A Novel Evaluation Method for Detecting Defects of the Bonded Orthodontic Bracket-Tooth Interface

Area of Science:

• Dental materials science
• Biomaterials engineering
• Orthodontic research

Background:

• Orthodontic patients face increased risk of dental caries.
• Interfacial defects between brackets and enamel can compromise treatment.
• Novel diagnostic methods are needed to assess bond integrity.

Purpose of the Study:

• To evaluate optical coherence tomography (OCT) for detecting interfacial defects between ceramic brackets and enamel.
• To compare the nanoleakage expression and bond strength of different bonding agents and conditions.
• To assess the influence of enamel surface moisture on bracket adhesion.

Main Methods:

• Ceramic brackets were bonded to human premolar enamel using Transbond XT primer or moisture insensitive primer (MIP) on dry or moist surfaces.
• Optical coherence tomography (OCT) was used to examine interfacial defects.
• Nanoleakage was evaluated using scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS).
• Bond strength was measured by debonding forces.
• Degree of conversion was assessed using FTIR/ATR.

Main Results:

• OCT successfully detected interfacial defects between ceramic brackets and tooth structure.
• Bonding to dry enamel surfaces (Transbond XT primer and MIP) resulted in significantly higher bond strength and less nanoleakage compared to bonding to moist enamel with MIP.
• The (XTD) and (MIPD) groups showed superior performance over the (MIPW) group (p > 0.05).

Conclusions:

• Optical coherence tomography is a viable clinical tool for detecting interfacial adhesive-tooth defects.
• Dry enamel surfaces significantly improve the quality of the enamel/primer interface, leading to better bond strength and reduced nanoleakage.
• These findings have implications for optimizing bonding procedures in orthodontics to minimize caries risk.