Use of a perforated scaffold-retaining abutment to achieve vertical bone regeneration around dental implants in the minipig.

Objective: To evaluate the effect of perforated scaffold retainers used in conjunction with dental implants and osteoinductive scaffolds to regenerate vertical supracrestal alveolar bone in an intraoral minipig model.

Methods: Three months after extraction of mandibular premolars and first molars from six adult minipigs, two titanium (Ti) custom implants were placed bilaterally in the edentulous mandibles for a total of four implants per animal. The upper 2.5 mm of the implant was left above bone level and covered with: (1) wide-neck healing caps; (2) perforated, overhanging custom scaffold retainers (umbrellas); or (3) scaffold retainers and demineralized minipig bone allograft (DBM) and nonglycosylated bone morphogenetic protein 2 (ng/rhBMP-2)-treated implants. All constructs were submerged beneath soft tissue flaps for 8 weeks. Two dental implant surfaces were compared: SLA and SLActive. Samples were retrieved after 8 weeks and analyzed by radiography, micro-computed tomography and histomorphometry.

Results: All implants were stable at the end of the experiment. Histomorphometry revealed that the use of the scaffold-retaining umbrellas led to increased, but not statistically significant, vertical bone regeneration as compared to the use of wide-neck healing caps (1.0 ± 0.4 mm vs 0.6 ± 0.3 mm). The combination of DBM and ng/rhBMP-2 released from the surface of the SLA implant resulted in the greatest amount of vertical bone regeneration (2.1 ± 0.2 mm). The bone-to-implant contact was similar for all groups. Mucosal dehiscence areas with healing cap or custom scaffold retainer exposures were reduced in the presence of ng/rhBMP-2.

Conclusions: The combined use of custom perforated Ti scaffold retainers, DBM, and ng/rhBMP-2 regenerated a substantial amount of vertical supracrestal alveolar bone around Ti implants in an intraoral minipig model.