Hard tissue volume stability of guided bone regeneration during the healing stage in the anterior maxilla: A clinical and radiographic study.

BACKGROUND: Guided bone regeneration (GBR) is currently the most widely used technique to reconstruct localized peri-implant bone defects. OBJECTIVES: To evaluate hard tissue volume stability during the healing stage of GBR with particulate bone graft and resorbable collagen membrane. MATERIALS AND METHODS: Twenty-eight patients who were missing a single maxillary incisor and required implant placement combined with GBR were randomly assigned to 2 groups: submerged (n = 14) and transmucosal (n = 14) healing groups. Cone-beam computed tomography (CBCT) was performed before, immediately after and 6 months post-surgery. The 3 sets of CBCT data were three-dimensionally reconstructed and superimposed. Horizontal hard tissue alterations at different vertical levels were recorded. The relative position and distances from the boundary line of the bony defect envelope to the outlines of the augmented ridge were determined immediately post-augmentation and 6 months after healing. RESULTS: Augmented ridge underwent horizontal volume reduction during the healing period. Vertical levels (P = .000) rather than healing strategies (submerged or transmucosal) (P = .182) had statistically significant impacts on the reduction width. The boundary line of the ridge defect envelope located within the bony profile immediately after surgery, but outside of the bony profile after 6 months. CONCLUSIONS: GBR with resorbable membrane and particulate bovine bone would undergo horizontal volume reduction during the healing stage. New bone formation at the coronal site may only be predictable within the bony envelope.