T ooth-width ratios are used diagnostically to quantify the harmony between the mandibu-lar and maxillary arches. A number of analyses have been developed to compare the tooth-width ratios of malocclusions to standardized norms. 1-4 The Ho-Freer Graphical Analysis of Tooth-Width Discrepancy (GATWD) provides a simple graphic description of tooth-width relationships between the arches, a comprehe...

OBJECTIVE To determine the prevalence of tooth size discrepancies (TSDs) in an Irish orthodontic population among different malocclusion groups. MATERIALS AND METHODS From 850 pretreatment sets of orthodontic models at a university clinic, 240 were selected with 30 female and 30 male sets for each malocclusion (Class I, Class II division 1, Class II division 2, and Class III). Digital models ...

Objective: To determine the frequency of patients who require extraction of permanent premolars among those treated with extraction of deciduous teeth for the correction of incisor crowding in the mixed dentition and analyze possible associated variables. Methods: The sample was composed of orthodontic records of 70 patients with permanent dentition whose treatment had begun in the mixed dentit...

Introduction Load-carrying capacity of gears, especially the surface durability, is influenced by their tooth surface roughness in addition to their tooth profiles and tooth traces (Refs. 1 and 2). The harder the gears are, the smoother their tooth surfaces and the more accurately their tooth profiles should be finished in order to obtain high load-carrying capacity. Through research, the relat...

The main component of natural teeth was determined many years ago as calcium phosphate, mostly in the form of hydroxyapatite with different crystallites. In the past, the method used in tooth crystal investigation has been mainly powder X-ray diffraction analysis, but this method has its drawbacks, i.e. the destruction of the natural tooth structure and the difficulty in examining the preferred...

BACKGROUND Tooth replacement rate can be calculated in extinct animals by counting incremental lines of deposition in tooth dentin. Calculating this rate in several taxa allows for the study of the evolution of tooth replacement rate. Sauropod dinosaurs, the largest terrestrial animals that ever evolved, exhibited a diversity of tooth sizes and shapes, but little is known about their tooth repl...

BACKGROUND AND AIMS Hypodontia is a common developmental abnormality of dentition. This study aimed to determine tooth width in patients affected with mild hypodontia and compare the results with a control group without tooth agenesis. MATERIALS AND METHODS The orthodontic records of 25 patients with congenital missing of one or two teeth (hypodontia group), and 25 subjects with full dentitio...

In this paper, a diversity generating mechanism is proposed for an Evolutionary Programming (EP) algorithm that determines the basic structure of Multilayer Perceptron classifiers and simultaneously estimates the coefficients of the models. We apply a modified version of a saw-tooth diversity enhancement mechanism recently presented for Genetic Algorithms, which uses a variable population size ...

This paper presents the development of a novel application using motion analysis techniques to measure tooth movement in 3D. Measuring the relative displacements of teeth under load allows a greater understanding of the mechanical properties of the periodontal ligament (PDL). Two marker clusters were fixed onto the measured tooth and the reference tooth via orthodontic brackets and movements we...