Class II Malocclusion with Clear Aligners: How to Successfully Treat Your Patients

Table of Contents:

1.  General Overview

2. Methodology and Resources 

3. Biomechanics of Class 2 Malocclusion with Clear Aligners 

4. Diagnosis and Treatment Procedure

5. Discussion & Case study: Doctors’ suggestions

6. Results 

7. Conclusions 

8. FAQ

General Overview

Class II malocclusion stands out as one of the most common issues we encounter in the field of orthodontics. It's a concern that affects a significant portion of school-age children in Europe, afflicting approximately 37% of them. Furthermore, in the United States, it's found in roughly 33% of all orthodontic patients (1). This condition, known as Class II malocclusion, can sometimes be accompanied by craniofacial discrepancies, which can be addressed during a patient's adolescent years.

When it comes to treating Class II malocclusion in younger patients who are still growing, there are several options at our disposal. These include the use of extraoral headgears, functional appliances, and full fixed braces with intermaxillary elastics and, in some cases, the removal of certain teeth. On the other hand, when dealing with adults who have moderate Class II malocclusion, we often employ a combination of fixed braces along with intermaxillary elastics and, if necessary, extractions. For those with severe malocclusion, a treatment plan may involve fixed braces combined with orthognathic surgery. (2)

While advancements in these conventional treatment methods have led to improved outcomes, particularly in growing patients, it's crucial to note that most of them rely heavily on patient cooperation. This requirement for patient compliance can sometimes pose a significant challenge in achieving successful treatment outcomes.

The treatment options vary depending on the patient's age and the severity of the condition, ranging from extraoral headgears to orthognathic surgery. However, the importance of patient cooperation in achieving successful results cannot be overstated (2).

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Etiology Behind Class II malocclusion

Skeletal Class II malocclusions can present with variations in several key areas (3):

• Maxillo-mandibular relationship, which may involve mandibular retrognathism, midface protrusion, or a combination of both.

• The cranial base, where an elongated anterior cranial base can contribute to midface protrusion, while lengthening of the posterior cranial base tends to reposition the temporomandibular joint more posteriorly.

• Vertical dysplasia, often characterized by an increased height of the anterior upper face compared to normal.

• A steep occlusal plane, reflecting vertical skeletal dysplasia.

For many years, orthodontists have traditionally considered Class II Div. 1 and 2 malocclusions to primarily result from sagittal jaw discrepancies. However, it is crucial to recognize that in most of these cases, a significant vertical component is also at play and should not be overlooked. 

While it is true that a sagittal skeletal discrepancy often accompanies these malocclusions and contributes to the Class II molar occlusion in some instances, there is frequently a dento-alveolar discrepancy associated with these malocclusions that can likewise lead to a Class II molar relationship. (12) Surprisingly, in certain cases, there may be no sagittal or horizontal skeletal discrepancy at all.

The reduction in the vertical jaw dimension is commonly assumed in patients with Class II, Div. 2 malocclusion. However, studies conducted by Cleall and BeGole (4) have revealed that, on average, the vertical face height is actually within the normal range. This finding might come as a surprise to many clinicians who expect these patients to exhibit reduced facial height.

Delving into the factors contributing to the development of this malocclusion. The primary culprit behind the development of Class II, Div. 2 malocclusions lies in the individual's facial growth pattern. While numerous articles have explored the facial morphology of patients with Class II, Div. 2 malocclusion, there is a scarcity of descriptions regarding the facial growth patterns in these patients. 

Methodology and Resources 

A retrospective study done by Dianiskova (5) compared the dental and skeletal effects of intermaxillary elastics, which are commonly used in traditional orthodontic treatment, on the correction of Angle’s Class II division I malocclusion with Clear Aligner Therapy as compared to fixed orthodontic therapy in growing patients. The study consisted of 49 patients who were treated with a non extraction treatment plan in which 24 patients were treated with clear aligner therapy while others were treated with fixed metal bracket systems. A cephalometric analysis was carried out during the start of the treatment and compared with the cephalometric readings at the end of a patient's treatment. The study revealed that Class II elastics combined with CAT and fixed metal therapy produced similar results on sagittal discrepancies. However, clear aligner therapy in class II cases produced a better control in the proclination of the lower incisors. Hence, clear aligner therapy for class II malocclusion is a good alternative to fixed therapy, especially in patients where further proclination of lower incisors would be an unwanted outcome. 

Biomechanics of Class 2 Malocclusion with Clear Aligners 

Class II malocclusion, characterized by the overjet resulting from the relative protrusion of maxillary teeth in relation to mandibular teeth, presents a common orthodontic challenge. The introduction of clear aligner therapy (CAT) has expanded the options available to orthodontists, offering a more discreet and patient-friendly approach. Let’s delve into the scientific mechanisms through which clear aligners can effectively correct Class II malocclusion (6).

1. Maxillary Incisor Retraction:

The hallmark of Class II malocclusion correction is the retraction of maxillary incisors to reduce the overjet. Clear aligners achieve this through controlled and sequential tooth movement. Each aligner in the series exerts a specific force on the target teeth, gradually retracting them. The application of continuous, gentle force stimulates bone remodelling, allowing the teeth to migrate into a more favourable position (7).

2. Anchorage Control:

Preserving anchorage is crucial in Class II correction to prevent undesired movement of posterior teeth. Clear aligners employ various mechanisms to achieve anchorage control, such as strategically placed attachments and optimized aligner design. These elements help distribute the force evenly, minimizing the risk of mesialization of molars or unwanted changes in the posterior dentition.

3. Interarch Relationship:

Correcting Class II malocclusion often requires adjustments to the interarch relationship, particularly the overbite. Clear aligners can be designed to incorporate features like precision cuts, elastics, or other auxiliaries to facilitate changes in the vertical dimension and encourage a more favourable bite relationship.

4. Skeletal and Soft Tissue Considerations:

While clear aligners primarily target dental movements, some skeletal and soft tissue effects may occur, especially in growing patients. Skeletal changes are influenced by patient age and growth potential. Orthodontists must consider these factors when planning Class II correction with clear aligners.

Clinical Considerations

1. Patient Selection:

Not all Class II malocclusions are suitable for treatment with clear aligners. Orthodontists must assess the severity of the malocclusion, patient compliance, and individual treatment goals. Severe Class II cases or those with significant skeletal discrepancies may necessitate a multidisciplinary approach involving other dental specialists.

2. Compliance and Patient Education:

Patient cooperation is paramount for the success of clear aligner therapy. Clear communication and patient education regarding the importance of wearing aligners as prescribed, using any recommended elastics, and maintaining proper oral hygiene are vital components of a successful treatment plan.

By carefully selecting appropriate patients, collaborating with other dental specialists when necessary, and ensuring patient compliance, orthodontists can achieve remarkable outcomes in Class II malocclusion treatment using clear aligner therapy. 

Diagnosis and Treatment Procedure

The clinical examination and subsequent diagnosis of Class II malocclusion represent pivotal aspects of orthodontic practice. Class II malocclusion, characterized by the relative protrusion of maxillary teeth in relation to mandibular teeth, requires a comprehensive evaluation to establish an accurate diagnosis.

Preliminary Assessment

Patient History:

The initial step in the clinical examination is a thorough review of the patient's medical and dental history. It is imperative to identify any relevant systemic conditions, previous orthodontic treatment, or familial predispositions to malocclusion.

Facial Analysis:

A comprehensive facial analysis is conducted to assess facial proportions, symmetry, and any noticeable asymmetries, which may be indicative of underlying skeletal issues contributing to Class II malocclusion.

Intraoral Examination

Dental Occlusion:

A meticulous evaluation of the dental occlusion is performed to identify the key features of Class II malocclusion, including an increased overjet, retruded mandible, and the presence of crowding or spacing.

Malocclusion Severity:

The severity of the malocclusion is quantified using established indices such as the Angle classification or the Bolton analysis, providing a framework for diagnosis.

Skeletal Assessment:

The examination extends to a skeletal assessment involving cephalometric analysis, assessing the relationship between the maxilla and mandible, and identifying the specific skeletal components contributing to the Class II discrepancy (8).

Diagnostic Tools

Radiographic Imaging:

Orthodontists employ radiographic imaging, including cephalometric and panoramic radiographs, to visualize the craniofacial structures in detail. These images assist in assessing skeletal relationships and identifying any abnormalities or deviations from the norm.

Impression and Cast Analysis:

Taking dental impressions and creating dental casts allow for precise measurements of tooth size and arch dimensions. This information aids in formulating an appropriate treatment plan.

Diagnosis

Differential Diagnosis:

Once all data has been gathered, the orthodontist undertakes a comprehensive analysis of the clinical findings. This involves ruling out other potential malocclusions and identifying any contributing factors, such as dental or skeletal discrepancies.

Angle Classification:

The Angle classification system is commonly employed for classifying malocclusions, with Class II malocclusions being categorized as either Division 1 or Division 2 based on specific dental characteristics (8).

Cephalometric Analysis:

Cephalometric measurements, such as the ANB angle and Wits appraisal, provide objective quantifications of the severity and type of Class II malocclusion.

Treatment Planning

The diagnosis guides the formulation of a tailored treatment plan, which may involve orthodontic appliances, such as braces or clear aligners, or, in severe cases, surgical intervention to address skeletal issues.

Discussion & Case study: Doctors’ suggestions

Class II malocclusion patients often present with various dental arch misalignments, a convex facial profile, and mandibular retrusion. In cases involving growing patients with a retrognathic mandible, traditional functional appliances are typically recommended. These appliances aim to stimulate horizontal mandibular growth. However, a notable drawback frequently observed with traditional functional appliances is the unintended proclination of the lower anterior teeth.

Treating Class II malocclusion with clear aligners presents a potential advantage, primarily through precise control over the positioning of the lower incisors. This control is attributed to the rigidity of the aligner trays, which effectively maintain the dental arch in a stable configuration. A recent study conducted in 2022 shed light on the potential benefits of aligner therapy when combined with elastics, highlighting a more evenly distributed force application compared to traditional fixed brackets (9).

Clear aligner therapy offers an additional advantage by providing superior vertical control, mainly due to its bite block effect. (13)

Additionally, it tends to result in shorter treatment durations compared to traditional metal brackets. The key contributing factor here is the ability of Class II patients treated with clear aligners to utilize elastics from the very beginning of treatment, a marked contrast to the time-consuming process of fixed mechanotherapy.

Moreover, a study conducted by Deregibus et al. reported a substantial increase in arch width following treatment with clear aligners. This expansion of the maxillary arch often translates into a more forward positioning of the lower jaw, thus improving the patient's convex profile. Clinicians can also anticipate that clear aligner therapy effectively restrains molar extrusion, thus preventing undesirable clockwise rotation of the mandible—a phenomenon attributed to the interaction between clear aligners and occlusal splints (10).

Incorporating mandibular advancement with clear aligner therapy has been documented as an aesthetically pleasing, comfortable, and sanitary approach. Furthermore, this approach reduces the need for frequent revisits, potentially revolutionizing Class II malocclusion correction by offering a more patient-friendly and effective treatment modality (11).

Results & Conclusion 

Clear aligner therapy in the correction of Class II malocclusion emerges as an effective treatment modality, offering superior vertical control and minimizing the undesirable proclination of incisors. Notably, this approach can be seamlessly combined with mandibular advancement appliances, further enhancing its versatility and efficacy. What sets clear aligner therapy apart is its capacity to facilitate a stable and precise treatment outcome with reduced patient discomfort. 

The reduced frequency of clinical visits and the ability for patients to achieve satisfactory results with fewer inconveniences contribute significantly to heightened patient satisfaction. This combination of clinical effectiveness and patient-centred benefits underscores the profound impact of clear aligner therapy in the realm of Class II malocclusion correction, aligning it as a favourable and scientifically grounded approach.