2020, Number 3
Resin-based adhesive system in orthodontics: a perspective
Language: English/Spanish [Versión en español]
References: 3
Page: 166-168
PDF size: 62.12 Kb.
Direct bonding was first described by Newman in 1965, it started using epoxy resin bonded to plastic brackets where there were concerns about the immersion of the brackets in saliva that could deteriorate the adhesive system. Over the years, the available adhesive systems have been modified with a variety of fillers, vehicles, and components that allow a great variety of systems and techniques to find one that best suits the working method of each professional.1
It is well known that the correct placement and cementation of brackets in orthodontic treatment is one of the main factors that determine the success or failure of the treatment; however, one of the inconveniences that is constantly presented is the failure in the adhesion of the brackets, which implies an important expense in the time of consultation, treatment time and efficiency of the treatment. For this reason, the quality of the adhesive system has been improved over time when it comes to direct bonding. Direct bonding can be influenced by multiple factors such as the light curing system, the type, and condition of enamel to be bonded, acid etching time, adhesive composition, bracket base, design, and material.2
Conventional adhesive systems are those that belong to the systems that employ the total etching technique as a conditioning mechanism for the tooth structure. The mechanism of action of these systems is summarized as follows: after conditioning the enamel surface with an application of 37% phosphoric acid for 15 seconds, the enamel surface is washed with water and excess moisture is removed, the adhesive is applied, which penetrates the pores created by the acid thanks to its low surface tension, wetting capacity and capillarity. As it penetrates the porosities, it forms the so-called resin macro and/or microtags, which are extensions of the resin (mainly of the bonding agent) at the sites of micro retentions created by the conditioning of the phosphoric acid. It has been demonstrated that, due to the homogeneous composition of enamel, its surface type, and high surface energy, it is possible to obtain high bond strength values after the application of the conditioning agent, these values being always higher than those obtained in dentin, due to the special characteristics of that substrate.
One of the most frequent causes of early adhesive failure is the contamination of the operative field by saliva and/or blood. To reduce the number of clinical steps and thus reduce the likelihood of error in the handling and application of dental adhesives, the development of self-etching adhesive systems which condition the tooth enamel without the need for rinsing, thus reducing the risk of saliva contamination, and which aim to maintain a healthy and intact enamel surface after removal of orthodontic appliances, has resulted in the development of self-etching adhesive systems which condition the tooth enamel without the need for rinsing, thus reducing the risk of saliva contamination. The etchants in these systems contain organic acids and monomers in an aqueous base; the itatonic acid acts as a primer, light-curing with the bonding agent subsequently used, and its carboxylic groups bond to the calcium of the tooth surface. However, it has been reported that etching before the application of the self-etch adhesive significantly increases the effectiveness of the latter when used on dental enamel; that is, the importance of the conditioning acid on the enamel is ratified.
Although bonding materials have evolved favorably in recent years, there are still some limitations and disadvantages in the cementation of brackets such as:3
- 1. Frequent disbonding of brackets at the enamel-resin or resin-bracket interface.
- 2. Difficulty in removing all remaining adhesive and restoring structural integrity to the enamel after treatment is completed.
- 3. Failure of bracket bonding.
Therefore, it is important to continue the search for an ideal material that allows the enamel-resin-bracket bond to be achieved in an ideal way and that at the same time offers adequate strength for debonding without causing damage to the enamel.
REFERENCES
AFFILIATIONS
1 Doctor en Ciencias, Cirujano Dentista. Facultad de Odontología de la Universidad Nacional Autónoma de México (UNAM). México.
CORRESPONDENCE
Osmar Alejandro Chanes-Cuevas. E-mail: oachanesc@gmail.com