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L3 Wisdom Teeth

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Wisdom Teeth1

Presentation Overview

This presentation provides a comprehensive overview of wisdom teeth management, presented by Dr. Richard Hague (Richard.hague@uwa.edu.au).

Learning Outcomes2

By the end of this session, participants should be able to:

  • Recognise and describe 3rd molar impactions.
  • Explain how to identify the proximity of other close anatomical structures.
  • Manage cases of pericoronitis effectively.
  • Discuss various management strategies for 3rd molars.
  • Explain the basic clinical steps involved in the surgical removal of a 3rd molar.
  • Describe the anatomical development and eruption patterns of third molars
  • Identify and classify impacted third molars using standard classification systems
  • Recognize clinical symptoms and pathologies associated with impacted third molars
  • Interpret radiographic signs indicating proximity to the inferior alveolar nerve (IAN)
  • Understand the indications and contraindications for third molar removal
  • Explain the principles of surgical management, including coronectomy and active surveillance
  • Identify and manage complications associated with third molar surgery

Anatomy and Development of Third Molars3

Factors Contributing to Impaction

  • Last teeth to develop
    • 3rd molar germ will not appear until ages 4-5 years
    • Mineralization of the crown occurs between 7-10 years
    • Crown formation complete between 12-16 years
    • Eruption varies between 17-25 years
      • Eruption can occur as early as 15 years in some documented cases
  • Lack of space
  • Irregularity in position - most likely to be ectopic
  • **Density of overlying and surrounding bone

Bone Density

In the mandible, the posterior bone is extremely dense (often compared to oak or mahogany), which is favorable for implants but provides significant resistance to eruption. **

Clinical Symptoms of Impacted Third Molars4

Patient Presentation

  • Pain
    • May be very specific
    • May be very vague (e.g., “dull ache”, “pressure”)
    • Potential earache
      • Earache is typically associated with maxillary third molars due to anatomical proximity
    • Potential headache
      • Headaches may present as pulsating sensations in the temples
      • Pain may be worse when lying down or radiate to the floor of the mouth and throat
  • Swelling
  • Infection
  • **Trismus

Clinical Note

Intraoral examination may reveal no visible pathology or pocketing behind second molars, even when radiographic evidence confirms impaction.

  • Trismus results from infection or proximity to the medial pterygoid, masseter, or temporalis muscles
  • Bad breath (halitosis) often indicates a chronic infection
  • Swelling may be associated with eruption cysts **

Classification of Third Molar Impactions5

Purpose of Classification

Classifying impactions is a useful exercise as it assists with:

  • Estimation of difficulty
  • Determining the surgical approach

Note

While these systems provide useful guidelines for treatment planning, clinical judgment remains essential as radiographic appearance does not always correlate with surgical complexity.

Soft Tissue Impaction

Overlying Tissue Classification678

Degree of Impaction

  • Soft tissue impaction
  • Bony impaction - partial
    • OPGs provide 2D images of 3D structures, making precise assessment challenging as lingual bone may be present without buccal bone, or vice versa
    • Complete bony impaction requires an osteotomy for access to the tooth
  • Bony impaction - complete

Winter’s Classification9

Inclination-Based Classification

Third molars are classified based on their inclination compared to the long axis of the 2nd molar.

Info

Proposed in 1926, Winter's classification is the most commonly used system for categorizing mandibular third molars.

Six Classifications:

  • Vertical (10 to -10 degrees)
  • Mesio-angular (80 to 10 degrees)
  • Horizontal (80 to 100 degrees)
  • Disto-angular (-10 to -80 degrees)
  • Transverse (buccolingual)
  • Inverted (180 degrees)

Pell and Gregory Classification101112

Depth Classification

This system evaluates the depth of the tooth relative to the occlusal plane and the 2nd molar.

  • Level A: Highest portion of the impacted third molar is level with, or above the occlusal plane.
  • Level B: Highest portion of the impacted third molar is below the occlusal plane but above the cervical line of the 2nd molar.
  • Level C: Highest portion of the impacted third molar is below the cervical line of the 2nd molar.

Ramus Space Classification

This system evaluates the space available between the ramus and the 2nd molar.

  • Class 1: Sufficient space between the anterior border of the ascending ramus and the distal aspect of the 2nd molar (greater than the mesio-distal width of the 3rd molar crown).
  • Class 2: The space available between the anterior border of the ascending ramus and the distal aspect of the 2nd molar is less than the mesio-distal width of the 3rd molar crown.
  • Class 3: The third molar is embedded in the bone of the ascending ramus because of the lack of space

Info

This classification is particularly valuable in research contexts for standardizing surgical complexity comparisons. .

Summary of Pell and Gregory Categories

Depth Levels:

  • Level A: Level with or above the occlusal plane.
  • Level B: Below the occlusal plane but above the cervical line of the 2nd molar.
  • Level C: Below the cervical line of the 2nd molar.

Ramus Space Classes:

  • Class 1: Sufficient space distal to the 2nd molar.
  • Class 2: Space is less than the width of the 3rd molar crown.
  • Class 3: Tooth is embedded within the ascending ramus.

Archer’s Classification13

Upper Third Molar Classification

Upper third molars are classified based on inclination and depth.

  • Archer's system combines Winter's angulation with depth assessment specifically for maxillary teeth
  • A classification of A7E represents significantly greater surgical difficulty than A1A

Inclination Categories:

  1. Mesioangular
  2. Distoangular
  3. Vertical
  4. Horizontal
  5. Buccoangular
  6. Linguoangular
  7. Inverted

Depth Categories:

  • a: Occlusal surface of the 3rd molar level with the 2nd molar.
  • b: Occlusal surface of the 3rd molar at the middle of the crown of the 2nd molar.
  • c: Occlusal surface of the 3rd molar at the cervical line of the 2nd molar.
  • d: Occlusal surface of the 3rd molar along the root of the 2nd molar.
  • e: Occlusal surface of the 3rd molar above the root of the 2nd molar.

![](L3 Wisdom Teeth_figures\page_13\fig_0.png) ![](L3 Wisdom Teeth_figures\page_13\fig_1.png) ![](L3 Wisdom Teeth_figures\page_13\fig_2.png)

Complications of Lower Third Molar Removal14

Case Study: Lingual Root Displacement

During a theater procedure with Dr. Fu, a root was displaced through the lingual plate into the submandibular tissues. Recovery required:

  • External pressure applied to the submandibular region
  • Approximately five minutes of manipulation to guide the root back to a visible position
  • Retrieval with aspiration suction

Management: If retrieval fails, referral to maxillofacial surgery for extraoral access (potentially via neck incision) may be required, with risk to salivary glands.

Potential Post-Surgical Issues

  • Displacement of root or tooth
    • Loss of control during luxation, particularly when the lingual plate is absent, can result in displacement into the submandibular space. Gravity works against retrieval, pushing the root posteriorly.
  • Dry socket
  • Bony defect distal to the 2nd molar
  • Periodontal defect distal to the 2nd molar
  • Altered sensation to the lip, chin, or tongue (injury to the Inferior Alveolar Nerve [IAN] or lingual nerve)
    • Lingual nerve injury mechanisms include direct sectioning during tooth division, perforation of lingual plate, crushing during suturing (nerve often within 2 mm of alveolar crest), or stretching from retraction.
  • Mandibular Fracture: Rare but documented, particularly with deeply impacted teeth or excessive force.
  • Retained Root Fragments: Generally acceptable to leave fragments <2–3 mm that are infection-free and non-mobile; however, mobilized fragments should be removed if possible.

Mandibular Third Molars and Inferior Alveolar Nerve Proximity1516

Sensory Risks and Radiographic Indicators

Risk of Altered Sensation:

  • Potential for temporary or permanent paraesthesia to the lip, chin, and tongue.
    • Temporary paraesthesia: 0.5–5%
    • Permanent paraesthesia: <1%

Radiographic Signs on OPG:

  • Darkening of the roots
    • Reduced radiopacity where the root overlays the canal, indicating the canal has carved a notch into the root or vice versa.
  • Interruption of the radiopaque line (loss of the corticated border)
  • Diversion of the ID canal
  • Dark and bifid apex
  • Deflection of the roots
  • Narrowing of the ID canal
  • Narrowing of the roots
  • Juxta-apical area

Radiographic Signs of Nerve Proximity17

Specific Radiographic Findings

  • Changes to the canal
  • **Juxta-apical area
    • Rare but highly prognostic darkened area just distal to the root (described by Tara Renton, a leading expert on paresthesias). **

![](L3 Wisdom Teeth_figures\page_17\fig_0.png) ![](L3 Wisdom Teeth_figures\page_17\fig_1.png)

Maxillary Third Molars1819

Complications and Assessment

Potential Complications:

  • Oroantral communication
  • Displacement into adjacent anatomical spaces
    • Tooth can rotate 180° and displace superiorly into the pterygopalatine fossa during luxation.
  • Fracture of the maxillary tuberosity
    • Risk is higher with long-standing second molars; may lead to severance of the maxillary artery.
  • Root fracture
    • Highly variable anatomy (conical vs. multiple spindly roots).

Imaging and Assessment:

  • Assessment is difficult from PA/OPGs due to projection.
  • CBCT is the best modality for showing relationships, though not necessarily indicated in all cases.

Predicting Oroantral Communication

  • ==No overlap between tooth and sinus on radiograph = likely safe.==
  • Darkening of roots indicates intimate sinus relationship.
  • Breaking of cortical border: Disruption of the sinus floor radiopaque line indicates high risk.

Case Study: High-Risk Oral Antral Communication

A colleague referred a patient where the radiograph showed breaking of the cortical border of the sinus floor over the distal root. During extraction:

  • The tooth delivered in approximately 45 seconds.
  • A 5–6 mm OAC was confirmed visually.
  • The adjacent first molar (extracted immediately prior) had taken 5–6 minutes, highlighting the unpredictable nature of high-risk extractions.

![](L3 Wisdom Teeth_figures\page_19\fig_0.png) ![](L3 Wisdom Teeth_figures\page_19\fig_1.png) ![](L3 Wisdom Teeth_figures\page_19\fig_2.png)

Suggested Reading20

Academic Publications

  • Themkumkwun, S et al, ‘Maxillary Molar Root Protrusion into the Maxillary Sinus: A Comparison of Cone Beam Computed Tomography and Panoramic Findings’ (2019) 48(12) International Journal of Oral and Maxillofacial Surgery 1570

  • Renton, T. (various publications on paresthesia and nerve injury in oral surgery)

  • Pell, G.J. & Gregory, G.T. (1933) - Classification systems

  • Winter, G.B. (1926) - Impaction classification

  • Archer, W.H. - Maxillary third molar classification

![](L3 Wisdom Teeth_figures\page_20\fig_0.png)

Pathology Associated With Third Molars21222324

Pericoronitis Clinical Presentation

Pericoronitis is the inflammation of the gingival tissues overlying a partially erupted tooth. Common symptoms include:

Pathophysiology

Pericoronitis occurs when an operculum (flap of gingival tissue) overlies a partially erupted tooth, trapping food and debris. It is the most common pathology, particularly affecting mandibular third molars.

  • Erythema
  • Swelling
  • Suppuration
    • Check for purulent discharge by running a finger along the buccal sulcus to the distal aspect
  • Radiating pain to the floor of the mouth (FOM), ear, or throat
  • Halitosis
  • Trismus (in severe cases)

Management Strategies

  • Flushing around the tooth and flap with saline
    • Use monoject syringes for irrigation with warm saline
  • Administration of antibiotics depending on severity (indicated if there is a risk of spreading infection)
  • Removal of the opposing tooth, as trauma from the upper tooth often exacerbates the condition
  • Removal of the impacted tooth
  • Operculectomy (generally not advised except for very short-term relief)
    • Tissue often regrows unless the tooth erupts fully

Associated Pathological Conditions

  • Pericoronitis
  • Periodontitis
  • Caries
  • Tumors

Types of Odontogenic Tumors

Various types of tumors are described in the literature associated with retained third molars, including:

  • Ameloblastoma
  • Odontogenic keratocyst
  • Odontogenic fibroma
  • Squamous cell carcinoma
  • Secondary metastatic lesions

Common Pathologies

  • Pericoronitis
  • Periodontitis
  • Caries
  • Tumors
  • Cysts

Dentigerous Cysts

The dentigerous cyst is the most common type of cyst associated with third molars. It is characterized as:

  • An epithelial-lined developmental cyst
  • Formed by an accumulation of fluid between the formed enamel surface and the reduced enamel epithelium
  • Typically appears radiolucent at the cementoenamel junction

Comprehensive List of Associated Pathologies

  • Pericoronitis
  • Periodontitis
  • Caries
  • Tumors
  • Cysts
  • Local and deep space infections
  • Root resorption
    • External resorption of adjacent second molars, typically observed in patients in their 50s–60s
    • Deep space infections involving submandibular, pterygomandibular, or sublingual spaces

![](L3 Wisdom Teeth_figures\page_21\fig_0.png) ![](L3 Wisdom Teeth_figures\page_22\fig_0.png) ![](L3 Wisdom Teeth_figures\page_23\fig_0.png) ![](L3 Wisdom Teeth_figures\page_24\fig_0.png)

Indications for Removal25

The decision to remove third molars is based on several clinical indicators and treatment requirements:

  • Ongoing pain
  • Infection (either a single severe episode or repeated mild occurrences)
    • Pericoronitis is the most common form of repeated mild infection associated with third molars.
  • Caries
    • Removal is indicated for non-restorable caries or when moisture control is impossible for restoration.
  • Presence of cysts or tumours
  • Resorption of the roots of the adjacent second molars
  • Necessity of a clear surgical field (e.g., for orthognathic surgery or Open Reduction Internal Fixation - ORIF)
  • Requirements of an orthodontic treatment plan
  • Socioeconomic factors and patient preference
  • Financial and insurance factors vary globally, with significantly higher removal rates observed in the US and Australia compared to other regions.
  • Prophylactic removal remains controversial; current evidence suggests wisdom teeth do not cause anterior crowding, though incisor resorption is a primary factor for consideration.

Management Strategies for Third Molars26

Assessment of Surgical Difficulty

The complexity of third molar removal can generally be estimated by evaluating the following factors:

  • Surgical difficulty correlates with patient age (easier at 17 than 40)
  • Classification of the impaction
  • Classification of the impaction
  • Maturation stage of the tooth
  • Age of the patient

Potential Surgical Complications

Practitioners must be aware of risks associated with the procedure, including:

  • Tooth or root displacement
  • Injury to nerves (such as the inferior alveolar or lingual nerves)
  • Injury to blood vessels
  • Damage to adjacent teeth

General Principles of Surgical Technique2728

The surgical approach to third molar extraction typically follows a standardized sequence of steps:

Lingual Retraction Controversy

Some surgeons place instruments in the lingual sulcus to reflect tissue and protect the lingual nerve. While this may cause temporary paresthesia from stretching, proponents argue it prevents permanent damage from incorrect sectioning. Opponents cite the risk of temporary nerve injury from the retraction itself.

  1. Flap: Reflection of mucoperiosteal tissue to gain access.
    • Buccal flap raised with periosteal elevator; lingual tissue reflected (with or without retraction)
  2. Trough: Removal of bone around the tooth to create space.
    • Troughing around the crown to minimize bone removal to reduce postoperative pain and infection risk
  3. Section: Dividing the tooth into smaller portions to facilitate removal.
    • Dividing the tooth (e.g., splitting crown from roots or sectioning mesioangular teeth through the crown and furcation)
  4. Elevate: Using instruments to luxate and remove the tooth segments.
    • Creating purchase points if necessary to facilitate luxation
  5. Irrigate: Thorough cleaning of the socket to remove debris.
    • Curettage of granulation/follicular tissue and thorough irrigation to remove debris
  6. Close: Repositioning and suturing the soft tissue.

Coronectomy29

Coronectomy is the deliberate retention of the roots of a third molar, often utilized to minimize the risk of nerve injury.

Indications and Outcomes

Indicated for high-risk cases where roots are intimately related to the inferior alveolar nerve, or for patients requiring preserved sensation (e.g., wind musicians, singers). Roots typically migrate coronally over time, potentially allowing safer removal later. Failure occurs if roots are mobilized during surgery or migrate unfavorably.

Procedural Steps

  • Flap: Surgical access to the site.
  • Sectioning: The crown is sectioned off approximately 2–4mm below the Cemento-Enamel Junction (CEJ).
  • Enamel Removal: All residual enamel must be removed from the remaining root structure.
    • Enamel is recognized as foreign by the body, whereas dentine is recognized as bone
  • Root Stability: It is critical that the roots are NOT mobilised during the procedure.

Clinical Technique Details

  • The drill is used 2–4mm below the crown level before elevation.
  • Final reduction should ensure the root surface is 3–4mm below the alveolar crest.

![](L3 Wisdom Teeth_figures\page_29\fig_0.png) ![](L3 Wisdom Teeth_figures\page_29\fig_1.png)

Active Surveillance

  • Regular monitoring of periodontal pocketing distal to second molars
  • Periodic radiographic surveillance (OPGs every 5 years unless symptomatic)
  • Patient education regarding risks and symptoms

Case Study: Incidental Dentigerous Cyst Detection

A patient under active surveillance presented for routine examination. Clinical observation of suspicious findings prompted an OPG, which revealed a previously impacted third molar that had randomly developed a giant dentigerous cyst. This case illustrates the importance of periodic surveillance imaging even in asymptomatic patients to detect pathological changes.

Footnotes

  1. Original PDF page 1: L3 Wisdom Teeth, p.1 ↩

  2. Original PDF page 2: L3 Wisdom Teeth, p.2 ↩

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