['The purpose of this study was to evaluate the stability of maxillary advancement using bone plates for skeletal stabilization and porous block hydroxyapatite (PBHA) as a bone graft substitute for interpositional grafting.', 'The records of 78 patients (55 female, 23 male) with a diagnosis of anteroposterior maxillary hypoplasia were retrospectively evaluated. All patients underwent greater than 5 mm Le Fort I maxillary advancement with rigid fixation and PBHA interpositional grafting. The study sample was divided into 3 groups on the basis of the concurrent superior or inferior positioning of the maxillary incisors. Presurgery (T1), immediately postsurgery (T2), and longest follow-up (T3) lateral cephalometric tracings were superimposed to analyze for horizontal and vertical changes at the following landmarks: (1) point A, (2) incisal edge of the maxillary incisor, and (3) mesial cusp tip of maxillary first molar.', 'The maxilla was inferiorly repositioned in 27 patients, superiorly repositioned in 21 patients, and advanced horizontally without a significant vertical change in 30 patients. All groups showed 0.5 mm or less horizontal and vertical relapse. There was no statistically significant difference between the 3 groups.'] Do stability of the Le Fort I osteotomy for maxillary advancement using rigid fixation and porous block hydroxyapatite grafting?