Davide Decesari – Luisa Iannotti

Lingual or Palatal bow

sections mixed and variable

cobalt-chrome sintered

2014

Lingual or Palatal bow sections mixed and variable

cobalt-chrome sintered

Nowadays lingual and palatal arches used to expand from inside to outside maxillary

or mandibular teeth are cold shaped using pliers fit for the purpose and cobalt-chrome

or other materials’ s wires usually circular with a diameter of 0,36 “.

The activation given to these arches is a calibration action that takes place plastically

deforming a piece of wire.

So to the arch is given the force required to act on elements with which it is in contact

causing them to move.

Due to the geometrical characteristic of the section of the wire used, which,as

mentioned above, is circular, during the calibration operation can cause a non-

symmetric system forces that unbalance the action of the arch.

Therefore, it is necessary to change the portion of wire where calibration is done using

a square section instead of a circular one.

We crushed the wire segment indicated with special molds. This system shows critical

points of possible breakage where the section changes from flat to circular. The same

happened grinding the section with small abrasive wheels.

Another try consists on the union of the two sections by welding or brazing with a laser

welding machine.

The solution is not satisfactory because both welding methods alter the physical

characteristics of the material at the junction points and pose the problem of the

possible detachment of the parts joined.

The same applies to the need to vary the diameter of the circular section of the arch in

relation to the parts which compose it, for example the parts of arch used for anchoring

.For all that it was decided to build the arches through the selective laser sintering.

After having received the STL dental arch’s ´file obtained with 3D scanning, the arch

is made with a CAD modeler .In this way we get a very precise design of the shape and

you can derive more complex shapes than with the modeling made with pliers and

wire.

In the progectual drawing we create the sections we need varying with diameters

and thicknesses finally realizing a single piece.

Printing followed by sintering allows to obtain the full respect of geometries. Chrome-

cobalt used is much more performing than that used in the traditional bending with

pliers.

This material may undergo the heat treatment, therefore reacting optimally, but more

important is that you use a high quality product due to the variety of the sections in the

application and is safe because we don’t risk the disjunction of the parties or a breakage

from mechanical stress.

Davide Decesari – Luisa Iannotti

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