Control of vertical dimension during maxillary orthognathic surgery. A clinical trial comparing internal and external...

The accuracy of vertical control during maxillary orthognathic surgery was assessed in 45 patients, comparing the use of traditional internal measurements across the osteotomy lines (15 subjects) with measurements between the incisor teeth and an external reference point consisting of a bone screw placed at nasion (two groups of 15 subjects each). Although use of a fixed external reference point can significantly decrease positioning error (p < 0.001), considerable care is required during application of rigid fixation to maintain the correct vertical dimension.