title: Preprosthetic periodontal surgery in the proximal area with modification of the col area: results following the reestablishment of the contact point.
abstract: BACKGROUND
  Anatomic characteristics of interproximal areas are dependent on the anatomy, position, and proximal contact of adjacent teeth. The objective of this study was to investigate the influence of the reestablishment of the interproximal contact following the restorative alveolar interface (RAI) procedure on the interproximal gingival COL and formation of the interdental gingival papilla.
  
  
  METHODS
  Six mongrel dogs received bilateral apically positioned flaps, crown lengthening, and the RAI procedure on the maxillary fourth bicuspid and first molar. After 2 weeks, in a randomized manner, one side was prepared to receive metallic crowns and the opposite side remained as the control. The crowns were cemented at the 4-week postoperative period, and the dogs were sacrificed after another 4 weeks, totaling a period of 4 weeks with the full crowns in position and a total of 8 postoperative weeks. Histologic specimens were stained with hematoxylin and eosin and Mallory dyes. Sections 6 micro m thick were obtained in a bucco-lingual plane allowing ample visualization of the interproximal area.
  
  
  RESULTS
  Clinical measurements revealed that, in the restored sides, four animals had complete fill of the interdental spaces with gingival papilla, whereas the other two dogs had a distance from the contact point to the tip of papilla varying from 0.02 to 0.021 mm. In the control group, papillae were totally reepithelialized with keratinized epithelium and a convex form. The epithelium completely covered the connective tissue and showed both epithelial projections and surface desquamation. On the test group, despite the presence of the prosthesis, the COL morphology modified by preprosthetic surgery was not altered, presenting a convex papilla with a triangular form and with a keratinized epithelium. Additional histologic characteristics were the same as found in the control group.
  
  
  CONCLUSIONS
  Based on the results of this study, the reestablishment of the contact point does not revert what was obtained with the RAI procedure; the interproximal tissues remain convex and keratinized.
authors.affiliation: Health Science Center, School of Dentistry, Pontifical Catholic University of Paraná, Paraná, Brazil.
authors.forename: Vula
authors.initials: V
authors.lastname: Papalexiou
authors.forename: Arthur B
authors.initials: AB
authors.lastname: Novaes
authors.forename: Guilherme O
authors.initials: GO
authors.lastname: Macedo
authors.forename: Sonia Mara
authors.initials: SM
authors.lastname: Luczyszyn
authors.forename: Valdir A
authors.initials: VA
authors.lastname: Muglia
mesh_terms: D000539:Alveolar Process / Q000601:surgery*; D000818:Animals; D016723:Bone Remodeling; D016556:Crown Lengthening; D003442:Crowns; D003739:Dental Cementum / Q000601:surgery*; D004285:Dogs; D004846:Epithelial Attachment / Q000502:physiology*; D005881:Gingiva / Q000502:physiology*; D007633:Keratins; D008297:Male; D013516:Oral Surgical Procedures, Preprosthetic / Q000379:methods*; D010027:Osteotomy / Q000379:methods; D011897:Random Allocation; D013524:Surgical Flaps
chemical_list: D007633:Keratins