United Reference Method for three-dimensional treatment evaluation

Abstract

BackgroundReproducible and descriptive Three-dimensional treatment evaluation can enhance future treatment based on realistic results. So, the purpose of this study was to describe a new method for three-dimensional treatment evaluation showing how to use fully-automated craniofacial superimposition of CBCT records combined with reference system to obtain descriptive and comparable results. This new method was named United Reference Method (URM).MethodsURM is a combination of automated 3D superimposition on anterior cranial base surface anatomy and measurements based on reference system. It was developed to show how to use fully-automated superimposition to obtain descriptive numerical comparable values. The method is based on: one main reference system for both superimposed CBCT records, semi-automation to increase accuracy, all measurements are projections and auxiliary references to aid in landmarks identification and measurements.The method steps can be described following a four-step approach: (1) Superimposition performed through a fully automated, voxel-wise, rigid registration considering only cranial base as a stable structure; (2) Identification of reference landmarks once on the superimposed records for corrected Frankfort Horizontal plane (C-FH) construction and a new semi-automated constructed Sella point to correct Orbital asymmetry; (3) Head orientation of superimposed CBCT images based on the C-FH; (4) Identification of landmarks affected by treatment with the aid of auxiliary reference planes. Evaluation of linear or angular changes derived by projection of same pre- and post-treatment landmarks on the C-FH. Pre- and post-expansion CBCT scans of 20 unilateral cleft lip and palate patients were used to calculate intra and inter-rater reliability. (X, Y and Z) coordinates, mean, standard deviation (SD) and Intra-class Correlation Coefficient (ICC) were calculated.ResultsThe proposed coordinates for C-FH construction showed ICC ≥ 0.998 and SD ranging from 0.064 to 0.242 mm. On the other hand, excluded coordinates due to expected natural craniofacial asymmetry had the lowest reliability ICC ≥0.742 and SD dramatically increased up to 1.112 mm.ConclusionURM showed adequate reliability so it can be used to produce three-dimensional descriptive data of craniofacial structural changes.

Influence of Orthodontic Treatment with Premolar Extraction on the Spatial Position of Maxillary Third Molars in Adult Patients: A Retrospective Cohort Cone-bean Computed Tomography Study

“…To address this issue, our study innovatively used only four easily recognizable landmarks: left orbitale, right orbitale, ANS, and PNS. Their stability has been con rmed in previous studies (15)(16)(17). Superimposition according to these four landmarks was performed in this study pre-and post-treatment, con rming the stability of this space coordinate system and suggesting its reliability under low radiation dose.…”

“…It is widely agreed that measuring three-dimensional objects using two-dimensional images routinely leads to errors, such as projection, superimposition of anatomic structures, and magni cation distortions (14,15). CBCT is designed to overcome these issues, and it is widely applied in research and in the clinic.…”

Influence of Orthodontic Treatment with Premolar Extraction on the Spatial Position of Maxillary Third Molars in Adult Patients: A Retrospective Cohort Cone-bean Computed Tomography Study

“…To address this issue, our study innovatively used only four easily recognizable landmarks: left orbitale, right orbitale, ANS, and PNS. Their stability has been con rmed in previous studies (13)(14)(15). Superimposition according to these four landmarks was performed in this study pre-and post-treatment, con rming the stability of this space coordinate system and suggesting its reliability under low radiation dose.…”

“…Measuring three-dimensional objects using two-dimensional images routinely leads to inevitable errors (12,13). Previous similar studies have all been based on two-dimensional images (lateral cephalogram or panoramic radiograph).…”

Influence of orthodontic treatment with premolar extraction on the spatial position of maxillary third molars in adult patients: a retrospective cohort cone-bean computed tomography study

“…Measuring three-dimensional objects using twodimensional images routinely leads to inevitable errors [12,13]. Previous similar studies have all been based on two-dimensional images (lateral cephalogram or panoramic radiograph).…”