Change of incisor inclination effects on points A and B.
OBJECTIVE
To identify and evaluate changes in the cephalometric position of points A and B due to an incisal inclination change caused by orthodontic treatment.


METHODS
A total of 103 pairs of consecutive pretreatment and posttreatment lateral cephalographs that met the inclusion criteria were systematically collected from the departmental database and digitized using a customized software program (Gela). Repeatability analyses showed good reliability and no evidence of bias. A statistical model was generated using a Generalized Estimating Equation approach to analyze the data accounting for growth and bodily movement because both factors influence the position of points A and B (P < .001, P < .001). Changes in tooth length were also accounted for, as these changes may influence the calculated position of the centroid (P = .002).


RESULTS
Each 10 degrees change in the maxillary incisor inclination results in a statistically significant average change in point A of 0.4 mm in the horizontal plane (P = .028). Each 10 degrees change in the mandibular incisor inclination results in a borderline statistically significant average change in point B of 0.3 mm in the horizontal plane (P = .058). There were no significant changes in the vertical position of points A and B.


CONCLUSIONS
The effects of incisal inclination changes, due to orthodontic treatment, are of no clinical relevance to the position of point A and B, even though they may be statistically significant. The validity of points A and B as skeletal landmarks generally holds true, and accounting for treatment changes is unnecessary.
Department of Orthodontics, UCL Eastman Dental Institute, 256 Gray's Inn Road, London WC1X 8LD, UK. toothfairy999@hotmail.com
Rasha
R
Al-Abdwani
David R
DR
Moles
Joseph Harold
JH
Noar
D000293:Adolescent; D000328:Adult; D000465:Algorithms; D002508:Cephalometry / Q000706:statistics & numerical data; D002648:Child; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007180:Incisor / Q000473:pathology*; D008297:Male; D008334:Mandible / Q000254:growth & development / Q000473:pathology*; D008437:Maxilla / Q000254:growth & development / Q000473:pathology*; D009811:Odontometry; D009971:Orthodontics, Corrective; D012189:Retrospective Studies; D014087:Tooth Movement Techniques; D014716:Vertical Dimension; D055815:Young Adult