title: A prospective, randomized-controlled clinical trial to evaluate bone preservation using implants with different geometry placed into extraction sockets in the maxilla.
abstract: OBJECTIVE
  The primary objective of this study was to determine the association between the size of the void established by using two different implant configurations and the amount of buccal/palatal bone loss that occurred during 16 weeks of healing following their installation into extraction sockets.
  
  
  METHODS
  The clinical trial was designed as a prospective, randomized-controlled parallel-group multicenter study. Adults in need of one or more implants replacing teeth to be removed in the maxilla within the region 15-25 were recruited. Following tooth extraction, the site was randomly allocated to receive either a cylindrical (group A) or a tapered implant (group B). After implant installation, a series of measurements were made to determine the dimension of the ridge and the void between the implant and the extraction socket. These measurements were repeated at the re-entry procedure after 16 weeks.
  
  
  RESULTS
  The study demonstrated that the removal of single teeth and the immediate placement of an implant resulted in marked alterations of the dimension of the buccal ridge (43% and 30%) and the horizontal (80-63%) as well as the vertical (69-65%) gap between the implant and the bone walls. Although the dimensional changes were not significantly different between the two-implant configurations, both the horizontal and the vertical gap changes were greater in group A than in group B.
  
  
  CONCLUSIONS
  Implant placement into extraction sockets will result in significant bone reduction of the alveolar ridge.
authors.affiliation: Postgraduate Periodontology, Faculty of Odontology, University Complutense of Madrid, Madrid, Spain. marianosanz@odon.ucm.es
authors.forename: Mariano
authors.initials: M
authors.lastname: Sanz
authors.forename: Denis
authors.initials: D
authors.lastname: Cecchinato
authors.forename: Jorge
authors.initials: J
authors.lastname: Ferrus
authors.forename: E Bjarni
authors.initials: EB
authors.lastname: Pjetursson
authors.forename: Niklaus P
authors.initials: NP
authors.lastname: Lang
authors.forename: Jan
authors.initials: J
authors.lastname: Lindhe
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016301:Alveolar Bone Loss / Q000517:prevention & control* / Q000601:surgery; D003758:Dental Implantation, Endosseous / Q000379:methods*; D019250:Dental Implants, Single-Tooth; D017267:Dental Prosthesis Design; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014081:Tooth Extraction; D020390:Tooth Socket / Q000601:surgery*; D016896:Treatment Outcome