References

Sadowsky PL, Retief DH, Cox PR Effects of etchant concentration and duration on the retention of orthodontic brackets: an in vivo study. Am J Orthod Dentofacial Orthop. 1990; 98:417-421
Alzainal AH, Majud AS, Al-Ani AM, Mageet AO Orthodontic bonding: review of the literature. Int J Dent. 2020; 14 https://doi.org/10.1155/2020/8874909
Burns A, Hughes A, O'Sullivan M Orthodontic bonding in special circumstances. Br Dent J. 2024; 237:400-406 https://doi.org/10.1038/s41415-024-7791-z
Smyth RS, Hunt NP, Sharif MO An overview of orthodontic bonding. Orthod Update. 2020; 13:130-133
Prado N, Caldwell S, Ashley M Orthodontic bonding to atypical tooth surfaces. Orthod Update. 2020; 13:57-62 https://doi.org/10.12968/ortu.2020.13.2.57
Mandall NA, Hickman J, Macfarlane TV Adhesives for fixed orthodontic brackets. Cochrane Database Syst Rev. 2018; 4:(4) https://doi.org/10.1002/14651858.cd002282.pub2
Sayinsu K, Isik F, Sezen S, Aydemir B Light curing the primer-beneficial when working in problem areas?. Angle Orthod. 2006; 76:310-313

Optimization of orthodontic bond strength to defective enamel

From Volume 18, Issue 1, February 2025 | Pages 46-48

Authors

Catherine Brierley

BDS, MFDS RCS(Ed), MOrth RCS(Ed), Consultant Orthodontist

BDS (Hons), MFDS, MClinDent Orth, MOrth, FDS Orth

Articles by Catherine Brierley

Abstract

Defective enamel can render conventional methods for bonding orthodontic brackets ineffective and compromise orthodontic tooth movement. There are various techniques proposed in the literature to optimize the orthodontic bond strength. A clinical case is presented here with some additional lesser-known techniques to aid bonding. These include etching the enamel surfaces twice, curing the resin adhesive (primer) after etching, and placing composite ‘pads’ to maximize the surface area for bonding. These techniques may be implemented when the primary objective is to improve the bond strength. However, the need to maximize bond strength must be balanced against the risk of causing iatrogenic damage to weaker enamel.

CPD/Clinical Relevance: Defective enamel can present an orthodontic challenge owing to compromised bond strength between the adhesive and enamel.

Article

Successful orthodontic tooth movement relies upon the predictable bonding of brackets to the enamel surface. Conventionally, this is achieved by first conditioning the tooth surface with 37% phosphoric acid etch for 15–30 seconds to create surface microporosities.1,2 The resultant uneven surface texture facilitates micromechanical bonding, usually via an uncured primer (an unfilled resin), to composite resin, which is frequently the adhesive material of choice for bonding orthodontic brackets. This is predominantly owing to its good shear and tensile bond strength, which helps it withstand orthodontic and masticatory forces.3 While the primer is usually cured to increase the strength of the bond during usual restorative composite bonding, in orthodontics, the primer is often left uncured to help facilitate de-bonding of the brackets without shearing off the enamel.

There are, however, additional complexities to consider when bonding brackets to atypical tooth surfaces, especially defective enamel, which can be seen in conditions such as dental fluorosis, molar–incisor hypomineralization (MIH), and amelogenesis imperfecta (AI). The literature highlights that the risk of bond failure is higher in these cases, potentially owing to the higher protein content of the enamel and, consequentially, resistance to acid etch.4

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