INTRODUCTION Friction measurements in orthodontics are often derived from models by using brackets placed on flat models with various straight wires. Dental arches are convex in some areas. The objectives of this study were to compare the frictional forces generated in conventional flat and convex dental arch setups, and to evaluate the effect of different archwires on friction in both dental a...

OBJECTIVE To evaluate the quantitative effects on torque expression of varying the slot size of stainless steel orthodontic brackets and the dimension of stainless steel wire, and to analyze the limitations of the experimental methods used. MATERIALS AND METHODS In vitro studies measuring torque expression in conventional and self-ligating stainless steel brackets with a torque-measuring devi...

This paper is devoted to the method developed in Ref. [1] for 3D reconstruction of the straight tracks in the tracking system consisting of the drift-chamber stereo layers. The method is based on the Hough-transform approach [2] – the discrete case of more general Radon transform [3] – and takes into account both coordinates of the hit wires and drift distances not only for the measurements in ...

We characterize the self-parallel (mitered) offsets of a general nonconvex polytope Q in 3-space and give a canonical algorithm that constructs a straight skeleton for Q.

The straight skeleton of a polygon is the geometric graph obtained by tracing the vertices during a mitered offsetting process. It is known that the straight skeleton of a simple polygon is a tree, and one can naturally derive directions on the edges of the tree from the propagation of the shrinking process. In this paper, we ask the reverse question: Given a tree with directed edges, can it be...

We study the computation of the straight skeleton of a planar straight-line graph (PSLG) by means of the triangulation-based wavefront propagation proposed by Aichholzer and Aurenhammer in 1998, and provide both theoretical and practical insights. As our main theoretical contribution we explain the algorithmic extensions and modifications of their algorithm necessary for computing the straight ...