title: Influence of wound closure on the volume stability of particulate and non-particulate GBR materials: an in vitro cone-beam computed tomographic examination. Part II.
abstract: OBJECTIVE
  To test whether GBR with an L-shaped soft-block bone substitute and particulate bone substitute differs from GBR with particulate bone substitute as regards the volume stability of the augmented region during flap closure.
  
  
  METHODS
  Twenty peri-implant box-shaped bone defects were created in 10 pig mandibles. Every bone defect was augmented with each of the following two GBR procedures in turn: control group - particulate xenograft applied buccally + collagen membrane + pins; test group - particulate xenograft applied buccally + L-shaped soft-block xenograft applied buccally and occlusally + collagen membrane + pins. Cone-beam computed tomography scans were obtained before and after wound closure. The horizontal thickness (HT) of the augmented region (bone substitute + membrane) was assessed at the implant shoulder (HT0 mm) and at 1 mm to 5 mm apical to the implant shoulder (HT1 mm-HT5 mm). In the test group, the vertical thickness (VT) and 45° thickness (45-T) of the augmented region were measured from the implant shoulder. The changes in HT during flap suturing were calculated as absolute (mm) and relative values (%). Repeated-measures ANOVAs were used for statistical analysis.
  
  
  RESULTS
  The reduction in HT0 mmwas 20.5 ± 23.3% (SD) in the control group and 2.4 ± 9.2% (SD) in the test group (P = 0.014). There were no statistically significant differences in changes in HT1-5 mmbetween the groups (P > 0.05). In the test group, the reduction in VT amounted to 28.0 ± 11.9% (SD) and the reduction in 45-T amounted to 24.8 ± 10.2% (SD) (P < 0.001).
  
  
  CONCLUSIONS
  The addition of an L-shaped soft-block bone substitute to a particulate xenograft, covered by a collagen membrane and fixed with pins, significantly improved the horizontal volume stability of the augmented region during wound closure.
authors.affiliation: Oral Surgery and Implantology Department, Dental School, University of Barcelona, Barcelona, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Mir-Mari
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: Oral Surgery and Implantology Department, Dental School, University of Barcelona, Barcelona, Spain.
authors.forename: Eduard
authors.initials: E
authors.lastname: Valmaseda-Castellón
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: D000540:Alveolar Ridge Augmentation / Q000379:methods*; D000704:Analysis of Variance; D000818:Animals; D001861:Bone Regeneration; D018786:Bone Substitutes; D003094:Collagen; D054893:Cone-Beam Computed Tomography; D064593:Heterografts; D066298:In Vitro Techniques; D008334:Mandible; D023421:Models, Animal; D013524:Surgical Flaps; D013552:Swine
chemical_list: D018786:Bone Substitutes; D003094:Collagen
keywords: 
  in vitro
  ; alveolar ridge augmentation; bone; bone substitutes; collagen; cone-beam computed tomography; dental implants; graft; granulate; guided bone regeneration; guided tissue regeneration; membrane; pin; regeneration; soft block; tack