Comparison of the physico-chemical impact of chlorhexidine and silver nanoparticles on orthodontic appliances made with laser and silver solder: An in vitro study.

OBJECTIVE: The aim of this study was to evaluate the physical-chemical changes in orthodontic devices made with laser and silver solder after immersion in different antiseptic solutions. METHODS: Wire/band assemblies were fabricated using different types of solders (silver and laser). The devices were immersed in different antimicrobial solutions (chlorhexidine - CHX 0.12% and Silver nanoparticles - NAg 0.12% and 0.18%). Non-immersion in solution and immersion in artificial saliva were used as initial and negative control, respectively (n=12). Surface morphological analysis was performed using Scanning Electron Microscopy (SEM). The quantitative analysis of the chemical elements present after the immersions in the solutions was analysed by Energy Dispersive X-ray Spectroscopy (EDS). The data were subjected to the Kruskal-Wallis test followed by Bonferroni, with a significance level of 5%. RESULTS: Greater amounts of copper, silver and zinc were released from silver soldering, on the other hand, iron, nickel, and chromium ions were the most prevalent metal ions in laser soldering. Regarding mouthwashes, the lowest amounts of metal ions were released in CHX, and the highest amounts of ions were released in the 0.12% NAg and 0.18% NAg solutions. CONCLUSIONS: Laser welding seems to be less susceptible to corrosion. The different antiseptic solutions did not contribute to an increase in ion release.

Cutting mechanism of straight-tooth milling process of titanium alloy TC21 based on simulation and experiment.

Due to the characteristics of high strength, high chemical activity and low heat conduction, titanium alloy materials are generally difficult to machine. As a typical titanium alloy with higher strength and lower heat conductivity, the machinability of titanium alloy TC21 is very poor and its cutting process is companied with larger cutting force and rapid tool wear. Straight-tooth milling tool is often used to cut the groove and side surface in the titanium alloy parts. And the milling method can be used to investigate the cutting mechanism because the cutting force has only two components and the better chip morphology is obtained. To investigate the straight-tooth milling process of TC21 alloy, a series of milling force experiments have been done. In addition, a 3D finite element model (FEM) for the straight-tooth milling process of TC21 alloy is presented to simulate the milling process. In the model, the constitutive material model, the failure model, the friction model and the heat transfer model were adopted. Through the simulation, chip formation, stress distribution, cutting force and milling temperature were obtained. The cutting force reaches its maximum when the spindle speed reaches about 13000 rpm, and then decreases as the speed continues to increase. The results confirmed that the similar "Salomon" phenomenon existed in the cutting process of TC21 alloy.

Comparison between traditional and alternative biocompatible welding techniques used in orthodontic devices.

OBJECTIVE: To compare the mechanical strength of joints made by conventional soldering with those made by alternative, more biocompatible, methods (spot, tungsten inert gas [TIG] and laser welding), and to compare the microstructural morphology of wires welded with these techniques. DESIGN: In vitro, laboratory study. METHODS: Forty stainless-steel wire segments with 0.8-mm diameter were joined by silver soldering, spot, laser and TIG welding. Ten specimens were produced for each one. Tensile strength test was performed 24 h after welding on the Emic DL2000™ universal testing machine, using a load cell of 1000 N with a crosshead speed of 10 mm/min. RESULTS: The highest tensile strength mean values were obtained with silver soldering (532 N), next were laser (420 N), spot (301 N) and TIG (296 N) welding. Statistically significant differences were observed between the groups; the Dunn post-hoc test revealed differences between laser and spot welding (p=0.046), laser and TIG (p = 0.016), spot and silver (p <0.001), and silver and TIG (p <0.001). CONCLUSION: Laser welding strength is high, and comparable to silver welding. Spot and TIG techniques present comparable and significantly lower strengths. The four methods presented resistance values compatible with orthodontic use. The microstructural morphology is different for each technique. The association between the mechanical performance and the microstructure evaluation shows that laser presented the highest quality joint.

Oral rehabilitation of maxilla: technical consideration.

Oral rehabilitation of edentulous maxilla is particularly difficult because of the lack of bone in correspondence of maxillary sinuses, therefore, the surgeon is forced to place implants in sites where bone is more prevalent. In addition, patients require more frequent oral immediate rehabilitation in order to reduce the discomfort related to wearing a total denture. A viable solution to provide stability and retention of the prosthesis in a short time is represented by the technique of intraoral welding supporting total denture or fixed prosthesis. This goal may be achieved thanks to the technique of welding titanium bars onto implant abutments. In fact, the procedure can be performed directly in the mouth, eliminating the possibility of errors or distortions due to prosthetic procedures. This paper describes a case report and the most recent data regarding long-term success and high predictability of intraorally-welded titanium bar in immediate loading implants.

Systematic review and meta-analysis of welding procedures in one-piece cast implant-supported frameworks.

The objective of this systematic review and meta-analysis was to evaluate the effect of welding techniques on implant-supported prostheses and determine whether they contribute to a better adaptation compared with a one-piece cast. A search was conducted using the PubMed/MEDLINE, Embase, and Cochrane Library databases, and articles published until November 2017 were obtained from these databases. This review followed the PRISMA criteria and is registered on the PROSPERO platform (CRD42017081865). The PICO question was "Do welding procedures in one-piece cast implant-supported frameworks influence implant/abutment-framework marginal misfits?" Eleven studies were selected for a qualitative analysis, and seven studies were selected for a quantitative analysis. A total of 189 specimens were fabricated using different materials (cp-Ti, Ni-Cr, Cr-Co, and noble alloys), and welding techniques such as laser welding, conventional welding, tungsten inert gas, and brazing were applied. A vertical marginal misfit was measured using an optical microscope, a stereomicroscope, and/or a scanning electron microscopy. The qualitative analysis in the studies demonstrated a positive effect of the welding techniques on the adaptation of the infrastructures. The meta-analysis confirmed the results (p < 0.00001; MD: -36.14; 95%CI: -48.69 to -23.59). Within the limitations of this study and regarding the heterogeneity of the samples, we conclude that the soldering point technique is effective for obtaining relatively low values of marginal misfit, with laser welding as the most effective technique. However, additional studies were recommended due to the heterogeneity of different variables (alloys, connection, and misfit evaluation) in the included studies.

Evaluation of ceramic flexural strength of a cobalt-chromium alloy subjected to airborne particle abrasion and tungsten inert gas welding

Aim: The aim of this study was to evaluate the influence of tungsten inert gas (TIG) welding and airborne particle abrasion using aluminum oxide particles on the flexural strength of a joint between ceramic and cobalt-chromium alloys. Methods: The specimens were cast and welded using TIG, then divided into 6 groups (n = 10) and subjected to blasting with 250 µm, 100 µm, and 50 µm aluminum oxide particles. Ceramic systems were applied to the central part of all specimens. A three-point bending test using a velocity of 0.5 mm/m was performed on the specimens to measure flexural strength. Data were analyzed using two-way analysis of variance and Tukey's test. Results: TIG welding demonstrated the lowest resistance compared with the non-welded groups. Airborne particle abrasion using 250 µm aluminum oxide particles demonstrated greater resistance in the welded groups (p < 0.05). Mixed faults were found in all specimens. Conclusion: TIG welding decreased the bond strength, and the particle size of aluminum oxide did not affect the metal-ceramic bond in groups without TIG welding

Modification of clinically short Locator abutments using laser welding.

As dental implants continue to survive longer, managing and maintaining implant prostheses can be complicated by the lack of compatible parts or the discontinuation of implant systems. This report describes a laser welding procedure for the management of clinically short Locator abutments (Zest Anchors Inc) that lacked a commercially available, compatible alternative.

Multitechnique characterization of conventional and experimental Ag-based brazing alloys for orthodontic applications.

OBJECTIVES: To characterize the microstructure, mechanical properties, ionic release and tarnish resistance of conventional and experimental Ag-based soldering alloys for orthodontic applications. METHODS: Disk shaped specimens were prepared from four commercial Ag based soldering alloys [Dentaurum Universal Silver Solder (DEN), Orthodontic Solders (LEO), Ortho Dental Universal Solder (NOB), and Silver Solder (ORT)] and four experimental alloys Ag12Ga, Ag10Ga5Sn, Ag20In and Ag7Sn. The elemental composition and microstructure was determined by SEM/EDX and XRD analysis, while the mechanical properties were determined by Instrumented Indentation Testing. Ionic release of Ag, Cu, Zn, Ga, In and Sn was determined by ICP-EAS in 0.9% NaCl and Ringer's solutions after 28, 49 and 70 days. Tarnish resistance was also tested and colorimetry was applied to quantify the differences in color (DE) before and after immersion in testing media. DSC was used to determine the melting range of the experimental alloys. Mechanical properties, ionic release and DE were statistically compared by ANOVA and Holm-Sidak multiple comparison test (a=0.05). RESULTS: All commercially alloys belong to the Ag-Zn-Cu ternary system and consist a Ag rich face centered cubic (FCC) and Cu (FCC) phase. The former is the predominant phase also in experimental alloys. Conventional alloys demonstrated higherhardness, less ductility and lower melting rangers compared to experimental alloys. Immersion testing revealed the release of Cu and Zn ions from the commercially alloys and Ga ions from AgGa and AgGaSn while no ionic release was identified for AgIn and AgSn. All alloys failed tarnish testing according to ISO 10271 showing DE values much higher than the clinical acceptable limit (3.7). SIGNIFICANCE: The conventional Ag based soldering alloys showed substantial differences in their microstructure, mechanical properties and ionic release, and thus different clinical performance is anticipated. Ga, Sn and In might be employed as alloying addition to modify the properties of Ag brazing alloys.

Bone response to functionally loaded, two-piece zirconia implants: A preclinical histometric study.

OBJECTIVE: To evaluate the bone response to a two-piece zirconia implant in comparison with a control titanium implant in the canine mandible 4 and 16 weeks after restoration. MATERIAL AND METHODS: Zirconia and titanium implants were alternately placed bilaterally in healed mandibular molar and premolar sites of five canines. Full-ceramic single-tooth restorations were cemented after 6 weeks of transmucosal healing, allowing for full functional loading of the implants. Histologic and histometric analyses were performed on orofacial and mesiodistal undecalcified sections of the specimens obtained upon sacrifice after 4 and 16 weeks of functional loading. Bone-to-implant contact (BIC), multinucleated giant cells-to-implant contact (MIC), crestal bone level, and peri-implant bone density were histometrically assessed. RESULTS: All 60 implants and 60 restorations were still in function after 4 and 16 weeks of loading in both test and control groups. No implant loss, no implant or abutment fracture, and no chipping of the restorations could be detected. Histometric analysis showed no statistically significant differences between zirconia and titanium implants in BIC, crestal bone level, and peri-implant bone density at both time points. Between 4 and 16 weeks, the crestal bone level around zirconia implants showed a small but statistically significant increase in its distance from the implant shoulder. MIC was very low on both implant types and both time points and decreased statistically significantly overtime. CONCLUSION: The present two-piece zirconia implant showed a similar bone integration compared to the titanium implant with similar surface morphology after 4 and 16 weeks of loading.

Comparative analysis of ceramic flexural strength in co-cr and ni-cr alloys joined by TIG welding and conventional brazing

Aims: The purpose of the present study was to evaluate the flexural strength of specimens made of nickel-chromium(Ni-Cr) and cobalt-chromium (Co-Cr) alloys and joined by tungsten inert gas (TIG) welding and conventional brazing. Ni­Cr and Co­Cr base metal specimens (n = 40, each) were cast and welded by TIG or brazing. The specimens were divided into six groups (2 base metals, four welded specimens). Ceramic systems were applied to the central part of all the specimens. A three-point bending test with a velocity of 0.5 mm/m was performed on the specimens up to the point of the first ceramic bond failure by measuring the flexural strength. Data were analyzed using two-way ANOVA and Bonferroni's tests. Conventional welding showed the lowest flexural strength results for both alloys, while the TIG weld and the control group presented with varying bond strengths for the alloys studied. We concluded that TIG welding was superior to the conventional welding method for both Ni­Cr and Co­Cr alloys with regard to the flexural strength of the ceramic (AU)

Mondani intraoral welding: historical process and main practical applications.

The intraoral welder was invented by Dr. Pierluigi Mondani during the early 70’s to weld titanium needle implants to a titanium bar in patient’s mouth and to load them immediately by means of resin prosthesis. The clinical use documented dates back to 1972. Over the years, many practical applications have been added to the initial one, which have expanded the use of this device. In this scientific work, main applications are described. The aim of the work was to trace the historical process of intra-oral welding according to Mondani and describe the main practical applications. Intra-oral welding is a process introduced by dr. Pier Luigi Mondani of Genova (Italy) which allows to firmly conjoin titanium implants of any shape by means of a titanium bar or also directly between them in the mouth during surgery. The immediate stabilization achieved by intraoral welding increases implants success rate, allows immediate loading even in situations of bone atrophy, saves implants that are running into failure, re-evaluates fractured implants, allows to stabilize submerged implants postponing prosthesis management, allows to achieve efficient rehabilitation protocols to deal with difficult cases. The 40-years’ experience with intra-oral welding described in this article, confirms the ease of use and efficiency in providing immediate stabilization of titanium implants of all types.

Avaliação da resistência flexural em diferentes métodos de soldagem / Evaluation of flexural resistance in different welding methods

O objetivo do presente estudo foi avaliar três diferentes tipos de soldagem: Chama Direta a maçarico (convencional\brasagem), Solda Mista representada por fixação de dois pontos (Solda Elétrica Fixator - Kernit, Brasil), e completada com solda convencional, e o método de Solda a Laser (Soldadora Desktop - Sisma LM 500, Itália). Dois implantes plataforma Bränemark 4.1 mm (Neodent, Curitiba/Brasil) foram fixados em uma matriz de alumínio para simular uma ponte fixa implanto-suportada de três elementos. Os espécimes foram obtidos a partir de um bloco de cera CAD-CAM (Ceramill-Amammgirrbarch). Trinta e duas UCLAs hexágono externo foram fresadas e posteriormente unidas a uma barra pré-fabricada em cera com 2,5mm. Os corpos de prova foram fundidos em liga de cobalto-cromo simulando uma prótese fixa de três elementos. Esses espécimes foram divididos aleatoriamente e separados em três grupos (n=6): grupo A (solda chama direta), grupo B (solda mista), grupo C (solda laser). Os espécimes foram seccionados ao meio e unidos com resina acrílica para simular uma soldagem em prótese fixa. Os corpos foram soldados e tratados de acordo com a proposição. Após a soldagem os corpos de prova foram usinados e levados ao teste de flexão na técnica de três pontos. Os dados foram submetidos aos testes estatísticos de Tukey. Os cálculos estatísticos foram conduzidos adotando-se o nível de significância de 5% (α = 0,05). Houve diferença estatisticamente significativa entre os grupos soldados. Os resultados demonstraram valores mais elevados nos grupos A e B, solda convencional e solda mista, e menor valor no grupo C, solda a laser. No entanto, considerando a metodologia aplicada, a solda a laser mostrou uma menor resistência flexural comparada à soldagem convencional e mista, e a fixação prévia de solda elétrica com complemento de solda convencional (solda mista) não alterou a resistência flexural, produzindo resultado semelhante à solda convencional

The objective of this study was to evaluate three different types of welding, blowtorch; (conventional/brazing), welder Joint; represented by securing two points (Arc Welding Fixator - Kernit, Brazil), and supplemented with conventional welding), and Laser welding method (welder Desktop - Sisma LM 500, Italy). Two implants Bränemark 4.1 mm platform (Neodent, Curitiba/Brazil) were fixed in an aluminum matrix. Specimens were obtained from a CAD-CAM wax block (Ceramill - Amammgirrbarch) were milled 32 UCLAs (external hexagon, Bränemark platform), and subsequently joined to a prefabricated bar also wax 2.5 mm, the specimens were casted in cobalt-chromium alloy. These specimens were randomly divided and separated into 3 groups: group A (welding direct flame), Group B (mixed welding), C (laser welding), with 6 samples for each group. The specimens of each group were cut in half to simulate a fixed prosthesis in welding, and put together with acrylic resin. The bodies were welded and treated according to the statement. After the specimens were welded, they were manually grinded and submitted to the 3 points bending test technique. Data were subjected to statistical tests of Tukey. Statistical calculations were performed adopting the significance level of 5% (α = 0.05), using SPSS 20 (SPSS Inc., Chicago, IL, USA). There were differences between the soldered groups. The data showed the highest values obtained in groups A and B, conventional welding and soldering joint, and lower in group C, the laser welding. However, within the applied methodology, the laser welding showed a lower flexural strength compared to conventional and mixed welding, and that the advance fixing of electric welding, conventional welding complement (mixed welding), does not change its flexural strength, producing results similar to conventional welding

Cytotoxic outcomes of orthodontic bands with and without silver solder in different cell lineages.

INTRODUCTION: The safety of orthodontic materials is a matter of high interest. In this study, we aimed to assess the in-vitro cytotoxicity of orthodontic band extracts, with and without silver solder, by comparing the viability outcomes of the HaCat keratinocytes, the fibroblastic cell lineages HGF and MRC-5, and the kidney epithelial Vero cells. METHODS: Sterilized orthodontic bands with and without silver solder joints were added to culture media (6 cm2/mL) and incubated for 24 hours at 37°C under continuous agitation. Subsequently, the cell cultures were exposed to the obtained extracts for 24 hours, and an assay was performed to evaluate the cell viability. Copper strip extracts were used as positive control devices. RESULTS: The extracts from orthodontic bands with silver solder joints significantly reduced the viability of the HaCat, MRC-5, and Vero cell lines, whereas the viability of HGF was not altered by this material. Conversely, the extracts of orthodontic bands without silver solder did not significantly modify the viability index of all evaluated cell lines. CONCLUSIONS: Except for HGF fibroblasts, all tested cell lines showed decreased viability percentages after exposure to extracts of orthodontic bands containing silver solder joints. These data show the relevance of testing the toxicity of orthodontic devices in different cell lines.

Assessing different patterns of laser welding with NickelChromium (Ni-Cr) alloy for structures applicable to fixed prosthesis / Avaliação de diferentes parâmetros de soldagem a laser em liga de Níquel-Cromo levando em consideração estruturas aplicáveis à Prótese Fixa

Objectives: Among all desired requirements to dental prosthesis, marginal adaptation and passive fit are the most important. In some cases, in order to achieve these goals, it is necessary to cut and weld the teeth / implant-supported framework. Nowadays, the laser welding process shows a great advantage in comparison to other methods. The aim of this study was to evaluate the optimal laser welds point that is more appropriate to Ni-Cr prosthetic framework. Material and methods: A total of 60 specimens of Ni-Cr (35 mm x 4 mm) were designed and welded using a Nd:YAG laser device model EV 900. They were fixed in a metal piece 0.27 mm between the ends to be welded. All specimens were welded with 21 laser pulses diametrically opposed (frequency of 1.0Hz, load time 3.0 ms and 0.5 mm of diameter pulse). They were divided into three groups according to the electric current of the laser weld: A ­ 180A; B ­ 200A; C ­ 220A; and D- control group with no welding process. To determinate the flexural mechanic strength, all specimens were submitted to a three-point bending test. Results: The results obtained were: Group A = 553,76 Mpa; B = 751,02 Mpa and C = 802.13 Mpa. The control group was 1040.9 Mpa. ANOVA and Tukey's test were performed and statistical significance differences were observed between group A and B as well as between group A and C. However, no significant difference was observed between B and C. The group D (no welding process), significant difference was observed between A, B and C. Conclusion: According to the methodology used, the groups B and C, among the welded groups, produced higher values of mechanical strength than the group A. The groups B and C were similar.(AU)

Objetivos: Entre os requisitos de uma prótese fixa estão a adaptação marginal e seu assentamento passivo. Em alguns casos, para alcançarmos estes requisitos, devemos realizar o seccionamento e soldagem da infraestrutura metálica. Os procedimentos de soldagem a laser apresentam várias vantagens em relação aos outros processos de união. O objetivo deste trabalho foi avaliar os parâmetros ideais para soldagens a laser em de infraestruturas protéticas em Ni-Cr. Material e métodos: Foram confeccionados 60 infraestruturas (35 mm X 4,0 mm), que foram soldadas utilizando um aparelho de solda a laser Nd:YAG modelo EV 900. As amostras foram fixadas em uma peça metálica, mantendo padronizada uma distância de 0,27 mm entre as extremidades a serem unidas. Todas as amostras foram soldadas com 21 pulsos diametralmente opostos (frequência de 1,0 Hz, tempo de carga de 3,0 ms e 0,5 mm de diâmetro do pulso) e foram divididas em três grupos experimentais, alterando-se a intensidade da corrente elétrica da solda a laser: A) 180 A; B) 200 A; C) 220 A e D) grupo controle -sem processo de soldagem. Para se determinar a resistência mecânica flexural, todas as amostras foram submetidas ao teste de flexão de três pontos em máquina de teste universal. Resultados: Os resultados médios obtidos foram: grupo A) 553 Mpa, B) 751,0 Mpa, C) 802,1 Mpa e para a amostra controle foi de 1040,9 Mpa. Foram realizados o teste estatístico paramétrico ANOVA e o teste de Tukey, e foi observado diferença estatisticamente significante entre os grupos A x B e grupos A x C. No entanto, não foi observado diferença significante entre os grupos B x C. No Grupo D (sem processo de soldagem) foi observado diferença significante quando comparado com os grupos A, B e C. Conclusão: De acordo com a metodologia utilizada o grupo C produziu os maiores valores de resistência flexural, seguidos pelos grupos B e A respetivamente.(AU)

Análise do assentamento passivo de barras metálicas fundidas obtidas a partir do uso de diferentes resinas durante o processo de moldagem / Analysis of the passive fit of metal bars obtained through the use of different resins during the molding process

Esta pesquisa tem como propósito avaliar a técnica de moldagem tipo moldeira aberta com emprego de transferentes quadrados unidos com cinco diferentes resinas usualmente utilizadas como agentes de união e a influência que esta possa conduzir ao assentamento passivo de estruturas metálicas de próteses protocolos (barras) sobre os pilares de implantes. Como metodologia, vinte cinco amostras de moldagens foram obtidas a partir de mandíbula metálica fundida edêntula (modelo-mestre) e instalados análogos de implantes de titânio com plataforma 4.1 tipo hexágono externo. Em seguida, fixou-se os pilares cônicos sobre os análogos de implantes e realizou-se cinco esplintagens por grupo com emprego de cada agente de união. Após a moldagem, obteve-se os modelos de trabalho em gesso pedra tipo IV (corpos de prova) e, em seguida, confeccionou-se os padrões em cera das barras. Cada barra foi previamente fundida sob o modelo através do sistema de barra parafusada e sem soldas, adaptada sobre os análogos dos pilares do modelo-mestre. Posteriormente, a desadaptação foi avaliada em estereomicroscópio com aumento de 45x e os valores obtidos foram tabulados. Testes estatísticos não paramétricos foram aplicados. Não foram encontradas diferenças estatisticamente significantes entre as cinco resinas de união, porém o material que obteve melhores médias de desajustes marginais foi a resina acrílica Dencrilay Speed. Concluiu-se que os valores das médias encontrados nos cincos materiais não inviabilizam o uso da técnica de moldagem estudada, pois esta requer o ato de soldagem quando da estrutura fundida, o que, de certa forma, ameniza os desajustes encontrados (AU).

This research aims to evaluate the open tray molding technique using square transfers with five different acrylic resins - usually used as agent of union - and its influence over the passive fit of the metal bars on the pillars of implants. Twenty five molds were obtained from a metal edentulous mandible (master model) already installed analogue titanium implants with 4.1 platform external hexagon type were employed. Then, the conical pillars were set up on the analogue of the implant of the master model and five splinting were performed in each group using each bonding agent. After the molding procedure, were obtained the working models with plaster stone type IV (test samples) and then made in wax bars. Each bar was previously fused on the model through the system of screwed bar without welds and adapted on the analogue of the pillars of the master model. Subsequently, the misfit was evaluated in stereomicroscope with 45x magnification and the obtained values were tabulated and then applied non-parametric statistical tests. No statistically significant differences was found between the 5 union agents, however, the material that obtained best average of marginal misfits was Dencrilay. It was concluded that the values of the averages observed for the five materials do not compomise the use of the studied molding technique, since it requires the act of welding when fused structure, which in some ways minimize the misfits found (AU).

Análise da desadaptação marginal vertical e horizontal de infraestruturas de próteses fixas implantossuportadas confeccionadas através de diferentes técnicas / Analysis of vertical and horizontal marginal misfit of implant-supported fixed prosthesis made through different techniques

O objetivo deste trabalho foi avaliar a desadaptação marginal vertical, horizontal e interna de infraestruturas e próteses fixas implantossuportadas confeccionadas através de diferentes técnicas. Além disso, realizar uma revisão sistemática e meta-análise avaliando o efeito da soldagem de infraestruturas de próteses fixas implantossuportadas em uma melhor adaptação quando comparada as infraestruturas confeccionadas em monobloco. Um total de 30 infraestruturas foram confeccionadas e divididas em 3 grupos: G1) Técnica convencional da cera perdida (n=10); G2) CAD/CAM (n=10); G3: CAD/CAM + Técnica da cera perdida (n=10). Uma matriz foi utilizada para simular uma prótese fixa implantossuportada de três elementos com um pôntico central. A infraestrutura do grupo G1 foi confeccionada em Ni-Cr, do grupo G2 em zircônia e G3 fresada em cera e fundida em Ni-Cr. Em todos os grupos a desadaptação marginal vertical e horizontal (subcontorno e sobrecontorno) foi avaliada através de um microscópio óptico tridimensional (Quick Scope, Mitutoyo). A revisão sistemática seguiu o critério PRISMA e está cadastrada na plataforma PROSPERO (CRD81865) e a busca foi realizada nas bases de dados Pubmed/MEDLINE, Embase and The Cochrane Library com artigos publicados até novembro de 2017. A questão PICO foi: "A técnica do ponto de solda contribui para uma melhor adaptação quando comparada a confecção em monobloco de infraestruturas e próteses fixas implantossuportadas?". O estudo in vitro demonstrou maior valor de desadaptação marginal vertical para o grupo G3 (83.5µm), seguido dos grupos G1 (55 µm) e G2 (42 µm) (p<0,001). Quanto à desadaptação marginal horizontal, o maior valor de desadaptação foi do grupo G2 (118 µm), seguido de G3 (102 µm), ambos apresentando sobre contorno. O grupo G1 (- 85 µm) apresentou valores de sub contorno (p<0,001). Na revisão sistemática, 12 estudos foram selecionados para análise qualitativa e 7 estudos para análise quantitativa. Um total de189 espécimes foram avaliados, em diferentes ligas metálicas (cp-Ti; Ni-Cr; Cr-Co e ligas nobres) e técnicas de soldagem: laser welding, solda convencional, TIG e brazing. As desadaptações marginais verticais foram mensuradas através de microscópio óptico, estereomicroscópio e MEV. Uma análise qualitativa dos estudos foi realizada demonstrando um efeito positivo da soldagem na adaptação das infraestruturas quando comparadas aquelas confeccionadas em monobloco. A meta-análise confirmou o efeito positivo da soldagem na adaptação (P<0.00001; MD: -36.14; IC 95%: -48.69 to -23.59). Dentro das limitações pertinentes a um estudo in vitro pode-se concluir a confecção de infraestruturas através dos sistemas CAD/CAM apresentou os menores valores de DMV. A associação dos sistemas CAD/CAM e a técnica convencional da cera perdida, apresentou maior DMV. A DMH foi mais favorável quando confeccionadas infraestruturas pela técnica da cera perdida, apresentando sub-contorno. A revisão sistemática demonstrou que a técnica do ponto de solda é eficaz para obtenção de menores valores de desadaptação marginal, sendo a técnica do laser (laser welding) a mais eficaz(AU)

The aim of this study was to evaluate the marginal vertical, horizontal and internal misfit of implant-supported prostheses made through different techniques. In addition, to perform a systematic review and meta-analysis evaluating the effect of the welding technique on fixed prosthesis implants supported in make a better adaptation when compared the infrastructures made in one piece cast. A total of 30 infrastructures were made and divided into 3 groups: G1) Conventional- lost wax technique (n = 10); G2) CAD/CAM (n = 10); G3: CAD/CAM + lost wax technique (n = 10). A reference model was used to to simulate a 3-unit implant-supported fixed prostheses with a central pontic. In the G1 group the frameworks were made of Ni-Cr alloy, G2 group in zirconia and G3 milled in wax and fused in Ni-Cr alloy. In all groups, vertical and horizontal marginal misfit (under-contour and over-contour) was evaluated using a 3D optical microscope (Quick Scope, Mitutoyo, Japan). The systematic review and meta-analysis followed the PRISMA criteria and is registered on the PROSPERO (CRD81865). The search was performed in the Pubmed/MEDLINE, Embase and The Cochrane Library databases with selection of articles published until November 2017. The PICO question was: "The welding technique contributes to a better adaptation when compared to the one-piece cast frameworks of implant-supported prostheses?" The in vitro study showed a higher value of vertical marginal misfit for the G3 group (83.5µm), followed by G1 (55µm) and G2 (42µm) (p <0.001). As for horizontal marginal misfit, the highest value of misfit was G2 (118 µm), followed by G3 (102 µm), both presenting over-contour. The G1 group (-85 µm) had under-contour values (p <0.001). In the systematic review, 12 studies were selected for qualitative analysis and 7 studies for quantitative analysis. A total of 189 specimens were evaluated in different metal alloys (cp-Ti, Ni-Cr, Cr-Co and noble alloys) and welding techniques: laser welding, conventional welding, TIG and brazing. Vertical marginal misfits were measured by optical microscope, stereomicroscope and/or SEM. A qualitative analysis of the studies was performed demonstrating a positive effect of welding technique on the adaptation of the frameworks when compared to those made in one piece cast. The meta-analysis confirmed the positive effect of welding on marginal adaptation (P <0.00001; MD: -36.14; 95% CI: -48.69 to -23.59). Within the limitations of an in vitro study it can be concluded that the construction of infrastructures through CAD/CAM systems presented the lowest values of DMV. The association of the CAD/CAM systems and the conventional lost wax technique presented higher DMV. The DMH was more favorable when frameworks were made by the lost wax technique, presenting under-contour. The systematic review showed that the welding technique is effective to obtain lower values of marginal misfit and the Laser Welding technique is the most effective(AU)

Immediate loading of two flapless placed mandibular implants supporting cross-arch fixed prostheses: A 5-year follow-up prospective single cohort study.

PURPOSE: To evaluate the clinical outcome of two implants placed flapless in fully edentulous mandibles and immediately restored with metal-resin screw-retained cross-arch prostheses 5 years after loading. MATERIALS AND METHODS: Eighty consecutive patients were recruited. To be immediately loaded, implants had to be inserted with a minimum torque of 80 Ncm. Forty-six laser-welded titanium and 34 cast silver-palladium frameworks with resin teeth were initially delivered within 8 and 48 h, respectively. Outcome measures, evaluated by two independent assessors included prosthesis and implant failures, complications, marginal bone level changes, implant stability quotient (ISQ) values and patient satisfaction. RESULTS: Five years after loading one patient did not return to the control and 10 prostheses were remade. Two implants failed early in two patients, but they were successfully replaced. Thirty-six complications occurred in 28 patients but were all successfully treated. After 5 years, mean marginal bone loss was 0.69 mm, mean ISQ values decreased from 75.4 to 73.8, and all patients were fully satisfied with the therapy. A post-hoc comparison between the outcome of laser-welded and cast frameworks showed that laser-welded frameworks were affected by significantly more complications (19 patients out of 46 and 6 patients out of 34, respectively; difference in proportion = 0.23, 95% CI: 0.03 to 0.43; Pearson's chi-square test, P = 0.032), therefore such a framework construction should be considered as a long-term temporary prosthesis and not a definitive prosthesis. CONCLUSIONS: Immediately loaded mandibular cross-arch prostheses can be supported by only two implants up to 5 years, if made with a robust cast framework. Longer follow-ups (around 10 years) are still needed to know the prognosis of this treatment modality.

Efeito da soldagem híbrida (plasma + maçarico) na suavização da assinatura torque-ângulo em supraestruturas de COCR sobre minipilares de zircônia ­ parte 1 / Effect of hybrid soldering (plasma + gas torch) technique on suavization of torque-angle signatures at Co-Cr frameworks over zirconia mini-abutmets ­ part I

Objetivo: avaliar as desadaptações em supraestruturas de implantes e a curva de assinatura torque-ângulo dos parafusos protéticos nas condições monobloco e pós-soldagem. Material e métodos: uma base retangular de aço inox recebeu três implantes de hexágono externo (4,1 mm x 10 mm), onde foram parafusados minipilares de zircônia. Após o enceramento e inclusão, as supraestruturas foram fundidas em monobloco com uma liga de cobalto-cromo, e os cilindros foram numerados sequencialmente (1, 2 e 3). A leitura na interface supraestrutura/pilar foi realizada com um microscópio comparador (precisão de 1 µm), três vezes em cada cilindro. A tensão de torque nos parafusos foi medida com um torquímetro eletrônico odontológico (OsseoCare, Nobel Biocare). Depois, as supraestruturas foram seccionadas e soldadas a plasma (pontos de estabilização) e maçarico (preenchimento da área restante). Novamente, as desadaptações e assinaturas dos parafusos foram avaliadas pela mesma metodologia. Resultados: as médias de desadaptações foram maiores nas supraestruturas em monobloco (C1=3,5 µm; C2=0 µm; C3=31,2 µm) do que nas supraestruturas pós-soldagem (C1=3,0 µm; C2=2,9 µm; C3=18,1 µm). Dentro de cada condição, o teste de Kruskal-Wallis mostrou diferença estatisticamente significativa apenas para o cilindro 3 (monobloco: p < 0,00003 / pós-soldagem: p=0,008) em relação aos cilindros 1 e 2. Uma diferença estatisticamente significante foi encontrada apenas no C3, comparando as condições monobloco e pós-soldagem (teste t pareado, p=0,03). A assinatura dos parafusos se mostrou melhor na condição pós-soldagem. Conclusão: a fundição monobloco gera instabilidade na assinatura dos parafusos. A desadaptação nos parafusos protéticos de supraestruturas sobre minipilares de zircônia melhora após secção e soldagem híbrida.

Objective: to evaluate the misfi t at implant frameworks and the torque-angle signature curves at the prosthetic screws at one-piece and after soldering conditions. Material and methods: a stainless steel rectangular base received 3 external hex implants (4.1 x 10 mm) where zirconia mini-abutments were fastened. After wax-up and investing, the frameworks were one-piece cast with a Co-Cr alloy, and the prosthetic cylinders sequentially identified (1, 2, and 3). The misfit at the framework/abutment interface was measured with a microscope (reading error 1 µm) 3 times for each cylinder. The screw tension was investigated with an electronic torqued device (Osseocare, Nobel Biocare). After, the frameworks were sectioned and soldered with plasma (stabilization points) and gas torch (filling of the remaining areas). Again, the misfit and torque-angle signatures were measured as described. Results: mean misfit values were greater for one-piece castings (C1=3.5 µm; C2=0 µm; C3=31.2 µm) than after soldering (C1=3.0 µm; C2=2.9 µm; C3=18.1 µm). Within each condition, the Kruskal-Wallis test demonstrated a statistically significant difference only for C3 (one-piece casting: p < 0.00003 / after soldering: p=0.008) compared to C1 and C2. Between each condition, a significant difference was seen only for C3 in the one-piece and after soldering conditions (paired t test, p=0.03). The torque-angle signatures demonstrated a better behavior after soldering. Conclusion: one-piece castings provide instability at torque-angle signatures. Thus, the seating of the prosthetic abutments over the zirconia mini-abutments improves after sectioning and hybrid soldering.

Hybrid framework with cobalt-chromium alloy and gold cylinder for implant superstructure: Bond strength and corrosion resistance.

PURPOSE: The aim of this in vitro study was to evaluate tensile bond strengths and corrosion resistance of CoCr alloys joined with gold cylinder by a soldering system in comparison with the conventional cast-joining system. METHODS: CoCr alloys joined with gold cylinder by a soldering system using a high-fusing gold solder (CoCr/Solder/Gold cylinder), gold alloy joined with gold cylinder by a cast joining system (Gold alloy/Gold cylinder) and CoCr castings were fabricated. The tensile bond strength and corrosion resistance in 0.9% NaCl solution (pH 7.4 and pH 2.3) were evaluated. Scanning electron microscopy (SEM) of the fractured surface and electron probe microanalysis (EPMA) of the joined interfaces were also performed. RESULTS: The tensile bond strengths of the CoCr/Solder/Gold cylinder specimens showed similar values as the Gold alloy/Gold cylinder specimens. SEM observation and EPMA analyses suggested firm bonding between the CoCr alloy and gold cylinder. The released elements from the CoCr/Solder/Gold cylinder specimens were similar to ones from CoCr castings. CONCLUSIONS: Results showed that superstructures made of CoCr alloys joined with the gold cylinder using a high-fusing gold solder had sufficient bond strength and high corrosion resistance. These hybrid frameworks with cobalt-chromium alloy and gold cylinder are promising prosthesis for implant superstructures with the low cost and favorable mechanical properties instead of conventional high-gold alloys.

Ultrasonic Welding of Thermoplastic Composite Coupons for Mechanical Characterization of Welded Joints through Single Lap Shear Testing.

This paper presents a novel straightforward method for ultrasonic welding of thermoplastic-composite coupons in optimum processing conditions. The ultrasonic welding process described in this paper is based on three main pillars. Firstly, flat energy directors are used for preferential heat generation at the joining interface during the welding process. A flat energy director is a neat thermoplastic resin film that is placed between the parts to be joined prior to the welding process and heats up preferentially owing to its lower compressive stiffness relative to the composite substrates. Consequently, flat energy directors provide a simple solution that does not require molding of resin protrusions on the surfaces of the composite substrates, as opposed to ultrasonic welding of unreinforced plastics. Secondly, the process data provided by the ultrasonic welder is used to rapidly define the optimum welding parameters for any thermoplastic composite material combination. Thirdly, displacement control is used in the welding process to ensure consistent quality of the welded joints. According to this method, thermoplastic-composite flat coupons are individually welded in a single lap configuration. Mechanical testing of the welded coupons allows determining the apparent lap shear strength of the joints, which is one of the properties most commonly used to quantify the strength of thermoplastic composite welded joints.