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

Objective

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.

Materials and Methods

Preoperative and 6-months postoperative cephalograms and stereophotogrammetric images of 45 subjects (mean age:21.66±2.97 years) that underwent orthognathic surgery for Class III correction were retrieved. Subjects were divided into 3 groups: maxillary advancement-only (AO); maxillary advancement+impaction (AI), 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), 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<0.05).

Results

Mean value of maxillary movements were: 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<0.05). 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>0.05).

Conclusion

Intergroup comparisons showed no statistically significant difference, revealing similar reduction in all three groups despite the differences in the vertical movement variable.

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