Introduction

Vertical elastics are essential tools in orthodontic therapy for closing open bites, extruding teeth, and correcting vertical skeletal discrepancies. These intraoral elastics apply vertical forces to the dentition, moving posterior teeth posteriorly and superiorly while extruding anterior teeth. Proper application, appropriate force levels, and management of patient compliance are critical for successful vertical elastic therapy.

Vertical Bite Problems and Indications for Vertical Elastics

Anterior Open Bite

An anterior open bite exists when the maxillary and mandibular anterior teeth fail to overlap vertically in centric occlusion. The extent of open bite is measured as the distance between the incisal edges of the maxillary and mandibular central incisors.

Causes of anterior open bite include skeletal anterior open bite (resulting from excessive posterior facial height or inadequate posterior facial development), dental anterior open bite (resulting from tongue thrust, mouth breathing, or occlusal interferences), or mixed anterior open bite with both skeletal and dental components.

Vertical elastics are effective for closing dental anterior open bites and can contribute to closure of skeletal open bites when used in conjunction with other appliances or surgical planning.

Posterior Open Bite and Vertical Problems

Some patients develop localized posterior open bites, often in combination with anterior open bite. Vertical elastics can help close these posterior openings by extruding posterior teeth into contact.

Deep Bite Correction Using Intrusive Forces

While vertical elastics are primarily used to extrude teeth (creating more open bite), they are occasionally configured to apply intrusive forces to anterior teeth for deep bite correction. Intrusion of maxillary anterior teeth reduces anterior overbite.

Force Characteristics and Mechanics

Optimal Force Levels

Vertical elastics should deliver force between 2 to 4 ounces (approximately 57 to 113 grams of force). This force level is effective for tooth movement without causing excessive discomfort or tissue damage.

Forces below 2 ounces may be insufficient to move teeth effectively. Forces above 4 ounces create excessive tissue reaction, discomfort, and risk of root resorption.

Elastic Types and Force Degradation

Intermaxillary elastics (rubber bands connecting maxillary and mandibular teeth) are commonly used for vertical elastics. These elastics lose force over time—typically losing 20 to 40% of initial force within the first 24 hours and continuing to degrade over subsequent days.

Patients must replace elastics daily or multiple times daily to maintain consistent therapeutic force. The daily replacement schedule is critical; elastics worn for several days significantly lose force and become therapeutically ineffective.

Direction of Force Application

Vertical elastics can be configured to apply force in different directions. Elastics attached to anterior maxillary bracket hooks and posterior mandibular hooks apply a distalizing and extruding force to mandibular posterior teeth while extruding maxillary anterior teeth. This combination helps close anterior open bite.

Box Elastics

Mechanics and Application

Box elastics are configured with four attachment points: two on the maxillary anterior teeth and two on the mandibular posterior teeth. This creates a "box" configuration when viewed from the frontal aspect.

Box elastics apply force from maxillary anterior teeth directly downward to mandibular posterior teeth. This creates an extruding force on maxillary anterior teeth and an extruding force on mandibular posterior teeth. The vector of force creates a downward opening movement of the occlusal plane, which is beneficial for closing anterior open bite.

Force Direction and Magnitude

The force direction in box elastics is primarily vertical (up and down), with minimal horizontal (anterior-posterior) component. Box elastics extrude both anterior and posterior teeth, which is appropriate for anterior open bite where increasing vertical overlap is desired.

The force magnitude can be adjusted by using different elastic sizes or different attachment points. Larger elastics or attachment points farther apart deliver greater force.

Clinical Advantages

Box elastics provide direct vertical force application without significant horizontal components. They are relatively simple to apply and understand, making patient compliance more feasible.

Box elastics are effective for dental anterior open bite closure when compliance is good. Typical treatment duration for open bite closure is 6 to 12 months with consistent elastic wear.

Disadvantages and Limitations

Box elastics cannot selectively extrude anterior teeth without also extruding posterior teeth. In patients with skeletal open bite or posterior facial height excess, extruding posterior teeth worsens the skeletal problem.

Box elastics are not ideal for patients with reduced vertical dimension or deep bite, as they tend to increase vertical dimension.

Triangle Elastics

Configuration and Mechanics

Triangle elastics use three attachment points: typically two on maxillary anterior teeth and one on the mandible. The mandibular attachment point may be on a canine or from the mandibular body via a chin cup or external appliance.

Triangle elastics create a triangular force vector. The elastic pulls the maxillary anterior teeth downward and backward (distally), while also creating a vertical component depending on the specific attachment point configuration.

Force Vectors and Tooth Movement

The specific force vector depends on the attachment points. If the mandibular attachment is on the canine, the elastic pulls maxillary anterior teeth distally and downward. If the attachment is inferior on the mandible, the force vector is more vertical.

Triangle elastics can be configured to primarily extrude maxillary anterior teeth while applying minimal force to posterior teeth. This selective extrusion pattern is beneficial for anterior open bite closure without significant posterior extrusion.

Clinical Applications

Triangle elastics are particularly useful when anterior open bite closure requires selective maxillary anterior extrusion without posterior tooth movement. They can also be used in combination with other elastics or appliances for more complex bite correction.

Limitations

Triangle elastics require precise attachment point planning. Incorrect attachment points create unpredictable force vectors and less effective tooth movement.

Vertical Wear Schedule and Compliance

Recommended Wear Protocol

Vertical elastics should be worn 20 hours or more per day for optimal efficacy. Minimum effective wear is considered 16 to 18 hours daily, though less frequent wear dramatically reduces effectiveness.

Elastics should be replaced multiple times daily as they lose force rapidly. Many orthodontists recommend replacement 2 to 3 times daily, and at minimum, daily replacement with fresh elastics.

Patient Instructions

Provide clear written and verbal instructions regarding elastic wear. Show the patient exactly how to apply elastics, where to attach them, and the replacement frequency required.

Many patients initially underestimate the importance of consistent wear. Emphasize that intermittent wear or less frequent replacement will dramatically extend treatment time and may fail to achieve the desired outcome.

Managing Poor Compliance

Some patients struggle with consistent elastic wear. Assess barriers to compliance—whether the patient is uncomfortable wearing elastics, forgets to replace them, or questions whether they're necessary.

Explain that vertical elastics are not optional; consistent wear is essential for successful open bite closure. Without compliance, treatment duration extends significantly and results may be compromised.

Some clinicians use reminder systems or apps to help patients remember elastic replacement. Positive reinforcement when compliance is excellent encourages continued excellent wear.

Biological Response to Vertical Forces

Tissue Response

Application of appropriate vertical force causes bone remodeling. Areas of the periodontium under compression show osteoclastic activity and bone resorption, allowing the tooth to move. Areas under tension show osteoblastic activity and new bone formation.

Extrusion of teeth via vertical elastic forces is relatively fast compared to intrusion—extraction typically occurs within weeks to months with appropriate forces. Posterior tooth extrusion in response to vertical elastics occurs at rates of approximately 0.3 to 0.5 millimeters per month.

Root Resorption Risks

Excessive force, prolonged force application, or patient-specific factors increase root resorption risk. While minor root resorption is occasional with any orthodontic movement, excessive resorption can compromise tooth viability.

Vertical elastics applied at appropriate force levels (2-4 ounces) with appropriate wear schedules have acceptably low root resorption risk. However, patients with previous root resorption, older patients, or patients with thin roots should be monitored carefully.

Vertical Elastics with Fixed Appliances

Bracket Considerations

Vertical elastics are attached to bracket hooks or crimpable tabs. Modern brackets typically have hooks on both maxillary and mandibular molars and canines, allowing flexible elastic attachment points.

Some bracket systems allow vertical elastics to be attached to power arms or crimpable hook extensions, providing greater flexibility in force direction and magnitude.

Timing of Application

Vertical elastics are typically initiated only after initial tooth alignment is substantially completed. Applying elastics before alignment is complete can interfere with alignment and reduce efficiency.

Once alignment is substantially complete, vertical elastics can be introduced for bite correction. Treatment duration depends on the severity of the open bite, force magnitude, and patient compliance.

Treatment Duration and Expected Results

Open Bite Closure Timeline

Dental anterior open bites typically close over 6 to 12 months with consistent vertical elastic wear and good compliance. Some cases close more rapidly, while others require longer treatment.

Skeletal anterior open bites may partially respond to vertical elastics, particularly in growing patients. However, significant skeletal open bite may require surgical correction in combination with or following orthodontic treatment.

Stability of Results

Vertical dimension changes achieved with vertical elastics can be stable, particularly if the underlying cause of open bite (such as tongue thrust) is addressed. However, if parafunctional habits or tongue thrust persist after treatment, open bite may recur.

Retention following vertical elastic therapy is important. Many patients require permanent fixed lingual retention or removable retainers to prevent relapse.

Adverse Effects and Management

Discomfort and Soreness

Some patients experience discomfort when vertical elastics are first applied. This is usually mild and resolves within a few days as the periodontal ligament adapts to the force.

Excessive discomfort may indicate excessive force or improper elastic configuration. Adjust the force or remove elastics temporarily if discomfort is severe.

Gingival Effects

Vertical elastics sometimes irritate the gingiva if they rub against gingival tissues or if the elastic is positioned improperly. Proper positioning at bracket hooks rather than against the gingiva prevents this problem.

Temporomandibular Joint Symptoms

Some patients report TMJ discomfort when vertical elastics are first applied. This is usually mild and temporary. If symptoms persist, assess the bite relationship and elastic force magnitude.

Monitoring and Adjustment

Regular Assessment

Assess open bite closure at each appointment. Measure the extent of anterior open bite and record any changes. Expected closure rates of approximately 1 to 2 millimeters per month indicate appropriate progress.

Assess the elastic wear patterns at each appointment. Ask patients how many times daily they replace elastics and observe any patient wear patterns or skipped wear times.

Modification of Elastic Configuration

As the open bite closes and the bite relationship changes, the elastic attachment points may need modification. As posterior teeth erupt or extrude, elastic vector may need to be adjusted to maintain appropriate force direction.

Conclusion

Vertical elastics are highly effective for anterior open bite closure when appropriate force levels, wear schedules, and patient compliance are achieved. Box elastics and triangle elastics offer different force vectors suitable for different clinical situations. Success depends on clear patient instruction, consistent compliance with wear schedules, and regular monitoring. With proper application and management, vertical elastics provide efficient, predictable open bite closure and improved bite relationships.