An in vitro investigation on friction generated by ceramic brackets

Area of Science:

• Orthodontics
• Biomaterials Science
• Dental Mechanics

Background:

• Orthodontic bracket friction impacts treatment efficiency.
• Ceramic brackets offer aesthetic advantages over traditional metal brackets.
• Understanding friction differences between bracket materials is crucial for clinical application.

Purpose of the Study:

• To compare the friction of conventional stainless steel brackets with various ceramic brackets.
• To evaluate friction under different archwire and environmental (dry/wet) conditions.
• To assess the influence of bracket slot material on friction.

Main Methods:

• Tested polycrystalline alumina (PCA), PCA with stainless steel slot (PCA-M), and monocrystalline sapphire (MCS) brackets against stainless steel controls.
• Utilized a 10-bracket sliding model with elastic ligatures and various archwires.
• Evaluated friction in both dry and wet (saliva) environments.
• Performed Scanning Electron Microscopy (SEM) to analyze bracket surface characteristics.

Main Results:

• PCA and MCS brackets showed significantly higher friction than stainless steel and PCA-M brackets with rectangular archwires (P<.01).
• PCA brackets exhibited significantly higher friction than MCS brackets with 0.014 x 0.025-inch nickel-titanium (Ni-Ti) archwires (P<.01).
• Mean friction values were generally higher in the wet state compared to the dry state.
• SEM revealed distinct surface differences among the tested bracket materials.

Conclusions:

• Polycrystalline alumina (PCA) brackets demonstrated significantly higher friction than monocrystalline sapphire (MCS) brackets specifically with 0.014 x 0.025-inch Ni-Ti archwires.
• The 10-aligned-bracket model yielded comparable results to single-bracket systems, with notable exceptions in friction levels involving specific archwires.
• Friction levels are material-dependent and influenced by environmental conditions and archwire type.