title: The influence of root surface distance to alveolar bone and periodontal ligament on periodontal wound healing.
abstract: OBJECTIVE
  The purpose of this animal study was to perform a 3-dimensional micro-computed tomography (micro-CT) analysis in order to investigate the influence of root surface distance to the alveolar bone and the periodontal ligament on periodontal wound healing after a guided tissue regeneration (GTR) procedure.
  
  
  METHODS
  Three adultSus scrofa domesticusspecimens were used. The study sample included 6 teeth, corresponding to 2 third mandibular incisors from each animal. After coronectomy, a circumferential bone defect was created in each tooth by means of calibrated piezoelectric inserts. The experimental defects had depths of 3 mm, 5 mm, 7 mm, 9 mm, and 11 mm, with a constant width of 2 mm. One tooth with no defect was used as a control. The defects were covered with a bioresorbable membrane and protected with a flap. After 6 months, the animals were euthanised and tissue blocks were harvested and preserved for micro-CT analysis.
  
  
  RESULTS
  New alveolar bone was consistently present in all experimental defects. Signs of root resorption were observed in all samples, with the extent of resorption directly correlated to the vertical extent of the defect; the medial third of the root was the most commonly affected area. Signs of ankylosis were recorded in the defects that were 3 mm and 7 mm in depth. Density and other indicators of bone quality decreased with increasing defect depth.
  
  
  CONCLUSIONS
  After a GTR procedure, the periodontal ligament and the alveolar bone appeared to compete in periodontal wound healing. Moreover, the observed decrease in bone quality indicators suggests that intrabony defects beyond a critical size cannot be regenerated. This finding may be relevant for the clinical application of periodontal regeneration, since it implies that GTR has a dimensional limit.
authors: Division of Periodontology and Implantology, Department of Biomedical and Neuromotor Sciences, Alma Mater Studiorum, University of Bologna School of Dentistry, Bologna, Italy .
authors: Marco
authors: 0000-0001-7312-802X
authors: M
authors: Montevecchi
authors: BITTA Laboratory, Rizzoli Orthopaedic Institute, Bologna, Italy .
authors: Annapaola
authors: 0000-0003-0251-5094
authors: A
authors: Parrilli
authors: Preclinical and Surgical Studies Laboratory, Rizzoli Orthopaedic Institute, Bologna, Italy .
authors: Milena
authors: 0000-0002-3732-3570
authors: M
authors: Fini
authors: Division of Periodontology and Implantology, Department of Biomedical and Neuromotor Sciences, Alma Mater Studiorum, University of Bologna School of Dentistry, Bologna, Italy .
authors: Maria Rosaria
authors: 0000-0003-0216-9056
authors: MR
authors: Gatto
authors: Faculty of Veterinary Medicine, Teramo University, Teramo, Italy .
authors: Aurelio
authors: 0000-0002-2133-4144
authors: A
authors: Muttini
authors: Division of Periodontology and Implantology, Department of Biomedical and Neuromotor Sciences, Alma Mater Studiorum, University of Bologna School of Dentistry, Bologna, Italy .
authors: Luigi
authors: 0000-0002-2578-3983
authors: L
authors: Checchi
keywords: Bone and bones; Guided tissue regeneration; Periodontium; Research design; Root resorption; Three-dimensional imaging