Static and kinetic frictional forces of silica-insert ceramic brackets with coated archwires in artificial saliva

Comparative in vitro analysis of the sliding resistance of a modern 3D-printed polymer bracket in combination with different archwire types

Objectives

To analyse the sliding resistance of a modern 3D-printed polymer bracket combined with different archwire types and to compare the results with conventionally used polymeric, ceramic and metal brackets. It was of further interest which bracket-archwire combination could be best qualified for clinical use.

Materials and methods

The sliding behaviour was tested using an orthodontic measurement and simulation system (OMSS) for the use of two bracket types of the polymer, ceramic and metal group in combination with a 0.016 inch × 0.022 inch and 0.017 inch × 0.025 inch archwire of nickel-titanium (NiTi), titanium-molybdenum alloy (TMA) and stainless steel. Six bracket types were combined with six different archwire types and compared to each other.

Results

The sliding resistance showed significant differences between various the bracket-archwire complexes. The combination of 3D-printed polymer brackets with both steel archwire cross-sections showed the least values of sliding resistance (average 23–29%), while the combination of ceramic brackets with TMA archwires presented the highest (average 47%).

Conclusions

The present study could show that modern 3D-printed bracket materials can have similar or even better mechanical properties than conventional ones regarding sliding resistance. Although the combination of bracket and archwire material is decisive for low sliding resistance values, the selection of the bracket material seems to have a greater influence than the selection of the archwire material or its cross section.

Clinical relevance

It might be possible in future to combine aesthetic and biomechanical requirements for aesthetic brackets by using 3D-printing technology.

Comparative evaluation of Stainless-steel wires and brackets coated with nanoparticles of Chitosan or Zinc oxide upon friction: An in vitro study

OBJECTIVE

The present study was performed to affirm surface characterization, as well as to compare the effect of coating of stainless-steel (SS) orthodontic brackets and wires by nanoparticles Chitosan (CTS) or Zinc oxide (ZnO) during friction.

MATERIAL AND METHODS

Seventy SS brackets for the upper right central incisors with a 0.022-inch system and seventy 0.019×0.025-inch SS rectangular wires, with and without ZnO and CTS nanoparticle coating, were used. Coating was analysed by SEM. A universal testing machine was used to calculate the friction between the wires and brackets. Statistical analysis was performed using one-way ANOVA and Tukey's tests.

RESULTS

Significant differences were detected between coated and uncoated wires and brackets for friction with either ZnO or CTS nanoparticles. The mean values of the wires and brackets coated with ZnO and CTS nanoparticles were 0.64±0.24N and 0.85±0.23N, respectively, while they were 1.79±0.61N for the uncoated group. In addition, there was a significant decrease of about 64% and 53% found after coating with ZnO and CTS nanoparticles, respectively. The results of CTS nanoparticle coating were consistent with those of ZnO nanoparticles.

CONCLUSIONS

Friction force decreased significantly after coating of CTS or ZnO nanoparticles. These nanoparticles provide an opportunity to reduce friction during tooth movement, resulting in better anchorage control, reduced treatment time and risk of root resorption.