[Protective effect on enamel of ultra-micronized hydroxyapatite in combination with orthodontic composite cement. In vivo study].

In this work the authors have studied in vivo, the protective action of ultramicronized hydroxylapatite combined with a cement for orthodontic use. An etching gel with 30% acid orthophosphoric for 30'' has been put on a selected group of teeth to be extracted. Then some ultramicronized hydroxylapatite has been applied and some brackets or bands bonded with composite cement. Besides, on another group of teeth selected for the control, some brackets have been bonded with the traditional technique without hydroxylapatite. Some photographic rebuilts of the surface of the teeth to be analysed have been executed at scanning electron microscopy. Further observations have been executed at the aplanatic microscopy stereo to identify the possible macroscopic alterations. The hydroxylapatite proves to have a protective action on the enamel near the orthodontic bands or brackets, fixes with cement and subjected to the action of an acid.