Histological study of the hydroxyapatite-collagen complex implants in periodontal osseous defects in dogs

Chitosan-collagen-hydroxyapatite membranes for tissue engineering

Tissue engineering is growing in developing new technologies focused on providing effective solutions to degenerative pathologies that affect different types of connective tissues. The search for biocompatible, bioactive, biodegradable, and multifunctional materials has grown significantly in recent years. Chitosan, calcium phosphates collagen, and their combination as composite materials fulfill the required properties and could result in biostimulation for tissue regeneration. In the present work, the chitosan/collagen/hydroxyapatite membranes were prepared with different concentrations of collagen and hydroxyapatite. Cell adhesion was evaluated by MTS assay for two in vitro models. Additionally, cytotoxicity of the different membranes employing hemolysis of erythrocytes isolated from human blood was carried out. The structure of the membranes was analyzed by X-rays diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermal stability properties by thermogravimetric methods (TGA). The highest cell adhesion after 48 h was obtained for chitosan membranes with the highest hydroxyapatite and collagen content. All composite membranes showed good cell adhesion and low cytotoxicity, suggesting that these materials have a significant potential to be used as biomaterials for tissue engineering. Graphical abstract.

Histologic and histomorphometric evaluation of two bone substitute materials for bone regeneration: an experimental study in sheep

INTRODUCTION

In the past decade, there has been an increase focus on regeneration approaches as related to periodontics and implant therapies. The main objective of the present study is the evaluation of quality, density, and thickness of the newly formed bone in experimental defects treated with deproteinized bovine bone mineral (DBBM) and bioapatite-collagen.

MATERIALS

Fifteen identical cuboidal defects were prepared in the alveolar edentulous mandibular ridges in 10 male sheep. Defects were randomly assigned to be treated either with DBBM, Bioapatite-collagen or remained unfilled as the control group. Defects of these 3 groups were histologically examined after 6 months.

RESULTS

The mean percentages of bone regeneration with DBBM, Bioapatite-collagen, and control group were 51.40% +/- 3.57%, 27.66% +/- 4.18%, and 19% +/- 1%, respectively (P < 0.05). Defects filled with Bio-Oss and control defects did not show foreign body reaction, whereas Biostite particles had a reaction in 40% of the specimens. Trabecular thickness and type of new regenerated bone were also significantly different between Bio-Oss and Biostite (P < 0.05) and control group (P < 0.05).

CONCLUSION

The results of the present study suggest that using of DBBM particles can promote bone regeneration more effectively than Bioapatite-collagen, and both materials were more promising than the control group.

Tricalcium phosphate and glutaraldehyde crosslinked gelatin incorporating bone morphogenetic protein--a viable scaffold for bone tissue engineering

Bone defects caused by various etiologies must be filled with suitable substances to promote bone repair. Autogenous iliac crest graft is most frequently used, but is often associated with morbidities. Several bone graft substitutes have been developed to provide osteoconductive matrices as well as to enhance osteoinductivity. A tricalcium phosphate and glutaraldehyde crosslinked gelatin (GTG) scaffold, incorporated with bone morphogenetic proteins (BMPs), was developed to provide an alternative mean of bone tissue engineering. This study investigated differences between GTG and BMP-4 immobilized GTG (GTG-BMP) scaffolds on neonatal rat calvaria osteoblast activities. The GTG scaffold possessed an average pore size of 200 microm and a porosity of 75%. HE staining revealed uniform cell distribution throughout the scaffold 24 h post cell seeding. Alkaline phosphatase (ALP) activity of the GTG samples increased initially and then stabilized at 3 weeks postseeding. ALP activity of the GTG-BMP samples was similar to that of the GTG samples in the second and third weeks, but it continued increasing and became significantly greater than that of the GTG samples by the fourth week. Gla-type osteocalcin (Gla-OC) activity of the GTG-BMP samples was initially lower, but also became significantly greater than that of the GTG samples by the fourth week. An HE stain revealed greater numbers of attached cells and a richer matrix deposits in the GTG-BMP samples. A von Kossa stain showed larger mineralizing nodules, in greater numbers, after 4 weeks of in vitro cultivation. These findings suggest that the GTG scaffold provides an excellent porous structure, conductive to greater cell attachment and osteoblast differentiation, and that utility can be significantly enhanced by the inclusion of BMPs. A GTG-BMP scaffold holds promise as a superior bioactive material for bone tissue engineering.

A comparative study on the use of a HA/collagen/chondroitin sulphate biomaterial (Biostite) and a bovine-derived HA xenograft (Bio-Oss) in the treatment of deep intra-osseous defects

OBJECTIVES

This parallel-group, randomized, clinical trial was designed to evaluate the clinical outcome of deep intra-osseous defects following reconstructive surgery with the use of a synthetic hydroxyapatite/equine Type I collagen/chondroitin sulphate biomaterial (Biostite), as compared to a bovine-derived hydroxyapatite xenograft (Bio-Oss).

MATERIAL AND METHODS

Twenty-four systemically healthy subjects with moderate to advanced periodontitis, 11 females and 13 males, aged 30-64 years, seven smokers, were selected. Patients presented with one interproximal deep intra-osseous defect (intra-osseous component >or=4 mm) as clinically and radiographically evaluated. Immediately before surgery and 12 months after surgery, pocket probing depth (PPD), clinical attachment level (CAL) and radiographic depth of the defect (DEPTH) were evaluated.

RESULTS

Thirteen defects were treated with Biostite (test) and 11 defects with Bio-Oss (control). In the test group, PPD amounted to 7.8+/-1.3 mm before surgery, and decreased significantly to 3.6+/-1.6 mm 12 months following surgery, while in the control group PPD significantly decreased from 7.5+/-2.0 mm pre-surgery to 3.1+/-1.0 mm post-surgery. At 1 year, CAL gain and DEPTH gain were 2.9+/-1.9 and 2.5+/-1.4 mm, respectively, in the test group, and 4.0+/-2.4 mm and 3.1+/-1.8 mm, respectively, in the control group. No statistically significant differences for PPD reduction, CAL gain and DEPTH gain were detected between the groups.

CONCLUSIONS

The results of the present study indicate that both Biostite and Bio-Oss grafting biomaterials have determined a clinically and statistically significant improvement in terms of CAL gain, PPD reduction and radiographic DEPTH gain when used for the treatment of deep intra-osseous defects.

Preparation, characterization, and in vitro release of gentamicin from coralline hydroxyapatite-alginate composite microspheres

In this work, composite microspheres were prepared from bioactive ceramics such as coralline hydroxyapatite [Ca(10)(PO(4))(6)(OH)(2)] granules, a biodegradable polymer, sodium alginate, and an antibiotic, gentamicin. Previously, we have shown a gentamicin release from coralline hydroxyapatite granules-chitosan composite microspheres. In the present investigation, we attempted to prepare composite microspheres containing coralline hydroxyapatite granules and sodium alginate by the dispersion polymerization technique with gentamicin incorporated by absorption method. The crystal structure of the composite microspheres was analyzed using X-ray powder diffractometer. Fourier transform infrared spectra clearly indicated the presence of per-acid of sodium alginate, phosphate, and hydroxyl groups in the composite microspheres. Scanning electron micrographs and optical micrographs showed that the composite microspheres were spherical in shape and porous in nature. The particle size of composite microspheres was analyzed, and the average size was found to be 15 microns. The thermal behavior of composite microspheres was studied using thermogravimetric analysis and differential scanning calorimetric analysis. The cumulative in vitro release profile of gentamicin from composite microspheres showed near zero order patterns.

Preparation, characterization and in vitro release of gentamicin from coralline hydroxyapatite-gelatin composite microspheres

Composite microspheres have been prepared from bioactive ceramics such as coralline hydroxyapatite [CHA, Ca10(PO4)6(OH)2] granules, a biodegradable polymer, gelatin and an antibiotic, gentamicin. In our earlier work, we have shown a gentamicin release from CHA granules--chitosan composite microspheres. In the present investigation, an attempt was made to prepare the composite microspheres containing coralline hydroxyapatite and gelatin (CHA-G), which were prepared by the dispersion polymerization technique and the gentamicin was incorporated by the absorption method. The crystal structure of the composite microspheres was analyzed using X-ray powder diffractometer. The Fourier transformed infrared spectrum clearly indicated the presence of amide and hydroxyl groups in the composite microspheres. Scanning electron micrographs and optical micrographs show that the composite microspheres are spherical in shape and porous in nature. The particle size of composite microspheres was analyzed and the average size was found to be 16 microm. The thermal behavior of composite microspheres was studied using thermogravimetric analysis and differential scanning calorimetric analysis. The cumulative in vitro release profile of gentamicin from composite microspheres showed near zero order patterns.

Ring-opening polymerization of lactones in the presence of hydroxyapatite

The ring-opening polymerization of epsilon-caprolactone, delta-valerolactone (VL) and D,L-lactide, respectively, in the presence of different proportions of hydroxyapatite (HA) was catalyzed by stannous (II)octoate (SnOct2) at 130 degrees C and resulted in composites. The lactones were almost completely converted to the polymers within a reaction time of 70 up to 240 min. The number-average molecular weights Mn as determined by size exclusion chromatography decreased with increasing content of HA. The initiating efficiency of HA as calculated from the difference of the polymerization degrees P. obtained with and without HA turned out to be relatively low with ca. 11 to 0.5% for 1 to 80 wt% HA, respectively. For the polymerization of VL, the initiating efficiency of HA was on the average threefold higher. The quantitative proof of non-extractable polymer on HA by means of thermogravimetric analysis, fourier transform infrared spectroscopy with photoacoustic detection and differential scanning calorimetry confirmed the initiating efficiency of HA as mentioned above. This poly(lactone) can be debound from HA by treatment with aqueous HCl. Hence it is assumed to be ionically bound.

Clinical comparison of resorbable and non-resorbable barriers for guided periodontal tissue regeneration

The purpose of this study was to compare the clinical results of guided periodontal tissue regeneration (GPTR) using a resorbable barrier manufactured from a copolymer of polylactic and polyglycolic acids (Resolut Regenerative Material) with those of non-resorbable e-PTFE barrier (Gore-Tex Periodontal Material). 12 subjects participated, 6 with similarly paired class II furcations and 6 with 2 similar 2, 3-wall periodontal lesions. The resorbable and non-resorbable barriers were randomly assigned to 1 defect in each subject. Non-resorbable barriers were removed in six weeks. Plaque index (PlI), gingival index (GI), probing depth (PD), clinical attachment level (CAL) and gingival recession (R) were recorded at baseline, (i.e., immediately prior to surgery) and at 12 months postsurgically. The clinical healing was similar and uneventful in both groups. Intrabony pockets depicted significant changes from baseline (p < 0.05) for probing depth reduction and gain in clinical attachment levels. No differences were found between treatments. Class II furcations showed significant improvements from baseline (p < or = 0.05) for probing depth reduction and clinical attachment gain. No differences were detected between treatments. It is concluded that the resorbable barrier tested is as effective as the nonresorbable e-PTFE barrier for the treatment of class II furcations and intrabony defects.

A prospective multi-center study evaluating periodontal regeneration for Class II furcation invasions and intrabony defects after treatment with a bioabsorbable barrier membrane: 1-year results

The purpose of this prospective multi-center study was to evaluate a resorbable barrier membrane designed for periodontal regeneration. Thirty-one Class II furcations and 30 two- and three-wall intrabony defects were treated by flap debridement and bioabsorbable barrier membrane augmentation. The efficacy of treatment was evaluated in terms of changes in vertical probing depth (PD), horizontal probing depth (HPD), clinical attachment levels (CAL), and recession. Five centers participated in the study. Changes in clinical parameters are reported by individual center and by the average of the centers. All patients had either one molar with a Class II furcation or an intrabony defect. Baseline data were taken on the day of surgery. Post-treatment data were collected at 6 months and 1 year. This report is based on the 1-year findings. The average initial PD for Class II furcations was 6.1 mm. At 1 year the average PD was reduced to 3.6 mm, a 2.5 mm change. These differences were clinically and statistically significant (P < 0.0001). There was an average gain of 2.1 mm of clinical attachment (P < 0.0001) and 0.4 mm of recession (P < 0.04). There was a mean of 1.8 mm change in HPD (P < 0.0001). For intrabony defects, at 1 year there was an average PD reduction of 4.1 mm (P < 0.0001) and a mean gain of CAL of 2.9 mm (P < 0.0001). At 1 year the average recession was 0.9 mm which was statistically significant. When treatment outcomes were compared between centers there were no differences for either group of treated defects. There were differences between centers when baseline PD for furcations and intrabony sites were compared. The results of this study indicate that clinically and statistically significant improvements in PD, CAL, and HPD occurred after treatment of Class II furcations and 2- to 3-wall intrabony defects with the bioabsorbable periodontal membrane.

Healing response to anorganic bone implantation in periodontal intrabony defects in dogs. Part I. Bone regeneration. A microradiographic study

The purpose of the present study was to explore the regenerative potential of anorganic bone plus collagen (AB-C) in experimental intrabony defects. Eight healthy female beagle dogs, 3 to 4 years old and weighing 15 to 16 kilos, were used. After extraction of the mandibular third premolars (P3), surgical defects were created and inflammation induced by placement of cotton and steel braids. Eight weeks later, the braids were removed. The experimental lesions thus obtained were either treated by plain flap curettage (group 1: control) or were, in addition, implanted with AB-C (group 2: experimental). Blocks of AB-C alone were observed by scanning electron microscopy (SEM). The results show that the surface of the particles have the characteristics of a bone tissue. These particles are gathered together with a fibrillar network. Six, 18, and 36 weeks postoperative (PO), non-decalcified specimens from both groups were examined histologically by contact microradiography. In group 1, no significant bone regeneration was observed at 6, 18, or 36 weeks PO. In group 2, trabeculae undergoing mineralization and circumscribing dense particles above the reference notch were seen at 6 weeks PO; 18 and 36 week specimens showed significant bone regeneration with more or less dense remaining particles. The periodontal ligament space was always clear and the only signs of ankylosis noticed were deep in the notch on one 18 week group 2 specimen and on one 36 week group 1 specimen.

In vitro induction of a calcifying matrix by biomaterials constituted of collagen and/or hydroxyapatite: an ultrastructural comparison of three types of biomaterials

The induction of a calcifying matrix was studied in vitro and compared for three biomaterials (collagen sponge, hydroxyapatite material and a mixture of both (Biostite)) cultured with human osteoblast-like cells. The influence of biomaterials on organic matrix synthesis and the calcification process was analysed at the ultrastructural level (transmission electron microscopy and X-ray microanalysis). Biomaterials were well tolerated by bone cells. Whichever biomaterial was used, osteoblasts proliferated and synthesized a new matrix constituted of fibrillar and non-fibrillar elements. This activity appeared earlier and was more intense with Biostite than with collagen sponge alone. A deposition of a mineral substance in this newly formed matrix was observed with the collagen sponge and Biostite, but never with hydroxyapatite alone. The mineral deposits were identified as hydroxyapatite crystals, similar to those observed and analysed in bone tissue. These in vitro observations clearly demonstrated the property of Biostite to produce a calcified collagenous matrix similar to bone tissue. However, in vivo confirmation is required before extending the use of this biomaterial to periodontology.

The diagnostic value of subtraction radiography in the assessment of granular hydroxylapatite implants

Although histologic analysis of osseous changes around hydroxylapatite (HA) implants can be highly accurate, it is of limited use in human beings. Digital subtraction radiography may provide a noninvasive alternative. Ten patients with bony lesions were operated on and nine of the iatrogenic defects were filled with granulated HA. In one patient, the defect was left unfilled for reference. Customized film holders provided standardized radiography. Follow-up images after 4 to 6 months were subtracted from immediately obtained postoperative images, and changes around the implants were noted. From ten pairs of radiographs, eight could be successfully subtracted, whereas two pairs required corrective image transformation before subtraction. Although no bone loss was observed in any of the patients, the implants did not appear to enhance physiologic bone regeneration either. Hence, subtraction radiography holds the potential of clinical utility for the follow-up of HA implants. However, technical improvements are necessary to yield quantitative data.

Effects of atelocollagen on the wound healing reaction following palatal gingivectomy in rats

Collagen membrane preparations have been manufactured with the aim of enhancing wound healing following periodontal surgery. After cross-linking by various processing methods (with ultraviolet radiation or hexamethylenediisocyanate) and to various extents, atelocollagen membranes were applied into dissection sites within palatal gingival tissue. Applied atelocollagen was histopathologically compared with applied lyophilized porcine dermis (LPD) and controls in rats, with regard to the time course of healing. The atelocollagen-applied group showed more satisfactory regeneration of the epithelium and connective tissue in an artificially created gingival defect than did the control group or the LPD-applied group. Epithelial downgrowth along the root surface was significantly suppressed by the use of atelocollagen. In addition, the post-operative inflammatory reaction and foreign body giant cell reaction subsided rapidly after surgery in the atelocollgen-applied group. Our results show that the use of atelocollagen membrane in periodontal wounds should be the method of choice.