Combination of a distaliser and aligners for Class II correction

To optimise bodily distalisation in terms of precision and efficiency, integrating the Beneslider into aligner therapy has proved to be an innovative approach.^{6, 7} Two approaches to such therapy can be taken: two-phase treatment, where distalisation is first achieved using the Beneslider before finishing the occlusion with aligners, and one-phase treatment which enables concurrent molar distalisation and aligner therapy. Both approaches have shown promising clinical outcomes and expand the range of aligner-based treatment options.

Skeletal anchorage for distalisation in the maxilla

The introduction of skeletal anchorage has led to a paradigm shift in orthodontic therapy in recent years. It significantly reduces the dependence on patient cooperation, ensuring more consistent and reliable results.⁸ Mini-implants are minimally invasive, relatively low cost and versatile in application, making them a favourable option for both practitioners and patients.^9–11The anterior palate has become the preferred insertion region for skeletal anchorage for maxillary molar distalisation.^{12, 13} This area, called the T zone, is located posterior to the palatal rugae and is characterised by dense cortical bone and minimal soft-tissue thickness and thus provides ideal conditions for stable and reliable anchorage.¹⁴

The distaliser

Among the established distalisation appliances, the Beneslider is known for its efficient sliding mechanics and high clinical success rate.^{15, 16} The distaliser was developed as an alternative solution to the Beneslider and utilises a screw mechanism.¹⁷ The screw mechanism ensures precise, controlled and predictable movement of the teeth throughout the treatment. The distaliser, typically activated by the patient on a weekly basis, offers a clearly defined activation distance per time unit, simplifying synchronisation in the aligner staging process in a one-phase treatment approach. However, the distaliser is bulkier than the Beneslider, and this factor should be considered, especially for adult patients.

Patient case

A 35-year-old female patient presented with an increased overbite, an increased overjet of 7 mm, and a bilateral Class II molar relationship, exhibiting a three-quarter unit distal occlusion on the right and a half unit distal occlusion on the left (Figs. 1–3). Orthognathic surgery had previously been recommended owing to the Class II skeletal relationship evident in the cephalometric analysis, but the patient declined this option.

For correction of the increased overbite, the incisors were first proclined and then bodily intruded to prevent excessive palatal tipping during retraction. Additionally, Class II elastics and anterior bite ramps were used. The mandibular arch crowding was addressed through interproximal enamel reduction.

The first sequence of aligner treatment consisted of 62 aligners, followed by ten aligners for refinement. During the course of treatment, the posterior teeth were asymmetrically distalised on both sides, anterior crowding in the maxillary and mandibular arches was resolved, the sagittal discrepancy was reduced and the midline deviation was corrected (Figs. 8 & 9). Afterwards, the patient wore vertical elastics for two months to achieve settling in the molar region. The total active treatment duration was 19 months.

Summary and discussion

The case presented demonstrates that a severe Class II malocclusion including an increased overbite can be successfully treated in adults using effective molar distalisation, anterior bite ramps and Class II elastics. The use of a skeletally anchored distalisation appliance allows for precise and reliable synchronisation of bodily tooth movement with aligner staging. Furthermore, it offers an aesthetically pleasing and effective treatment option for adult patients.

Reduction of excessive vertical overlap using aligners remains a challenging treatment objective. When designing the distalisation appliance, it is possible to angle the rails in such a way that the molars are extruded during distalisation, increasing the posterior vertical dimension of occlusion. This applies to both the Beneslider and the distaliser.