Maybe you could simply iterate using ParentLink reference.

Here is the extension method snippet:

using System.Collections.Generic;
using System.Linq;
using EPiServer;
using EPiServer.Core;

namespace ContentAreaWithPreview.Business
{
    public static class ContentLoaderExtensions
    {
        public static IEnumerable<IContent> GetAllParents(this IContentLoader contentLoader, ContentReference contentReference)
        {
            if (ContentReference.IsNullOrEmpty(contentReference))
            {
                return Enumerable.Empty<IContent>();
            }
            contentReference = contentLoader.Get<IContent>(contentReference).ParentLink;

            var contentReferences = new List<IContent>();
            while (!ContentReference.IsNullOrEmpty(contentReference))
            {
                var content = contentLoader.Get<IContent>(contentReference);
                contentReferences.Add(content);

                contentReference = content.ParentLink;
            }
            return contentReferences;
        }
    }
}

and using the method in code:

 ContentReference cr = new ContentReference(1234);

var contentRepository = ServiceLocator.Current.GetInstance<IContentRepository>();
var contentLoader = ServiceLocator.Current.GetInstance<IContentLoader>();

contentRepository.GetAllParents(cr);
contentLoader.GetAllParents(cr);

_contentLoader.GetAncestors(currentPage.ContentLink)

You could also simply use GetAncestors:

IEnumerable<IContent> ancestors = contentRepository.GetAncestors(currentPage.ContentLink);

Edit: Gayathri beat me to it :-)