Unilateral sagittal split mandibular ramus osteotomy: indications and geometry.

Small mandibular asymmetries may be corrected by unilateral sagittal split ramus osteotomy (USSO). This study had two objectives: first to define the geometric changes in the mandibular condyle and the lower incisor teeth that result from the rotation of the major segment (n=26), and secondly to examine in a clinical study the temporomandibular joints (TMJ) of 23 patients after correction of mandibular asymmetry by USSO to find out if there were any long-term adverse effects. Small mandibular asymmetries (<5mm) can be corrected by USSO.

The influence of the segmentation process on 3D measurements from cone beam computed tomography-derived surface models.

To compare the accuracy of linear and angular measurements between cephalometric and anatomic landmarks on surface models derived from 3D cone beam computed tomography (CBCT) with two different segmentation protocols was the aim of this study. CBCT scans were made of cadaver heads and 3D surface models were created of the mandible using two different segmentation protocols. A high-resolution laser surface scanner was used to make a 3D model of the macerated mandibles.

Application of cone beam computed tomography in facial imaging science.

The use of three-dimensional (3D) methods for facial imaging has increased significantly over the past years. Traditional 2D imaging has gradually being replaced by 3D images in different disciplines, particularly in the fields of orthodontics, maxillofacial surgery, plastic and reconstructive surgery, neurosurgery and forensic sciences. In most cases, 3D facial imaging overcomes the limitations of traditional 2D methods and provides the clinician with more accurate information regarding the soft-tissues and the underlying skeleton.

Practical limitations of cone-beam computed tomography in 3D cephalometry.

3D cone beam computed tomography (CBCT) images offer a unique and new appreciation of the anatomical structures and underlying anomalies not possible with conventional radiographs. However, in almost all aspects of CBCT imaging, from utilization to application, inherent limitations and pitfalls exist. Importantly, these inherent limitations and pitfalls have practical implications which need to be addressed before the potential of this technology can be fully realized.

Combined 3-dimensional and mirror-image analysis for the diagnosis of asymmetry.

Three-dimensional imaging techniques have greatly improved our ability to assess asymmetry by means of linear and angular measurements. However, visualizing deformities enables a unique appreciation of the underlying deformity, which might not be possible by looking at quantitative numbers alone. This article describes the method of a mirror-image analysis technique to visualize the asymmetry to assist in diagnosis and treatment planning.

Reliability and the smallest detectable difference of measurements on 3-dimensional cone-beam computed tomography images.

Introduction: The aim of this study was to determine the reliability and the measurement error (by means of the smallest detectable error) of 17 commonly used cephalometric measurements made on 3-dimensional (3D) cone-beam computed tomography images.

Methods: Twenty-five cone-beam computed tomography scans were randomly selected, and 3D images were rendered, segmented, and traced with the SimPlant Ortho Pro software (version 2.1, Materialise Dental, Leuven, Belgium).

Segmentation process significantly influences the accuracy of 3D surface models derived from cone beam computed tomography.

Aims: To assess the accuracy of surface models derived from 3D cone beam computed tomography (CBCT) with two different segmentation protocols.

Materials And Methods: Seven fresh-frozen cadaver heads were used. There was no conflict of interests in this study.

Evaluation and comparison of postero-anterior cephalograms and cone-beam computed tomography images for the detection of mandibular asymmetry.

The aim of this study was to evaluate and compare postero-anterior (PA) cephalograms and cone-beam computed tomography (CBCT) images for the detection of mandibular asymmetry. Six asymmetric anonymous dry human skulls with visible chin deviation were available for this study. Metallic markers were glued on the anatomical landmarks to avoid identification error.

A three-dimensional comparison of a morphometric and conventional cephalometric midsagittal planes for craniofacial asymmetry.

Morphometric methods are used in biology to study object symmetry in living organisms and to determine the true plane of symmetry. The aim of this study was to determine if there are clinical differences between three-dimensional (3D) cephalometric midsagittal planes used to describe craniofacial asymmetry and a true symmetry plane derived from a morphometric method based on visible facial features. The sample consisted of 14 dry skulls (9 symmetric and 5 asymmetric) with metallic markers which were imaged with cone-beam computed tomography.

Reliability and the smallest detectable differences of lateral cephalometric measurements.

Introduction: The aim of this study was to determine the reliability and the measuring error (by means of the smallest detectable error) of 11 angular and 4 linear measurements commonly used for cephalometric analysis.

Methods: Twenty-five digital lateral cephalograms were randomly selected and traced with Viewbox software (version 3.1.

Evaluation of anthropometric accuracy and reliability using different three-dimensional scanning systems.

The aim of this study was to evaluate the accuracy and reliability of standard anthropometric linear measurements made with three different three-dimensional scanning systems namely laser surface scanning (Minolta Vivid 900), cone beam computed tomography (CBCT), 3D stereo-photogrammetry (Di3D system) and to compare them to physical linear measurements. The study sample consisted of seven cadaver heads. The reliability and accuracy were assessed by means of a series of 21 standardized, linear facial measurements derived from 15 landmarks taken both directly on the face with a set of digital callipers and indirectly from a three-dimensional (3D) soft tissue surface models derived from CBCT, laser surface scans and 3D photographs.

Accuracy and repeatability of anthropometric facial measurements using cone beam computed tomography.

Objective: The purpose of this study was to determine the accuracy and repeatability of linear anthropometric measurements on the soft tissue surface model generated from cone beam computed tomography scans.

Materials And Methods: The study sample consisted of seven cadaver heads. The accuracy and repeatability were assessed by means of a series of 21 standardized, linear facial measurements derived from 11 landmarks taken both directly on the face with a set of digital calipers and indirectly from a three-dimensional soft tissue surface model generated from a cone beam computed tomography scan of the heads using SimPlant® Ortho Pro software.

Comparison between two-dimensional and midsagittal three-dimensional cephalometric measurements of dry human skulls.

The aim of this study was to compare two- and three-dimensional cephalometric values by using a three-dimensional analysis based on the midsagittal plane. Spherical metal markers were fixed on to the anatomical landmarks of 10 human skulls, which were examined radiographically with conventional lateral cephalograms and cone-beam computed tomographic (CBCT) scans. Preprogrammed analyses calculated the 18 angular and linear two- and three-dimensional cephalometric values.

Accuracy and reliability of facial soft tissue depth measurements using cone beam computer tomography.

It is important to have accurate and reliable measurements of soft tissue thickness for specific landmarks of the face and scalp when producing a facial reconstruction. In the past several methods have been created to measure facial soft tissue thickness (FSTT) in cadavers and in the living. The conventional spiral CT is mostly used to determine the FSTT but is associated with high radiation doses.

Accuracy of linear measurements from cone-beam computed tomography-derived surface models of different voxel sizes.

Introduction: The aims of this study were to determine the linear accuracy of 3-dimensional surface models derived from a commercially available cone-beam computed tomography (CBCT) dental imaging system and volumetric rendering software and to investigate the influence of voxel resolution on the linear accuracy of CBCT surface models.

Methods: Glass sphere markers were fixed on 10 dry mandibles. The mandibles were scanned with 0.

Simple technique to achieve a natural position of the head for cone beam computed tomography.

We developed a modified laser level technique to record the natural position of the head in all three planes of space. This is a simple method for use with three-dimensional images and may be valuable in routine craniofacial assessment.

Antero-posterior and transverse changes in the positions of palatal rugae after rapid maxillary expansion.

The purpose of this study was to investigate the stability of the medial aspects of the rugae in patients where rapid maxillary expansion (RME) was performed in addition to fixed appliance therapy. Nineteen subjects that met the inclusion criteria for each group were randomly selected from the archive of one orthodontist office. The RME/fixed appliances group consisted of 8 males and 11 females (mean age pre-treatment 12.