Production and optimization of aesthetic composite brackets and archwires by wear damages

Sliding forces as well as aestheticism are important properties for orthodontic appliances. In this study, a developed prototype aesthetic biocomposite brackets and archwires compared with commercially available products. To produce archwires a flexible polymeric shrinkage tube was used as a die, resins reinforced with glass fibers (GF). Whereas a pultrusion process was used for the production of brackets, epoxy reinforced with braided GF. This study included: (i) the sliding characteristics, (ii) scanning electron microscope (SEM) images and (iii) geometric comparisons of brackets before and after loading in sliding mechanics. Specimens of each bracket-archwire combination were tested in universal testing machines. The sliding force involved in a ligated bracket-archwire is measured by a self-designed jig for wear. The interfaces of the two soft matrix is changed during sliding which causes shearing deformation and damaged the contact surfaces. Although penetrations through the soft matrix are observed, the GF reinforcement is undamaged for most of the combinations tested but exposed severely. This finding implies the risk of GF release due to the depletion of soft matrix of composites during clinical use is significant. Saliva had a consistent effect of increasing the friction, in contrast to the inconsistent effect reported in the literature.