Hello Adriano

How you try this.

public class TestController : SurefaceController {
    private readonly IndexRebuilder _indexRebuilder;

    public TestController(IndexRebuilder indexRebuilder) {
         _indexRebuilder = indexRebuilder;
    }

    public ActionResult Index() {
         _indexRebuilder.RebuildIndex(indexName);
    }
}

i know the Umbraco Code, the are using the IndexRebuilder class when you hit the rebuild index button in examin dashboard. Hope it will work!