Comparison of scleral show alterations following Le Fort I osteotomy with either maxillary impaction or lengthening

Abstract

This study aimed at evaluating changes in scleral show following Le Fort I osteotomy with either impaction or lengthening of the mid face. Patients who underwent Le Fort I osteotomy were included. The patients were divided according to the direction of the movement: group 1 underwent maxillary advancement and impaction, while group 2 underwent maxillary advancement and lengthening. Standardized preoperative and 6-month postoperative photos were superimposed using Microsoft PowerPoint. The inferior visible scleral area was assessed with landmarks and measured separately using ImageJ software. Marked scleral surface area was determined using pixel count. A total of 36 consecutive patients were included. The mean maxillary advancement in the patients was 4.16 ± 2.14 mm. The mean impaction in group 1 (n= 21) was 1.06 ± 1.49 mm, while the mean vertical lengthening in group 2 (n = 15) was 1.54 ± 1.65 mm. The difference in improvement in the inferior scleral show between the groups was not statistically significant. Preoperative (180 ± 118.2 mm) and postoperative (147.75 ± 92.2 mm) scleral show significantly improved (p = 0.012) in both groups. Scleral show can be overlooked for movements under 6 mm while planning for maxillary orthognathic movement, as it improves regardless of the desired movement.

Introduction

Satisfactory appearance and improved quality of life are the main expected outcomes for patients undergoing orthognathic surgery (Pusic et al., 2013). Various malocclusions and skeletal deformities are treated by bringing one or more segments of the jaw into harmony with the peri-oral soft tissues. Therefore, a goal of orthognathic surgery is to evaluate a patient's perception of his/her facial appearance and to use this clinical information to achieve a desired clinical outcome while also considering the functional demands.

Le Fort I osteotomy is capable of altering the hard and soft tissues (Vasudavan et al., 2012) that affect the appearance of the upper jaw and cheekbones. (Khamashta-Ledezma et al., 2017). Surgical maxillary movements combined with orthodontic movement of the teeth assist in facial contour restoration and treatment of soft tissue discrepancies in all three planes (Nagori and Fattahi, 2017).

In the orbital region, the position of the eyes, the distance between them, and their visible parts are influenced by the relationship between the maxilla and the mandible, as well as by aging. Additionally, the inferior orbital rims, malar eminence, and piriform areas should be evaluated prior to orthognathic surgery to determine the degree of maxillary projection required with respect to the overlying soft tissues of the mid face. If these regions are deficient, maxillary advancement is indicated.

Inferior scleral show can be defined as the visible white scleral portion between the lower border of the cornea and the margin of the lower eyelid. Prior to orthognathic surgery, facial photographs are obtained while the patient is in a standing position with a relaxed body posture, a neutral head position, and relaxed forehead and eyebrows. Excessive scleral show is a characteristic orbital feature of patients with midfacial hypoplasia, retrognathia, or endocrine orbitopathy (Krause et al., 2018). However, maxillary surgical movements can lead to a change in the position of the moveable lower eyelids, and subsequently, a change in the extent of inferior scleral show (Soydan et al., 2014). Ideally, there should be no more than 0.5 mm of scleral show on direct forward gaze.

Additionally, quantitative data on the surgical movement and the resulting soft tissue changes need to be considered during treatment planning (Pearlman et al., 2006), because excessive scleral show leads to an undesirable facial appearance and is a sign of midfacial hypoplasia. Scleral exposure alterations resulting from soft and hard tissue changes after orthognathic surgeries have been thoroughly investigated; however, only a few retrospective studies have explored the differences in such alterations following different types of Le Fort I osteotomy (Soydan et al., 2014; Magraw et al., 2015; Posnick et al., 2015; Norouzi et al., 2018). Therefore, this study compared the differences in improvement in inferior scleral show following Le Fort I maxillary advancement with either vertical impaction or vertical lengthening.