A new method for successful indirect bonding in relation to bond strength

Area of Science:

• Biomaterials Science
• Orthodontics
• Polymer Chemistry

Background:

• Indirect bonding of orthodontic brackets is a common clinical procedure.
• Bracket loss during treatment can lead to increased chair time and costs.
• Current indirect bonding methods may lack uniform pressure application, potentially affecting bond strength.

Purpose of the Study:

• To develop and evaluate a new transfer method for indirect bracket bonding using shape memory polymers (SMPs).
• To improve bond strength and reduce bracket loss by applying uniform contact pressure.
• To assess the transfer accuracy and bond strength achieved with SMP-enhanced transfer trays.

Main Methods:

• Shape memory polymer (SMP) platelets were prepared and integrated into various transfer trays.
• In vitro experiments were conducted to transfer brackets from plaster models to human tooth models.
• Transfer accuracy was assessed using 3D-overlay analysis.
• Bond strength was evaluated using shear tests.

Main Results:

• Transfer accuracy varied depending on the tray design, with SMPs and self-curing silicones showing higher accuracy than vacuum-formed trays with SMPs.
• Indirectly bonded brackets using SMP-enhanced trays demonstrated an average bond strength 1-2 MPa higher than those bonded with conventional trays.
• The SMP-equipped trays provided more uniform contact pressure during the bonding process.

Conclusions:

• Transfer trays incorporating shape memory polymers offer a significant improvement in bond strength for indirect bonding.
• The developed SMP method has the potential to reduce bracket debonding rates in clinical orthodontics.
• Further adjustments to tray design may optimize transfer accuracy and clinical efficacy.