Amorphous calcium phosphate-containing orthodontic composites. Do they prevent demineralisation around orthodontic brackets?

Abstract

Abstract Background A preliminary study using laser fluorescence suggested that amorphous phosphate-containing orthodontic composites may prevent demineralisation around bonded orthodontic brackets. Objective To compare the microhardness of the enamel around brackets bonded with an amorphous calcium phosphate-containing orthodontic composite (ACP-containing) with the microhardness of the enamel around brackets bonded with a conventional composite resin. Methods Forty extracted upper premolars were used. Orthodontic brackets were bonded to the teeth with either an ACP-containing composite resin (N = 20) or a conventional composite resin (N = 20). The latter were used as the control. The crowns of all teeth were painted with an acid resistant varnish, leaving a 2 mm ring of exposed enamel around the brackets. The teeth were then subjected to a daily cycle of demineralisation for 6 hours and remineralisation for 18 hours for 21 days. Each tooth was sectioned and the microhardness of the enamel determined 25, 50, 75, 100 and 150 μm from the surface. Results The enamel was significantly harder 25 μm (p = 0.000) and 50 μm (p = 0.001) from the enamel surface in the teeth with brackets bonded with the ACP-containing composite resin as compared with the control teeth. Conclusion ACP-containing orthodontic composite resins may reduce the enamel decalcification found in patients with poor oral hygiene.