Hydrothermally induced nanostructured TiO2 coatings - with special reference to biologic events of peri-implant tissue integration

Soft tissue integration between the oral implant and the surrounding tissue is considered crucial for implant success. Various surface modifications have been used to obtain bioactive TiO2 coatings on the implant surface to improve osseointegration, bioactivity, and antibacterial properties. Among these methods, the hydrothermal (HT) coating technique has recently gained attention to produce anatase crystalline TiO2 coating for improved bioactivity and enhanced osteoconductivity. However, little is known about HT induced TiO2 coatings effect on the peri-implant soft tissue attachment. The objectives of this series of experimental studies were to develop new HT treatment based TiO2 coatings for titanium implants, which promotes wound healing and enhances soft tissue attachment. Another aim was to investigate the effect of UV light treatment on the bioactivity and antibacterial properties of HT induced TiO2 coatings. Hydrothermal induced TiO2 coatings were prepared by mixing titanium dioxide, purified water and tetramethylammonium hydroxide at 150 ± 10 ºC for 48 hours. The HT coatings were characterized using X-ray photoelectron spectroscopy and scanning electron microscope. The surface wettability was determined using contact angle measurements. Blood clotting ability, plasma protein adsorption, platelet adhesion, and activation, were evaluated. Human gingival fibroblast adhesion and proliferation were studied in a cell culture environment. The effect of UV light on the surface wettability, blood coagulation, and cellular response was investigated on coated and non-coated substrates. A novel tissue culture model using pig mandibular block, including alveolar bone and gingival tissues, was used to evaluate the tissue attachment on coated and non-coated titanium implants. Early biofilm formation on the coated and non¬coated titanium substrates was examined in vivo. The effect of UV light treatment on the biofilm formation was also studied. The HT treated titanium surfaces were entirely covered with coating crystals consisting of nearly spherical TiO2 nanoparticles. Higher carbon contents were observed on non-UV treated surfaces compared to UV treated surfaces, and carbon content was noticed to reduce with increasing UV exposure time. TiO2 coated substrates accelerated blood clotting and improved platelet responses compared with non-coated substrates. Coated substrates showed higher surface free energy and better wettability than non-coated ones. UV treatment enhanced the wettability and improved blood clotting of all examined surfaces. Although no differences in protein adsorption was observed. Fibroblast cell adhesion strength was significantly higher on coated substrates. Histological analysis of pig tissue explants showed epithelial, connective, and bone tissue attachment to both coated and non-coated implant surfaces. The peri-implant epithelium appeared to be in close contact with the coated surfaces. Immunohistochemical staining showed CK14 positivity in the basal cell layer of stratified gingival epithelium. TiO2 coating does not enhance salivary microbial adhesion and initial biofilm formation in vivo. The UV treatment provided titanium surfaces with antibacterial properties and showed a trend towards less biofilm formation than non-UV treated surfaces. It can be concluded that HT derived TiO2 coatings enhance biological events related to wound healing and soft tissue integration on the titanium alloy surface. The UV light treatment improved wettability, thrombogenicity and provided the titanium surfaces with antibacterial properties.Hydrotermaalisesti indusoidut nanorakenteiset TiO2 pinnoitteet–tutkimuksia peri-implanttikudosten kiinnittymiseen liittyvistä biologisista tapahtumista. Pehmytkudosten kiinnittyminen hammasimplantin pinnalle on tärkeää implanttihoidon onnistumiselle. Erilaisten pintakäsittelyiden avulla implantteihin on pyritty tuottamaan bioaktiivisia TiO2 pinnoitteita parantamaan osseointegraatiota, bioaktiivisuutta ja antimikrobisia ominaisuuksia. Näistä erityisesti hydrotermaalinen (HT) pinnoitusmenetelmä on herättänyt mielenkiintoa kiteisen anataasimuotoisen TiO2 pinnoitteen teossa paremman bioaktiivisuuden ja osteokonduktiivisuuden saavuttamiseksi. Menetelmän vaikutuksia implanttia ympäröivien pehmytkudosten kiinnittymiseen ei tunneta. Tämän väitöskirjan tutkimusten tavoitteina oli kehittää titaani implantteihin uusi HT menetelmällä valmistettu TiO2 pinnoite, joka edesauttaa haavan paranemista ja parantaa ienkudosten kiinnittymistä. Toisena tavoitteena oli tutkia UV-valo käsittelyn vaikutusta HT menetelmällä tuotettujen TiO2 pinnoitteiden bioaktiivisuuteen ja antimikrobisiin ominaisuuksiin. Hydrotermaaliset TiO2 pinnoitteet valmistettiin sekoittamalla titaanidioksidia, puhdistettua vettä ja tetrametyyliammonium hydroksidia 150 ± 10 ºC 48 tunnin ajan. HT pinnoitteet karakterisoitiin RTG-fotoelektronispektroskopiaa ja pyyhkäisyelektronimikroskopiaa käyttämällä. Pintojen kostumisominai¬suuksia tutkittiin kontaktikulmamittausta käyttäen. Veren reaktioita selvitettiin mittaamalla hyytymistä ja plasmaproteiinien kiinnittymistä sekä tutkimalla verihiutaleiden tarttumista ja morfologiaa. Ihmisen ikenen fibroblastisolujen vaste – kiinnittyminen ja jakautuminen -tutkittiin soluviljelyolosuhteissa. UV-valon vaikutus pinojen kostumiseen, veren hyytymiseen ja solujen käyttäytymiseen tutkittiin pinnoitetuilla ja pinnoittamattomilla näytteillä. Uutta kudosviljelymallia käytettiin tutkittaessa sian alaleuan blokkeihin asetettujen pinnoitettujen ja pinnoittamattomien titaani-implanttien kiinnittymistä luuhun ja implanttia ympäröivään ienkudokseen. Varhaisen biofilmin muodostumista pinnoitettuihin ja pinnoittamattomiin titaaninäytteisiin tutkittiin in vivo olosuhteissa. Lisäksi selvitettiin UV-valo käsittelyn vaikutusta biofilmin muodostumiseen. HT menetelmällä käsitellyt pinnat olivat kokonaan kiteisten lähes pyöreiden TiO2 nanopartikkeleiden peittämät. UV-valolla käsittelemättömillä pinnoilla todettiin suurempi hiilikontaminaatio UV-käsiteltyihin pintoihin verrattuna ja hiilipitoisuuden havaittiin pienenevän UV-käsittelyajan pidentyessä TiO2 pinnoite nopeutti veren hyytymistä ja paransi verihiutaleiden reaktioita pinnoittamattomiin näytteisiin verrattuna. Pinnoitettujen titaaninäytteiden vapaa pintaenergia sekä pintojen kostuminen olivat selvästi pinnoittamattomia paremmat. UV käsittely paransi pintojen kostumista ja nopeutti veren hyytymistä kaikilla pinnoilla. Proteiinin adsorboitumisessa ei kuitenkaan havaittu eroja. Fibroblastit kiinnittyivät selvästi voimakkaammin pinnoitetuille näytteille. Sian kudosnäytteillä tehty tutkimus osoitti epiteeli-, side¬ja luukudoksen kiinnittyvän hyvin sekä pinnoitettuihin että pinnoittamattomiin implantteihin. Peri¬implantti epiteeli oli läheisessä kontaktissa pinnoitettuihin pintoihin. Immunohistokemiallinen värjäys osoitti CK14 positiivisuutta stratifioidun ienepiteelin basaalisolukerroksessa. TiO2 pinnoite ei lisää syljen mikrobien kiinnittymistä tai varhaisen biofilmin muodostumista in vivo. UV-valo käsittely muutti pintoja antimikrobisiksi ja vähemmän biofilmin muodostusta suosivaksi käsittelemättömiin pintoihin verrattuna. Tulokset osoittivat, että HT menetelmällä valmistetut TiO2 pinnoitteet tehostavat haavan paranemisen biologisia tapahtumia ja pehmytkudosten kiinnittymistä titaanin pinnalle. UV-valo käsittely lisää pintojen kostumista, trombogeenisyyttä ja muuttaa pintojen ominaisuuksia antimikrobisiksi

Computational Simulation: Selected Applications In Medicine, Dentistry, And Surgery

This article presents the use of computational modelling software (e.g. ANSYS) for the purposes of simulating, evaluating and developing medical and surgical practice. We provide a summary of computational simulation mo delling that has recently been employed through effective collaborations between the medical, mathematical and engineering research communities. Here, particular attention is being paid to the modelling of medical devices as well as providing an overview o f modelling bone, artificial organs and microvascular blood flows in the machine space of a High Performance Computer (HPC)

Assessment of the survival of dental implants in irradiated jaws following treatment of oral cancer: A retrospective study

Background: In patients undergoing head and neck surgery for various pathologic conditions, implants are one of the best restorative options and are increasing widely used. Therefore, we evaluated the success of dental implants in the irradiated jaws of patients following treatment of oral cancer oral cancer treated patients. Materials and Methods: Data of oral cancer treated patients was collected retrospectively from 2002 to 2008. We took 46 oral cancer treated patients in which implants were placed in irradiated jaws for rehabilitation.Results: It was found that out of 162 dental implants placed, 52 failed. Furthermore, there was no variation in the implant survival rate in between both the jaws.  Radiation dose of <50 Gy units also showed significantly increased amount of implant survival rate.Conclusions: Implant survival is multifactorial and depends upon a number of factors like level of radiation exposure in that area, time gap between last radiation doses etc., Further research is required in this field to improve the esthetics and quality of life of cancer treated patients.Keywords: Cancer, dental implants, radiation therap

Análisis del comportamiento bioregulatorio de la cicatrización ósea en alvéolo humano pos-exodoncia y con implante inmediato

Introducción: Varios estudios in vitro, in vivo, en animales y en humanos esclarecen los procesos de cicatrización ósea en alvéolos pos-exodoncia con y sin colocación implantes, sin embargo, estos tienen que analizarse con mucha cautela por la dificultad de extrapolación a situaciones reales. Es por esto que actualmente se proponen modelos matemáticos por simulación computacional, con el fin de reunir los datos obtenidos de estudios previos e interrelacionarlos para generar un punto de vista global de la cicatrización ósea sin los posibles sesgos y problemas éticos del estudio en humanos. Objetivo: Esclarecer cuál es la mejor condición clínica para colocar un implante pos-exodoncia a partir del análisis de modelos bio-regulatorios de alvéolos pos-exodoncia y con implante inmediato. Materiales y métodos: Estudio observacional–analítico, donde se realizaron modelos conceptuales a partir de la búsqueda de literatura en bases de datos como Pubmed, Science Direct, Wiley, Springerlink, Embase, Scielo y el análisis de los modelos bioregulatorios de la cicatrización espontánea del alvéolo pos-exodoncia y la cicatrización ósea del alvéolo pos-exodoncia con colocación de implante inmediato. Resultados: Se encontraron 12.897 artículos, de los cuales se eligieron 89 artículos con los que se elaboraron los modelos conceptuales, encontrando que inmediatamente luego de la extracción el alvéolo se llena de sangre para formar el coágulo que luego es reemplazado por tejido de granulación. A la primera semana comienza una deposición de tejido mineralizado, después de 2 a 4 semanas se pueden observar eritrocitos dispersos entre células mesenquimales. Entre las semanas 6 a la 8 la mayoría del tejido es reemplazado por matriz provisional y hueso inmaduro. La organización del hueso y su arquitectura a menudo no es completa a las 24 semanas después de la extracción del diente. La cicatrización del alvéolo pos-extracción alrededor de implantes inmediatos es influenciada por varios factores, incluyendo el protocolo quirúrgico adoptado, la morfología, dimensiones del alvéolo y las características del implante. Después de la colocación de implantes rápidamente se forma hueso nuevo y relativamente inmaduro, este hueso es luego reemplazado por un hueso más fuerte y complejo a lo largo de la interfase. Conclusiones: Se esclareció a partir de los modelos bioregulatorios que los procesos biológicos son exitosos en condiciones muy específicas de salud, si estas condiciones no se cumplen es mejor posponer la implantación hasta que se haya dado la cicatrización correcta, ya sea por medio de injertos de tejidos duros o blandos.Abstract. Introduction: Several studies in vitro, in vivo, in animals and in humans have showed the processes of bone healing in alveolar post-extraction with and without implants placement, however, these must be analyzed with caution because of the difficulty of extrapolating to real situations. Mathematical models is currently proposed by computer simulation in order to gather data from previous studies and interrelate to generate a global view of the bone healing without potential biases and ethical problems of human study. Objective: To clarify what is the best clinical condition to place a post-extraction implant from the analysis of bioregulatory models of cells post-tooth extraction with immediate implant. Materials and Methods: Observational-analytic study where conceptual models were made from the literature search in databases such as PubMed, Science Direct, Wiley, SpringerLink, Embase, Scielo and analysis of bioregulatory models of spontaneous healing postextraction socket and alveolar bone healing of post-tooth extraction with immediate implant placement. Results: 12,897 articles were found, of which 89 items were chosen to developed conceptual models, finding that immediately after extraction, the socket was filled with blood to form a clot, which is then replaced by granulation tissue. In the first week begins deposition of mineralized tissue, after 2 to 4 weeks scattered erythrocytes could be observed between mesenchymal cells. Between weeks 6 through 8 most tissue was replaced by provisional matrix and immature bone. Bone organization and architecture are not complete at 24 weeks after tooth extraction. Several factors were influenced the healing of post-extraction socket around immediate implants, including surgical protocol adopted, morphology, dimensions of the socket and characteristics of the implant. After implant placement is quickly formed new and immature bone, then it was replaced by stronger complex along the interface. Conclusions: It is clarify from the bioregulatory models that, biological processes are successful in very specific health conditions, is better to postpone implementation if these conditions are not found until it has given proper healing, either by grafting hard tissue or soft.Otr

Titania nanotube arrays: interfaces for implantable devices

2012 Spring.Includes bibliographical references.For the 8-10% of Americans (20-25 million people) that have implanted biomedical devices, biomaterial failure and the need for revision surgery are critical concerns. The major causes for failure in implantable biomedical devices promoting a need for re- implantation and revision surgery include thrombosis, post-operative infection, immune driven fibrosis and biomechanical failure. The successful integration of long-term implantable devices is highly dependent on the early events of tissue/biomaterial interaction, promoting either implant rejection or a wound healing response (extracellular matrix production and vasculature). Favorable interactions between the implant surface and the respective tissue are critical for the long-term success of any implantable device. Recent studies have shown that material surfaces which mimic the natural physiological hierarchy of in vivo tissue may provide a possible solution for enhancing biomaterial integration, thus preventing infection and biomaterial rejection. Titania nanotube arrays, fabricated using a simple anodization technique, provide a template capable of promoting altered cellular functionality at a hierarchy similar to that of natural tissue. This work focuses on the fabrication of immobilized, vertically oriented and highly uniform titania nanotube arrays to determine how this specific nano-architecture affects skin cell functionality, hemocompatibility, thrombogenicity and the immune response. The results in this work identify enhanced dermal matrix production, altered hemocompatibility, reduced thrombogenicity and a deterred immune response on titania nanotube arrays. This evidences promising implications with respect to the use of titania nanotube arrays as beneficial interfaces for the successful implantation of biomedical devices

The effect of platelet rich fibrin (PRF) on inter-proximal papillary height around dental implants

The original study design called for twenty patients. Fourteen patients with 13 implants have thus far been recruited for a prospective proof of principle study to assess the effect of addition of Platelet Rich Fibrin (PRF) on interproximal papillary height (I.P.H.) at the restorative line angles when used during the second stage uncovering procedure for dental implants. The secondary objective of this study was to assess the effect on the height of the direct interproximal tissue thickness (I.T.T.) at 6 weeks following uncovering. Implants placed 3 or more months prior at Boston University School of Dental Medicine Periodontics Department were scheduled to be uncovered by the principal investigator. Second stage uncovering was performed with a conventional mid-crestal incision to place standard healing abutments. PRF membrane(s) were inserted around the implants before flap closure in an attempt to augment or thicken the interproximal papillary area. The I.P.H. was measured at the four line angles of each abutment at the highest aspect of the interproximal tissue immediately following the uncovering procedure and at 2, 4 & 6 week intervals. I.T.T. was also measured prior to surgical exposure and at 6 weeks following the uncovering procedure. Results: The use of PRF membranes around dental implants did not significantly improve I.P.H. However, a positive correlation was observed between the use of P.R.F and I.T.T. Further studies are warranted to assess the effect of PRF on the peri-implant papillary tissue