Authors: Angus Burns, Annie Hughes, Michael O’SullivanBritish Dental Journal, Volume 237, Issue 5, Pages 400–406
Background
Orthodontic treatment relies on the secure bonding of orthodontic brackets and other attachments to tooth surfaces. While bonding to enamel is straightforward with standard methods, certain clinical scenarios present significant challenges. These include patients with existing dental restorations (such as composite, amalgam, or porcelain), those with enamel conditions like fluorosis or amelogenesis imperfecta, and individuals who have undergone tooth whitening. These unique circumstances require tailored bonding strategies to ensure successful bracket retention, minimise bond failure, and prevent damage to both natural tooth surfaces and restorations.
Methods
The study explored various bonding techniques designed for specific dental conditions:
- Bonding to Restorative Materials: Bonding to materials such as ceramic crowns, zirconia, and composite fillings requires careful surface treatment. For example, ceramic surfaces, known for their acid resistance, require etching with hydrofluoric acid (HF) followed by a silane coupling agent to enhance adhesion.
- Fluorosis and Amelogenesis Imperfecta: These conditions result in weaker, more porous enamel, which can make bonding more difficult. Modifications to the etching process—such as extended etching times and the use of deproteinising agents like sodium hypochlorite—can improve the bond strength.
- Teeth Whitening: Tooth bleaching introduces oxidative agents that inhibit the polymerisation of composite materials. The study suggests waiting 1-2 weeks after whitening before bonding to ensure optimal bonding strength.
- Specialised Adhesives: The study also examines new adhesive systems, such as self-etching primers and phosphate monomer-containing adhesives, which are effective in bonding to challenging surfaces like zirconia and composite restorations.
Results
The results highlight significant differences in bonding effectiveness depending on the technique and materials used. For example, hydrofluoric acid etching and silane coupling agents were highly effective in bonding brackets to ceramic surfaces. On the other hand, teeth with fluorosis required extended etching times (30–60 seconds) to achieve adequate bonding strength. In cases of hypocalcified amelogenesis imperfecta, deproteinising with sodium hypochlorite showed promising results in improving the bond strength. However, severe enamel damage, such as that seen in dentinogenesis imperfecta, often required the use of indirect restorations to achieve stable bracket bonding.
Conclusion
This study underscores the importance of adapting orthodontic bonding techniques to address the unique challenges posed by non-enamel surfaces and dental conditions. By utilising methods such as air abrasion, specialised primers, and modified etching protocols, orthodontic practitioners can significantly improve bracket retention on difficult surfaces. These advancements offer a more reliable approach to orthodontic treatment for patients with restorative dental work or specific dental conditions, ensuring both aesthetic outcomes and treatment stability.
Research Summary Written By: Aneesa Aslam, University of Manchester, BDS 2