Improvement in adhesion of the brackets to the tooth by sandblasting treatment

In oral orthodontic treatments, achievement of a good adhesion between brackets and teeth surfaces is essential. One way to increase adhesion is to apply a surface treatment of teeth facing surfaces through the projection of abrasive particles to produce a surface roughness which improves adhesion of the bracket to the tooth, because of the significantly increased contact between the two surfaces. The effect on adhesion through the use of this technique in different types of brackets, as well as through the use of different blasting particles, however, is yet not well described. In this study we have included three types of brackets which are commonly used in orthodontic therapies (two of them a mesh-type and the third one a micro-milled type) with a contact surface area of 11.16, 8.85 and 6.89 mm(2) respectively. These brackets were used combined with a sandblasting treatment with two different types of abrasive particles, alumina (Al(2)O(3)) and silicon carbide (SiC) and applied to natural teeth in vitro. The abrasive particles used are bio-compatible and usually used in achieving increased roughness for improved adherence in biomedical materials. Sandblasting was performed at 2 bars for 2 s; three particle sizes were used: 80, 200 and 600 μm. Non-blasted samples were used as control. Each of the pieces were cemented to natural teeth with a self-curing composite. Samples were stored in physiologic serum at 5°C temperature. Tensile tests were performed with a universal testing machine. Brackets treated with sandblasted particles were measured to have an increased adhesion as compared to the control sample. The highest bond strength was measured for samples sandblasted with alumina particles of 80 and 200 μm combined with micro-milled brackets. The recorded stresses did not exceed the tensile strength of tooth enamel.