Reliability of Anterior Nasal Spine as a Reference Point After LeFort I Surgery Using Three-Dimensional Analysis

Abstract

To evaluate the stability of maxilla following orthognathic surgery, it is necessary to consider the positional change of various landmarks according to bone remodeling of the maxilla. This study aimed to evaluate the stability of the anterior nasal spine (ANS) as a reliable landmark after orthognathic surgery. Forty-seven patients with skeletal class III malocclusion who underwent bimaxillary orthognathic surgery were included. Skeletal changes were measured using cone-beam computerized tomography at 3 time points: preoperative (T0), 1-month postoperative (T1), and 12-month postoperative (T2). Linear changes of the 6 landmark points of the maxilla were measured in 3 directions: anteroposterior, vertical, and transverse. The data were analyzed with paired t tests, independent t tests, and multiple regression analysis. At 12-month postoperatively, the ANS showed mean (standard deviation) 1.23 (1.07) mm posterior movement (P = 0.00), while other landmarks did not show positional changes, implying bony resorption of ANS. Multiple regression test showed surgical forward movements of ANS (T1-0) affect the postoperative backward changes (β = –0.05, P < 0.05). There was a negative correlation between the surgical movement and postoperative change of ANS by Pearson correlation test (r = –0.38, P < 0.05). The ANS is not a reliable measurement point in three-dimensional superimposition after orthognathic surgery. Therefore, in studying the stability and positional change pattern after LeFort I surgery, it is not recommended to use ANS as a reference point, as changes can occur in the measurement point itself.

Artificial Intelligence Splint in Orthognathic Surgery for Skeletal Class III Malocclusion: Design and Application

“…It has also been shown that the anterior nasal spine is not recommended as a measurement indicator due to its instability. 27 The mandibular deviation may be caused by the rotation of the mandible or the deviation of condyle position. These deviations are common in orthognathic surgery of skeletal class III malocclusion.…”

“…This may be due to the removal of excess bone spurs during surgery. It has also been shown that the anterior nasal spine is not recommended as a measurement indicator due to its instability 27. The mandibular deviation may be caused by the rotation of the mandible or the deviation of condyle position.…”

Metric evaluation of the anterior nasal spine to estimate sex and population group in South African individuals

“…Bone resorption after tooth loss does result in alveolar bone resorption [ 57 , 58 ] but the extent of the number of teeth lost and the time that the teeth have been missing on the ANS still requires further investigation. Other instances, like harvesting of the bone of the ANS to treat bone loss around implants or surgical procedures in the midfacial region [ 59 – 61 ], will also alter the anatomy and render the ANS of no value for identification.…”