A novel hydroxyapatite fiber material for the regeneration of critical-sized rabbit calvaria defects.

Hydroxyapatite (HA) [Ca10 (PO4)6 (OH)2] has a high degree of chemical similarity with the mineral composition of animal bone. Hydroxyapatite fiber scaffold (HAF) is a biological material with a highly interconnected porous structure. We aimed to study the physical and biological characteristics of HAF and compare the osteogenic effects of HAF, natural osteogenic materials (NOM), and carbonate apatite (CO3Ap-DP) in the parietal defects of a rabbit's skull. X-ray analysis and histological assessment showed that HAF followed a trend of early initial osteogenesis and bone trabecular structure formation, especially at the cortical bone portion.Compared to the other two materials, HAF was more absorptive. Results indicated that HAF had the same osteoconductive and new bone formation properties as NOM and CO3Ap-DP. These findings will provide options for future material development and novel protocols for use in surgeries, ultimately leading to better patient outcomes.

Vertical ridge augmentation using a porous composite of uncalcined hydroxyapatite and poly-DL-lactide enriched with types 1 and 3 collagen.

BACKGROUND: Previous studies have shown that porous composite blocks containing uncalcined hydroxyapatite (u-HA; 70 wt%) with a scaffold of poly-DL-lactide (PDLLA, 30 wt%) are biodegradable, encourage appropriate bone formation, and are suitable for use as a bone substitute in vertical ridge augmentation. The present study aimed to accelerate osteogenesis in vertical ridge formation by adding types 1 and 3 collagen to the u-HA/PDLLA blocks and assessing the effect. MATERIAL AND METHODS: The bone substitute in the present study comprised porous composite blocks of u-HA (70 wt%) with a PDLLA (27-29 wt%) scaffold and enriched with types 1 and 3 collagen (1.7 ~ 3.4 wt%). The control blocks were composed of u-HA (70 wt%) and PDLLA (30 wt%). The materials were formed into 8-mm diameter, 2-mm high discs and implanted onto the cranial bones of six rabbits. The animals were sacrificed 4 weeks after implantation, and histological and histomorphometrical analyses were performed to quantitatively evaluate newly formed bone. RESULTS: New bone formation occurred with both block types, showing direct contact with the original bone. Mean ± standard deviation bone formation was significantly greater in the experimental blocks (25.6% ± 4.8%) than in the control blocks (17.0% ± 4.7%). CONCLUSIONS: Histological and histomorphometrical observations indicated that new bone was formed with both block types. The u-HA/PDLLA block with types 1 and 3 collagen is a more promising candidate for vertical ridge augmentation than the u-HA/PDLLA alone block.

Guided bone regeneration using a hydrophilic membrane made of unsintered hydroxyapatite and poly(L-lactic acid) in a rat bone-defect model.

The effectiveness of a previously developed unsintered hydroxyapatite (uHA) and poly(L-lactic acid) (PLLA) hydrophilic membrane as a resorbable barrier for guided bone regeneration (GBR) was evaluated. Critical-size 8-mm diameter bone defects were surgically generated in the parietal bones of 24 12-week-old male Wistar rats, which were then divided into three groups in which either a uHA/PLLA or a collagen membrane or no membrane (control) was placed onto the bone defect. Following sacrifice of the animals 2 or 4 weeks after surgery, bone defects were examined using microcomputed tomography and histological analysis. Bone mineral density, bone mineral content, and relative bone growth area values 2 or 4 weeks after surgery were highest in the uHA/PLLA group. Four weeks after surgery, the relative bone growth area in the uHA/PLLA group was larger than that in the collagen group. The resorbable uHA/PLLA membrane is thus potentially effective for GBR.