Objectives: The objective of this study was to develop a reproducible method to measure the change of palatal volume and area through superimposition using maxillary expansion digital cast models. Materials and Methods: A total of 10 pre-and 10 postexpansion dental cast models were scanned by the same cone-beam computed tomography machine. Superimposition was performed using a fully automated surface-best fit of the palatal surfaces on the digital cast models. A gingival plane, identified only once on superimposed casts, and a distal plane with the lateral closing border and the palatal surface were used to localize this selection of air. Area and volume were calculated for pre-and postexpansion records. Pre-and postexpansion palatal volume and area were measured by the main investigator and three different observers for inter-and intra-observer reproducibility assessment. Results: The level of intra-and inter-observer agreement was very strong (intraclass correlation coefficients 0.953; P value , .0001) for all measurements. Conclusions: Palatal volume and area measurements based on the proposed superimposition are reproducible and can be used reliably. (Angle Orthod. 2018;88:397-402.)

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.

No abstract

Objectives To compare the changes of palatal volume and area in patients treated with tooth-tissue-borne palatal expanders (conventional Haas) and miniscrew-supported palatal expanders (modified Haas). Materials and Methods The sample included casts of 22 patients treated as part of a clinical study at the Department of Orthodontics, Al-Azhar University, to correct their crossbite malocclusion. Patients were divided equally into two groups upon arrival. The first group, with a mean age of 12 years and 6 months, received the miniscrew-supported palatal expander. The second group, with a mean age of 12 years and 2 months, received the Haas design-palatal expansion appliance. Pre- and post-expansion dental casts were cone beam computed tomography scanned and the slices were constructed into 3D volumes. Fully automated superimposition was done for pre- and post-expansion 3D models. Palatal volume and area were determined, and all measurements were carried out blindly. Paired t-test was used to assess the mean differences within each group and Welch's t-test was applied to assess the mean changes between the two groups. Shapiro-Wilk test was used to test for the normality of the data. Results There were no statistical differences in volume changes either within each group or between the groups. Although area changes were statistically significant within each group, the difference between the groups was not significant. Conclusions Changes that result from the use of either method to expand the upper arch occur primarily in the shape of the palate, but not in its size.