Scleral exposure changes after Le Fort I maxillary advancement with vertical component in individuals with skeletal Class III malocclusion-A stereophotogrammetric image study.

Abstract

This retrospective study aimed to evaluate inferior scleral exposure changes in Class III patients that underwent orthognathic surgery with Le Fort I osteotomy with and without vertical displacement. Preoperative and 6months postoperative cephalograms and stereophotogrammetric images of 45 subjects (mean age: 21.66±2.97years) who underwent orthognathic surgery for Class III correction were retrieved. Subjects were divided into 3 groups: maxillary advancement-only (AO), maxillary advancement+impaction (AI) and maxillary advancement+downfracture (AD). Exclusion criteria were mandibular-only surgery, occlusal canting, facial asymmetry, orbital surgery and craniofacial syndrome. One investigator measured inferior scleral exposure on both sides using following landmarks: upper eyelid margin (A), inferior limbus (B) and lower eyelid margin (C). Distance between A and C was recorded as overall eye height (E), and distance between B and C was recorded as inferior sclera exposure (S). S:E ratio in percentage was calculated to standardize sclera exposure relative to overall eye height. Wilcoxon signed-rank and Kruskal-Wallis tests were used for statistical analysis (P<.05). Mean value of maxillary movements was as follows: 4.21±1.82mm advancement in AO, 5.08±2.18mm advancement and 2.33±0.99mm impaction in AI, 3.95±1.45mm advancement and 3.1±0.71mm downfracture in AD. Change in reduction of scleral exposure was significant in all groups (P<.05). AI group bilaterally and AO group right side had highest differences (-4.96±4.86, -6.09±4.21, -4.99±3.23, respectively). There was no significant difference between groups in S:E ratio changes (P>.05). Intergroup comparisons showed no statistically significant difference, revealing similar reduction in all three groups despite the differences in the vertical movement variable.