Post surgical adhesions (PSAs) are an inevitable outcome of surgery and their presence leads to pathogeneses and significant economic impact. The studies within this thesis utilised standard and reproducible abrasion models, in rabbits, pigs and rats, to investigate the formation and maturation of PSAs with strict quantitative analyses. These studies have shown that the development of PSAs is a series of complex, multi-factorial processes. PSA development can be classified into two stages: (i) PSA modelling occurring up to/including 16 hours post injury characterised by the inflammatory response and fibrin deposition and maturation; and (ii) PSA remodelling occurring from 16 hours onwards and characterised by tissue repair, collagen deposition and maturation and chemical mediation by TGF-P. Treatment with VivostatTM System Derived (novel) Fibrin Sealant significantly reduced the formation of PSAs with mean PSA reduction of 80% for the rabbit uterine horn abrasion model, from 3 separate studies; 83% for the pig stomach/colon/caecum abrasion model, from 2 separate studies; 80% for the rat caecum abrasion model. This is significantly better than other fibrin sealants investigated in this thesis. PSA prevention with novel fibrin sealant demonstrated a similar pattern to PSA development, with two stages of development evident: (i) tissue generation modelling occurring up to/including 16 hours post injury characterised by the inflammatory response and fibrin deposition and maturation; and (ii) tissue generation remodelling occurring from 16 hours onwards and characterised by tissue repair, collagen deposition and maturation and chemical mediation by TGF-P. However the extent and subsequent time taken for these changes to occur was significantly reduced. The prevention of PSAs and alterations of wound healing by novel fibrin sealant is most probably due to the sealant acting as a haemostat, as well as a physical barrier. Thus preventing fibrinous and subsequent fibrous PSA formation.

Orientadores: Regina Maria Puppin Rontani, Mario Fernando de Goes / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-07-24T01:23:45Z (GMT). No. of bitstreams: 1 Sousa_MariadeFatimaAlvesde_M.pdf: 3394004 bytes, checksum: eb6d811292eb170c25158510f6fe88e1 (MD5) Previous issue date: 1998 / Resumo: A efetividade e sucesso clínico dos sei antes dependem da sua retenção na superfície oclusal. Este estudo avaliou a penetração do selante FluroShield (Dentsply) e do compômero Compoglass (Vivadent) e a infiltração do corante fucsina básica na interface esmalte/material. Foram selecionados 64 pré-molares hígidos, distribuídos em 8 grupos, dos quais 4 foram submetidos à técnica convencional (TC) e os outros à técnica Invasiva (TI). Os tratamentos realizados foram: grupo 1- TC e aplicação do Compoglass; grupo 2- TI e aplicação do Compoglass; grupo 3- TC, agente adesivo SCA e Compoglass; grupo 4- TI, agente adesivo SCA e Compoglass; grupo 5- TC e aplicação do FluroShield; grupo 6- TI e aplicação do FluroShield; grupo 7- TC, primer/adesivo PSA e FluroShield; grupo 8- TI, primer/adesivo PSA e FluroShield. Em seguida, os dentes foram submetidos a 500 ciclos térmicos, em banhos alternados de 5 o e 60°c e a seguir imersos em uma solução de fucsina básica a 0,5% por 24 horas. Os dentes foram seccionados no sentido vestíbulo-lingual, polidos e as superfícies observadas em um microscópio óptico, sendo as imagens processadas em um computador através do software (Diracom3). Os valores dos percentuais de penetração dos materiais foram submetidos à análise de variância e ao teste de Tukey (p< 0,05). O material Compoglass aplicado pela técnica convencional, sem o uso de adesivo apresentou média de penetração inferior aos demais tratamentos, sendo a diferença entre as médias estatisticamente significativa. O material FluroShield apresentou médias de penetração semelhantes quando aplicado por ambas as técnicas convencional e invasiva, com ou sem a prévia aplicação de adesivo (p>0,05). A ocorrência de infiltração para as amostras tratadas com Compoglass sem adesivo foi estatisticamente superior ao mesmo material aplicado com adesivo pelo Teste exato de Fisher (p<0,05). Entre as técnicas convencional e invasiva não houve diferenças estatisticamente significativas ao nível de 5%, na ocorrência de infiltração, tanto para Compoglass quanto para FluroShield, pelo teste exato de Fisher. FluroShield aplicado sem adesivo apresentou os menores percentuais de amostras com infiltração quando comparado com o mesmo material associado ao uso de adesivo. Conclui-se que, os maiores percentuais de penetração e os menores percentuais de infiltração foram encontrados para o material FluroShield aplicado sem o adesivo. Para o material Compoglass os maiores percentuais de penetração e menores percentuais de infiltração foram encontrados quando associado ao emprego de adesivo / Abstract: The sealants effectiveness and clinical success depend on retention and reduction of the occlusal caries. This study evaluated the penetration and the microleakage of the FluroShield Sealant (Dentsply) and the Compoglass compomer (Vivadent). Sixty-four premolars, noncarious were used and they were divided into eight groups. Four groups were submitted to Enameloplasty Sealant Technique (EST) and the other one to Conventional Sealant Technique (CST). The group 1: CST and applied Compoglass; group 2: EST and applied Compoglass; group 3: CST, primer SCA and Compoglass; group 4: EST, primer SCA and Compoglass; group 5: CST and applied FluroShield; group 6: EST and applied and Fluroshield; group 7: CST, primer PSA and FluroShield; grupo 8: EST, primer PSA and FluroShield. After that, the teeth were termocycled 500x at temperature 5° and 60°C, and imersed in a 0.5% solution basic fuchsin dye for 24 hours. The teeth were sectioned in a bucal-lingual direction, and they were polished. The surfaces were evaluated on the optical microscope. The images were captured into the computer (Diracom3 System). The percentage data of the penetration of both materiais were submitted to variance analyses and Tukey's Test (p<0.05). The penetration data from the Compoglass samples with no adhesive used by the conventional sealant technique were significantly lower than the other groups (p<0.05). The penetration means those were obtained with the use of FluroShield for both techniques, conventional and invasive, did not show significant differences statistically (p>0.05). Compoglass applied without adhesive showed more leakage percentages than the same material applied with adhesive. FluroShield no adhesive showed lower leakage percentages than the same material used with adhesive. FluroShield used no adhesive and Compoglass used with adhesive provided the highest percentage of penetration and the lowest leakage / Mestrado / Materiais Dentarios / Mestre em Odontologia

The need to close wounds and prevent air/liquid leakage is commonly faced in surgical operations. It is a necessary step required for proper post-operative tissue function and healing. In the past, sutures and staples have been used to carry out this function; however, these different methods each come with limitations based on material and application. Recent studies have shown sealant glues to be a new method with much promise in connecting tissues. Several commercially available products have shown biocompatibility, along with ease of application and strong adherence; however, these come with their own set of limitations. In this project I present a novel tissue adhering substance made from human protein elastin. This protein sealant will allow us to address several issues in tissue-engineered materials such as biocompatibility, cytotoxicity, adhesion strength, binding in wet environment and elasticity. Using recombinant technology, we have been able to purify this protein monomer and form glue-like hydrogels using a cross-linker and UV light activator. This sealant was tested in in vitro models and porcine ex vivo lung model. The results indicate an increased adherence to the tissue as well as a high elasticity allowing the sealant to move more naturally with the tissue. Further testing in large animal in vivo studies will be performed to show safety and efficacy before being implemented into clinical practice.

Fibrinogen concentrates are used widely as a sealant during and after surgery to reduce blood loss. Commercially available fibrin sealants are made from pooled human blood, which carries the risk of blood-borne diseases, and are expensive. These concerns have brought to focus the need for autologous fibrinogen concentrates. This need has been addressed by utilizing a unique approach in which fibrinogen is precipitated from plasma with protamine. The physical properties of fibrin sealant prepared from fibrinogen precipitated with protamine were evaluated. The optimal precipitation conditions included a plasma protamine concentration of 10 mg/mL at room temperature. Under these conditions 96% ± 4% of the fibrinogen present in the plasma was precipitated and 98% ± 0.9% of the precipitated fibrinogen was clottable. In addition, it was shown that almost 50% of the factor XIII in the plasma was also precipitated along with the fibrinogen. The tensile and adhesion strengths and kinetics of fibrin sealant prepared from protamine-fibrinogen concentrate were evaluated. Tensile strength and adhesion strength both increased with increasing fibrinogen concentration. Addition of calcium chloride significantly increased the tensile and adhesion strengths. The addition of aprotinin and ε-aminocaproic acid (used to inhibit natural fibrinolysis) to the fibrinogen concentrate was shown to have no effect on the mechanical properties of the sealant. Kinetic experiments showed that the clotting time decreased as the thrombin and fibrinogen concentrations were increased. A rat model with controlled renal incisions was employed to evaluate the hemostatic efficacy of the fibrin sealant made from the protamine-fibrinogen concentrate. The fibrin sealant significantly reduced the blood loss and bleeding time when compared with controls (no sealant, plasma, and a commercial product). The sealant also significantly reduced blood loss and bleeding time in rats that were anticoagulated with heparin. A mathematical model based on tensile strength and adhesion strength was developed to predict the bleeding time in the animal wound. Model predictions showed that the ability of the fibrin sealant to reduce bleeding time, and therefore blood loss, was limited by the adhesion strength.

No description available.

Syftet med denna studie var att kartlägga retentionen av resinbaserade fissurförseglingar på sexårsmolarer utförda på studentklinik. Karies registrerades även på övriga sexårsmolarer. Materialet utgjordes av 51 barn födda år 1999 eller 2000 med minst en fissurförsegling på sexårsmolaren utförd av tandläkarstudent. Fissurförseglingen skulle vara utförd i Delton® och ha en minsta uppföljningstid på ett år. Data registrerades från journaler avseende allmänhälsa, medicinering, kariesdata och riskgrupp. Vid den kliniska undersökningen registrerades sexårsmolarernas status avseende karies och retention av utförda fissurförseglingar (Simonsen´s index). De kliniska bedömningarna visade att 31,5 % av fissurförseglingarna var fullt retinerade och 50,0 % var partiellt retinerade, i 7,8 % av fallen saknades fissurförseglingen och 10,7 % av de förseglade tänderna hade fått karies eller en fyllning. Reförsegling hade skett i 41 % av fallen. Fullständig retention sågs i högre grad på överkäksmolarernas fissurförseglingar jämfört med underkäksmolarernas. Studien visar alltså att mer än två tredjedelar av fissurförseglingarna inte var fullständigt retinerade. Enligt tidigare studier krävs en fissurförsegling med fullständig retention för att det kariesförebyggande skyddet ska vara optimalt. Därmed bör samtliga bristfälliga fissurförseglingar, där denna preventiva behandling fortfarande är indicerad, kompletteras/revideras så att full retention uppnås. / The aim of this study was to study the retention of resin-based fissure sealants on first permanents molars performed in a student clinic. In addition the presence of caries on the first permanent molars was registered. The sample consisted of 51 children born 1999 or 2000 with at least one fissure sealant on the first permanent molar made by a dental student. The material was Delton® and the sealants had to be at least one year old from the first application. Data were registered from the dental patients’ records concerned general health, medications, caries data and risk assessment. Clinical evaluation of the condition of the first molars and the retention of the sealants (by Simonsen´s index) was made. The clinical evaluation showed that 31.5 % of all sealants had complete retention, 50.0 % had partial retention, in 7.8 % the sealants were missing and 10.7 % of the previously sealed teeth had caries or a filling. 41 % of the sealants had been resealed at least once. The sealants on the upper first permanent molars showed a higher rate of complete retention compared to the sealants on the lower first permanent molars. This study shows that more than two thirds of the fissure sealants were not completely retained. According to other studies a fissure sealant has to be completely retained to give a good protection. Consequently, all defect fissure sealants, where this preventive treatment still is indicated, should be completed/modified until the sealants have complete retention.

Lung diseases, cancers, and trauma can result in injury to the connective tissue lining the lung, i.e., the pleura. Pleural injuries lead to pneumothoraxes or pleural effusions, i.e., air or fluid leaking out of the lung respectively, and potential lung collapse - an immediately life threatening condition. While several bioengineered soft tissue sealants exist on the market, there is only one sealant FDA-approved for use in pulmonary surgery. In addition, very limited techniques are presented in the literature for characterizing the burst properties of hydrogel tissue sealants. For my thesis, I proposed to develop a protocol for characterizing the burst properties of hydrogel sealants using a novel burst pressure test chamber. I further proposed a novel combination of oxidation and methacrylation reactions of alginate for tissue sealant applications, with a particular focus on developing a pulmonary sealant. The proposed research objectives are: 1) To develop protocol for testing hydrogel sealants for soft tissue applications; 2) To verify alginate as a potential for tissue sealant applications; and 3) To optimize an alginate hydrogel sealant and perform ex vivo analysis for a pleural sealant application. Alginate materials with varying degrees of oxidation and methacrylation were synthesized and characterized. Oscillatory rheometry was used to characterize material properties such as viscosity, hydrogel gelation kinetics, and complex moduli. Burst pressure measurements properties and failure mechanisms, i.e. delamination or material failure, were collected for a liquid and dry-state application. Preliminary ex vivo mouse lung model testing demonstrated that methacrylated alginate hydrogels are able to withstand physiological pressures associated with breathing, and failure occurs within the hydrogel for adhesive alginate-based tissue sealants.

Magister Scientiae Dentium - MSc(Dent) / BACKGROUND: The application of dental sealants is a recommended procedure to prevent and control dental caries. However, despite strong evidence for the safety and effectiveness of dental sealants, their use still remains low, especially among children from lower socioeconomic communities. The World Health Organization (WHO), Centres for Disease Control and Prevention (CDC) and the Association of State and Territorial Dental Directors (ASTDD) strongly endorse the implementation of school based dental sealant programmes as a community-based preventive strategy to increase sealant use and reduce dental caries. However, in the WHO African Region, oral health is seen as a very low priority and this is compounded by limited technical and managerial resources. The availability of human resources and equipment are crucial for the successful placement of dental sealants. A gap in the research literature was identified for determining the effectiveness of fissure sealants placed under field conditions. AIM: To evaluate the caries preventive effect as well as retention status of a resin-based fissure sealant that was placed under field conditions as part of a school based sealant programme. METHODOLOGY: A cross-sectional comparative study was conducted at two primary schools in close proximity of each other in the same low socio-economic area in Beaufort West, South Africa. The study population consisted of grade two children between the ages of 7-9 years who had fully erupted first permanent molar teeth. The case group consisted of 100 learners who received dental sealants on caries-free first permanent molar teeth 12 months earlier. The control group consisted of a random selection of the same number of learners from the adjacent school. Dental caries on the occlusal surfaces of the first permanent molar teeth was detected by making use of the decayed (D) portion of the decayed, missing and filled tooth (DMFT) score, while a separate diagnosis distinguished between cavitated and non-cavitated lesions. Sealant retention was determined by a calibrated examiner who was not involved in the placement of the sealants. RESULTS: The response rate of the study was 80.0% (n=100) and 78.9% (n=356) of the fissure sealants that were originally placed were evaluated. When the sealants were placed in 2013, 52.0% of the children were female and at the 12 month follow-up, 51.3% were female. The average age of the female children at follow-up was 8 years and 4 months (99.9 months) and 8 years and 5 months (101.8 months) for the males. The standard deviation of the gender profiles differed by 1 month only and implies an equal distribution of age between female and male children throughout the study. Just less than ten per cent (7.8%) of the sealants were fully intact at the 12 month follow-up examination and 91% were totally lost, which is a higher sealant loss rate than what is generally reported on in the literature. Of the 7.8% fully retained sealants, a statistically significant proportion (p=0.044) were found on the mandibular molar teeth. The caries incidence rate in the sealed group was 7.1% versus 9.1% in the control group. Relative risk (RR) calculations was slightly lower for the sealed (RR=0.79) than the unsealed (RR=1.02) teeth. CONCLUSION: The study showed a 2% lower caries prevalence rate on the occlusal surfaces of the sealed versus the unsealed teeth. However, this does not represent a statistically significant finding (P=0.39). The study also showed a low retention rate for the resin-based sealants placed under field conditions (12 month retention rate of 7.8%). The results from this study has therefore shown that resin-based fissure sealants placed on grade 1 learners under field conditions appear to be not ideal in preventing the onset of dental caries on the occlusal surfaces of the first permanent molar teeth.

Låglutande tak har alltid varit utpekade som en riskfylld konstruktion med många följande problem. Speciellt utpekade nationellt är de i nordligare breddgrader och fjällmiljöer. Konstruktionen är väldigt hårt ansatt av väder och vind och många byggnader får vattenskador till följd av läckage. Trots alla rapporterade problem med det låglutande taket i fjällmiljö så fortsätter dessa att byggas kontinuerligt. Studien har som syfte att analysera branschverksammas perspektiv på konstruktionstypen, dess problem och hur de arbetar för att skapa så goda förutsättningar som möjligt. En kvalitativ metod användes genom semistrukturerade intervjuer som sedan sammanställdes och kodades. Intervjuerna var riktade mot yrkesverksamma inom den utförande parten av takets konstruktion. Resultatet kunde identifiera problemfaktorer till olika delar inom takets livscykel. Tidigt som utformningsfel eller utförande fel och i ett senare skede som underhållsfel. Skador uppkomna i tätskiktet är vad som utpekas där läckage är följden. Dock har studien inte kunnat påvisa under vilken fas av takets livscykel som bidrar mest till uppkomna problem. Under samtliga kategorier har tidsbrist och kompetensbrist styrkts som de mest bidragande faktorerna till skadeproblematiken. / Low pitching roof systems has always been seen as a construction method full of risk. The design of the roof makes it vulnerable for winds and snow and could therefore be considered not suited for mountainous environments. Many of these roofs end up with water damages as a result from leakage trough the outermost layer of the roof. Despite all known problem factors with this type of construction they are continuously being built. The purpose of this study has been to analyze the perspectives from professionals in the Swedish building sector. How the experienced field think of the problems regarding the construction method and how they work around them. A qualitative method has been used to answer the studies purpose by using semi-structured interviews that were compiled and coded. In the results of these interviews, it was found that the problems could be coded in three categories throughout the roofs life cycle. Early in the life cycle as design flaws and poorly executed assembly and later with faulty maintenance. In all these categories lack of time and competent personnel is seen as leading causes to the problems. / <p>2023-06-23</p>

Widespread use of solid oxide fuel cells is hindered by a lack of long-term durability of seals between metallic and ceramic components caused by thermal expansion mismatch induced cracking. A novel gas seal design incorporating an engineered thermal expansion gradient in a SrO-La₂O₃-A₂O₃-B₂O₃-SiO₂ glass matrix with a TiNiHf shape memory alloy mesh for active stress relief and crack healing is being developed. Coefficient of thermal expansion (CTE) measurements of the seal and fuel cell components shows the possibility for a thermal expansion gradient. Differential scanning calorimetry and microscopy have shown that the TiNiHf alloy has a shape memory transition in the desired range of 200-250ºC. The oxide glass partially crystallizes during thermal cycling which has been observed through X-ray diffraction and dilatometry. The CTE decreases from 9.3Ã 10-6/°C to 6.6Ã 10-6/°C after thermal cycling. Neutron diffraction data from TiNiHf /glass composite samples reveals that the TiNiHf alloy has the ability of absorbing residual stresses from a glass matrix during martensitic phase transition. There is evidence from microscopy that the glass composition is important in determining if reaction will occur with the TiNiHf alloy. The TiNiHf alloy mesh structures can be created using the 3D printing process. This process has been adapted to allow for printing of very thin wire mesh structures of Ni and NiTi powders with a more suitable binder solution. A bi-layer test fixture has been developed which will be useful for assessing leak rate through seal materials. / Master of Science