Digital live-tracking 3-dimensional minisensors for recording head orientation during image acquisition.

Introduction: Our objective was to test the value of minisensors for recording unrestrained head position with 6 degrees of freedom during 3-dimensional stereophotogrammetry.

Methods: Four 3-dimensional pictures (3dMD, Atlanta, Ga) were taken of 20 volunteers as follows: (1) in unrestrained head position, (2) a repeat of picture 1, (3) in unrestrained head position wearing a headset with 3-dimensional live tracking sensors (3-D Guidance trackSTAR; Ascension Technology, Burlington, Vt), and (4) a repeat of picture 3. The sensors were used to track the x, y, and z coordinates (pitch, roll, and yaw) of the head in space.

Cranial base superimposition for 3-dimensional evaluation of soft-tissue changes.

Introduction: The recent emphases on soft tissues as the limiting factor in treatment and on soft-tissue relationships in establishing the goals of treatment has made 3-dimensional (3D) analysis of soft tissues more important in diagnosis and treatment planning. It is equally important to be able to detect changes in the facial soft tissues produced by growth or treatment. This requires structures of reference for superimposition and a way to display the changes with quantitative information.

Primary failure of eruption and PTH1R: the importance of a genetic diagnosis for orthodontic treatment planning.

Introduction: Primary failure of eruption (PFE) is characterized by nonsyndromic eruption failure of permanent teeth in the absence of mechanical obstruction. Recent studies support that this dental phenotype is inherited and that mutations in PTH1R genes explain several familial cases of PFE. The objective of our study was to investigate how genetic analysis can be used with clinical diagnostic information for improved orthodontic management of PFE.

Pharyngeal airway volume and shape from cone-beam computed tomography: relationship to facial morphology.

Introduction: The aim of this study was to assess the differences in airway shape and volume among subjects with various facial patterns.

Methods: Cone-beam computed tomography records of 62 nongrowing patients were used to evaluate the pharyngeal airway volume (superior and inferior compartments) and shape. This was done by using 3-dimensional virtual surface models to calculate airway volumes instead of estimates based on linear measurements.

Primary failure of eruption: further characterization of a rare eruption disorder.

Introduction: Posterior open bite has several possible causes, including primary failure of eruption (PFE) that affects all teeth distal to the most mesial involved tooth, mechanical failure of eruption (MFE) (primarily ankylosis) that affects only the involved tooth or teeth, and soft-tissue interferences with eruption (other).

Methods: Radiographs and other clinical records for 97 cases of failure of posterior eruption submitted for consultation were analyzed to further characterize PFE and distinguish it from MFE.

Results: Of the 97 cases, 38 were judged to be clear-cut PFE; 19 were diagnosed as MFE; 32 were classified as indeterminate failure because they were too young to be certain of the distinction between PFE and MFE; and 8 were placed in the "other" category.

Pitch, roll, and yaw: describing the spatial orientation of dentofacial traits.

The value of systematically enhancing the Angle classification by including transverse and vertical characteristics in addition to anteroposterior relationships for the face and the dentition is universally accepted. Three aeronautical rotational descriptors (pitch, roll, and yaw) are used here to supplement the planar terms (anteroposterior, transverse, and vertical) in describing the orientation of the line of occlusion and the esthetic line of the dentition. Each of the latter traits affects the modern clinical practice of orthodontics because of its greater focus on dentofacial traits beyond the correction of malocclusion.