title: Regenerative Dentistry: Animal Model for Regenerative Endodontology.
abstract: BACKGROUND
  Ectopic tissue has been observed frequently in human root canal specimens when cell homing studies were performed at the dorsum of rodents. In contrast, pulp-like tissue formed when immature teeth were implanted on top of the rat calvaria. It was surmised, yet not tested, that the implantation site might affect tissue ingrowth.
  
  
  METHODS
  Four root sections from human immature molars cleaned with 5% sodium hypochlorite (NaOCl) followed by 17% ethylenediaminetetraacetic acid (EDTA) were implanted per rat (n = 5). Two specimens were placed at the dorsum (control), while the other two specimens were implanted at the calvaria. After 6 weeks, the specimens were investigated for histological structure, immunoreactivity to dentine sialoprotein (DSP) and bone sialoprotein (BSP), per-area percentage of tissue ingrowth, and gene expression (DSPP, COL1, NGFandVEGF). Data were statistically compared.
  
  
  RESULTS
  Tooth specimens placed at the calvaria generally showed pulp-like tissue and odontoblast-like cells at the dentinal wall where DSP and BSP immunoreactivity were intense. The area of tissue ingrowth was significantly larger in the specimens placed at the calvaria compared to those placed at the dorsum.DSPPwas the only gene that was upregulated significantly when specimens were implanted at the calvaria.
  
  
  CONCLUSIONS
  Our findings suggest that the calvarial site is superior to the dorsum to study pulp regeneration in human teeth in the rat.
authors: Oral Biotechnology &amp; Bioengineering, Cranio-Maxillofacial and Oral Surgery, Center for Dental Medicine, University of Zurich, Zurich, Switzerland; Department of Pharmacology, Faculty of Dentistry, Mahidol University, Bangkok, Thailand.
authors: Nisarat
authors: N
authors: Ruangsawasdi
authors: Preventive Dentistry, Periodontology, and Cariology, Center for Dental Medicine, University of Zurich, Zurich, Switzerland.
authors: Matthias
authors: M
authors: Zehnder
authors: Orthodontics and Pediatric Dentistry, Center for Dental Medicine, University of Zurich, Zurich, Switzerland.
authors: Raphael
authors: R
authors: Patcas
authors: Oral Biotechnology &amp; Bioengineering, Cranio-Maxillofacial and Oral Surgery, Center for Dental Medicine, University of Zurich, Zurich, Switzerland.
authors: Chafik
authors: C
authors: Ghayor
authors: Oral Biotechnology &amp; Bioengineering, Cranio-Maxillofacial and Oral Surgery, Center for Dental Medicine, University of Zurich, Zurich, Switzerland.
authors: Franz E
authors: FE
authors: Weber
keywords: Animal model; Cell homing; Endodontics; Pulp; Regeneration; ­Odontoblast