Evaluation of the biocompatibility and osteoproductive activity of ostrich eggshell powder in experimentally induced calvarial defects in rabbits

Physicochemical characterization and effects of monetite obtained from titania-reinforced eggshell on bone repair: a new possibility for tissue bioengineering?

OBJECTIVES

To carry out physicomechanical characterization of the HA/DCPA/TiO2 and to evaluate the tissue repair in rat calvaria.

METHODS

Two bone defects were made in the calvaria of 36 Wistar rats, divided into groups: HA/DCPA, HA/DCPA/TiO2 and sham (blood clot). The animals were euthanized at 30, 60 and 90 days and calvaria slides were processed with hematoxylin/eosin. The newly formed bone, connective tissue, biomaterial remnant, and total tissue repair percentages were calculated in relation to the total defect area. The HA/DCPA/TiO2 was characterized structurally by scanning electron microscopy (SEM), and chemically by energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). It was submitted to apparent density (AD), apparent porosity (AP), water absorption (WA) and compressive strength (CS) physical tests. The ANOVA test was applied, followed by Turkey's test and Student's t-test (p ≤ 0,05).

RESULTS

The SEM showed biomaterials inside the bone defects and newly formed bone. EDS identified oxygen, calcium, phosphorus, and titanium in the sample. The HA/DCPA/TiO2 and HA/DCPA groups presented a total tissue repair area that was larger than the sham group (p < 0.001).

CONCLUSIONS

The physical-mechanical assays showed that HA/DCPA/TiO2 has AD and CS properties within the limits of trabecular bone and with values higher than HA/DCPA.HA/DCPA/TiO2 presented higher densification and compressive strength rates than HA/DCPA.

CLINICAL RELEVANCE

Potential as a scaffold for bone.

Osteogenic stimulation of osteoprogenitors by putamen ovi peptides and hyaluronic acid

Eggshell peptides (EP) majorly contribute to rapid bone building in chicks, wherefore this paper investigated their potential for stimulating osteogenesis in vitro. In this study, the effects of EP, also called putamen ovi peptides and a combination of hyaluronic acid with EP in cell culture medium were tested towards proliferation, differentiation, gene expression and mineralization of bovine osteoprogenitors and primary human osteoblasts. The influence of EP at concentrations of 0.005 g/L, 0.5 g/L and 0.5 g/L with 0.25% hyaluronic acid was analyzed using immunocytochemical staining of bone-specific matrix proteins, namely collagen type I, osteonectin, osteopontin and osteocalcin, to prove osteoblastic differentiation. Additionally, Richardson-staining was performed. All tests revealed a superior osteoblastic differentiation with EP at 0.5 g/L after 5 days of cultivation. Hyaluronic acid alone showed controversial results and partially constrained osteoblastic differentiation in combination with EP to a level as low as for pure EP at 0.005 g/L. Of particular interest is the osteoblast-typical mineralization, as an important indicator of bone formation, which was measured indirectly via the calcium concentration after cultivation over 4 weeks. The mineralization showed an increase by a factor of 286 during the cultivation of primary human osteoblasts with hyaluronic acid and EP. Meanwhile, cell cultures treated with EP (0.5 g/L) only showed an 80-fold increase in calcium concentration.The influence of EP (0.5 g/L) on primary human osteoblasts was investigated by gene expression after 2 weeks of cultivation. Microarray and qRT-PCR analysis showed a strongly increased expression of main important genes in bone formation, bone regeneration and the physiological bone remodelling processes. Namely, BMP 2, osteopontin and the matrix metalloproteinases 1 and 9, were present during in vitro osteoprogenitor culture with EP. By explicitly underlining the potential of eggshell peptides for stimulating osteogenesis, as well as emphasizing complex and controversial interaction with hyaluronan, this manuscript is relevant for developing new functionalized biomaterials for bone regeneration.

Evaluation of Struthio camelus eggshell as an in vitro alternative to extracted human teeth in preliminary screening studies on dental erosion

OBJECTIVES

This in vitro work investigates the potential of ostrich eggshell as a substitute for extracted human teeth in preliminary screening studies on dental erosion. Additionally, it aims to demonstrate the potential of ostrich eggshell compared to human enamel in evaluating the efficacy of a preventive agent in protecting against dental erosion, using an artificial mouth model.

METHODS

The experiment utilized 96 erosion testing specimens from each substrate, human enamel, and ostrich eggshell. The specimens were subjected to six different experimental regimens of increasing erosive challenge, simulating the consumption of an acidic drink. The acidic drink was delivered at a consistent volume and duration range. Both artificially stimulated and unstimulated saliva flowed throughout the experimental regimens. Surface hardness was measured using a Through-Indenter Viewing hardness tester with a Vickers diamond, while surface profiling was done using a surface contacting profilometer with a diamond stylus. An automated chemistry analyzer system was used to detect calcium and phosphate ions.

RESULTS

The study found that ostrich eggshell specimens demonstrated predictable surface loss, hardness drop, and ion loss due to the acidic challenge. Meanwhile, enamel appeared to fall short in terms of surface hardness predictability. The transient hardness loss phase, which manifests as an overlooked decrease in surface hardness despite significant ion and structural loss, may explain this phenomenon.

CONCLUSIONS

The experiment showed that assessing surface loss is essential in addition to hardness testing, particularly as certain experimental conditions may produce a false perception of tissue recovery despite the actual surface loss. By analyzing the response of ostrich eggshell specimens to erosive challenges, researchers were able to identify an "overlooked" reduction in hardness in enamel specimens. The differences in the structure, chemical composition, and biological response to erosion in the presence of artificial saliva between enamel and ostrich eggshell could explain their distinct behaviors.

Feeds of animal origin in rabbit nutrition – a review

Rabbits are classified as obligate herbivores. However, under natural conditions, some members of the family Leporidae incorporate animal products into their diets. Therefore, it seems biologically justified to supplement the diets of farmed rabbits with feeds of animal origin as sources of protein, fat and minerals. The aim of this review was to describe, from a historical perspective, the use of various feeds of animal origin in rabbit nutrition. The applicability of by-products from mammal, poultry, fish and invertebrate processing for rabbit feeding was evaluated, including the future prospects for their use. A review of the available literature revealed that various animal-based feeds can be valuable protein sources in rabbit diets, but their inclusion levels should not exceed 5-10%. Studies investigating their efficacy have been conducted since the 1970s. In some regions of the world, the use of animal-derived protein in livestock feeds was prohibited due to the risk of spreading bovine spongiform encephalopathy (BSE). However, the interest in animal by-products as protein sources in livestock diets is likely to increase since the above ban has been lifted.

Use of Eggshells as Bone Grafts around Commercially Pure Titanium Implant Screws Coated with Nano Calcium Sulfate

Background. Implant insertion in regions with poor bone quantity, such as the posterior maxilla, is potentially associated with an increased rate of implant failure. Calcium sulfate can be used as the coating material for commercially pure titanium (CpTi) and as the bone graft material around implants when bound to eggshell powder to enhance the bone quality and quantity of bone defect regions. This study performed a torque removal test to evaluate the effectiveness of eggshell powder as a bone substitute for filling bone defects around CpTi-coated implants coated with nanocrystalline calcium sulfate. Materials and Methods. Eighty screw implant designs were used in the tibiae of 20 white New Zealand rabbits. A total of uncoated 20 screws constituted the control group, and the remaining 60 screws coated with nano calcium sulfate nanoparticles were used as the experimental groups as follows: 20 screws coated with nano calcium sulfate were used alone in the tibiae without gaps around them, 20 screws coated with nano calcium sulfate were used with the gaps made around them and filled with eggshell powder as the bone graft material, and 20 screws coated with nano calcium sulfate were used with the gaps made around them left unfilled. Results. After 2 to 6 weeks of healing, a significant improvement in bone regeneration and an increase in torque removal values were observed when the bone defect around the CpTi implant coated with nano calcium sulfate was filled with eggshell powder as the bone substitute. Conclusions. Nano calcium sulfate particles applied through the dip-coating method can successfully work as the coating material of CpTi implants. These particles work in synergy with eggshell powder to act as the bone graft around the implants.

Avian Egg: A Multifaceted Biomaterial for Tissue Engineering

Most components in avian eggs, offering a natural and environmentally friendly source of raw materials, hold great potential in tissue engineering. An avian egg consists of several beneficial elements: the protective eggshell, the eggshell membrane, the egg white (albumen), and the egg yolk (vitellus). The eggshell is mostly composed of calcium carbonate and has intrinsic biological properties that stimulate bone repair. It is a suitable precursor for the synthesis of hydroxyapatite and calcium phosphate, which are particularly relevant for bone tissue engineering. The eggshell membrane is a thin protein-based layer with a fibrous structure and is constituted of several valuable biopolymers, such as collagen and hyaluronic acid, that are also found in the human extracellular matrix. As a result, the eggshell membrane has found several applications in skin tissue repair and regeneration. The egg white is a protein-rich material that is under investigation for the design of functional protein-based hydrogel scaffolds. The egg yolk, mostly composed of lipids but also diverse essential nutrients (e.g., proteins, minerals, vitamins), has potential applications in wound healing and bone tissue engineering. This review summarizes the advantages and status of each egg component in tissue engineering and regenerative medicine, but also covers their current limitations and future perspectives.

Features of a simvastatin-loaded multi-layered co-electrospun barrier membrane for guided bone regeneration

A novel tri-layer membrane consisting of polycaprolactone (PCL) fibrous sheets and structured nanofibers with a gelatin (Gt) shell and a simvastatin-containing PCL core (PCL-Gt/PCL-simvastatin membrane) was prepared. The soft external layer comprised of Gt/PCL-simvastatin, the external layer of PCL and the middle layer of both microfilaments, interwoven together. The membrane was designed to promote osteoinduction and act as a barrier against cells but not against water and molecules in order to promote guided bone regeneration. The structure of the membrane was characterized by scanning electronic microscopy. The in vitro release rates of simvastatin over 32 days were determined by high-performance liquid chromatography. For in vitro biological assays, bone marrow mesenchymal stem cells and human fibroblasts were cultured on the different surfaces of the membrane. Cell adhesion, proliferation, distribution, and differentiation were examined. For in vivo testing, cranial defects were created in rabbits to assess the amount of new bone formed for each membrane. The results revealed that membranes with multi-layered structures showed good cell viability and effective osteoinductive and barrier properties. These results suggest that the novel multi-layered PCL-Gt/PCL-simvastatin membranes have great potential for bone tissue engineering.

The Influence of Eggshell on Bone Regeneration in Preclinical In Vivo Studies

Simple Summary

The aim of this study is to review the available information on the use of avian eggshell as bone regeneration material. Five databases were searched up to October 2020. Animal studies with a bone defect model using eggshell as a grafting material were included. Risk of bias and the quality of the papers were assessed. Overall, a total of 581 studies were included in the study, 187 after duplicate removal. Using the inclusion and exclusion criteria 167 records were further excluded. The full text of the remaining 20 articles was assessed for eligibility and included in the review. There were different methods of obtaining eggshell for grafting purposes. Eggshell is a biocompatible grafting material, with bone formation capabilities. It forms new bone similar to other products currently in use in clinical practice. It can be combined with other materials to enhance its proprieties. Eggshell is a promising biomaterial to be used in bone grafting procedures, though further research is needed.

Abstract

The aim of this study is to systemically review the available evidence on the in vivo behavior of eggshell as a guided bone regeneration substitute material. Five databases (PubMed, Cochrane, Web of Science, Scopus, EMBASE) were searched up to October 2020. In vivo animal studies with a bone defect model using eggshell as a grafting material were included. Risk of bias was assessed using SYRCLE tool and the quality assessment using the ARRIVE guidelines. Overall, a total of 581 studies were included in the study, 187 after duplicate removal. Using the inclusion and exclusion criteria 167 records were further excluded. The full text of the remaining 20 articles was assessed for eligibility and included in the qualitative and quantitative assessment synthesis. There were different methods of obtaining eggshell grafting materials. Eggshell is a biocompatible grafting material, with osteoconduction proprieties. It forms new bone similar to Bio-Oss and demineralized freeze-dried bone matrix. It can be combined with other materials to enhance its proprieties. Due to the high variability of the procedures, animals, production and assessment methods, no meta-analysis could be performed. Eggshell might be considered a promising biomaterial to be used in bone grafting procedures, though further research is needed.

Clinical applications of avian eggshell-derived hydroxyapatite

The search for bone reconstruction materials and methods is an ongoing challenge. The aim of this review is to systemically search the available literature concerning the clinical performance of eggshell as a substitute material in guided bone regeneration in oral surgery. Five databases (PubMed, Cochrane, Web of Science, Scopus, and Embase) were searched up to February 2020. Clinical trials that used eggshell as a bone substitute material were included in the review. Animal and in vivo studies were excluded from the review. ROBINS-I was used to evaluate the risk of bias. A total of 840 studies were retrieved, out of which 55 full-text articles were screened. Five studies were finally included: one study showed critical and four serious risk of bias. A total of 74 patients and 88 intervention sites were included in the five studies. Clinical and radiological evaluation showed complete healing during the follow-ups. Statistically significant radiological and clinical evidence of new bone formation was achieved for socket preservation, grafting after third molar extraction, and cystic/apicectomy grafting. One patient with complications was reported. Histological analysis and micro computed tomography confirmed that it promotes bone regeneration. A comparison with synthetic hydroxyapatite showed similar healing characteristics. Within the limitations of the included studies, the eggshell can be safely and efficiently used in guided bone regeneration procedures, but more research is needed to completely evaluate the full potential of this material.

Histomorphometric evaluation of a nano-sized eggshell-containing supplement as a natural alloplast: An animal study

Background

Limitations of autogenous grafts have dictated the need for development of new biomaterials that can serve as allografts. A paradigm shift directed manufacturers to revert to nature in the search for such allografts. This study aimed to evaluate an eggshell-based supplement, Membrell’s® BONEhealth Plus D₃ & K₂, indicated to support bone mineral density, as a natural bone graft material.

Methods

Twelve 5 × 10 × 1 mm full-thickness cranial bone defects were created in six adult male New Zealand rabbits. Six defects were filled with Membrell’s® BONEhealth™ Plus D₃ & K_2, and the others were left empty as control. The animals were sacrificed 14 days postoperatively. The defects were dissected and prepared for histological assessment. Bone formation was compared both qualitatively and quantitatively. The area percent of newly-formed bone was evaluated in five successive regions using image analysis. Statistical analysis was performed using unpaired t-test. Differences between the two groups were considered significant at p ≤ 0.05.

Results

Cranial bone defects filled with the nano-sized eggshell powder “Membrell’s® BONEhealth™ Plus D₃ & K₂” revealed significantly higher levels of osteoid, newly-formed, regularly-arranged bone trabeculae in the center of the defects (47.37% ± 1.12) compared to the control defects (21.6% ± 4.92), which revealed no bone formation. A rapid rate of resorption of the nano-sized eggshell powder and consequently a rapid osteogenic effect was evident.

Conclusions

The eggshell-based graft powder, Membrell’s® BONEhealth™ Plus D₃ & K₂, is a biocompatible material which has the potential to enhance new bone formation.

Nanosized strontium substituted hydroxyapatite prepared from egg shell for enhanced biological properties

The fabrication and application of bioactive hydroxyapatite has always been a research hot spot in the fields of orthopaedics. Now it is common to use calcium (Ca) salt as Ca²⁺ source to synthesise hydroxyapatite. And egg shell could be another promising raw material as Ca²⁺ source, which is not only economical but also biogenic. In this study, egg shell (ES)-hydroxyapatite was prepared by using egg shells via hydrothermal method. Furthermore, ES-Sr hydroxyapatite was synthesized by incorporation of bioactive element strontium (Sr²⁺) into ES-hydroxyapatite. The in vitro experiment showed that compared with hydroxyapatite, ES-hydroxyapatite showed better biological performances, which could be attributed to the trace elements in egg shell, such as magnesium (Mg). And the incorporation of Sr²⁺ could further enhance the bioactivity. These results indicated that apatite with high biological activity, which had great application prospects in orthopedics, could be produced by egg shells and the incorporation of Sr²⁺.

Eggshells as natural calcium carbonate source in combination with hyaluronan as beneficial additives for bone graft materials, an in vitro study

Introduction

In bone metabolism and the formation especially in bone substitution, calcium as basic module is of high importance. Different studies have shown that the use of eggshells as a bone substitute material is a promising and inexpensive alternative. In this in vitro study, the effects of eggshell granulate and calcium carbonate towards primary bovine osteoblasts were investigated. Hyaluronan (HA) was used as artificial extracellular matrix (ECM) for the used cells to facilitate proliferation and differentiation and to mimic the physiological requirements given by the egg in vivo.

Methods

Hyaluronan, eggshells, a combination of hyaluronan and eggshells and CaCO₃ were applied to the cells as additive to the used standard medium (modified High Growth Enhancement Medium) in a concentration of 0,1 g/l. The effect of the additives in the culture medium was examined by proliferation tests, immunohistochemical staining (anti-collagen type I, anti-osteopontin, anti-osteonectin and anti-osteocalcin) and kinetic oxygen measurements.

Results

Our investigations revealed that all investigated additives show beneficial effect on osteoblast activity. Cell proliferation, differentiation and the metabolic activity of the differentiated cells could be influenced positively. Especially in the case cell cultures treated with eggshells the strongest effects were detected, while for the hyaluronan compared with eggshells, a weaker increase in cell activity was observed.

Conclusion

In summary, it can be stated that the investigated components come into consideration as beneficial supplements for bone graft materials especially for maxillo facial surgery application.

Determination of a critical size calvarial defect in senile osteoporotic mice model based on in vivo micro-computed tomography and histological evaluation

PURPOSE

To evaluate differences in the spontaneous healing capacity of senescence-prone inbred strains (SAMP6) and senescence-resistant inbred strains (SAMR1) and determine the critical defect size in a mouse model of senescence-accelerated osteoporosis.

METHODS

Unilateral full-thickness calvarial defects 2 or 4mm in diameter were made in 6-month-old male SAMP6 and SAMR1. Defects were evaluated in vivo by micro-CT at day 0 and 6 and 12 weeks postoperatively. Calvarial specimens were harvested at 12 weeks for hematoxylin and eosin staining, Masson's trichrome staining, and tartrate-resistant-acid-phosphatase (TRAP) staining.

RESULTS

Less new bone was observed in defects in SAMP6 compared to SAMR1 at 12 weeks postsurgery, with <5% healing in SAMP6 for both 2- and 4-mm defects compared to >5% healing in 2-mm defects in SAMRI (P<0.05). Histological analysis revealed dense connective tissue but little bone healing in 2- and 4-mm defects in SAMP6 and 4-mm defects in SAMR1. New bone was observed at the periphery of the 2-mm defects in SAMR1. Masson's trichrome staining also supported these findings. No obvious TRAP-positive cells were observed at the defect margins, but SAMP6 exhibited greater osteoclast numbers and surface areas in the diploë of contralateral bone compared to smaller osteoblast numbers and surface areas at the defect sites in SAMR1.

CONCLUSIONS

Defects of 2mm or larger in the cranium was critical-size or nonhealing defects in both SAMP6 and SAMR1. The differential findings on micro-CT and histomorphometry for the calvarial defect sites between SAMP6 and SAMR1 may imply different regenerative abilities of intramembranous ossification in these two strains.

Histologic and histomorphometric assessment of eggshell-derived bone graft substitutes on bone healing in rats

OBJECTIVE

The objective of this study was to histologically and histomorphometrically evaluate the efficacy of the new formulations of eggshell-derived calcium carbonate in rats.

STUDY DESIGN

The study was conducted on 30 adult male rats. Four standardized and circular intrabony defects were created in the both maxilla and mandibula of each animal. Three different graft materials were prepared as follows: 1) Material A: Eggshell-derived calcium carbonate combined with carrageenan gel, 2) Material B: Eggshell-derived calcium carbonate combined with xanthan gum gel, and 3) Material C: Eggshell-derived calcium carbonate powder. The right mandibular defect sites were grafted with Material A in all animals, and defects on the left were grafted with Material B. Defects on the right side of maxilla were received Material C in all animals, and all left maxillary defects were remained untreated as controls. The animals were sacrificed either postoperatively on the 15th day, postoperatively on the 30th day or postoperatively on the 45th day. Histomorphometric measurements were made of the areas of newly formed bone, necrotic bone, fibrous tissue and residual graft material.

RESULTS

Material A exhibited the highest level of osteoid formation followed by Material B and Material C on the 45th day. In terms of osteoid formation, statistically significant differences were observed between graft materials and controls at 45th day compared to 15th and 30th day (p<0.05).

CONCLUSIONS

Eggshell-derived graft substitutes in both gel and powder forms are biocompatible materials which may have the potential to enhance the new bone formation. Key words:Bone graft material, bone defects, eggshell, histopathological evaluation, rat.

Zinc-coated carbonate apatite derived from avian eggshell for potential use as bone substitute. Part I: preparation and properties

PURPOSE

To develop antibacterial bone substitutes derived from avian eggshell using microwave processing to convert natural calcium carbonate (CaCO3) into zinc-coated carbonate apatite (CHA).

METHODS

Zinc-coated carbonate apatite was prepared using domestic microwave and then characterized with scanning electron microscopy (SEM), x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and energy dispersive x-ray analysis (EDXA). The trial animal study was conducted by filling different bone substitutes into 5-mm-diameter standard defects on the parietal bone of New Zealand rabbits to observe new bone formation for 8 weeks.

RESULTS

SEM, XRD, FT-IR, and EDXA confirmed characteristics of zinc-coated CHA derived from avian eggshell using microwave method. Histological analysis demonstrated that the defects filled with carbonate apatite had more calcified bone and less uncalcified bone formation than other groups.

CONCLUSIONS

The present research demonstrated the efficient use of microwave in the conversion of natural CaCO3 into CHA with zinc coating. The examined properties showed the potential use of the new material as an antibacterial bone substitute in oral surgery. The trial animal study implied favorable osteoconductive ability of carbonate apatite in new bone formation.

Reconstruction of cranial bone defects using Struthio camelus eggshell

BACKGROUND

There are many synthetic materials for the treatment of bone defects, which have their own advantages and disadvantages. We aimed to compare the efficacy of ostrich eggshell, which is cheap and easily available, and demineralized bone matrix in healing of cranial bone defects.

METHODS

A full-thickness circular bone defect was created in the frontal bone of 40 Wistar rats. Group 1 was the operative control group. In group 2, demineralized bone matrix applied into the defects; in group 3, Struthio camelus (ostrich) eggshell implants (OSIs) were applied into the defects; and in group 4, ostrich eggshell powders were applied into the defects. Computed tomographic analysis was performed to evaluate the healing of bone defects, the bone density, the OSI area measurements, and the OSI volume and density. At the end of the 24th week, all rats were killed. New bone formation, infection, resorption, and tissue reactions were evaluated.

RESULTS

Ostrich eggshell implants were slightly resorbed, integrated with bone, stable, and supplied good cranial completeness. Ostrich eggshell powders were totally resorbed at the sixth month. There were no significant differences between control and ostrich eggshell groups in new bone formation.

CONCLUSIONS

Ostrich eggshell did not seem to be an osteoproductive material, but it has some important advantages as an implant. Ostrich eggshell has a strong structure, is cheap, is shaped easily, and does not cause tissue reaction or infection. Ostrich eggshell could be a good alternative graft material for craniomaxillofacial procedures. Further studies are required to find out the potential use of the ostrich eggshell in craniomaxillofacial reconstructions.

Synthesis of three-dimensional calcium carbonate nanofibrous structure from eggshell using femtosecond laser ablation

BACKGROUND

Natural biomaterials from bone-like minerals derived from avian eggshells have been considered as promising bone substitutes owing to their biodegradability, abundance, and lower price in comparison with synthetic biomaterials. However, cell adhesion to bulk biomaterials is poor and surface modifications are required to improve biomaterial-cell interaction. Three-dimensional (3D) nanostructures are preferred to act as growth support platforms for bone and stem cells. Although there have been several studies on generating nanoparticles from eggshells, no research has been reported on synthesizing 3D nanofibrous structures.

RESULTS

In this study, we propose a novel technique to synthesize 3D calcium carbonate interwoven nanofibrous platforms from eggshells using high repetition femtosecond laser irradiation. The eggshell waste is value engineered to calcium carbonate nanofibrous layer in a single step under ambient conditions. Our striking results demonstrate that by controlling the laser pulse repetition, nanostructures with different nanofiber density can be achieved. This approach presents an important step towards synthesizing 3D interwoven nanofibrous platforms from natural biomaterials.

CONCLUSION

The synthesized 3D nanofibrous structures can promote biomaterial interfacial properties to improve cell-platform surface interaction and develop new functional biomaterials for a variety of biomedical applications.

Spontaneous healing capacity of rabbit cranial defects of various sizes

Purpose

This study evaluated the spontaneous healing capacity of surgically produced cranial defects in rabbits with different healing periods in order to determine the critical size defect (CSD) of the rabbit cranium.

Methods

Thirty-two New Zealand white rabbits were used in this study. Defects of three sizes (6, 8, and 11 mm) were created in each of 16 randomly selected rabbits, and 15-mm defects were created individually in another 16 rabbits. The defects were analyzed using radiography, histologic analysis, and histometric analysis after the animal was sacrificed at 2, 4, 8, or 12 weeks postoperatively. Four samples were analyzed for each size of defect and each healing period.

Results

The radiographic findings indicated that defect filling gradually increased over time and that smaller defects were covered with a greater amount of radiopaque substance. Bony islands were observed at 8 weeks at the center of the defect in both histologic sections and radiographs. Histometrical values show that it was impossible to determine the precise CSD of the rabbit cranium. However, the innate healing capacity that originates from the defect margin was found to be constant regardless of the defect size.

Conclusions

The results obtained for the spontaneous healing capacity of rabbit cranial defects over time and the underlying factors may provide useful guidelines for the development of a rabbit cranial model for in vivo investigations of new bone materials.