Maxillary Changes Following Facial Bipartition – A Three-Dimensional Quantification

Abstract

Introduction: Children with Apert syndrome have hypertelorism and midfacial hypoplasia, which can be treated with facial bipartition (FB), often aided by rigid external distraction. The technique involves a midline osteotomy that lateralizes the maxillary segments, resulting in posterior cross-bites and midline diastema. Varying degrees of spontaneous realignment of the dental arches occurs postoperatively. This study aims to quantify these movements and assess whether they occur as part of a wider skeletal relapse or as dental compensation. Methods: Patients who underwent FB and had high quality computed tomography scans at the preoperative stage, immediately postsurgery, and later postoperatively were reviewed. DICOM files were converted to three-dimensional bone meshes and anatomical point-to-point displacements were quantified using nonrigid iterative closest point registration. Displacements were visualized using arrow maps, thereby providing an overview of the movements of the facial skeleton and dentition. Results: Five patients with Apert syndrome were included. In all cases, the arrow maps demonstrated initial significant anterior movement of the frontofacial segment coupled with medial rotation of the orbits and transverse divergence of the maxillary arches. The bony position following initial surgery was shown to be largely stable, with primary dentoalveolar relapse correcting the dental alignment. Conclusions: This study showed that spontaneous dental compensation occurs following FB without compromising the surgical result. It may be appropriate to delay active orthodontic for 6-months postoperatively until completion of this early compensatory phase.

Discussion of Maxillary Changes Following Facial Bipartition: A Three-Dimensional Quantification

“…Cassio Eduardo Raposo-Amaral, MD, PhD Ãy T he Great Ormond Street Hospital for Children (GOSH) craniofacial group is to be commended for their interesting study entitled ''Maxillary Changes Following Facial Bipartition -A Three-Dimensional Quantification'' which, offers novel insights regarding maxilla dynamics following facial bipartition monobloc. 1 The authors measured the maxilla changes of 5 Apert syndrome patients to determine whether subsequent amelioration of frontal incisor diastema following medialization of the hemi-halves of the face results from maxillary relapse or spontaneous dental compensation. 1 To verify their clinical observations, the authors utilized bony landmarks derived from imaging superimposition via validated computerized tomography cephalometric methodology.…”

“…1 The authors measured the maxilla changes of 5 Apert syndrome patients to determine whether subsequent amelioration of frontal incisor diastema following medialization of the hemi-halves of the face results from maxillary relapse or spontaneous dental compensation. 1 To verify their clinical observations, the authors utilized bony landmarks derived from imaging superimposition via validated computerized tomography cephalometric methodology.…”

“…The Great Ormond Street Hospital for Children (GOSH) craniofacial group is to be commended for their interesting study entitled “Maxillary Changes Following Facial Bipartition – A Three-Dimensional Quantification” which, offers novel insights regarding maxilla dynamics following facial bipartition monobloc 1 …”

Comparison of Internal and External Distraction in Frontofacial Monobloc Advancement: A Three-Dimensional Quantification

“…A preexisting workflow detailed by van de Lande et al was used, starting with rigid alignment of meshes on the skull base, in this case using six landmarks. 17,18 Nonrigid iterative closest point registration was then guided by a further 28 manually placed landmarks as specified in Table 1, using open-source software (R3DS WRAP v3.4, Voronezh, Russia). 19 Color maps were computed to visualize the global displacements across the entire facial skeleton.…”

10. Comparison of Internal and External Distraction in Frontofacial Monobloc Advancement: A Three-Dimensional Quantification

“…was used, starting with rigid alignment of meshes on the skull base, in this case using six landmarks. 17,18 Non-rigid iterative closest point registration (NICP) was then guided by a further twenty-eight manually placed landmarks as specified in Table 1, utilising open-source software (R3DS WRAP v3.4, Voronezh, Russia). 19 Colour maps were computed to visualise the global displacements across the entire facial skeleton.…”