Early implant loading after vertical ridge augmentation (VRA) using e-PTFE titanium-reinforced membrane and nano-structured hydroxyapatite: 2-year prospective study

Abstract

Conflict of interest: self-supported study, no conflict of interest to declare

Aims: This 2-year prospective multi-centre study aimed to evaluate the survival of implants loaded 14 weeks after vertical ridge augmentation (VRA).

Materials and methods: Twenty consecutive patients scheduled for VRA around implants were selected for this study in three private centres. Nano-structured Mg-enriched hydroxyapatite (Mg-e HAP) was used as the only augmentation filler material. It was covered with a titanium reinforced extended polytetrafluoroethylene (e-PTFE) membrane (Gore-Tex). A total of 42 rough-surface implants were inserted in the same surgical session. Healing abutments 2 mm long were used instead of cover screws to optimise aesthetics. All patients underwent a second surgery after 3 months. Thereafter, definitive restorations were seated within 2 weeks using a platform-switching concept. Outcome measures were amount of vertical bone gain, prosthesis and implant success, complications and radiographic marginal bone level changes assessed at 12 and 24 months of prosthetic loading. Frequency resonance analysis expressed using ISQ (implant stability quotient) values was performed at implant insertion (T0), when definitive restoration was seated (T1) and after 24 months of prosthetic loading (T2).

Results: At the end of the study, no patient dropped out, all implants were clinically stable and no prosthesis failed. Initial clinical evaluations showed an average defect height of 4.1 mm. Only one late membrane exposure was registered. Complete bone filling of the regeneration volume was obtained in 19 out of 20 cases. The mean bone height gain was 5.6 mm. Radiographic assessments of inter-implant regenerated bone levels after 24 months of loading presented a mean value of 1.0 mm (SD 0.48 mm), stable compared to the same analysis at the 12-month follow-up. A statistically significant loss of peri-implant bone level occurred over time. Mean peri-implant bone levels were 0.3 mm at the time of prosthetic loading, 0.90 mm after 1 year and 0.98 after 2 years. ISQ values statistically significantly increased over time. At implant placement the mean ISQ value was 49.3, at delivery of the final restoration it was 63.9 and after 2 years of loading it was 73.6.

Conclusion: This clinical study suggests that VRA around rough-surface implants using e-PTFE membrane and nano-structured Mg-e HAP can be successful even in cases with early loading.