Histological Evaluation of Tooth Root Resorption

Prior to staining, sections incubated for 30 min at 60 °C followed by incubation for 20 min in xylene (9713.2, Carl Roth, Karlsruhe, Germany). After hydrogenation by a descending alcohol series, they were stained with Mayer hematoxylin solution (1.07961.0500, Sigma Aldrich, St. Louis, MO, USA) for 10 min. After 5 min under running warm water, sections were counterstained for one minute with 0.5% eosin G solution (X883.2, Carl Roth, Karlsruhe, Germany). Again, they were rinsed with warm water and dehydrated by the ascending series of alcohol. After 20 min in xylene, they were covered using entellan (1.07961.0500, Merck, Darmstadt, Germany). The stained histological sections were digitized using an Olympus IX50 microscope (Hamburg, Germany) at 100 fold magnification, and evaluation of root resorptions at the disto-buccal tooth root of the moved first molar in relation to the respective root surface area was assessed with ImageJ (Ver.1.4.7, National Institutes of Health, Bethesda, MD, USA), as described before [16 (link),19 (link)].