Preclinical animal model for de novo bone formation in human maxillary sinus.

OBJECTIVES: Up to now the effect of bone-substitute materials on de novo bone formation has been tested in a variety of preclinical animal models. We hypothesized that there is no significant difference in bone regeneration after application of autogenous bone (AB) and bone substitutes in a porcine calvarial monocortical defect model and in human maxillary sinus. STUDY DESIGN: Twenty-four weeks after application of ss-tricalcium phosphate (betaTCP), hydroxyapatite (HA), and AB in each of 3 defects on the sculls of 6 adult pigs (N = 54) and the application in 44 sinus floor elevations (11x betaTCP, 6x HA and 24x AB) in 41 patients, bone regeneration rates where compared microradiographically. Wilcoxon rank-sum test was used for statistical analysis. RESULTS: Comparing the human with the animal specimens microradiographically, no significant difference of the mineralization rate could be found. CONCLUSION: The chosen porcine model is a valuable method for preclinical testing of bone-substitute materials in maxillofacial surgery.

Antibiotic-containing collagen for the treatment of bone defects.

Recent studies have explored the use of biodegradable implants that incorporate antibiotics for the treatment of bone infections. In this study, a biodegradable composite containing bovine collagen and teicoplanin (Targobone) was used for the treatment of mandibular nonunion defects. Patients with mandibular nonunion defects subsequent to osteosynthesis were treated with Targobone (n = 9) or with autologous bone grafts (n = 12). Clinical and radiological evaluations were performed preoperatively, immediately postoperatively, and 4 and 24 weeks postoperatively. Bone regeneration was defined relative to the original defect area in the panoramic radiograph by using image analysis software. In the Targobone group, the defect area decreased to 78% (SD +/- 21.8%) of the preoperative area within 4 weeks and to 21% (SD +/- 9.7%) of the preoperative area within 24 weeks. In the autologous bone graft group, the defect area decreased to 69% (SD +/- 32.4%) of the preoperative area within 4 weeks and to 4.7% (SD +/- 5.6%) of the preoperative area within 24 weeks. Thus, Targobone is a promising option for the treatment of bone defects.

Different substitute biomaterials as potential scaffolds in tissue engineering.

PURPOSE: To find the optimal scaffold for tissue-engineered bone, one approach is to test existing biomaterials on their suitability as scaffolds. In this study, the suitability of different alloplastic and xenogenic biomaterials as scaffolds for ex vivo osteoblast cultivation was investigated. MATERIALS AND METHODS: Normal human osteoblast cells were cultured on the surface of bovine collagenous materials, bovine hydroxyapatite, porcine gelatin, synthetic polymer, and collagen-containing bovine hydroxyapatite, and the investigation of proliferation was performed after 24, 72, and 120 hours. Measurement of the differentiation marker alkaline phosphatase and osteocalcin was made after 20 days of incubation. RESULTS: The obtained data showed significantly higher proliferation and differentiation rates in cells cultivated on collagen-rich biomaterials in comparison to noncollagenous or collagen-poor biomaterials (P < .05). DISCUSSION: In tissue engineering the scaffold should be biocompatible and serve as a proper matrix for the cells to produce the new structural environment of extracellular matrix ex vivo. Collagen supports initial cell attachment and cell proliferation, allowing immature osteogenic cells to differentiate into mature osteoblasts, but collagen may not be the only dominating factor for cell-matrix interaction during ex vivo bone formation. CONCLUSION: These data suggest that a 3-dimensional collagen matrix can provide a more favorable environment for the attachment, proliferation, and differentiation of in vitro osteoblastlike cells, at least until the initial stage of differentiation, than noncollagenous biomaterials.