Modified miniplates for orthopaedic skeletal anchorage

The use of temporary anchorage devices (TADs) in orthodontics has increased over recent years. One type of TAD, a modification of the titanium miniplate frequently used in orthognathic surgery for osteotomy or fracture fixation, has been used successfully as a skeletal anchorage device for various orthodontic applications . Most of these applications have focused on achieving dental movements, but recent case reports have demonstrated the use of TADs as an adjunct to orthopaedic treatment . Young patients with maxillary hypoplasia are usually treated with a facemask: heavy anterior traction is applied on the maxilla to stimulate its growth and to restrain or redirect mandibular growth. Titanium miniplates used for anchorage now offer the possibility to apply pure bone-borne orthopaedic forces between the maxilla and the mandible for 24 h per day, avoiding dentoalveolar compensation .

As a result, they eliminate the need for a means of extraoral anchorage such as headgear, which has been considered an effective means of orthodontic anchorage but requires good patient cooperation to achieve results. The difficulty of using an extraoral appliance and the aesthetic concerns related to its unusual appearance make patient cooperation difficult to maintain throughout the treatment .

Technique

A traditional maxillary miniplate was modified by cutting the edges according to the direction and magnitude of the orthopaedic force to be applied. It was recontoured to make it thinner and polished to eliminate sharp edges ( Figs 1 and 2 ).

Fig. 1
Maxillary modified miniplate.

Fig. 2
Mandibular modified miniplate.

An L-shaped, 1.5-cm incision was made over the zygomatic buttress region under local anaesthesia. A mucoperiosteal flap was elevated and the cortical bone surface at the implantation side was exposed. The zygomatic plates were adapted to the bone contour of the zygomaticomaxillary buttress, fixed with three miniscrews (2.0 mm diameter and 5 or 7 mm length), covered with mucoperiosteum and sutured with 3.0 Vicryl. In the lower canine region an inverted L-shaped incision was made and pre-bent L shaped plates were adapted and fixed with two miniscrews. The horizontal part of the incision is near the muco-gingival boarder. The sutures were removed 1 week after the operation, and the orthopaedic force was applied 2 weeks later ( Fig. 3 ). After 5 months following De Clerck’s protocol , the anterior crossbite was corrected ( Fig. 4 ). The plates were well tolerated by the patient and no infection was present.

Fig. 3
Placement of intermaxillary elastics.

Fig. 4
Post-treatment photograph after 5 months of orthopaedic traction of the maxilla.

Discussion

The location of the miniplate’s point of exposure to the oral cavity is absolutely critical. A higher exposure point may lead to mucosal irritation, inflammation, and hypertrophy. Nevertheless, zygoma plates should be inserted to the highest position on the zygomatic buttress to maintain a thicker bone. In some cases, it is not possible to expose the plates through the keratinized gingiva or the mucogingival junction because of the variations in the thickness of the attached gingiva and morphology of the infrazygomatic crest. In these cases, the position of the miniplates on the zygomatic buttress can be changed, but the possibility of complications such as contact between the TAD and brackets, damaging the buccal fat pad, hypertrophy of the buccal mucosa related to irritation, and injuring of the roots of the teeth adjacent to the screws should be considered. Manufacturing the zygoma plates in variable lengths may help to overcome these problems or as in the present case using modified miniplates ( Fig. 5 ).

Jan 26, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Modified miniplates for orthopaedic skeletal anchorage
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