Nasolabial changes after two different approaches for surgically assisted rapid maxillary expansion

Abstract

This retrospective study evaluated the nasolabial changes in patients who underwent surgically assisted rapid maxillary expansion (SARME) using two different approaches. Nineteen patients were included in the study, divided into two groups according to the kind of surgical approach performed: group 1 (n = 9), SARME performed through the standard Le Fort I circumvestibular approach followed by the alar base cinch, and group 2 (n = 10), SARME performed through a subtotal vestibular approach associated to a V-shaped incision at the maxillary midline in the labial frenulum region, without alar base cinch. Measurements of width, length, and nasal projection as well as upper lip length were taken from cone beam tomographic images obtained before surgery (T1) and 6 months postoperatively (T2). Both groups presented an increase in the alar base width postoperatively ( P < 0.05). The approach used in group 2 resulted in smaller changes in the alar base width as measured at the superior alar curvature ( P < 0.05). Nasal length and projection and upper lip length were not altered by SARME. The type of surgical approach influenced nasolabial changes, but did not eliminate increase in width of the alar base.

Surgically assisted rapid maxillary expansion (SARME) is the standard procedure for correction of transverse maxillary deficiency in adult patients. It can be performed as an isolated procedure or associated with maxillary repositioning for correction of anteroposterior and vertical anomalies . Sagittal separation of the maxilla widens the piriform aperture and nasal floor . Facial soft tissues, such as the alar base and upper lip, have insertions around the piriform aperture. Thus, changes can be expected in the morphology and position of those structures after SARME .

Soft tissue changes result not only from the increase in the transverse dimension of the maxilla, but also from the mucosal incision and muscle detachment necessary for performing the corticotomies . Other factors, such as the direction and amount of maxillary change, skeletal pattern, tonus, and thickness of the soft tissues, may also influence postoperative changes in the alar base and upper lip .

The standard circumvestibular incision for the Le Fort I osteotomy extends from the first molar to its correspondent on the other side. The mucoperiosteum is elevated from the anterior maxilla, including the area around the piriform apertures . Postoperatively, muscle reinsertion tends to occur with reduction in the length of the related muscles because of tissue retraction, resulting in changes at the alar base . Several methods have been employed to exert control upon such changes .

The alar base cinch suture, described by Collins and Epker , has been widely used to minimize the increase in the width of the alar base produced by the Le Fort I osteotomy. However, the effectiveness of the method has been contested . Enlargement of the pirirform aperture also promotes widening of the nose and overcorrection of the soft tissues become necessary in patients where such increase is not desirable .

The subtotal segmented approach for SARME involves bilateral incisions which run from the first molar to the canine bilaterally, associated with a V-shaped incision at the midline. This is done to preserve muscle insertions around the piriform aperture. The aim is to minimize the widening of the alar base and eliminate the need for cinch sutures .

Several techniques have been proposed to increase the effectiveness of SARME. The literature is scarce in relation to the influence of the surgical approach over the soft tissues after maxillary expansion. This study used the cone beam computed tomography (CBCT) to compare nasolabial soft tissue alterations in patients who received SARME by means of two different surgical approaches.

Materials and methods

This retrospective study evaluated the CBCT records from 19 patients (14 women and 5 men) who underwent SARME. Inclusion criteria were adult patients with transverse maxillary deficiency greater than 5 mm, the presence of posterior crossbite, SARME performed with subtotal Le Fort I osteotomy involving the lateral maxillary wall, median palatine suture, and separation of the pterygoid plates. Patients presenting with craniofacial syndromes, cleft lip and palate, or who had previous orthodontic treatment were excluded from the study. Approval was obtained from the Ethics Committee of the Araraquara Dental School, Unesp (Protocol 44820615.0.1001.5416).

The patients were divided into two groups, according to the kind of surgical approach that was employed: group 1 (n = 9), SARME performed through the standard Le Fort I circumvestibular approach followed by alar base cinch ( Fig. 1 ) and group 2 (n = 10), SARME performed through a subtotal vestibular approach associated to a V-shaped incision at the maxillary midline in the labial frenulum region, without alar base cinch ( Fig. 2 ).

Dec 14, 2017 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Nasolabial changes after two different approaches for surgically assisted rapid maxillary expansion
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