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Notizen: Background: Several oral implant design advances have been suggested to overcome poor bone quality, an impediment for successful implant treatment. A novel titanium porous oxide (TPO) surface has been shown to offer favorable results in several settings. The objective of this study was to evaluate the local bone formation and osseointegration at TPO-modified implants in type IV bone.Method: Three TPO surface-modified implants (TiUnite™) were installed into the edentulated posterior maxilla in each of 8 Cynomolgus monkeys. The animals were injected with fluorescent bone labels at 2, 3, 4 and 16 weeks post-surgery and were euthanized at week 16 when block biopsies were collected for histologic analysis.Results: The predominant observation of the TPO implant surface was a thin layer of new bone covering most of the implant threads. Mean (±SE) bone–implant contact for the whole study group was 74.1±4.8%. There was a significant variability in bone–implant contact between animals (P=0.0003) and between sites of the same animal (P〈0.0001). The variance in bone–implant contact was 30% larger among sites of the same animal than between different animals (187.5 vs. 144.8, respectively). There was a small but significant difference in bone density immediately outside, compared to within the threaded area of the implants (37.1±3.2% vs. 32.1±3.2%, P〈0.0001). Bone density outside the implant threads was significantly correlated (β=0.682, P〈0.0001) with the bone density within thethreaded area. Bone density within the threaded area was significantly correlated (β=0.493, P=0.0002) with bone–implant contact, whereas bone density outside the implant threads did not have a significant effect (β=0.232, P=0.1).Conclusions: The results suggest that the TPO surface possesses a considerable osteoconductive potential promoting a high level of implant osseointegration in type IV bone in the posterior maxilla.

Notizen: Background: Recombinant human bone morphogenetic protein-2 (rhBMP-2) has been shown to induce clinically relevant bone formation for orthopedic, craniofacial, and oral indications. It appears critical, in particular for onlay indications, that the associated carrier technology exhibits structural integrity to offset compressive forces in support of rhBMP-2-induced bone formation. The objective of this study was to evaluate a calcium phosphate (CP) cement, Ceredex™, as a candidate carrier for rhBMP-2 in a defect model with limited osteogenic potential.Materials: Bilateral, critical size, 6-mm, supra-alveolar, periodontal defects were created in six, adult, male, Hound Labrador mongrels. Three animals received rhBMP-2/Ceredex™ (rhBMP-2 at 0.20 and 0.40 mg/ml) in contralateral defect sites (implant volume/defect ∼1 ml). One defect site in each of the three remaining animals received Ceredex™ without rhBMP-2 (control). The animals were euthanized at 12 weeks postsurgery for histologic and histometric analysis.Results: Mean induced bone height exceeded 80% of the defect height for supra-alveolar periodontal defects receiving rhBMP-2/Ceredex™ without major differences between rhBMP-2 concentrations compared with approximately 40% for the control. The newly formed bone, a mixture of lamellar and woven bone in fibrovascular tissue, circumscribed relatively large portions of the residual Ceredex™ biomaterial. Inflammatory lesions were associated with limited bone formation in some sites. From a periodontal perspective, sites receiving rhBMP-2/Ceredex™ exhibited increased cementum formation compared with control, but without a functionally oriented periodontal ligament, and increased ankylosis and root resorption. Control sites exhibited early wound failure and exposure, loss of the Ceredex™ biomaterial, and limited bone formation.Conclusions: The Ceredex™ CP cement appears a potentially promising carrier technology for rhBMP-2 onlay indications. However, a slow resorption rate may prevent its wider use. This study does not support use of the rhBMP-2/Ceredex™ combination for periodontal indications.

Notizen: Objectives: Recombinant human bone morphogenetic protein-2 (rhBMP-2) has been shown to stimulate alveolar bone and cementum formation in periodontal defects but not a functionally oriented periodontal ligament (PDL). Subcutaneous and intramuscular implants of BMP-12 have been shown to induce tendon formation and ligament-like tissue. The objective of this study was to evaluate rhBMP-12 for periodontal regeneration, in particular PDL formation.Methods: Six young adult Hound Labrador mongrel dogs were used. Routine supraalveolar periodontal defects were created around the mandibular premolar teeth. Three animals received rhBMP-12(0.04 mg/ml) in an absorbable collagen sponge (ACS) carrier vs. rhBMP-12(0.2 mg/mL)/ACS in contralateral defects. Three animals received rhBMP-12(1.0 mg/ml)/ACS vs. rhBMP-2(0.2 mg/ml)/ACS (total implant volume/defect ∼1 ml). The animals were euthanized 8 weeks postsurgery and block biopsies were processed for histometric analysis.Results: Bone regeneration appeared increased in sites receiving rhBMP-2/ACS compared to sites receiving rhBMP-12/ACS. Cementum regeneration was similar comparing sites implanted with rhBMP-2/ACS to sites implanted with rhBMP-12/ACS. In contrast, sites receiving rhBMP-12/ACS exhibited a functionally oriented PDL bridging the gap between newly formed bone and cementum whereas this was a rare observation in sites receiving rhBMP-2/ACS. Ankylosis appeared increased in sites receiving rhBMP-2/ACS compared to those receiving rhBMP-12/ACS.Conclusions: The outcomes of this study suggest that rhBMP-12 may have significant effects on regeneration of the PDL. Additional preclinical evaluation is needed to confirm these initial observations prior to clinical application.

Notizen: Objectives: Subcutaneous and intramuscular implants of bone morphogenetic protein-12 (BMP-12) have been shown to induce formation of tendon and ligament tissue. BMP-12 induced a new attachment with a distinct fibrocartilaginous zone at the tendon-bone interface in the rat tendon-bone attachment model. Surgical controls showed poor healing and failure to reform the appropriate tendon–bone attachment morphologically. Application of recombinant human BMP-12 (rhBMP-12) to periodontal defects suggests that rhBMP-12 has the potential to support regeneration of the periodontal ligament (PDL). The objective of this pilot study was to evaluate this effect of rhBMP-12 in a tooth replantation model.Methods: Six, young adult, male Hound Labrador mongrel dogs were used. Maxillary and/or mandibular incisor and premolar teeth were extracted and the PDL was either left “intact” or removed by root planing. rhBMP-12 (1.0 mg/ml) or a buffer control was topically applied to teeth with “intact” PDL in contralateral jaw quadrants in each of 3 animals. The teeth were immersed in 1.0 ml of the rhBMP-12 or the buffer solution for 10 min and then replanted. The remaining three animals received rhBMP-12 (1.0 mg/ml) and the buffer control in a similar fashion applied to teeth instrumented to remove the PDL and cementum, and surface demineralized with citric acid. The animals were euthanized at 8 weeks postsurgery and block sections were collected and processed for histopathologic analysis.Results: No dramatic differences were found between teeth receiving topical rhBMP-12 and the buffer control. Application of rhBMP-12 did not have an apparent effect on new cementum and PDL formation in the tooth replantation model. Moreover, application of rhBMP-12 did not increase nor did it decrease the apparent presence and extent of ankylosis along the root surface compared to the control.Conclusions: The observations from this study do not support the use of topical rhBMP-12 to support the reestablishment of the PDL including regeneration of cementum and functionally oriented fibers, and to prevent ankylosis and root resorption following replantation of teeth.