Histological and Histometrical Evaluation of two Synthetic Hydroxyapatite Based Biomaterials in the Experimental Periodontal Defects in Dogs.

AIM: The present study was to evaluate histologically and histometrically the efficacy of Chitra granules in the regeneration of alveolar bone and to compare it with that of OsteoGenR (HA Resorb)(TM) in iatrogenically created alveolar bone defects in mongrel dogs. MATERIALS AND METHODS: Four dogs (16 sites) were used for this split-mouth study. The animals were divided randomly into two groups of two animals. Same animals were used as control and test. Each dog had four implantation sites. The periodontal defects were prepared by acute defect model. Animals were sacrificed at 3 months (n=2), 6 months (n=2) and histologic and histometric evaluation was carried out. STATISTICAL ANALYSIS: The data was analysed using statistical package Graph pad Software. Comparison of the hard and soft tissue parameters in the two groups was done using the Wilcoxan (Man Whitney), two tailed t-test. A p-value less than 0.05 were considered significant. RESULTS: Maturing bone with immature periodontal ligament fibers were observed at three months and advanced osteogenesis at six months with both the types of bone graft materials. The mean values showed that amount of new bone formed with OsteoGenR (HA Resorb)(TM) was slightly more than that obtained by Chitra granules in histometric evaluation. CONCLUSION: Histological study showed similar healing pattern with both the types of bone graft materials with maturing bone at 3 months and advanced osteogenesis at six months in experimental intraosseous periodontal defects in dogs. However, histological evaluation for longer period is necessary to determine the time taken for complete replacement of the bone graft materials with new bone.

Calcium phosphate cement as an alternative for formocresol in primary teeth pulpotomies.

BACKGROUND: Formocresol remains to be the preferred medicament in pulpotomy, despite the concerns regarding tissue devitalization and systemic toxicity. Several materials were used as alternatives, but none proved significantly advantageous. Of recent, calcium phosphate cement (CPC) has been projected as an ideal pulpotomy material considering its tissue compatibility and dentinogenic properties. This study explores the suitability of a CPC formulation for pulpotomy, in comparison with formocresol. MATERIALS AND METHODS: This comparative case study included 10 children (8-12 age group) having a pair of non-carious primary canines (both maxillary and mandibular) posted for extraction. Pulpotomy was performed with CPC in the right canines and formocresol in the left and sealed with IRM ® (Dentsply). The teeth were extracted at 70 ± 5 days and sectioned and stained for the histopathological evaluation. Parameters such as pulpal inflammation, tissue reaction to material, dentine bridge formation, location of dentine bridge, quality of dentine formation in bridge, and connective tissue in bridge etc. were evaluated. RESULTS: The histological assessment after 70 days showed no statistically significant difference between the two groups in any of the parameters. However, CPC gave more favorable results in pulpal inflammation, with a lower score of 1.6 against 2.6 for formocresol. CPC samples showed better formation of dentine bridge in quantity and quality. The mean scores for CPC for the extent of dentine bridge formation, quality of dentine bridge and connective tissue in the bridge, were 2.0, 1.4, and 1.2 respectively, whereas the corresponding values for formocresol were 0.8, 0.2, and 1.0. CONCLUSION: CPC is more compatible to pulp tissues than formocresol and it shows good healing potential. CPC is capable of inducing dentine formation without an area of necrosis.

Influence of curing agent on fibrosis around silicone implants.

Severe capsular contracture around silicone expander breast implants leading to pain and failure is a major clinical problem. Even though earlier studies have implicated the immunogenicity of silicone, the role of physical and chemical properties of the silicone material in excessive collagen deposition and fibrosis has been less addressed. The present study investigates whether there is any correlation between the type of curing systems i.e. addition and free radical curing and the fibrosis around silicone elastomer. The experiment carried out uses commercially available silicone ventriculo-peritoneal shunt material elastomer cured by platinum and the results are compared with results obtained in a similar study carried out by the authors using commercially available silicone tissue expander material cured by peroxide. Ultra-high molecular weight poly-ethylene (UHMWPE), the standard reference for biocompatibility evaluation, was used as the control material. The materials were implanted in rat skeletal muscle for 30 and 90 days. Inflammatory cells, myofibroblasts, cytokines, and collagen deposition at the material-tissue interface were identified by haematoxylin-eosin and Masson's Trichrome stains and semi-quantitated based on immunohistochemical studies. Results indicate that even though the cellular response in the initial phase of wound healing was similar in both platinum and peroxide-cured materials, the collagen deposition in the proliferative phase was more around peroxide-cured material in comparison to the platinum-cured silicone elastomer. There is a need to look into the molecular mechanisms of this interaction and the possibility of using curing systems other than free radical peroxide in the manufacture of silicone elastomer expanders for breast prosthesis.

Mediatory role of interleukin-6 in α smooth muscle actin induction and myofibroblast formation around silicone tissue expander.

Materials used for medical devices are usually tested for their biocompatibility, before use. However, it is known that long-term implantation in the body may lead to degradation of the material leading to an adverse tissue response. The failure of silicone breast implants due to excessive fibrosis and contracture has led to studies to delineate the cause of fibrosis around this material. To detect the biological moieties involved, conditioned media from RAW 264.7 macrophages seeded over commercially available silicone tissue expander material was added to L929 fibroblasts. Ultrahigh-molecular-weight polyethylene and tissue culture grade polystyrene served as the control materials. The gene expression of fibrogenic cytokines, interleukin-6 (IL-6), and transforming growth factor beta (TGFß) in the RAW macrophages and myofibroblast marker alpha smooth muscle actin (αSMA) in L929 cells were quantitated by real time polymerase chain reaction. Protein expression analysis of αSMA was carried out by immunocytochemical staining and confocal microscopy. An in vitro degradation study of silicone expander material in pseudoextracellular fluid (PECF) and the αSMA expression in fibroblasts incubated with the silicone extract containing PECF has revealed the role of silicone leachants in induction of myofibroblasts. This in vitro expression study revealed the additional profibrotic role of IL-6 in fibroblast to myofibroblast transition and the synergy between material aspects and biomolecules in regulating fibrosis around Silicone implants. These findings may help in targeting newer biological moieties in the profibrotic pathway and in devising better manufacturing processes aiding the life of millions of patients.

F-actin and α-actinin reorganization mediates initial fibroblast interaction with CoCr alloy particles in vitro.

Asceptic loosening remains the primary cause for failure of joint implant. The active role of fibroblasts in mediating asceptic loosening is however not well documented. In this study the initial interactions of fibroblasts with metal particles was studied by evaluating changes in the cytoskeletal structure and cytokine level. Murine L929 fibroblasts cultured with cobalt chromium particles were observed by phase contrast and scanning electron microscopy (SEM). Changes in the cytoskeletal rearrangement of F-actin and α-actinin focal adhesion plaques were studied by confocal microscopy. Expression of the proinflammatory cytokines IL-6 and IL-1α were analyzed by ELISA. The role of actin filaments and microtubules in particle uptake were determined at low temperature and in presence of colchicine and cytochalasin B. Phase contrast and SEM studies reveal that the metal particles adhere to the fibroblasts. The cellular cytoplasm was observed to grow over the particles and is suggestive of particle uptake. Confocal microscopy shows the presence of voids within the F-actin cytoskeletal framework corresponding to areas occupied by the metal particles, indicating the possible uptake of these particles. Aggregates of α-actinin into patches at the cell surface were also noted. Adherence and uptake of particles did not occur at low temperature and in presence of cytochalasin B, indicating that it is an active energy-dependent process involving actin filaments. Changes in the levels of cytokine IL-6 and IL-1α were not observed suggesting the role of other cytokine molecules in mediating the inflammatory response to wear debri by fibroblasts.

An X-ray micro-fluorescence study to investigate the distribution of Al, Si, P and Ca ions in the surrounding soft tissue after implantation of a calcium phosphate-mullite ceramic composite in a rabbit animal model.

Synthetic calcium phosphates, despite their bioactivity, are brittle. Calcium phosphate- mullite composites have been suggested as potential dental and bone replacement materials which exhibit increased toughness. Aluminium, present in mullite, has however been linked to bone demineralisation and neurotoxicity: it is therefore important to characterise the materials fully in order to understand their in vivo behaviour. The present work reports the compositional mapping of the interfacial region of a calcium phosphate--20 wt% mullite biocomposite/soft tissue interface, obtained from the samples implanted into the long bones of healthy rabbits according to standard protocols (ISO-10993) for up to 12 weeks. X-ray micro-fluorescence was used to map simultaneously the distribution of Al, P, Si and Ca across the ceramic-soft tissue interface. A well defined and sharp interface region was present between the ceramic and the surrounding soft tissue for each time period examined. The concentration of Al in the surrounding tissue was found to fall by two orders of magnitude, to the background level, within ~35 µm of the implanted ceramic.

The reversal of diabetes in rat model using mouse insulin producing cells - a combination approach of tissue engineering and macroencapsulation.

Type 1 diabetes is a chronic disorder resulting from the autoimmune destruction of insulin-producing cells, a leading cause of morbidity and mortality all over the world. In this study a tissue engineering approach was compared with a macroencapsulation approach to reverse type 1 diabetes in a rat model, using mouse pancreatic progenitor cell (PPC)-derived islet-like clusters and mouse islets. For the tissue engineering approach the cells were cultured on gelatin scaffolds cross-linked with EDC in the presence of polyvinylpyrrolidone in vitro (GPE scaffolds), while for the macroencapsulation approach the cells were encapsulated in polyurethane-polyvinylpyrrolidone semi-interpenetrating networks. In the combination approach the cells cultured on GPE scaffolds were further encapsulated in a polyurethane-polyvinylpyrrolidone capsule. Real time PCR studies and the glucose challenge assay have shown that cells on GPE scaffolds could express and secrete insulin and glucagon in vitro. However, under in vivo conditions the animals treated by the tissue engineering approach died within 15-20 days and showed no reversal of their diabetes, due to infiltration of immune cells such as CD4 and CD8 cells and macrophages. In the macroencapsulation approach the animals showed euglycemia within 25 days, which was maintained for further 20 days, but after that the animals died. Interestingly, in the combination approach the animals showed reversal of hyperglycemia, and remained euglycemic for up to 3 months. The time needed to achieve initial euglycemia was different with different cell types, i.e. the combination approach with mouse islets achieved euglycemia within 15 days, whereas with PPC-derived islet-like clusters euglycemia was achieved within 25 days. This study confirmed that a combination of tissue engineering and macroencapsulation with mouse islets could reverse diabetes and maintain euglycemia in an experimental diabetes rat model for 90 days.

Pulsed electromagnetic field therapy results in healing of full thickness articular cartilage defect.

This study aimed to determine the efficacy of PEMF (pulsed electromagnetic field) treatment in experimental osteochondral defect healing in a rabbit model. The study was conducted on 12 New Zealand white rabbits. Six rabbits formed the study group and six rabbits the control group. The right knee joints of all 12 animals were exposed and a 3.5-mm diameter osteochondral defect was created in the trochlear groove. The defect was filled with calcium phosphate scaffold. Six animals from the study group were given PEMF of one hour duration once a day for six weeks with set parameters for frequency of 1 Hz, voltage 20 V, sine wave and current ±30 mA. At six weeks the animals were sacrificed and histological evaluation was done using H&E, Safranin O, Maissons trichrome staining and immunohistochemistry for type 2 collagen. The quality of the repair tissue was graded and compared between groups with the Wakitani histological grading scale and a statistical analysis was done. The total histological score was significantly better in the study group (p = 0.002) with regeneration similar to adjacent normal hyaline cartilage. Immunohistochemistry for collagen type II was positive in the study group. PEMF stimulation of osteochondral defects with calcium phosphate scaffold is effective in hyaline cartilage formation. PEMF is a non-invasive and cost effective adjuvant treatment with salvage procedures such as abrasion chondroplasty and subchondral drilling.

Investigative study of myofibroblasts and cytokines in peri-implant tissue of silicone breast expander by rt-PCR in a rat model.

The excessive collagen deposition around silicone breast implants followed by contracture and development of severe pain is a major clinical problem. This study was conducted to investigate the profibrotic and antifibrotic cytokines secreted by inflammatory cells and development of myofibroblasts at the tissue material interface around silicone breast expander and ultra-high-molecular-weight polyethylene (UHMWPE). Both materials were implanted in rats for 30, 90 and 180 days. Inflammatory cells and collagen deposition at the material-tissue interface were assessed with Haematoxylin-Eosin and Masson's Trichrome stain. Gene expression of TGFbeta, IL-1beta, IFNgamma, IL10 and alpha-SMA was quantitated by real-time (RT)-PCR in the peri-implant tissue. Results indicate a difference in collagen deposition and myofibroblast development around both materials with involvement of TGFbeta, IFNgamma and IL10. The results emphasise the need for further investigation into the molecular mechanisms of protomyofibroblast and myofibroblast formation around silicone implants, which would provide information on these target cells for inhibitory therapy in the clinical situation.

In vitro and in vivo performance of a dual drug-eluting stent (DDES).

This study reports on a dual drug-eluting stent (DDES) that has an anti-proliferative and an anti-thrombotic in a biodegradable polymer-coated onto a cobalt-chromium stent. The DDES was prepared by spray coating the bare metal stent with a biodegradable polymer loaded with sirolimus and triflusal, to treat against restenosis and thrombosis, respectively. The 2-layered dual-drug coated stent was characterized in vitro for surface properties before and after expansion, as well as for possible delamination by cross-sectioning the stent in vitro. The in vitro anti-platelet behavior of the triflusal-loaded films was investigated by using dynamic platelet adhesion measurements. Additionally, the in vitro degradation and release study of the films and the stents w/single sirolimus and dual sirolimus-triflusal in different formulations were examined. Finally, in vivo studies (in a porcine carotid artery model) were performed for acute thrombosis, inflammation and restenosis at 30 days. The in vitro results show DDES can sustain release both anti-proliferation drug (sirolimus) and anti-thrombosis drug (triflusal), two drugs were controlled in different rates to effectively reduce thrombosis and proliferation at the same time. In vivo results show a significant reduction in restenosis with dual-drug eluting stent compared with the controls (a bare metal stent, a sirolimus coated and a pure polymer-coated stent). The reduction in restenosis with a dual sirolimus-triflusal eluting stent is associated with an inhibition of inflammation, especially thrombus formation, suggesting that such dual-drug eluting stents have a role to play for the treatment of coronary artery disease.

Hypoxia-like effect of cobalt chromium alloy micro particles on fibroblasts in vitro.

Periprosthetic osteolysis leading to asceptic loosening remains the primary cause of failure of joint replacement. Although many inflammatory cell types have been implicated, the exact pathomechanisms of asceptic loosening have not been delineated. In the present study we have adopted a proteomic approach to elucidate the initial signals that are expressed to particulate material, using an in vitro cell culture system. Human lung fibroblasts MRC-5 were cultured with Cobalt Chromium (CoCr ASTM F-75, 1-7 µm) particles. Cells were harvested after 72 h incubation and total cellular proteins extracted for downstream analysis via 2D Gel Electrophoresis and tandem mass spectrometry using MALDI-TOF-TOF-MS. Thirteen protein spots showed greater than twofold increase, following 72 h incubation of fibroblast with CoCr particles. Four of these proteins were identified by tandem mass spectrometry. These were Annexin II, Pyruvate kinase, Triose phosphate isomerase, and N-myc downstream regulated gene 1 protein. Cobalt is a hypoxia mimicking agent and N-myc downstream regulated gene 1 protein, Triose phosphate isomerase, Pyruvate kinase, and Annexin II are important hypoxia regulated gene products that are found to be over expressed in cellular oxidative stress response. Our data indicates that exposure of fibroblast to CoCr alloy induces the transition of these cells into a hypoxia like state and oxidative stress even in normoxic culture conditions. The study reflects the possibility of the presence of a hypoxic environment in the periprosthetic tissue surrounding metallic implants.

Role of immune cells and inflammatory cytokines in regulation of fibrosis around silicone expander implants.

This study aimed to investigate the progress of wound healing around silicone expander with particular emphasis on fibroblasts, myofibroblasts and collagen in the repair phase. Semi-quantitative evaluation of inflammatory cells and their cytokines, fibroblasts and myofibroblasts at the tissue-material interface was carried out. Commercially available silicone expander was implanted in gluteus muscle of young female Wistar rats for 3, 7, 14, 30, 90 and 180 days. Ultra high molecular weight polyethylene served as control. The cellular response was studied by immunohistochemistry and Transmission Electron Microscopy. A thick collagenous fibrous capsule was observed around the silicone expander at 180 days, with persistent myofibroblasts, lymphocytes and macrophages as compared to the thin fibrous encapsulation around the UHMWPE implants. The regulatory role of cytokines and immune cells in myofibroblast persistence in tissue-implant interface around silicone expander has been extensively studied. Results of this study indicate the need to elucidate the signaling molecules in the transition of fibroblast to myofibroblast around silicone expander implants.

Effect of 980-nm diode laser and 1064-nm Nd:YAG laser on the intervertebral disc--in vitro and in vivo studies.

OBJECTIVE: Our aim was to histologically evaluate the thermal changes in bovine intervertebral discs caused by 980-nm diode and 1064-nm Nd:YAG lasers. Further aims were to standardize the technique for in vivo animal research and to study its efficacy for clinical practice. BACKGROUND: When conservative methods fail, surgery has so far been the only measure for severe back pain due to disc prolapse and herniation. Recently, the minimally invasive technique of laser disc decompression has become more popular because it has advantages over open surgery in properly selected cases. METHODS: In vitro studies were done with Nd:YAG and diode lasers (1064 and 980 nm, respectively) on bovine intervertebral discs using a bare fiber tip or a focusing lens attached to a fiber tip. These studies were followed by in vivo studies in a canine model using a Nd:YAG laser with a bare fiber tip. Autopsies were done immediately and at 3, 6, 9, and 12 mo after ablation and the histopathology of excised discs was evaluated. RESULTS: Depending upon the depth of ablation and the intensity of charring and carbonization, a standardized energy density and pulse duration were identified. CONCLUSION: Nd:YAG laser with initial delivery of 40-W laser power and a reduced power of 10-15 W thereafter, delivering a total energy density of 1500-2000 J/cm(2) using a bare fiber tip, is recommended for clinical applications.

The short-term effect on restenosis and thrombosis of a cobalt-chromium stent eluting two drugs in a porcine coronary artery model.

The aim of this article was to study the effect of dual drug-eluting stent (DES) on both restenosis and thrombosis in a porcine coronary artery model. This study reports on the use of two drugs coated on the stent to simultaneously minimize both restenosis and thrombosis. The DES was prepared by spray coating a bare metal stent with a biodegradable polymer loaded with sirolimus and triflusal, to treat against restenosis and thrombosis, respectively. The two-layered dual drug-coated stent was characterized in vitro for surface properties before and after expansion, as well as for possible delamination by cross-sectioning the stent in vitro. In vivo animal studies (in a pig model) were then performed for acute thrombosis, inflammation, and restenosis. The results show a significant reduction in restenosis with a stent coated with both drugs compared with the controls (a bare metal stent, a sirolimus-coated, and a pure polymer-coated stent). The reduction in restenosis with a sirolimus/triflusal-eluting stent is associated with an inhibition of inflammation and thrombus formation, suggesting that such dual DES have a role to play for the treatment of coronary artery diseases.

Surface-phosphorylated copolymer promotes direct bone bonding.

The bone bonding potential of surface-phosphorylated poly (2-hydroxyethyl methacrylate-co-methyl methacrylate) [poly (HEMA-co-MMA)] has been investigated and compared with commercially available poly (methyl methacrylate) bone cement (CMW1 radiopaque, Depuy; Johnson & Johnson, Blackpool, Lancashire, England, United Kingdom) as control. Poly (HEMA-co-MMA) is synthesized by free radical-initiated copolymerization and surface functionalized by phosphorylation. The X-ray photoelectron spectroscopy confirms the presence of surface-bound phosphate groups on poly (HEMA-co-MMA). The surface-phosphorylated poly (HEMA-co-MMA) promotes in vitro biomineralization, cell viability, cell adhesion, and expression of bone-specific markers such as osteocalcin and alkaline phosphatase. The bone implantation study performed in rabbits as per ISO 10993-6; 1994 (E) shows that surface-phosphorylated poly (HEMA-co-MMA) elicits bone bonding and new bone formation. New woven bone trabeculae are formed at the defect site of surface-phosphorylated poly (HEMA-co-MMA) within 1 week, while for control sample, inflammatory cells--predominantly, macrophages, fibroblasts, and fibrocytes--are present at the cortical margins around the defect. The 4 and 12 weeks postimplantation results show that the major part of the defects around the surface-phosphorylated poly (HEMA-co-MMA) implant is bridged with new woven bone, with significant remodeling (evident from resorption bays) along both the margins of the defect, but for control implants, the defects are only partially closed, with slight remodeling along the margins, but most of them are separated by fibrous tissue.

In vivo response of novel calcium phosphate-mullite composites: results up to 12 weeks of implantation.

In this paper, the in vivo response, in particular, the histocompatibility of newly developed CaP-mullite composites is reported. In the present experiments, the bioceramic implants were inserted in the long bones of healthy rabbits according to standard protocols (ISO-10993) and the tissue response was studied at different time intervals of up to 12 weeks. Ultra high-molecular weight polyethylene (UHMWPE) was used as control samples. The postimplant bone-material interfaces were analyzed by staining of histological sections, following bone tissue histopathology protocols. The interface zones were critically observed by fluorescent optical microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). Importantly, no inflammation, necrosis was observed during this tenure. New bone formation was observed at all the implantation time intervals (1-12 weeks). However, the bone integrity with the material was increased after 12 weeks of implantation. Although macrophages and fibrous tissue were present during the first week of implantation, they were not observed on histology sections after 12 weeks postimplantation. More importantly, foci of chondrocytes could be observed after 12 weeks of implantation. Remodeling of Haversian canal was observed at the interfacial area of natural bone and implant material. All the observations were assessed critically to analyze the in vivo biocompatibility of this novel composite material.

Preclinical and early clinical experience with a biodegradable polymer-based, rapamycin-eluting, Indian drug-eluting coronary stent: the BIO-RAPID study.

OBJECTIVE: To evaluate the performance of a biodegradable polymer based rapamycin-eluting coronary stent in a porcine model and demonstrate its safety and efficacy in the treatment of patients with de novo coronary stenosis. BACKGROUND: The indefinite presence of the polymer after the implantation of drug-eluting stents may initiate and sustain inflammation and contribute to the occurrence of late complications. METHODS: Seven study stents and 5 polymer-coated (control) stents were implanted in porcine carotid arteries. Histomorphometric analysis was performed 8 weeks after stent implantation. After establishing the safety of the stent in the animal model, a single-center, non-randomized study in patients with de novo coronary artery lesions was performed. Forty-nine stents were implanted in 43 patients. The 6-month clinical follow-up was 91% (39/43) and angiographic follow-up was 67% (29/43). The primary safety endpoint was the occurrence of 30-day major adverse cardiovascular events (MACE) and the principal efficacy endpoint was the 6-month angiographic late loss and binary restenosis rate. RESULTS: In the porcine model, the study stent showed acceptably low injury, inflammation and fibrin scores. There was a quantitative reduction in neointimal hyperplasia which was not statistically different from the control stent. However, in the first-in-man evaluation, there was significant suppression of intimal growth as evidenced by an angiographic late loss of 0.28 +/- 0.45 mm at 6 months. The restenosis rate was 10.3% (3/297). There was no death, stent thrombosis or myocardial infarction at 30 days or at 6 months. The 6-month target lesion revascularization rate was 3.47 percent; (1/29). CONCLUSION: This preclinical and early clinical experience demonstrates the safety and efficacy of a novel biodegradable polymer-based rapamycin-eluting coronary stent.

Evaluation of the effect of incorporation of dibutyryl cyclic adenosine monophosphate in an in situ-forming hydrogel wound dressing based on oxidized alginate and gelatin.

Cyclic adenosine monophosphate (cAMP) has long been regarded as a second messenger and a regulator of human keratinocyte proliferation. To explore more effective wound management, dibutyryl cyclic adenosine monophosphate (DBcAMP), a lipophilic analog of cAMP was incorporated into an in situ-forming hydrogel wound dressing based on periodate-oxidized alginate and gelatin. In vitro release of DBcAMP from the matrix into phosphate buffered saline was slow and increased with time. Only 50-60% of the compound was released into the medium over a period of 2 days suggestive of a sustained release into the wound bed over a period of few days. The wound-healing efficacy of the DBcAMP-incorporated dressing was evaluated on experimental full-thickness wounds in a rat model. It was found that dressing promoted wound healing leading to complete re-epithelialization of wounds within 10 days, whereas control wounds took 15 days for complete re-epithelialization. Data obtained in this study showed that the presence of DBcAMP accelerated healing and re-epithelialization of full-thickness wounds.

Characterisation and quantification of mucosal vasculature in oral submucous fibrosis.

AIM: Quantitative assessment of the mucosal vascularity in oral sub mucous fibrosis (OSF) by image analysis using OPTIMAS ver 6.0 software. The vascularity was assessed by estimating (a) the mean vascular density, (b) the mean vascular area percentage, and (c) the mean vascular luminal diameter. SUBJECT AND METHODS: Twenty (20) OSF and ten (10) age and sex matched healthy volunteers comprised the study group. The 5 microm thick H and E stained mucosal sections were examined and quantified in an image analyzer for number, size, density of vessels, and percentage of vascular area using an area morphometry tool. ANOVA is used to test equality of several means without affecting Type 1 error. RESULT: The mean vascular density is found to be more or less same in the test and control samples (F = 0.82, P>0.05). The mean vascular percentage area shows an increasing trend as the disease progresses (F = 8.63, p<0.01). The mean vascular luminal diameter also shows an increasing trend as the disease progresses (F = 34.1, p<0.001). CONCLUSION: The usual tissue reaction resultant to ischaemia / hypoxia does not seem to operate in this disease, which is preconditioned by significant stromal changes as part of the disease process. The mean vascular dilatation noted is assumed to be an adaptive response to compensate tissue ischaemia/hypoxia.

Comparative evaluation of absorbable hemostats: advantages of fibrin-based sheets.

Bioactive hemostats and wound dressings consist of either inherently active materials or act as delivery vehicles which contain such materials. Fibrin is a natural hemostat and scaffold, guiding the direction of wound contraction and closure. In order to improve the ease of application of liquid fibrin glue, we have made a freeze-dried form of polymerized fibrin that supports hemostasis and wound healing. The bleeding from the middle ear artery of rabbits was found to be arrested instantaneously on application of fibrin sheets, even when the animal was heparinized systemically. As the fibrin sheet was found to be fragile, gelatin was incorporated to the sheet and thus the mechanical stability was improved without compromising the hemostatic effect. The efficacy of the fabricated fibrin and fibrin-gelatin sheets to seal traumatized rat liver was compared with commercially available hemostats, Abgel (cross-linked gelatin) and Surgicel (cross-linked cellulose). Tissue compatibility of all the hemostats was studied by analyzing the liver tissue 15 days after application. While the hemostatic effect was best with fibrin and fibrin-gelatin sheets, both Surgicel and Abgel were not capable of arresting the bleeding quickly. Gross analysis of tissue on the 15th day of application, visibly, Abgel was not only degraded but resulted in severe adhesions of internal organs and histologically capsule formation around the implant was evident. Though Surgicel was also seen as cream soft material on the site of application that joined two pieces of liver, there was no adhesion of other internal organs and histologically, immune reaction and foreign-body-type giant cells were present in large amounts. Fibrin was not found grossly on application site whereas fibrin-gelatin was seen as a small white spot. Granulation tissue formation and cell migration into the fibrin-based sheets were evident, and therefore, fibrin-based sheets are not only efficient hemostats but showed optimum degradation and wound healing.