Changes in scleral exposure following Le Fort І maxillary advancement or impaction

Abstract

Background and objectives

Inferior scleral exposure is an aesthetic as well as functional concern. The purpose of this study was to evaluate and compare changes in scleral exposure following Le Fort I (LFI) maxillary advancement or impaction.

Methods

43 patients with inferior scleral show who underwent LFI osteotomy were studied. Patients underwent two types of surgery: maxillary advancement was performed in 21 patients and maxillary impaction in 22 patients. Preoperative and 6-month postoperative frontal photographs of patients were analyzed with Adobe Photoshop CC 2018 and compared for scleral exposure by the ratio of the distance between inferior eyelid margin and corneal limbus to eye height.

Results

The mean maxillary movement was 6.14 mm advancement in LFI advancement group and 4.4 mm impaction in LFI impaction group. The mean scleral show ratio decreased by 4.25% (4.4% in the right and 4.1% in the left eye) in LFI advancement and 3.65% (3.5% in the right eye and 3.8% in the left eye) in LFI impaction group. These changes were statistically different in each group but they were the same when comparing two groups (p-value > 0.05).

Conclusion

Both LFI advancement and LFI impaction significantly decreased scleral exposure in our patients.

Highlights

  • This study aimed the comparison of changes in scleral exposure following Le Fort I (LFI) maxillary advancement or impaction.

  • Since similar studies have not yet evaluated LFI with impaction independently, this suggestion needs to be further studied.

  • We hereby showed that LFI with impaction was as effective as LFI with advancement.

  • Hence, results are applicable to patients in whom LFI with impaction alone is warranted, such as long-face patients with VME.

Introduction

Lower eyelid scleral show is an unpleasant facial feature in a relaxed neutral gaze. In many cases, the underlying problem is a skeletal deformity, which causes distortions in the covering soft tissues. In others, a mixed maxillofacial deformity constitutes the etiology. Further involvement of the soft tissues exaggerates the scleral show and contributes to esthetic dissatisfaction [ ]. Besides the cosmetic implications, malalignment of the lower eyelid can cause lid laceration, foreign body sensation, blurry vision, and keratopathy. The latter could present as a chronic hypertrophic inflammation of conjunctiva with consequent keratinization and corneal damage [ ].

A thorough understanding of the facial anatomy is key to diagnosis and treatment of inferior scleral exposure. As conjunctival epithelium continues to cover the scleral surface, moving elements of the lower eyelid are affected by midfacial skeletal structures [ , ]. The optimal and desirable relationship between these structures is which in the lateral view, the most anterior point of the eyeball is seen posterior to the lower eyelid margin. Further forward position of the eyeball results in inferior scleral exposure and undermines the zygomatic prominence [ , ].

The role of midfacial skeletal structures in facial proportions has been further appreciated after observing the positive effects of inferior orbital rim and zygomatic augmentation. The excessive scleral show may be seen in patients with class III malocclusion and midfacial and maxillary deficiency who are candidates for Le Fort I (LFI) Advancement surgery, and patients with long-face syndrome and vertical maxillary excess (VME) who are candidates for LFI Impaction surgery [ ].

Classically, surgery aims to correct the relationship of facial structures to achieve a desirable occlusion and esthetics. This is especially helpful for patients with VME who benefit from the Le Fort procedure with superior repositioning of the maxilla, which relieves the tension in facial muscles and decreases the inferior scleral exposure. Similarly, LFI with advancement may correct facial proportions and improve esthetics [ ].

Soydan et al. [ ] and Posnick and Sami [ ] recently demonstrated the favorable results of advancement with or without superior repositioning of the maxilla for improvement of inferior scleral show. Advancement and impaction, however, have not been compared independently in the literature. We thus aimed to compare LFI advancement with LFI impaction for improving the scleral show in our patients.

Materials and methods

This study was conducted in accordance with the World Medical Association Declaration of Helsinki (of 1975 as revised in 2000) and was approved by the ethics committee of Shahid Beheshti University of Medical Sciences. In a retrospective chart review, we evaluated all patients with scleral show who underwent LFI advancement or LFI impaction in a Taleghani Hospital (Tehran, Iran) between 2003 and 2018. After exclusion of patients with systemic diseases, history of trauma, previous surgery, cleft lip or palate, and those with incomplete or inaccurate photographs or cephalograms, 43 patients were eligible.

All patients had standard frontal photographs in natural head position; otherwise, they were excluded from the study. Surgery had been performed by maxillofacial surgeons of Shahid Beheshti University of Medical Sciences (Tehran, Iran) from the pterygomaxillary fossa up to the piriform process (few millimeters above the maxillary teeth apices). For fixation, four plates (two on each side) and 16 titanium screws had been used in all patients.

Patients’ photographs and lateral cephalograms at baseline and at least 6 months postoperatively were analyzed using the Dolphin software (version 10.5, Canoga Park, CA), and vertical and sagittal maxillary changes were determined by superimposition of before and after tracings. Adobe Photoshop CC 2018 was used to measure the distances on frontal photographs of patients in order to calculate lower eyelid scleral exposure ( Fig. 1 ). All measurements were performed twice, 10 days apart, by a resident of orthodontics who was blinded to patient characteristics and groups.

Fig. 1
The lower scleral exposure was determined by pixel count of the distance from the lower eyelid margin (c) to corneal limbus (b). The number of pixels within the palpebral fissure (a to c) was determined to calculate the ratio of lower scleral exposure to palpebral fissure height.
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Aug 8, 2020 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Changes in scleral exposure following Le Fort І maxillary advancement or impaction
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