Class II Malocclusion: Causes, Diagnosis, and Treatment

Class II malocclusion is one of the most frequently encountered orthodontic conditions. It occurs when the lower first molar sits further back (distal) compared to the upper first molar, creating a mismatch between the upper and lower arches. This discrepancy can affect function, appearance, and long-term dental health if not corrected.

Table of Contents

What Is Class II Malocclusion?

In Angle’s classification of malocclusion:

Class I: molars align normally; misalignment may exist in other teeth.
Class II: lower molar sits behind the upper molar.
Class III: lower molar sits in front of the upper molar.

Within Class II, there are subtypes:

Division 1: upper incisors are proclined (tilted forward), often producing a pronounced “overjet” (horizontal overlap).
Division 2: upper incisors are retroclined (tilted backward), typically producing a deep bite.
Division 0: upper incisors are normally inclined, but the molar discrepancy remains.

Patients often present with a convex profile (curved outward facial shape) and a retrognathic mandible (lower jaw that sits back).

Etiology: Why Does Class II Malocclusion Happen?

Class II malocclusion is usually caused by a combination of skeletal, dental, soft tissue, and habit-related factors:

Skeletal Factors

Retrognathic mandible: lower jaw underdeveloped or positioned back.
Prognathic maxilla: upper jaw positioned forward.
Vertical variation: face height may be normal, increased, or reduced.
Transverse discrepancies: jaw asymmetries or crossbites.
Diagnostic markers: An ANB angle of ≥4° suggests a skeletal Class II.

Soft Tissue Factors

Lip incompetence: lips do not meet at rest.
Lip strain: lips must stretch to close.
Lower lip trap: lower lip rests behind upper front teeth, pushing them further forward.
Tongue posture: abnormal tongue resting or swallowing positions.

Habit-Related Factors

Thumb sucking, prolonged pacifier use, or tongue thrusting can tip upper teeth forward, tilt lower teeth backward, or narrow the arches — mimicking or worsening a Class II malocclusion.

Dental Factors

Proclined upper incisors (forward-tilted front teeth).
Bolton discrepancy: tooth-size mismatch between upper and lower arches.

Treatment Options for Class II Malocclusion

The choice of treatment depends on growth status (child vs. adult), severity, and etiology. Broadly, treatment falls into three categories:

1. Growth Modification (Growing Patients)

In children and adolescents, orthodontists can influence jaw growth to correct discrepancies.

Restraint of maxillary growth:
- Achieved with headgear (worn 12+ hours/day for about a year).
- Applies backward force to upper molars to slow forward growth of the upper jaw.
- Types of headgear:
  - Cervical pull: tends to rotate the lower jaw downward and backward, increasing lower face height.
  - Occipital pull: rotates the mandible upward and forward, reducing overbite.
  - Combination pull: blends both effects.
Encouraging mandibular growth:
- Achieved with functional appliances that posture the jaw forward, stimulating growth.
- Examples: Twin Block (removable appliance with bite blocks) and Herbst appliance (fixed, postures the lower jaw forward).
- Most effective in patients still undergoing significant growth (females ~11–14, males ~12–16).

2. Orthodontic Camouflage (Non-Growing or Mild Cases)

For patients with mild skeletal discrepancies who have finished growing, camouflage treatment repositions the teeth while accepting the underlying jaw relationship.

Removable appliances: limited use, mostly for mild cases with spacing.
Molar distalization: moving upper molars backward with appliances or headgear, typically followed by braces.
Fixed appliances with Class II elastics: rubber bands worn between upper and lower teeth to improve their relationship.
- Risks: may tip lower incisors forward excessively or extrude upper teeth, worsening bite in some cases.
Extractions:
- Often upper first premolars, sometimes paired with lower second premolars.
- Reduces overjet, relieves crowding, and improves profile.
- Example: extracting upper first premolars in a patient with excessive overjet allows the front teeth to be retracted for better alignment.

3. Surgical Treatment (Severe Skeletal Discrepancies)

In adults with severe Class II malocclusion, orthognathic surgery is often required because growth is complete.

Typically involves advancing the mandible (lower jaw surgery) and/or repositioning the maxilla.
Surgery is combined with orthodontics to align teeth before and after the operation.

Case Considerations

When planning Class II treatment, orthodontists consider:

Severity of skeletal discrepancy: mild cases may be camouflaged, severe cases require surgery.
Soft tissue profile: lip posture, nasolabial angle, and chin position affect extraction decisions.
Dental inclinations: proclined or retroclined incisors influence whether space must be gained or can be created by uprighting teeth.
Growth potential: growth modification is only effective in patients still growing.

Retention After Class II Treatment

Relapse is a risk after correction, so retainers are essential:

Bonded retainers: fixed wires behind anterior teeth for long-term stability.
Hawley retainers: removable with acrylic and wires; can include bite planes or headgear tubes for adjunct support.
Essix retainers: clear plastic trays, aesthetic but less durable.

Conclusion

Class II malocclusion is a common orthodontic challenge that can result from skeletal, dental, soft tissue, or habit-related factors. The hallmark is a distal position of the lower molars relative to the uppers, often accompanied by protrusive upper incisors and a convex facial profile.

Treatment varies depending on age and severity:

Growth modification in children (headgear, functional appliances).
Camouflage orthodontics in mild non-growing cases (braces, elastics, extractions).
Orthognathic surgery in severe adult cases.

With individualized diagnosis and planning, orthodontists can achieve functional, stable, and esthetic results for patients with Class II malocclusion.

Disclaimer

The contents of this website, such as text, graphics, images, and other material are for informational purposes only and are not intended to be substituted for professional medical advice, diagnosis, or treatment. Nothing on this website constitutes the practice of medicine, law or any other regulated profession.

No two mouths are the same, and each oral situation is unique. As such, it isn’t possible to give comprehensive advice or diagnose oral conditions based on articles alone. The best way to ensure you’re getting the best dental care possible is to visit a dentist in person for an examination and consultation.