Impact of the outcome of guided bone regeneration in dehiscence‐type defects on the long‐term stability of peri‐implant health: clinical observations at 4 years

OBJECTIVES: To investigate the impact of residual defect height (RDH) following guided bone regeneration (GBR) in dehiscence-type defects on the long-term stability of peri-implant health after a period of 4 years. MATERIAL AND METHODS: The RDH values in dehiscence-type defects at titanium implants were clinically assessed after 4 months of submerged healing following augmentation using a natural bone mineral (NBM) and a randomized application of either a cross-linked- (VN) or a native collagen membrane (BG) (n=12 patients each). The RDH values were classified as absent (0 mm, control; n=8), minimal (1 mm, test 1; n=8), or advanced (>1 mm, test 2; n=8). Clinical parameters (i.e. bleeding on probing [BOP], probing pocket depth [PD], mucosal recession [MR]) were recorded (mesio-, mid-, and disto-buccal aspects) at 4 years after prosthesis installation. RESULTS: The mean PD (2.9±0.7, 2.8±0.7, 2.7±0.8 mm) values at 4 years were comparable in all the groups investigated. The mean MR values tended to be increased in both the test groups (0.5±0.7, 0.4±0.6 mm, respectively), when compared with the control group (0.2±0.3 mm) (P>0.05, respectively). The mean BOP values were also increased in both the test groups (45.8±30.5%, 54.1±24.8%, respectively), even reaching statistical significance when comparing test 2 and control (29.1±21.3%) groups (P=0.02). CONCLUSION: The present study indicated that (i) implants exhibiting RDH values >1 mm are at a higher risk of developing peri-implant disease and (ii) positive RDH values may be associated with an increase in MR and may therefore compromise the overall esthetic outcome of implant therapy.