Lower face cephalometry based on quadrilateral analysis with cone-beam computed tomography: a clinical pilot study.
OBJECTIVE
As most orthognathic surgeries focus on the lower face, the aim of this study was to transfer previously developed two-dimensional cephalometry-which is useful for surgeons in the orthognathic surgery of the lower face-to three-dimensional (3D) cephalometry by using cone-beam computed tomography (CBCT). We selected the quadrilateral lower face analysis developed by the surgeon Di Paolo, who focused only for the lower face and mentioned that data in millimeters are more easy to use than angles for surgeons. Additionally, we wanted to create a 3D lower face analysis approach based on quadrilateral analysis and establish a reference table for surgical planning.


METHODS
Three investigators assigned 16 landmarks on CBCT images from 30 patients with normocclusion. Intra-class correlation coefficients (ICCs) and standard deviations (SDs) were calculated according to each landmark. The maxillary and mandibular lengths and widths and the anterior and posterior lower facial heights (ALFH and PLFH) are presented as means and SDs. The asymmetry of the face was calculated with paired t test, and the coherence of the lower face was assessed with correlation coefficients (r) and regression models.


RESULTS
The ICCs were ≥0.90, and the SDs of the landmarks were lower than 1.00 mm, except for the J-point, which was located at the junction of the anterior border of the ramus and the corpus of the mandible. The SDs of linear measurements were 3.06-5.20 mm, and there was no significant facial asymmetry. The r among the structures was greater than 0.3 in 13 of 15 assessments. Based on these values, we could establish a floating norm of the lower face using the following five regressions: one linear regression for the mandibular length, two quadratic models for the ALFH and PLFH, and two multivariate regressions for the posterior widths of the maxillae and mandible.


CONCLUSIONS
The adaptation of quadrilateral analysis can provide accurate 3D characterization of the morphology of the lower face and the floating norm based on millimeter values, which is practical for surgeons. As the 3D extension of quadrilateral analysis could provide references of the lower face, which might be an accurate 3D approach for presurgical planning, the further investigation in bigger sample would be relevant in the practice.
Department of Oro-Maxillofacial Surgery and Stomatology, Semmelweis University, Mária Street 52, Budapest, 1085, Hungary. adrienn.dobai@gmail.com.
Adrienn
A
Dobai
Department of Oro-Maxillofacial Surgery and Stomatology, Semmelweis University, Mária Street 52, Budapest, 1085, Hungary.
Tamás
T
Vizkelety
Kandó Kálmán Faculty of Electrical Engineering, Óbuda University, Tavaszmező Street 15-17, Budapest, 1084, Hungary.
Zsolt
Z
Markella
Dento-Cura Kft. Private Praxis, Kálvin Square 3, Budapest, 1053, Hungary.
Adrienne
A
Rosta
Dento-Cura Kft. Private Praxis, Kálvin Square 3, Budapest, 1053, Hungary.
Ágnes
Á
Kucsera
Department of Oro-Maxillofacial Surgery and Stomatology, Semmelweis University, Mária Street 52, Budapest, 1085, Hungary.
József
J
Barabás
D000293:Adolescent; D000328:Adult; D002508:Cephalometry / Q000379:methods*; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging*; D008437:Maxilla / Q000000981:diagnostic imaging*; D015999:Multivariate Analysis; D056948:Orthognathic Surgical Procedures; D010865:Pilot Projects; D012044:Regression Analysis; D055815:Young Adult
Biostatistics; Cephalometry; Computer-assisted three-dimensional imaging; Facial asymmetry