lingual (Temp + Permanant)
    0 - 0.5% Lingual (Permanant)
• Nguyen 2014
  
  • 0.68% - IAN (Temp + Permanant)
    0.24% IAN (Permanant)
  • 0.15% - Lingual (Temp + Permanant)
    0.079% - Lingual (Permanant)
    ​
• Pichler 2001
  
  • 8x more likely for lingual nerve injury with retraction
    Lingual retraction was not protective for permanant nerve injury
  • 6.4% - Lingual retraction (Temp + Permanant)
    0.6% - Lingual retraction (Permanant)
  • 0.6% No lingual retraction (Temp + Permanant)
    0.2% - No lingual retraction (Permanant)

Question 8

3rd Molar NICE Guideline review

Answer 8

• ​McArdle & Renton 2012 - The effects of NICE guidelines on management of third molars
  
  • Removal of wisdom teeth
    
    • Mean age increased 25 to 32 yrs old
    • Initial decrease for removal in secondary care setting by 30%
      But recent increase by over 97%
    • Caries and infection indication increased from 10% to 30%
  • Population health
    Increased cost per removal of wisdom teeth
    
    • Increased number of extractions in the secondary care setting (specialists)
    • Increased numbers of GA vs LA

Question 9

3rd Molar Perioperative Meds

Answer 9

• Antibiotics
  
  • Pre op antibiotics - Ren 2007
    
    • Dry socket: 14% to 6%
    • Surgical site infection: 6% to 4%
  • Post op antibiotics - Lodi 2012
    
    • Indications
      
      • Pre op infection
      • Immunocompromised
      • Higher risk of dry socket
        
        • Female
        • OCP
        • Smoking
        • Pericoronitis
        • Prev dry socket
        • Difficult extraction
          ​
• Steroids
  
  • Cho 2017
    
    • Pre op reduces swelling and trimus
    • Post op - No evidence
      ​
• Chlohexidine
  
  • Cho 2017
    
    • Reduces post op infection and dry socket
    • Pre op rinse + Post op for 1/52

Question 10

3rd Molar Prophylactic Removal vs Retention

Answer 10

Indications for prophylactic removal

Hyam 2018

• Med Assessment
  
  • Part of tumor resection
  • Pre-medication assessment
    
    • Bisphosphonates
    • Anticoagulants
  • Pre-geriatric assessment
  • Altered mental capacity
  • Reduced physical dexterity
    
    • Tremors
    • Neuromuscular disease
  • Pre-Treatment
    
    • ​Radiotherapy
    • Chemotherapy
  • Immuno-modifier therapy
    
    • ​Bacteraemia
    • Tissue-transfer patients
• Dental Assessment
  
  • Orthodontics
  • Orthognathic surgery
  • Prosthodontic inhibitor
  • Periodontal disease
• Financial
  
  • Future loss of income during infective episodes
  • One episode of recovery for removal of remaining wisdom teeth
  • Insurance policy
• Social
  
  • Military or scientific personal
  • Sports and Hobbies
  • Availability of home and community support

Risks of retention

Bouloux 2015

• 3% per yr of requiring removal
  65% risk overall

McArdle & Renton 2012 - The effects of NICE guidelines on management of third molars

• Mean age increased 25 to 32 yrs old
• Initial decrease for removal in secondary care setting by 30%
  But recent increase by over 97%
• Caries and infection indication increased from 10% to 30%
• Retention Risks
  
  • Caries 8, Caries 7
    
    • 23% higher for mesioangular - Toedtling 2019 MA
  • Periodontal complication
    
    • Pericoronitis
    • Periodontal defect of 7
    • 38% of ppl with perio will worsen within 2 yrs - Ghaemin 2016
  • Resorption of 2nd molar - 3% - Mercier 1992
  • Deep space infection - 0.8% - Yoshi 2001
  • Odontogenic cyst or tumor - 5% - Mello 2019
  • Increased difficulty and complications with age - Pogrel 2019
    
    • Benefits of removal before age 25
      
      • 50% non impacted and 75% of impacted teeth fail to erupt - Kruger 2001
      • After age 25 there is a 3% per yr risk of extraction
        64% chance of teeth needing to be removed by age 43 - Bouloux 2015
      • Reduced incidence of infection, dry socket, nerve injury, perio pocketing - Pogrel 2012
      • 7s distant caries increases - 40% - McArdle 2019

Question 11

Apicectomy Indications and Contraindications

Answer 11

• Indications
  
  • Orthograde root re-treatment not possible
    
    • Dense GP
    • Post core crown in situ
    • Broken instument
    • Complex root anatomy
    • Calcified canals
  • Iatrogenic displacement of material into root apex
  • Fracture of 1/3 distal root tip
  • Persistent lesion despite adequate Endo
• Contraindications
  
  • Re-treatment not attempted
  • Poor prognosis of tooth
  • No coronal seal
  • Apex near IAN or sinus
  • Short roots

Question 12

Apicectomy Outcomes

Answer 12

• Retrograde filling material - Ma 2016 (Cochrane review)
  
  • No difference in material
    ​
• Outcomes - Beck-Boichsitter 2018
  
  • 60% over 5 yrs, 50% over 10yrs
    
    • Retrograde filling improves survival by 10%
      ​
  • Surgical vs Non surgical management - Del Fabbro 2007
    
    • No difference is success outcome

Question 13

Canine impaction eruption prognosis

Answer 13

• Liu 2008
  CBCT study
  
  • 45% - Buccal
  • 40% - Palatal
  • 10% - Mid alveolus
    ​
• Prognosis of eruption
  
  • Ericson and Kurol 1987
    Midline of lateral is the demarcation line
    
    • 91% - if lateral to midpoint of lateral
    • 64% - if medial to midpoint of lateral
      ​
  • Warford 2003
    Broken into 4 zone based on the lateral
    
    • 94% - Lateral to lateral border of lateral incisor
    • 62% - Between lateral border and midpoint of lateral incisor
    • 13% - Between midpoint and medial border of lateral incisor
    • 1% - Medial to medial border of lateral incisor
      ​
• Sequelae of nil treatment - RCSEng 2016 Guidelines
  
  • 66% - Root resorption on laterals
    *

Question 14

Canine impaction risk factors

Answer 14

• Systemic
  
  • Syndromes
    
    • Gardners
    • Cleidocranial dysplasia
    • Downs
  • Metabolic
    
    • Hypothyroidism
    • Hypopituitary
  • XRT
• Local factors
  
  • Trauma
  • Cleft
  • Crowding
  • Ankylosis of C
  • Pathology
  • Supernumerary
  • Root dilaceration

Question 15

Canine impaction theories

Answer 15

• Genetics - Peck 1994
  
  • Factors supporting genetics
    
    • Anomalies associated with impacted canines
    • Bilateral occurrence
    • Gender predilection - more common in females
    • Familial occurrence
    • Population differences
• Guidance theory - Becker 1995
  
  • Missing lateral
  • Peg lateral

Question 16

Canine impaction treatment options

Answer 16

*

Question 17

CBCT signs re proximity to IAN

Answer 17

• Ghai and Choudhury 2018
  
  • Inter-radicular position of nerve
  • Thinning of lingual cortex
• Intraop nerve exposure = 20% risk of injury (Tay 2004)
• Loss of cortical integrity of canal = 12% risk of IAN injury (Park 2010)
• Therefore identify features associated with increased IAN exposure
  
  • Ghai and Choudhury 2018
    
    • Inter-radicular position of nerve
    • Thinning of lingual cortex
  • Cortical defect of canal >3mm
  • Dumbell/teardrop shape canal

Question 18

Coronectomy Indications & Contraindications

Answer 18

• Indications
  
  • OPG signs (1 out of 3 high risk Rood signs) - Blaeser
    Increases nerve injury risk from 1% to 3%
  • CBCT signs
    
    • Loss of cortication >3mm
    • Roots straddle nerve
    • Compression of nerve against cortex
    • Dumbell/Teardrop shaped canal
  • Social or occupational reasons why nerve injury is more critical
    ​
• Contraindications
  
  • Patient factors
    
    • Can’t attend followup
    • Immunosuppressed
    • Adjuvant chemoradiotherpy
  • Pathology
    
    • Caries to pulp
    • Periapical pathology
    • Mobile root
    • Nerve lies adjacent to crown (Horizontal impaction)
      ​

Question 19

Coronectomy Outcomes

Answer 19

• Pitros 2020 SR
  doi.org/10.1016/j.bjoms.2020.07.015
  Combined data from 4 RCT (including Renton Study)
  
  • IAN injury
    
    • Renton
      
      • Coronectomy - 0%
      • Failed Coronectomy - 8%
      • Surgical Removal - 19%
    • 1.3% - Coronectomy
      7.4% - Surgical Removal
      OR - 0.16
      Reduces nerve injury by 84%
  • Dry Socket
    
    • 2.8% - Coronectomy
      ​5.4% - Surgical removal
  • Infection
    
    • 3.0% - Coronectomy
    • 3.5% - Surgical removal
  • Root migration - Leung & Cheung 2018 RCT
    
    • Young patients more at risk
    • Average 2mm (up to 6mm)
    • 90% migration in the first 6month, 5% after 24 months
    • 2.3% requiring removal

Question 20

Coronectomy Technique

Answer 20

• Renton 2013 update
  
  • Buccal triangular flap
  • No lingual retraction
  • Fissure bur to expose tooth
    Do not drill below CEJ
  • Fissure bur used to section the tooth at CEJ
    Drill only as far as the pulp chamber (to protect lingual nerve)
  • Elevator to fracture the crown from tooth but care must be taken not to apply excessive force
  • Check for mobility of roots
  • Rose tip bur to trim enamel spurs
    Ensure cementum several mm below alveolar crest
  • Leave pulpal tissue to maintain vitality to the root
  • Primary closure
    Post op Chlorhex, No abx
    ​
• Pogrel 2004
  
  • Pre op abx
  • Buccal flap with relieving incision
    Lingual flap raised
    Broad base retractor - Walter lingual retractor
  • Crown completely sectioned at 45 degree angle
    Removed with tissue forceps
  • Fissure or Round bur to reduce remaining enamel
  • Ensure cementum 3mm below CEJ
  • Primary closure

Question 21

Factors affecting difficulty of wisdom teeth

Answer 21

• Patient Factors
  
  • Renton 2001
    
    • Patient weight
    • Age
    • Ethnicity
  • Proximity to IAN
    
    • Rood signs
    • CBCT signs
• Surgical Factors
  
  • Dental Factors
    
    • Classification
      
      • WHARFE
      • Pell and Gregory
      • Winter’s Line
      • Winter’s Classification
    • Renton 2001
      
      • Application depth
      • Bone impaction
      • Root formation

Question 22

Hyperdontia & Hypodontia Causes

Answer 22

• Hyperdontia
  
  • Cleidocranial dysplasia
  • Ehler Danlos
  • Fabry Disease
  • Gardners syndrome
  • Cleft lip and palate
  • Crouzon
    ​
• Hypodontia
  
  • Craniofacial microsomia
  • Treacher collins
  • Kabuki syndrome
  • Cleft lip and palate
  • Ectodermal dysplasia
  • Gorlin goltz syndrome
  • Downs syndrome

Question 23

Indications for pre radiotherapy extractions

Answer 23

• Ben David 2007
  
  • Teeth with unrestorable caries
  • Caries extending to gingival margins
  • Large compromised restorations with pocketing >5mm
  • Periodontal disease
    
    • Mobile teeth
    • Significant pocketing
    • Advanced recession or furcation involvement
  • Severe erosion or abrasion
  • Non functional teeth
  • Primary closure and alveoloplasty

Question 24

Rood Signs

Answer 24

• High Risk
  
  • Darkening of the root
  • Deviation of canal
  • Interruption of white line
• Low Risk
  
  • Deflection of root - Possibly clinically significant
  • Narrowing of root - Possibly clinically significant
  • Bifid root apex
  • Narrowing of canal