1. 1 Postgraduate Program, Dental School, Pontifical University Catholic of Rio Grande do Sul, Porto Alegre, Brazil.
2. 2 Department of Biological and Materials Sciences and Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA.
3. 3 Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI, USA.
4. 4 Cranio-Maxillofacial Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
5. 5 Department of Periodontics, Virginia Commonwealth University, Richmond, VA, USA.