Projeto de detalhe e desenvolvimento de um novo dispositivo médico auxiliar para extração de dentes e raízes

Dissertação de mestrado integrado em Engenharia BiomédicaEste trabalho tem como principal objetivo projetar e construir um protótipo de um novo dispositivo que permita auxiliar o médico dentista na extração de dentes humanos. Este protótipo pretende levar ao desenvolvimento de um dispositivo útil, simples, eficiente, de fácil adaptação e capaz de melhorar a extração dentária através do recurso à vibração. O projeto é constituído por diferentes fases. Numa primeira fase, apresenta-se uma descrição dos instrumentos atualmente utilizados e a sua aplicação nas diversas etapas do processo de extração. Segue-se um estudo preliminar ao fabrico e construção dos protótipos. Aqui são abordados os materiais e os processos envolvidos na construção e o sistema de vibração utilizado. Numa fase final, é apresentada, detalhadamente, a construção de um primeiro protótipo e as otimizações e ações que foram surgindo até à construção e experimentação do segundo prototótipo. Decorrentes do trabalho desenvolvido resultaram dois protótipos: o boticão vibratório e a alavanca vibratória. Comparativamente, a alavanca vibratória apresenta um melhor desempenho que o boticão vibratório. A alavanca vibratória será utilizada na luxação, fase muito importante da exodontia. Esta alavanca procurará diminuir os esforços realizados e ainda reduzir a sensação de “pressão” sentida durante e após a extração, bem como, evitar os possíveis danos nos dentes adjacentes. O boticão vibratório será utilizado, posteriormente, na extração dos dentes procurando diminuir o esforço realizado nos últimos movimentos. No que diz respeito à utilização da vibração, não há ainda dados experimentais que permitam avaliar a influência (facilitadora) da vibração no rompimento dos ligamentos periodontais e, portanto, no processo de extração. Todavia, espera-se que uma possível utilização conjunta melhore o processo de extração, dependendo do tipo de dente ou raiz a extrair.This work´s main goal was to design and construct a prototype for a new medical device to assist dentists during the dental extraction. This prototype aims to lead to the development of a useful device, simple, efficient, easy to adapt and able to improve the dental extraction through the vibration. This project is structured in different sections. In first section is presented the description of the currently instruments used and their use in several steps of the extraction process. Following is a preliminary study about manufature and construction of a prototype, which includes the materials and processes involved in this construction and the vibration system used. In the final section, is presented, in detail, the construction of a first prototype and the optimizations that were developed until the construction and testing of the second prototype. Arising from work emerged two prototypes: vibration fórcep and vibration luxator. The vibration luxator presents better results than vibration fórcep. The vibration luxator will be used in the luxation, very important phase in the process of extraction. This luxator will try to decrease the forces and reduce the sensation of pressure felt during and after of the extraction process, as well as, avoid the possible risk of damage to adjacent teeth. The vibration fórcep will be used later in the extraction of the teeth trying to reduce the efforts in last movements. There aren´t still experimental results to evaluate the positive influence of vibration on disruptions periodontal ligaments. However, it is expected that a combined use of the two prototypes cans improve the extraction process, depending on the type of tooth or root to extract

Customized root-analogue implants: a review on outcomes from clinical trials and case reports

(1) It is estimated that 10% of the world’s population will need a dental implant in their lifetime. Despite all the advances in the comprehension of dental implant designs, materials and techniques, traditional implants still have many limitations. Customized root-analogue implants are, therefore, gaining increased interest in dental rehabilitation and are expected to not only preserve more hard and soft tissues but also avoid a second surgery and improve patient overall satisfaction. In this sense, the aim of this review was to collect and analyse the clinical trials and case reports on customized root-analogue implants available in the literature; (2) This review was carried out according to the PRISMA Statement. An electronic database search was performed using five databases: PubMed, Google Scholar, Medline, Science Direct, and Scopus. The following keywords were used for gathering data: custom-made, dental implants, root-analogue, anatomical, customized and tooth-like; (3) 15 articles meeting the inclusion criteria—articles reporting clinical trials, case reports or animal studies and articles with root-analogue implants and articles with totally customized implant geometries—were selected for the qualitative synthesis. The design and manufacturing techniques, implant material and surface treatments were assessed and discussed; (4) The performance of some root-analogue implants with specific features (i.e., macro-retentions) was successful, with no signs of infection, periodontitis nor bleeding during the follow-up periods.This work was supported by FCT-Portugal through the grant PD/BD/140202/2018, and the projects POCI-01-0145-FEDER-030498-FunImp and UID/EEA/04436/2019

Tribological behavior of TiO2 PEEK composite and stainless steel for pediatric crowns

Dental decay still presents a major health problem among children. Its treatment usually requires the use of stainless steel crowns. This study compares the wear behavior of 316 L stainless steel and polyetheretherketone (PEEK) composite under identical test conditions. The wear tests were conducted in a reciprocating ball-on-plate tribometer (Plint TE67/R) using alumina balls as a counterface and artificial saliva as a lubricant at 37 °C to faithfully mimic oral conditions. The coefficient of friction (COF) and specific wear rate (k) values were determined and SEM/EDS examinations were performed to identify the predominant wear mechanisms. Results showed that PEEK exhibited a significantly lower coefficient of friction (COF = 0.094 ± 0.004) and thus lower wear volume (ΔV = 0.0078 ± 0.0125 mm3) and higher wear resistance, with an average value of specific wear rate of k = 9.07 × 10−6 mm3N−1m−1 when compared to stainless steel (COF = 0.32 ± 0.03, ΔV = 0.0125 ± 0.0029 mm3, k = 1.45 × 10−5 mm3N−1m−1). PEEK was revealed to be a potential material for use in pediatric crowns due to its high wear resistance while overcoming the disadvantages associated with steel at both an aesthetic and biological level.This research was funded by FCT (Fundação para a Ciência e a Tecnologia) through projects UIDB/04436/2020, UIDP/04436/2020, and UIDB/00285/2020

Improving the interface between orthopaedic implants and bone - a comparison between different surface treatments

Apresentação efetuada em "Junior Euromat 2022", em Coimbra, 2022Orthopedic implants for load-bearing applications are usually composed of titanium-based materials. However, insufficient bioactivity of metallic materials impairs the bonding with bone, compromising osseointegration at an early stage. The implant-bone interface may be improved by regulating some surface properties of the biomaterials, including surface chemical composition, surface energy, roughness and topography, which influence the behavior of bone cells. In the present study, commercially pure titanium and Ti6Al4V alloy were used to investigate the effect of three surface treatments, after performing two different chemical pre-treatments, on the characteristics of the obtained oxide films. Regarding the pre-treatments, no major differences were observed between performing alcohol cleaning or acidic pre-treatment, considering the surface crystallinity, roughness and wettability. However, the TiO2 layer formed upon anodic oxidation, hydrothermal treatment and anodic oxidation followed by hydrothermal treatment presented different characteristics regarding its crystallinity, roughness, thickness and wettability. This study compared specific surface treatments and the hydrothermal treatment is proposed as a simple treatment capable of improving the characteristics of the implant surface, thereby promoting osteoconductivity. In fact, the culture of human Mesenchymal Stem Cells on Ti-based materials subjected to hydrothermal treatment and consequent induction of osteogenic differentiation confirm the improved surface characteristics.This work was supported by FCT (Fundação para a Ciência e a Tecnologia) through the grant SFRH/BD/141056/2018 and the projects PTDC/EME-EME/1442/2020, POCI-01-0145-FEDER-030498, UIDB/04436/2019 and UIDP/04436/2020. In addition, this work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020, financed by national funds through the FCT/MEC (PIDDAC)

Human gingival fibroblast and osteoblast behavior on groove-milled zirconia implant surfaces

Two type of cells representing periodontal hard tissues (osteoblasts) and soft tissues (fibroblasts) were evaluated in response to microgroove-milled zirconia surfaces. A total of 90 zirconia discs were randomly assigned to four width-standardized milling microgroove-textured groups and a control group without grooves (UT). The sandblast and acid-etch protocol were applied to all samples. Both cell lines were cultured on zirconia discs from 1 day up to 14 days. Cell morphology and adhesion were evaluated after 1 day of culturing. Cell viability and proliferation of the cells were measured. Alkaline phosphatase activity, collagen I, osteopontin, interleukin 1β and interleukin 8 secretions were assessed at predefined times. The results obtained were presented in the form of bar graphs as means and standard deviations. Multi comparisons between groups were evaluated using two-away ANOVA or Mann–Whitney tests, and a p-value < 0.05 was established. Group comparisons with regard to cell viability, proliferation and secretion of collagen I, interleukin-1β and interleukin 8 revealed no statistically significant differences. The alkaline phosphatase activity and osteopontin secretion were significantly higher in the group with a large groove compared to the small one and the control group. Nevertheless, the viability of gingival and bone cells did not appear to be affected by the milled microgroove texture compared to the conventional sandblasted and acid-etched texture, but they seem to influence osteoblasts’ cellular differentiation.This research was supported by FCT project POCI-01-0145-FEDER-030498—Portugal, by FEDER funds through the COMPETE 2020—Programa Operacional Competitividade e Internacionalização (POCI) and ImpHib–Development of advanced Hybrid Implants—NORTE-01-0247- FEDER-034074

Optimization of zirconia surface textured designs using Nd:Yag laser for biomedical applications

The development of surface textured designs has influence in primary stability of surgically placed implants since a textured surface allows to firmer mechanical link to the surrounding tissue. Laser technology has been investigated to develop new surface designs on green zirconia compacts by cold pressing. Nd:Yag laser were used to produce several strategies and different laser parameters (laser power, speed and laser passages) were tested to evaluate their impact on cavities geometry and depth. The surface texture designs were analysed by Scanning Electron Microscopy (SEM) and regular geometries such as cavities or pillars were observed. The distance between lines have a strong impact on texturing quality and should be combined with optimum power and speed conditions. Regarding the optimized conditions, several surface textured patterns were created in both green and sintered zirconia compacts. This study allowed to conclude that only some texturing strategies are suitable to obtain high quality surface textured patterns. Otherwise, the remaining strategies are potential solutions for obtaining high quality machined structures (laser does not machine cavities but crosses the entire bulk). High strength zirconia scaffolds were machined by laser and CNC machining technologies and the two promising technologies were compared.This work is supported by FCT (Fundação para a Ciência e a Tecnologia) through the grant SFRH/BD/148031/2019, the project UIDB/04436/2020 and UIDP/04436/2020

Arbustus unedo essence: morphological and genetic characterization of the strawberry tree of Castelo de Paiva

O medronheiro é um arbusto da região mediterrânica que pode ser encontrada por todo o país. Ao contrário do que verifica na região sul do país, no concelho de Castelo de Paiva é atribuída uma reduzida importância económica a esta espécie. Com o intuito de preservar e potenciar a produção desta espécie e contribuir para a dinamização da economia do concelho, procedeu-se à caracterização morfológica e genética de uma amostra da população de medronheiros de Castelo de Paiva. A caracterização morfológica e genética foi realizada para um total de 10 genótipos. Para tal recolheram-se 70 folhas aleatoriamente em cada árvore. Em 40 folhas mediu-se o comprimento, largura, comprimento do pedúnculo, peso fresco, peso seco e determinou-se a área foliar. Dos caracteres morfológicos analisados, aqueles que se revelaram mais úteis na distinção dos vários genótipos foram: comprimento do pedúnculo, peso fresco e peso seco. As restantes 30 folhas foram utilizadas para a caracterização genética. Esta caracterização foi realizada recorrendo a um marcador de DNA, ISSR. Os 5 primeiros exemplaresutilizados na técnica de ISSR demonstraram-se polimórficos. Os resultados da caracterização genética sugerem que a variabilidade genética na população é média a alta.The strawberry tree is a shrub native in the Mediterranean region and it can be found throughout Portugal. Unlike the case in the southern region of the country, in Castelo de Paiva a minor economic importance is given to this species. In order to preserve, to enhance the production of this species and to contribute to the boosting of the economy of the region, we proceeded to the characterization of a small sample population of this fruit tree of Castelo de Paiva in what concerns to its morphology and genetics. The morphological and genetic characterization was performed for a total of 10 genotypes. For this, 70 leaves were randomly collected from each tree. For 40 leaves, it was measured the length, the width, the peduncle length, the wet weight, the dry weight and determined the leaf area. Of the morphological characteristics analyzed, the ones that proved most useful in distinguishing the various genotypes were: the length peduncle, the wet weight and the dry weight. The remaining 30 leaves were used in the genetic characterization. This characterization was performed using a DNA marker, the ISSR. The 5 primers used in the ISSR technique proved to be polymorphic. The results from the genetic characterization suggest that variability in population genetics is medium to high

Development of hybrid titanium-zirconia based materials by pressure-assisted sintering for dental implants

Tese de Doutoramento em Engenharia MecânicaO desenvolvimento de novas soluções na área dos implantes dentários que visem colmatar os problemas das soluções existentes no mercado é um atual desafio, sob o ponto de vista científico e da saúde. Neste contexto, esta tese foca-se no desenvolvimento, produção e caracterização de materiais híbridos com base em titânio-zircónia produzidos por um processo de sinterização assistida por pressão (prensagem a quente) com o objetivo de criar um novo implante dentário (produto). Este implante híbrido é constituído por uma parte interna de titânio que confere resistência mecânica e uma parte externa de zircónia que evita a libertação de iões metálicos para os tecidos envolventes e, simultaneamente, confere características estéticas semelhantes ao dente natural. A técnica de prensagem a quente revelou ser uma técnica eficaz na obtenção de amostras de zircónia e híbridas titânio-zircónia, com boa densificação através da seleção de pressão e temperatura de sinterização adequadas. A pressão de sinterização mostrou ter um papel importante nas propriedades e comportamento ao desgaste da zircónia, bem como na reação da interface entre o titânio e a zircónia, nos materiais híbridos. Além disso, verificou-se uma alteração de cor da zircónia como resultado da reação da interface, que é potenciada pelo aumento da pressão de sinterização. Demonstrou-se que a camada de óxido produzida na superfície do titânio via anodização permitiu controlar a difusão entre o titânio e a zircónia e, assim, evitar a alteração da cor da zircónia. Os testes preliminares de compressão e torsão realizados nos materiais híbridos produzidos revelaram que estes materiais apresentam boa resistência mecânica. Com base nestes resultados foi apresentado o primeiro protótipo do novo implante dentário. A produção de uma superfície híbrida de titânio-zircónia por tecnologia laser e sinterização assistida por pressão levou a uma redução significativa da taxa de desgaste do titânio. No final, foram produzidas estratégias antibacterianas via produção de microrasgos e funcionalização da superfície, através da tecnologia laser, para evitar a entrada de bactérias e sua adesão. Parte do trabalho desenvolvido nesta tese deu origem à patente com a referência (PCT/IB2018/058404_DENTAL IMPLANT WITH FUNCTIONAL GRADIENT AND RESPECTIVE PROCESS FOR THEIR MANUFACTURING).The development of new solutions regarding dental implants aiming to overcome the problems of the current solutions available at the market is, therefore, a current challenge from the scientific and healthcare points of view. In this context, this thesis is concerned with the development, production and characterization of hybrid titanium-zirconia based materials produced by hot pressing process with the purpose of create a new hybrid dental implant (product). This hybrid implant is composed by an inner material of Ti6Al4V which promotes mechanical resistance and an outer part of ZrO2 which avoids metallic ions release to surrounding tissues and, simultaneously, provides esthetic properties like natural teeth. Hot pressing showed to be an effective technique to produce zirconia and hybrid titaniumzirconia samples with near full densification through selection of adequate sintering pressure and temperature. Sintering pressure strongly influenced properties and wear behavior of zirconia as well as the interface reaction between titanium and zirconia of hybrid materials. Furthermore, a zirconia color change was attained resultant from the interface reaction which is potentiated by the sintering pressure increase. It was demonstrated that the produced continuous oxide layer via anodization process allowed to control diffusion between titanium and zirconia materials and, thus avoid blackening phenomenon of zirconia. The preliminary compression and torsion tests performed at hybrid titanium-zirconia materials revealed that these materials present good mechanical resistance. Based on these results, the first prototype of the new dental implant was presented. Hybrid titanium-zirconia surface produced by laser technology and hot pressing led to a significant reduction of titanium wear rate. Finally, antibacterial strategies, such as microgrooves and surface functionalization, were produced by laser technology to avoid bacteria entrance and its adhesion. Part of the work developed in this thesis gave rise to the patent with reference (PCT/IB2018/058404_DENTAL IMPLANT WITH FUNCTIONAL GRADIENT AND RESPECTIVE PROCESS FOR THEIR MANUFACTURING).Fundação para a Ciência e a Tecnologia (FCT) for the financial support throughout the BD - Bolsa de Doutoramento (FCT PhD Grant) with the reference SFRH/BD/112280/2015. I gratefully acknowledge the opportunity given to me to work at the Centre for Micro-Electro Mechanical Systems (CMEMS)

Development of a novel hybrid Ti6Al4V–ZrO2 surface with high wear resistance by laser and hot pressing techniques for dental implants

The development of implant metal-free surfaces has gained attention since non-benefic results have been re-ported related to the metallic ions released from metal implants to the human body. Ceramic coatings have been proposed as a possible solution however, the detachment of these coatings, during implantation or even in function, can compromise its function. In order to overcome this problem, this work proposes a novel hybrid Ti6Al4V-ZrO2 surface, starting with laser texturing of the Ti6Al4V substrate by Laser Nd:YV04, followed by the allocation of the zirconia (ZrO2) powder and its subsequent sintering by hot pressing process. Results revealed that zirconia strongly adheres to titanium textured surfaces since no detachment was found under tribological and adhesion scratch tests. Moreover, the tribological results showed that the incorporation of zirconia into textured titanium surface reduces significantly the wear rate of titanium (approximate to 93%), which is a good indicator of low metallic particles/ions released to the body. These results suggest that this novel surface with good aesthetic properties and improved wear resistance (given by zirconia) and mechanical resistance (from titanium) can be a promising solution for dental implants, especially for implant/abutment or abutment/ceramic contact zones, and thus have a huge impact on the long-term performance of implants.This work was supported by the project POCI-01-0247-FEDER-034074 (ImpHib) funded by Fundo Europeu de Desenvolvimento Regional (FEDER) funds, through Programa Operacional Com-petitividade e Internacionalizaao-COMPETE 2020, under Portugal 2020, by the ANI-Agencia Nacional de Inovação. This work was also supported by the project POCI-01-0145-FEDER-030498 (FunImp) through national funds and European Regional Development Fund by the FCT-Fundacao para a Ciencia e a Tecnologia I.P. and through national funds, under the national support to R & D units grant, by the FCT, in the scope of the projects UIDB/04436/2020 and UIDP/04436/2020

Light therapy on a functionalized zirconia surface with antimicrobial nanoparticles for dental applications

Light therapy on a functionalized zirconia surface with antimicrobial nanoparticles for dental applications Dental implants are considered the best solution for missing teeth but are sometimes associated with complications such as peri-implantitis, which is caused by bacteria and is characterized by tissue inflammation and bone loss which causes dental implants to fail over time [1]. Metal nanoparticles (NPs) can be a good antibacterial agent to be employed in dental implantology to prevent this pathology [2]. Furhermore these nanoparticles in conjunction with light energy, through a process known as photocatalysis, can produce harmful reactive oxygen species and with radiation in the red and near infrared region (660-940 nm) can also induce a localized photothermal therapy. On par with these effects, red and nir light radiation has also been shown to be positive for cell growth [3]. The present work was designed to, first, produce and characterize three different types of nanoparticles (gold, magnesium and zinc), obtained by laser ablation in distilled water and sodium dodecyl sulphate (SDS) using a Nd:YAG laser system. Secondly, validate their adhesion to zirconia surfaces. And finally, with the surfaces prepared, the antibacterial efficacy and cytotoxicity of these surfaces in conjunction with LED light radiation (with wavelengths of around 940, 850, 660 and 450 nm), were addressed, in order to confirm their potential use as an active functionalized antibacterial surface in dental implant abutments, to prevent peri-implantitis disease as shown in Figure 1