Introduction:

The use of external reference points (ERP) like the nasal pin (NP) and eye's medial canthus (EMC) provides a stable and reproductible landmarks for maxillary repositioning. ERP are widely used, for its practicality to achieve the desired aesthetic result in orthognathic surgery (OS).

Objectives:

The purpose of this study is to compare the ERPs: NP and EMC, to define which is the most accurate, and also define its limitations, in the intraoperative phase for vertical repositioning of the maxilla.

Patients and methods:

We performed a retrospective study on 26 patients who underwent OS from December 2015 to August 2018. Previous to the Le Fort I osteotomy, the vertical measurements were made. The most accurate ERP was considered to be the one that obtained the least average difference between the vertical measurement of the pre-surgical planning and that obtained in the intraoperative period.

Results:

The planned vertical movement was an average of -1.73 mm ± 1.97 SD, with the largest maxillary impaction movement of -6 mm and the largest maxillary descent of 2 mm. The difference between planned vertical movement and obtained measurements of vertical change for NP had an average 0.05 mm ± 0.51 SD (95 % CI, -0.15 - 0.26), and the difference between planned vertical movement and obtained measurements for EMC had an average 1.23 mm ± 1.29 SD (95 % CI, 0.71 - 1.75), with a statistically significant difference (p = 0.0001) between them of -1.18 mm± 1.23 (95 % CI, -1.67 - -0.68).

Conclusions:

The use of the NP as an ERP provides greater precision and predictability of movement in the vertical repositioning of the maxillomandibular-complex, compared to the use of EMC. Both techniques can be used as a complement, being aware of the effect of triangulation.

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