Someswar Datta

The repair of segmental bone defects with porous bioglass: an experimental study in goat.

This study was exclusively conducted to evaluate healing of surgically created defects on the radius of adult Black Bengal goat after implantation of porous bioglass blocks and compare the process kinetics with normal healing. Twelve Black Bengal goats were divided randomly into two groups: control and experimental group implanted with bioglass blocks. Unicortical bone defects in radius were generated in all animals under aseptic condition. Local inflammatory reaction and healing of wound, radiological investigations, histological studies, oxytetracycline leveling and angiographic studies were performed up to 90th day post-operatively and compared with normal healing. It has been found that extensive new bone formation originating from host bone towards the implant whereas in control, the process was active from both the ends; the defect site appeared as homogenous nonfluorescent area. Thus, porous bioglass promoted bone formation over the entire extension of the defect independent of size of block in comparison to control group.

Development of porous HAp and β-TCP scaffolds by starch consolidation with foaming method and drug-chitosan bilayered scaffold based drug delivery system

The inability to maintain high concentrations of antibiotic at the site of infection for an extended period of time along with dead space management is still the driving challenge in treatment of osteomyelitis. Porous bioactive ceramics such as hydroxyapatite (HAp) and beta-tri calcium phosphate (β-TCP) were some of the alternatives to be used as local drug delivery system. However, high porosity and high interconnectivity of pores in the scaffolds play a pivotal role in the drug release and bone resorption. Ceftriaxone is a cephalosporin that has lost its clinical popularity. But has recently been reported to exhibit better bactericidal activity in vitro and reduced probability of resistance development, in combination with sulbactam, a β-lactamase inhibitor. In this article, a novel approach of forming HAp and pure β-TCP based porous scaffolds by applying together starch consolidation with foaming method was used. For the purpose, pure HAp and β-TCP were prepared in the laboratory and after thorough characterization (including XRD, FTIR, particle size distribution, etc.) the powders were used for scaffold fabrication. The ability of these scaffolds to release drugs suitably for osteomyelitis was studied in vitro. The results of the study indicated that HAp exhibited better drug release profile than β-TCP when drug was used alone indicating the high influence of the carrier material. However, this restriction got relaxed when a bilayered scaffold was formed using chitosan along with the drug. SEM studies along with EDAX on the drug-chitosan bilayered scaffold showed closest apposition of this combination to the calcium phosphate surface.

Comparison of bioactive glass coated and hydroxyapatite coated titanium dental implants in the human jaw bone

BACKGROUND Current trends in clinical dental implant therapy include modification of titanium surfaces for the purpose of improving osseointegration by different additive (bioactive coatings) and subtractive processes (acid etching, grit-blasting). The aim of this study was to evaluate and compare the behaviour of hydroxyapatite and the newly developed bioactive glass coated implants (62 implants) in osseous tissue following implantation in 31 patients. METHODS Bioactive glass and hydroxyapatite was suitably coated on titanium alloy. Hydroxyapatite coating was applied on the implant surface by air microplasma spray technique and bioactive glass coating was applied by vitreous enamelling technique. The outcome was assessed up to 12 months after prosthetic loading using different clinical and radiological parameters. RESULTS Hydroxyapatite and bioactive glass coating materials were non-toxic and biocompatible. Overall results showed that bioactive glass coated implants were as equally successful as hydroxyapatite in achieving osseointegration and supporting final restorations. CONCLUSIONS The newly developed bioactive glass is a good alternative coating material for dental implants.

Organic–Inorganic Composites for Bone Drug Delivery

This review paper attempts to provide an overview in the fabrication and application of organic–inorganic based composites in the field of local drug delivery for bone. The concept of local drug delivery exists for a few decades. However, local drug delivery in bone and specially application of composites for delivery of drugs to bone is an area for potential research interest in the recent time. The advantages attained by an organic–inorganic composite when compared to its individual components include their ability to release drug, adopting to the natural environment and supporting local area until complete bone regeneration, which make them carriers of interest for local drug delivery for bone.

A new high temperature resistant glass-ceramic coating for gas turbine engine components

A new high temperature and abrasion resistant glass-ceramic coating system (based on MgO-Al2O3-TiO2 and ZnO-Al2O3-SiO2 based glass systems) for gas turbine engine components has been developed. Thermal shock resistance, adherence at 90°-bend test and static oxidation resistance at the required working temperature (1000°C) for continuous service and abrasion resistance are evaluated using suitable standard methods. The coating materials and the resultant coatings are characterized using differential thermal analysis, differential thermogravimetric analysis, X-ray diffraction analysis, optical microscopy and scanning electron microscopy. The properties evaluated clearly showed the suitability of these coatings for protection of different hot zone components in different types of engines. XRD analysis of the coating materials and the resultant coatings showed presence of a number of microcrystalline phases. SEM micrographs indicate strong chemical bonding at the metal-ceramic interface. Optical micrographs showed smooth glossy impervious defect free surface finish.

Converted marine coral hydroxyapatite implants with growth factors: In vivo bone regeneration

Herein we report rabbit model in vivo bone regeneration of hydrothermally converted coralline hydroxyapatite (HCCHAp) scaffolds without (group I) and with growth factors namely insulin like growth factor-1 (IGF-1) (group II) and bone morphogenetic protein-2 (BMP-2) (group III). All HCCHAp scaffolds have been characterized for phase purity and morphology before implantation. Calcined marine coral was hydrothermally converted using a mineralizer/catalyst to phase pure HAp retaining original pore structure and geometry. After sintering at 1250°C, the HCCHAp found to have ~87% crystallinity, 70-75% porosity and 2±0.5MPa compressive strength. In vitro growth factor release study at day 28 revealed 77 and 98% release for IGF-1 and BMP-2, respectively. The IGF-1 release was more sustained than BMP-2. In vivo bone healing of different groups was compared using chronological radiology, histological evaluations, scanning electron microscopy and fluorochrome labeling up to 90days of implantation. In vivo studies showed substantial reduction in radiolucent zone and decreased radiodensity of implants in group II followed by group III and group I. These observations clearly suggest in-growth of osseous tissue, initiation of bone healing and complete union between implants and natural bone in group II implants. A statistical score sheet based on histological observations showed an excellent osseous tissue formation in group II and group III scaffolds and moderate bone regeneration in group I scaffolds.

Aluminium Oxide Coating by Microwave Processing

Microwave processing is an energy-efficient advanced technique to prepare materials with finer microstructure and better mechanical properties. In the present paper, microwave energy was utilized for the development of oxide coatings on blocks of commercial aluminium of various geometrical shapes. Experimental results revealed that the geometrical term, i.e. the volume to surface ratio had a dominant influence on the microwave induced oxidation behaviour of the samples. In all the cases, coating thickness and its density progressively increased with increasing microwave exposure time. The coating phase was found out to be α-Al2O3 by XRD analysis. The coating microstructure and elemental analysis as examined by SEM and EDAX respectively have been discussed in detail. Adhesion of coatings was studied by using the scratch test.

Solution Combustion Synthesis of Calcium Hydroxyapatite Nanoparticles

Nanoparticles of calcium hydroxyapatite, Ca10(PO4)6(OH)2, (HA) an important material for biomedical applications and other non-medical uses were synthesized by combustion in the aqueous system Ca-nitrate—diammonium hydrogen orthophos-phate-urea. The combustion behaviour and phase evolution with respect to the Ca/P atom ratio in the starting materials were investigated. Single-phase hydroxyapatite particles were obtained when the Ca/P ratio in the starting batch was 1.75. Below this ratio the products contained mainly hydroxyapatite and tricalcium phosphate (Ca3(PO4)2, TCP), the relative abundance of these phases being dependent upon the batch composition. In all these cases, the particles were equiaxed, nanosized (60—130 nm) and occurred as easily dispersible soft agglomerates of sizes ranging from 0.1 to larger than 100 μm. The products were characterized for phase contents, particle size distribution and morphology.

Development and effect of different bioactive silicate glass scaffolds: In vitro evaluation for use as a bone drug delivery system

Local drug delivery systems to bone have attracted appreciable attention due to their efficacy to improve drug delivery, healing and regeneration. In this paper, development and characterization of new formulations of bioactive glass into a porous scaffold has been reported for its suitability to act as a drug delivery system in the management of bone infections, in vitro. Two new glass compositions based on SiO2-Na2O-ZnO-CaO-MgO-P2O5 system (BGZ and MBG) have been developed which after thorough chemical and phase evaluation, studied for acellular static in vitro bioactivity in SBF. Porous scaffolds made of these glasses have been fabricated and characterized thoroughly for bioactivity study, SEM, XRD, in vitro cytotoxicity, MTT assay and wound healing assay using human osteocarcoma cells. Finally, gatifloxacin was loaded into the porous scaffold by vacuum infiltration method and in vitro drug release kinetics have been studied with varying parameters including dissolution medium (PBS and SBF) and with/without impregnation chitosan. Suitable model has also been proposed for the kinetics. 63-66% porous and 5-50μm almost unimodal porous MBG and BGZ bioactive glass scaffolds were capable of releasing drugs successfully for 43 days at concentrations to treat orthopedic infections. In addition, it was also observed that the release of drug followed Peppas-Korsmeyer release pattern based on Fickian diffusion, while 0.5-1% chitosan coating on the scaffolds decreased the burst release and overall release of drug. The results also indicated that MBG based scaffolds were bioactive, biocompatible, noncytotoxic and exhibited excellent wound healing potential while BGZ was mildly cytotoxic with moderate wound healing potential. These results strongly suggest that MBG scaffolds appear to be a suitable bone drug delivery system in orthopedic infections treatment and as bone void fillers, but BGZ should be handled with caution or studied elaborately in detail further to ascertain and confirm the cytotoxic nature and wound healing potential of this glass.

Effects of bioactive glass, hydroxyapatite and bioactive glass - Hydroxyapatite composite graft particles in the treatment of infrabony defects

Background: Several synthetic alloplastic materials have been used in the past as an implant in infrabony defects with a goal to reconstruct the lost part of attachment apparatus via new osseous tissue formation. The present study was undertaken to evaluate and compare clinico-radiographically, the effect of bioactive glass (BG), hydroxyapatite (HA), and BG-HA composite bone graft particles in the treatment of human infra-bony periodontal defects. Materials and Methods: Indigenous synthetic HA, BG, and BG-HA composite bone graft materials were developed in the laboratory. Twenty eight infrabony periodontal defects were equally distributed (i.e., seven defects) into four groups. The defects were treated separately with three types of graft materials and non-grafted manner (open flap debridement alone, control) to evaluate both the soft and hard tissue responses after six months of surgery. Evaluation was done by studying different parameters such as plaque index, gingival index, relative attachment level, probing pocket depth, and radiographic bone fill in Intra Oral Peri-Apical radiograph. Results: The healing of defects was uneventful and free of any biological complications. The gain in relative attachment level, reduction of probing pocket depth, and bone fill was statistically significant in all four groups. BG and BG-HA synthetic bone graft implanted sites showed significant bone fill (P<0.05) than hydroxyapatite and unimplanted control sites. Conclusion: The performance of BG and its composite was better compared to HA and open flap debridement alone for the reconstruction of infrabony defects. The BG-HA composite particles may effectively be used as an alternative bone graft material for infrabony defects.