Palatal skeletal anchorage: multiple applications with a single appliance

Palatal vault is considered an election site for mini-screws placement, due to its availability, the presence of high-quality bone, and the absence of nerves and blood vessels, which makes the zone safe and suitable for many clinical applications.^[1]

As a matter of fact, palatal mini-screws could be effective for Class II malocclusion in young-adult patients to achieve both adequate transverse maxillary expansion (with both hybrid or bone-borne anchorage) and distalization of upper molars, avoiding or minimizing some common side effects of these procedures, such as vestibular tipping of molars, mesialization of premolars, and flaring of incisors.^[2]

This case shows how a hybrid T-Rex rapid palatal expander (RPE) could be an efficient option to achieve both transverse maxillary expansion and upper molar distalization, thus avoiding multiple appliances and waste of time. Moreover, it was applied for the recovery of maxillary canine too, without the undesired intrusion of contiguous teeth and the occurrence of anterior open bite. Furthermore, these mechanics were accomplished without asking for the patient’s compliance.

To fulfill all these objectives, a bicortical engagement of palatal mini-screws was ensured by MAPA protocol.^[3]

A 14-year-old Caucasian female patient presented a Class II malocclusion with skeletal maxillary constriction and inclusion of tooth 2.3. The total lack of space for its eruption was evident, with the upper dental midline shifted completely toward the second quadrant, whereas posterior teeth shifted mesially establishing a full cusp Class II molar relationship [Figure 1].

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Figure 1:

Initial intraoral photographs.

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Conventional orthodontic treatment alternatives would implicate an RPE, headgear extraoral appliance (to avoid premolars mesial shifting), and the recovery of the 2.3 with fixed appliances (FAs).^[4] Through digital planning [Figure 2], hybrid T-rex RPE was designed to perform all these biomechanics [Figure 3]. After the first phase of expansion (30 turns) [Figures 4 and 5] and 2 months of stabilization, TMA springs were inserted to perform upper molar distalization. After 9 months of repeated activations, a bilateral Class I molar relationship was achieved and the space for 2.3 recovered, together with the use of FAs [Figure 6]. After the surgical exposition, an extrusive force for 2.3 recovery was applied with a triple-looped 0.036-inch blue-Elgiloy spring [Figures 7 and 8] until also bilateral Class I canine relationship was obtained [Figure 9].

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Figure 2:

Initial x-rays and digital planning on cone-beam computed tomography system.

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Figure 3:

Hybrid T-rex rapid palatal expander appliance.

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Figure 4:

Bonded hybrid rapid palatal expander appliance.

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Figure 5:

Rate of expansion after 30 turns.

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Figure 6:

Insertion of TMA springs after removing expander arms and open coil inserted in fixed appliance.

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Figure 7:

2.3 Eruption and engagement with triple-looped TMA spring.

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Figure 8:

2.3 successfully aligned and engaged in the 0.019 × 0.025 SS archwire.

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Figure 9:

Final intraoral photographs.

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