increased overjet

Overjet refers to the horizontal distance between the incisal edge of the upper central incisors and the labial surface of the lower central incisors when the teeth are in centric occlusion. In a normal occlusion, the overjet ranges from approximately 2 to 4 millimeters. Any value exceeding this range is considered an increased or excessive overjet. Clinically, an increased overjet can significantly affect both function and aesthetics, leading to issues such as difficulty in lip closure, increased risk of dental trauma, and compromised facial harmony.

Understanding the aetiology, diagnostic features, and management approaches for increased overjet is fundamental to orthodontic practice. The etiology is multifactorial, involving skeletal, dental, and soft tissue components, and the management approach depends on the underlying cause, the patient’s age, and growth potential.

Aetiology of Increased Overjet

The causes of increased overjet can be broadly divided into skeletal, dental, and soft tissue factors. Each of these may exist independently or in combination, contributing to the observed malocclusion.

1. Skeletal Factors

The skeletal pattern plays a pivotal role in the development of an increased overjet. Skeletal discrepancies often manifest as a Class II skeletal relationship, characterized by either maxillary protrusion, mandibular retrusion, or a combination of both.

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Approximately 75% of increased overjet cases are associated with Class II Division 1 malocclusion. The skeletal basis of these cases can be attributed to:

  • Mandibular retrognathia: A posteriorly positioned mandible on the cranial base contributes to an apparent forward position of the maxilla and upper incisors relative to the mandible.
  • Maxillary prognathism: In some cases, the maxilla is excessively forward in relation to the cranial base, increasing the anteroposterior discrepancy between the jaws.
  • Vertical disproportions: An increase in lower anterior facial height can also contribute to a clockwise rotation of the mandible, thereby accentuating the horizontal overlap of the incisors.

 

From a cephalometric perspective, skeletal Class II relationships are often associated with an increased SNA (indicating maxillary prominence), decreased SNB (indicating mandibular retrusion), and consequently an increased ANB angle.

In these cases, treatment becomes challenging because the skeletal component limits the amount of overjet correction achievable through dental movement alone. Orthopedic or surgical intervention may be required depending on the patient’s growth status.

2. Soft Tissue Factors

Soft tissue dynamics play a significant role in both the etiology and maintenance of an increased overjet. The relationship between lip posture, tonicity, and the dentoalveolar structures often determines whether an existing skeletal discrepancy will be masked or accentuated.

  • Lip incompetence: Patients with an increased overjet often present with lips that do not meet at rest, resulting in a gap between the upper and lower lips.
  • Lower lip position: In some individuals, the lower lip may rest behind the upper incisors rather than in front of them. This position exerts a proclining force on the upper incisors while simultaneously exerting a retroclining force on the lower incisors, worsening the overjet.
  • Soft tissue compensation: The extent to which soft tissues can compensate for skeletal discrepancies depends on their tone and adaptability. For instance, strong perioral muscles can help mask minor skeletal discrepancies by maintaining tooth position within functional limits. Conversely, reduced muscle tone leads to instability and relapse after orthodontic correction.

 

The greater the skeletal discrepancy, the less likely it is that the soft tissues alone can provide sufficient compensation. Therefore, assessing lip competence and tonicity forms a crucial part of diagnosis and treatment planning.

3. Dental Factors

Dental factors contributing to increased overjet include both tooth positioning and habits that alter tooth inclination.

  • Proclination of upper incisors: Upper incisors that are proclined due to crowding, spacing, or habit-related forces contribute directly to an increased horizontal overlap.
  • Retroclination of lower incisors: This can occur due to lower arch crowding or compensatory changes in response to an increased overjet, further increasing the apparent discrepancy.
  • Digit-sucking habits: Thumb or finger-sucking applies a combination of anterior and superior pressure on the maxillary incisors, leading to their proclination and extrusion. Simultaneously, the lower incisors are often retroclined due to the placement of the thumb behind them. The overall effect is an increased overjet and often an anterior open bite.
  • Dental crowding: Crowding in either arch can influence tooth inclination, contributing indirectly to an increased overjet.

 

The correction of dental factors requires the elimination of deleterious habits, space management through extraction or expansion, and controlled tooth movement to achieve optimal inclination and occlusion.

 

Clinical Implications

The clinical significance of an increased overjet extends beyond aesthetics. The most notable consequences include:

  1. Trauma Risk: Children with a pronounced overjet and incompetent lips are at a much higher risk of traumatic dental injuries to the upper incisors.
  2. Speech Difficulties: Excessive overjet may affect articulation, particularly of labiodental and sibilant sounds.
  3. Functional Issues: An excessive horizontal overlap can interfere with incisal guidance and normal masticatory function.
  4. Psychosocial Effects: The aesthetic impact of prominent upper incisors can lead to reduced self-esteem, particularly in adolescents.
  5. Gingival Health: Lip incompetence can lead to mouth breathing and subsequent gingival inflammation in the anterior maxilla.

 

Diagnosis and Assessment

A thorough diagnostic evaluation includes:

  • Clinical examination: Assessment of incisor inclination, overjet measurement, lip competence, and facial proportions.
  • Cephalometric analysis: Determines skeletal relationships (SNA, SNB, ANB), dental inclinations (U1-SN, L1-MP), and vertical proportions.
  • Soft tissue evaluation: Determines whether the patient can achieve lip seal comfortably and assesses muscle tone.
  • Functional analysis: Includes observation of habits such as thumb sucking or tongue thrusting.

 

The diagnostic findings form the foundation for treatment planning and prognosis determination.

 

Management of Increased Overjet

The management strategy depends on the severity of the overjet, skeletal pattern, growth potential, and patient motivation. Treatment aims to establish functional occlusion, improve aesthetics, and enhance stability.

1. Class I or Mild Class II Skeletal Pattern

In patients with a Class I skeletal pattern or a mild Class II discrepancy, the overjet increase is usually dental in origin. These patients can typically be managed with orthodontic appliances alone.

Functional Appliances (FA):

Functional appliances are used primarily in growing patients to modify jaw relationships by influencing muscle function and guiding skeletal growth. In mild Class II cases, they help to retract the upper incisors and encourage forward growth of the mandible.

Extractions:

Extractions may be necessary to relieve crowding and create space for retraction of the upper incisors. Common extraction patterns include removal of the first premolars.

Anchorage control:

Anchorage reinforcement is essential to prevent unwanted tooth movement, especially when space closure involves significant incisor retraction. Anchorage can be achieved using headgear, mini-implants, or reinforced posterior anchorage.

When properly executed, this approach can produce excellent aesthetic and functional outcomes. However, long-term retention is critical to maintain results.

2. Moderate to Severe Class II Skeletal Pattern

In moderate to severe skeletal discrepancies, dental correction alone is inadequate. Treatment approaches include growth modification, orthodontic camouflage, or surgical correction, depending on the patient’s growth stage.

a. Growth Modification

Growth modification is effective primarily in growing patients with significant remaining skeletal development. The goal is to enhance mandibular growth or restrain maxillary forward growth, thereby reducing the anteroposterior discrepancy.

Common appliances include:

 

These appliances work by altering muscle function and redirecting skeletal growth. Growth modification is most effective during the pubertal growth spurt, and success depends on patient compliance and timing of intervention.

b. Orthodontic Camouflage

For patients who have completed growth or have mild-to-moderate skeletal discrepancies, orthodontic camouflage offers a non-surgical alternative. This involves dental compensations to mask the skeletal disharmony.

Typical approaches include:

  • Extraction of upper first premolars to allow bodily retraction of upper incisors.
  • Retraction mechanics using fixed appliances and appropriate anchorage reinforcement.
  • Controlled torque to maintain incisor inclination and lip support.

 

Camouflage treatment, however, has limitations. It cannot address underlying skeletal imbalances and may compromise facial aesthetics if overused. Therefore, case selection is critical.

c. Surgical Correction

When the skeletal discrepancy is severe, especially in adults, orthognathic surgery may be required to correct the jaw relationship.

Surgical options include:

  • Mandibular advancement (BSSO) for mandibular retrognathia.
  • Maxillary impaction or setback for maxillary prognathism.
  • Bimaxillary surgery when both jaws contribute to the discrepancy.

 

Orthognathic surgery offers the most stable and aesthetic correction for severe cases, but it requires interdisciplinary coordination and thorough patient counseling.

3. Retention and Stability

Retention is a vital phase of orthodontic treatment, particularly in cases involving increased overjet. The retention plan must consider:

  • Soft tissue balance: If lips remain incompetent post-treatment, relapse is more likely.
  • Growth changes: Continued mandibular growth may improve or worsen the correction depending on direction and magnitude.
  • Retention devices: Removable retainers such as Hawley’s or fixed lingual retainers are commonly used.

 

Patient education about long-term wear and periodic review ensures stable results.

 

Special Considerations

1. Habit Intervention

Digit-sucking habits must be eliminated early to prevent recurrence. Behavioral modification, reminder appliances, or counseling may be necessary.

2. Lip Incompetence

Gross lip incompetence reduces stability and can affect patient satisfaction. Soft tissue exercises and myofunctional therapy can be adjunctive.

3. Anchorage Reinforcement

In extraction cases, adequate anchorage is critical to control unwanted mesial movement of posterior teeth. Techniques include mini-implants, headgear, or reinforced molar units.

4. Aesthetic Implications

Overcorrection may reduce nasolabial support, resulting in an obtuse nasolabial angle and flat facial profile. Orthodontists must balance aesthetic and functional goals during incisor retraction.

 

Prognosis and Outcome

The prognosis for correcting increased overjet is generally favorable when treatment is initiated at the right time and tailored to individual needs.

  • Growing patients benefit most from growth modification, with long-term skeletal and dental improvement.
  • Non-growing patients can achieve satisfactory results through orthodontic camouflage or surgery, though relapse potential exists if soft tissue imbalance persists.
  • Early intervention in mixed dentition can reduce trauma risk and improve self-esteem.

 

Ultimately, treatment success depends on accurate diagnosis, appropriate appliance selection, patient compliance, and diligent retention.

 

Recent Advances and Evidence-Based Practice

Recent systematic reviews, such as the Cochrane Database review by Batista et al. (2018), highlight the benefits of early treatment in reducing the risk of incisor trauma and improving psychosocial outcomes in children with prominent upper incisors.

Advances in temporary anchorage devices (TADs) have revolutionized orthodontic camouflage by providing absolute anchorage, enabling more controlled incisor retraction. Similarly, 3D imaging and digital treatment planning allow for more precise assessment of skeletal and dental components, leading to individualized care.

 

Conclusion

Increased overjet represents a common but multifactorial orthodontic problem that requires a comprehensive diagnostic and therapeutic approach. The interplay of skeletal, dental, and soft tissue factors necessitates individualized management strategies that consider both growth potential and patient-specific aesthetic demands.

Early intervention through functional appliances can harness growth modification, while fixed appliance therapy and extractions offer effective camouflage for milder cases. In severe skeletal discrepancies, orthognathic surgery remains the treatment of choice.

Long-term stability depends on addressing the underlying etiologic factors, maintaining soft tissue harmony, and ensuring appropriate retention. Ultimately, the goal of treatment is not only to correct the dental alignment but also to achieve balanced facial aesthetics and functional occlusion.

 

References

Textbooks

  1. Proffit, W. R., Fields, H. W., Larson, B., & Sarver, D. M. (2019). Contemporary Orthodontics (6th ed.). Elsevier.
    → Standard reference for classification, cephalometric norms, and management of malocclusions including Class II and increased overjet.
  2. Graber, L. W., Vanarsdall, R. L., Vig, K. W., & Huang, G. J. (2016). Orthodontics: Current Principles and Techniques (6th ed.). Elsevier.
    → Comprehensive overview of functional appliances, growth modification, and surgical management of skeletal discrepancies.
  3. Moyers, R. E. (1998). Handbook of Orthodontics (5th ed.). Year Book Medical Publishers.
    → Classical description of overjet development and soft-tissue influences.
  4. Bishara, S. E. (2001). Textbook of Orthodontics. Saunders.
    → Discusses the interplay between skeletal, dental, and soft-tissue components in Class II malocclusions.
  5. Batista, K. B., Thiruvenkatachari, B., Harrison, J. E., & O’Brien, K. D. (2018). Orthodontic treatment for prominent upper front teeth in children. Cochrane Database of Systematic Reviews, (3), CD003452.
    → Landmark systematic review comparing early vs. late correction of increased overjet.
  6. Baccetti, T., Franchi, L., Toth, L. R., & McNamara, J. A. (2000). Treatment timing for Twin-block therapy of Class II malocclusion. American Journal of Orthodontics and Dentofacial Orthopedics, 118(2), 159–170.
    → Demonstrates optimal age and skeletal maturity indicators for functional appliance therapy.
  7. O’Brien, K., Wright, J., Conboy, F., et al. (2003). Effectiveness of early orthodontic treatment with the Twin Block appliance: A multicenter, randomized, controlled trial. American Journal of Orthodontics and Dentofacial Orthopedics, 124(3), 234–243.
    → Provides evidence on the effectiveness and limitations of growth modification in children.
  8. Tulloch, J. F. C., Phillips, C., & Koch, G. (1997). The effect of early intervention on skeletal pattern in Class II malocclusion: A randomized clinical trial. American Journal of Orthodontics and Dentofacial Orthopedics, 111(4), 391–400.
    → Classic RCT evaluating long-term outcomes of early Class II treatment.
  9. McNamara, J. A. Jr. (1981). Components of Class II malocclusion in children 8–10 years of age. Angle Orthodontist, 51(3), 177–202.
    → Defines skeletal and dental components of increased overjet and Class II patterns.
  10. Pancherz, H. (1982). The mechanism of Class II correction in Herbst appliance treatment: A cephalometric investigation. American Journal of Orthodontics, 82(2), 104–113.
    → Explains functional appliance biomechanics in reducing overjet.
  11. Zachrisson, B. U. (2007). Long-term stability of orthodontic treatment: Retention and relapse. European Journal of Orthodontics, 29(Suppl 1), i150–i158.
    → Reviews retention strategies and relapse risk, especially in overjet correction.
  12. Al-Khatib, A. A., Badran, S. A., Zawawi, K. H., & Saltaji, H. (2015). Trauma risk in children with increased overjet: A systematic review and meta-analysis. Dental Traumatology, 31(1), 1–14.
    → Quantifies the relationship between overjet magnitude and dental trauma incidence.
  13. Fleming, P. S., Lee, R. T., & McDonald, F. (2011). The role of anchorage reinforcement during incisor retraction. Journal of Orthodontics, 38(4), 268–275.
    → Discusses anchorage control techniques in extraction cases.
  14. Janson, G., Sathler, R., Fernandes, T. M. F., Branco, N. C., & Henriques, J. F. C. (2012). Correction of Class II malocclusion with Class II elastics: A systematic review. American Journal of Orthodontics and Dentofacial Orthopedics, 141(5), 561–572.
    → Evaluates non-extraction, fixed-appliance camouflage in increased overjet cases.