Quality of the brackets

 

Images speak better than a long speech. The first series of photographs proves that the quality of the brackets depend of the manufacuring process and demonstrate the necessity of orthodontic standards. the second series shows that chemical recycling deteriorate the brackets in spite of the claims of the laboratories.

Effet of the corrosion in cavity of mouth on the brackets :

The metal brackets are composed of stainless steel 304 or 316 L which is the most resistant.

A Liberty bracket from ORLINE munufacured in one piece of 316 L steel do not show any trace of corrosion and remain functional after long term resistance test (20 years in cavity of mouth and 15 recycling process by Ortho service).
 


The brackets welded with alloys rich in gold or noble metal of the mine of platinum (Ormco, 3 M, ORLINE) are as resistant as the cast solid brackets but the weldings low in noble metals of some others brackets corrode in cavity of mouth until it cause a rupture between the base and the tie wings.

In the two following examples, we see the effects of corrosion on a bracket which has just been removed and observe on a bracket whose base was separated from the tie wings the progression of the corrosion.

Impact of chemical recycling on the brackets. 

The chemical recycling used by many laboratories of recycling is the most economic process.

It brings considerable profits to those which practise it. Unfortunately its effects on quality of the brackets can be disastrous.
The chemical solvants able to destroy the adhesive release by combining with the resins very corrosive acids especially in the presence of moisture

This corrosion create an etching on all the surface of the bracket (grey aspect due to the reverberation of the light). the lost of retention may reach from 10 to 30% for each recycling process.
Protected by the adhesive, the base does not undergo any corrosion in th mouth. The strong corrosion of this is the result of chemical attack during the recycling by with chemical process.

The loss of retention measured with the tensile-test bech exceed 50%. the treatment of the chemical base by etching increase the retention of 20%. Finally the retention is 0.5x1.2=60% what remains lower than 1.

The retention of a bracket treated by Ortho service remains the same of a new one. It may be increase of 20% by laser etching or 40% by Microret. The final retention is 120% to 140%.