title: Effect of ridge preservation for early implant placement - is there a need to remove the biomaterial?
abstract: OBJECTIVE
  To assess (i) bone regeneration around implants placed early in sites with or without ridge preservation and (ii) if the bone substitute material (DBBM-C) has to be removed at implant placement.
  
  
  METHODS
  In eight beagle dogs, three sites were randomly assigned to ridge preservation (DBBM-C plus collagen matrix (CMX)) (two sites; RP) or spontaneous healing (1 site; SH). Four weeks later, in one of the RP sites, dental implants were placed without removing the DBBM-C (RP1), whereas in RP2 and SH sites all non-integrated DBBM-C and/or granulation tissue were removed before implant placement and concomitant GBR. Histomorphometric outcomes were assessed at 4 and 12 weeks.
  
  
  RESULTS
  The median buccal fBIC (first bone-to-implant contact) was located more apical in groups RP1: 1.34 mm (0.09; 2.96) and RP2: 1.41 mm (0.54; 2.72) than in group SH: 0.79 mm (0.26; 1.50) (p = 0.452) at 4 weeks. At 12 weeks, median buccal fBIC values were for RP1: 0.88 mm (0.00; 2.33), for RP2: 0.16 mm (0.00; 1.33) and for SH: 0.00 mm (0.00; 0.98) (p = 0.362). BIC values increased over 12 weeks in all groups.
  
  
  CONCLUSIONS
  Ridge preservation followed by early implant placement led to higher BIC values at 12 than at 4 weeks. There is no need to remove the biomaterial at implant placement to ensure osseointegration. No relevant differences were observed between the three groups for any outcome measure.
authors.affiliation: Clinic of Fixed and Removable Prosthodontics and Dental Material Science, Center of Dental Medicine, University of Zurich, Zurich, Switzerland.
authors.forename: Daniel S
authors.identifier: http://orcid.org/0000-0002-1764-7447
authors.initials: DS
authors.lastname: Thoma
authors.affiliation: Clinic of Fixed and Removable Prosthodontics and Dental Material Science, Center of Dental Medicine, University of Zurich, Zurich, Switzerland.
authors.forename: Nadja
authors.initials: N
authors.lastname: Naenni
authors.affiliation: Clinic of Fixed and Removable Prosthodontics and Dental Material Science, Center of Dental Medicine, University of Zurich, Zurich, Switzerland.
authors.forename: Goran I
authors.initials: GI
authors.lastname: Benic
authors.affiliation: Department of Veterinary Clinical Sciences, University of Santiago de Compostela, Lugo, Spain.
authors.forename: Fernando
authors.identifier: http://orcid.org/0000-0002-4130-1526
authors.initials: F
authors.lastname: Muñoz
authors.affiliation: Clinic of Fixed and Removable Prosthodontics and Dental Material Science, Center of Dental Medicine, University of Zurich, Zurich, Switzerland.
authors.forename: Christoph H F
authors.initials: CHF
authors.lastname: Hämmerle
authors.affiliation: Clinic of Fixed and Removable Prosthodontics and Dental Material Science, Center of Dental Medicine, University of Zurich, Zurich, Switzerland.
authors.forename: Ronald E
authors.initials: RE
authors.lastname: Jung
mesh_terms: D000539:Alveolar Process / Q000473:pathology / Q000502:physiology / Q000601:surgery; D000540:Alveolar Ridge Augmentation; D000818:Animals; D001861:Bone Regeneration; D018786:Bone Substitutes / Q000627:therapeutic use*; D003094:Collagen / Q000627:therapeutic use; D015921:Dental Implants; D004285:Dogs; D016557:Guided Tissue Regeneration, Periodontal; D008297:Male; D016348:Osseointegration; D011897:Random Allocation; D013997:Time Factors; D014945:Wound Healing
chemical_list: D018786:Bone Substitutes; D015921:Dental Implants; D003094:Collagen
keywords: alveolar ridge augmentation (MeSH); ridge preservation; volume stability