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Class II, Pattern II, orthodontic-surgical treatment, with mandibular deficiency, using mini-screws on the buccal shelf for uprighting the mandibular incisors

Henrique Mascarenhas VILLELA e Paula DRAGO

Introduction: Orthodontic-surgical treatments are used to correct dentofacial deformities in adult patients who have severe or moderate skeletal discrepancies that are incompatible with premolar extraction. Often, the therapeutic goals of orthodontic preparations for orthognathic surgery are opposite to the goals of compensatory orthodontic corrections. Class II premolar extraction in Pattern II patients with mandibular deficiency aims to reduce the overjet by decreasing the inclination of the maxillary incisors and/or increasing the inclination of the lower incisors. On the other hand, in presurgical orthodontic preparations, these dental compensations are eliminated with the correct positioning of the incisors in their bone bases. This makes the overjet compatible with the skeletal discrepancy, allow- ing for adequate surgical correction. Therefore, the initial assessment of incisor inclinations plays an important role in the guidelines for preparatory orthodontic treatment for orthognathic surgery. In order to reduce the inclination of the mandibular incisors, extractions of the mandibular first premolars or the distalization of the entire dental arch may be performed, with the use of skeletal anchorage. The recent use of extra-alveolar mini-screws in the buccal shelf region has enabled greater sagittal movements, through the retraction of the entire lower arch, when compared with intra-alveolar mini-screws. Compared to miniplates, this device has the same success rates and some advantages, such as lower risk of inflammation, lower cost, lower morbidity, less discomfort and simple installation and removal, eliminating the need for referral to a surgeon. Objective: This article presents a strategy of preparatory orthodontic treatment for orthognathic surgery, through a clinical case report, in the correction of Class II, in a Pattern II patient, with mandibular deficiency. In this case, the mandibular incisors were decompensated, using skeletal anchorage with extra-alveolar mini-screws in the buccal shelf region. Conclusion: The use of extra-alveolar mini-screws in the buccal shelf region proved to be efficient to perform the retraction of the mandibular arch, since there was a 13o reduction in the mandibular incisor inclination (initial IMPA of 118o to IMPA of 105o ) in a period of 7 months of retraction in presurgical treatment. This strategy, in addition to avoiding the indication of mandibular premolar extraction, promoted an increase in the overjet and enabled the correct positioning of the mandibular incisors in the bone base, as well as providing adequate conditions to correct the skeletal discrepancy by means of orthognathic surgery.

Keywords: Orthodontic-surgical treatment. Buccal shelf. Extra-alveolar mini-screw. Mini-implants.

How to cite: Villela HM, Drago P. Class II, Pattern II, orthodontic-surgical treatment, with mandibular deficiency, using mini-screws on the buccal shelf for uprighting the mandibular incisors. Clin Orthod. 2021 Apr-May;20(2):38-57.

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