Three-dimensional finite element analysis of cement flow in abutment margin-crown platform switching / 北京大学学报(医学版)

OBJECTIVE@#To analyze the cement flow in the abutment margin-crown platform switching structure by using the three-dimensional finite element analysis, in order to prove that whether the abutment margin-crown platform switching structure can reduce the inflow depth of cement in the implantation adhesive retention.@*METHODS@#By using ANSYS 19.0 software, two models were created, including the one with regular margin and crown (Model one, the traditional group), and the other one with abutment margin-crown platform switching structure (Model two, the platform switching group). Both abutments of the two models were wrapped by gingiva, and the depth of the abutment margins was 1.5 mm submucosal. Two-way fluid structure coupling calculations were produced in two models by using ANSYS 19.0 software. In the two models, the same amount of cement were put between the inner side of the crowns and the abutments. The process of cementing the crown to the abutment was simulated when the crown was 0.6 mm above the abutment. The crown was falling at a constant speed in the whole process spending 0.1 s. Then we observed the cement flow outside the crowns at the time of 0.025 s, 0.05 s, 0.075 s, 0.1 s, and measured the depth of cement over the margins at the time of 0.1 s.@*RESULTS@#At the time of 0 s, 0.025 s, 0.05 s, the cements in the two models were all above the abutment margins. At the time of 0.075 s, in Model one, the gingiva was squeezed by the cement and became deformed, and then a gap was formed between the gingiva and the abutment into which the cement started to flow. In Model two, because of the narrow neck of the crown, the cement flowed out from the gingival as it was pressed by the upward counterforce from the gingival and the abutment margin. At the time of 0.1 s, in Model one, the cement continued to flow deep inside with the gravity force and pressure, and the depth of the cement over the margin was 1 mm. In Model two, the cement continued to flow out from the gingival at the time of 0.075 s, and the depth of the cement over the margin was 0 mm.@*CONCLUSION@#When the abutment was wrapped by the gingiva, the inflow depth of cement in the implantation adhesive retention can be reduced in the abutment margin-crown platform switching structure.

The assessment of periimplant soft tissue condition with morse taper abutment connection: a rapid review

Aim: This study aims to evaluate the clinical assessment results of periimplant soft tissue with morse taper (internal abutment connection). Methods: The study was conducted using a rapid review by searching the articles from PubMed NCBI and Cochrane by using keywords. All articles were selected by the year, duplication, title, abstract, full-text, and finally, all selected articles were processed for final review. Following clinical parameters were included; Periimplant Probing Pocket Depth (PPD), Plaque Score (PS), modified Plaque Index (mPI), Mucosal Thickness (MTh), Gingival Height (GH), periimplant mucosal zenith, Pink Esthetic Score (PES), Bleeding On Probing (BOP), Sulcus Bleeding Index (SBI), and modified Gingival Index (mGI). Results: 9 selected articles were obtained from the initial literature searching count of 70 articles. The overall samples included 326 morse taper implants. Based on the evaluation, 3 out of 4 articles reported pocket depth < 4 mm, no bleeding was reported in 2 out of 4 articles. 4 out of 4 articles reported low plaque accumulation, low soft tissue recession was reported in 3 out of 3 articles, and 4 out of 4 articles reported acceptable PES values. Conclusion: The evaluations indicate that the morse taper (internal abutment connection) has favorable assessment results based on various clinical parameters

Avaliação do tipo de retenção e o uso de diferentes intermediários na adaptação de próteses unitárias sobre implantes / Evaluation of the type of retention and the use of different abutments in the adaptation of single prostheses on implants

Atualmente, devido a perda do elemento dentário e a procura por um tratamento estético e principalmente funcional, a reabilitação com próteses sobre implante tem sido amplamente empregada, com elevada previsibilidade a longo prazo. Com isso, muito tem sido relatado na literatura acerca das possíveis complicações dessa modalidade de tratamento, principalmente relacionado às possibilidades de falhas mecânicas das próteses implantossuportadas. Por isso, o objetivo do presente projeto foi avaliar a influência na adaptação marginal e interna, da utilização do intermediário protético e do tipo de retenção das próteses (parafusada e cimentada) em implantes cone morse submetidos à ciclagem mecânica. Foram confeccionados 40 corpos de prova, no qual cada um tinha a presença de um implante, com as dimensões de 4mm de diâmetro e 11,5mm de comprimento cone morse (n = 40). Dessa forma, foi avaliado a influência da utilização do intermediário e dos sistemas de retenção em cada conexão de maneira específica. Metade dos corpos de prova de cada sistema de conexão foram confeccionados em UCLA (n=20, sendo 10 parafusadas e 10 cimentadas), enquanto que a outra metade foi utilizado um intermediário pré-fabricado (Pilar Universal (n=20, sendo 10 parafusadas e 10 cimentadas). Os corpos de prova foram submetidos à ciclagem mecânica submersos em água destilada simulando um tempo clínico de cinco anos. Além disso, foram avaliados quanto ao torque e destorque (N) e adaptação marginal e interna (µm) antes e após a ciclagem mecânica. Os dados provenientes das mensurações foram organizados em tabela em formato Excel (Microsoft Office Excel, Redmond, WA, Estados Unidos) e submetidos ao software SigmaPlot (SigmaPlot, San Jose, CA, EUA) versão 12.0. Todos os dados foram analisados inicialmente com a utilização da estatística descritiva. Em seguida, os dados para intrusão (valores positivos), extrusão (valores negativos), destorque inicial, destorque final, e descimentação foram analisados em relação a distribuição de normalidade (teste Shapiro-Wilk e igualdade de variância) e, posteriormente, foi adotada a Análise de Variância (ANOVA) a um fator (Grupos diferentes materiais: G1 a G4), quando houve normalidade dos dados, o pós teste de Tukey foi adotado para as comparações múltiplas, quando não foi identificado uma distribuição normal, empregou-se o teste de Kruskall-Wallis e pós-teste de Dunn's ou Tukey, semelhantemente foi realizada a análise específica das variáveis pilares (UCLA e Pilar Universal) e sistemas de retenção (Parafusado e Cimentado). Para todos os testes aplicou-se nível de significância de 5% (α=0,05). A análise gráfica foi considerada através de um gráfico de barras para os dados que apresentaram normalidade com valores de média e desvio padrão, e as demais análises que não apresentaram normalidade foi considerado a confecção de um boxplot para cada grupo comparativo. As próteses sobre implante utilizando pilares em zircônia tem ganhado cada vez mais espaço, além do estudo in vitro, foi realizada uma revisão sistemática para comparar a perda óssea marginal e as complicações próteticas de reabilitações utilizando pilares de zircônia cimentado e parafusado. Em relação as próteses cimentadas e parafusadas, devido as evidências conflitantes e a presença de muitas revisões sistemáticas sobre o tema, foi realizada uma overview de revisões sistemáticas, com o objetivo de compilar as informações disponiveis e avaliar a qualidade metodologica desses estudos a respeito das complicações presentes nas próteses sobre implante cimentadas ou parafusadas(AU)

Currently, due to the loss of the dental element and the search for an aesthetic and mainly functional treatment, rehabilitation with implant prostheses has been widely used, with high long-term predictability. Thus, much has been reported in the literature about the possible complications of this treatment modality, mainly related to the possibility of mechanical failure of implant-supported prostheses. Therefore, the objective of the present project was to evaluate the influence on the marginal and internal adaptation, the use of the prosthetic intermediate and the type of retention of the prostheses (screwed and cemented) in morse taper implants submitted to mechanical cycling. 40 specimens were made, in which each one had an implant, with dimensions of 4 mm in diameter and 11.5 mm in length (n = 40). In this way, the influence of the use of intermediaries and retention systems in each connection was evaluated in a specific way. Half of the specimens of each connection system were made in UCLA (n=20, being 10 screwed and 10 cemented), while the other half was used a prefabricated intermediate (Universal Abutment (n=20, being 10 screwed) and 10 cemented). The specimens were submitted to mechanical cycling submerged in distilled water simulating a clinical time of five years. In addition, they were evaluated for torque and detorque (N) and marginal and internal adaptation (µm) before and after mechanical cycling. Data from measurements were organized in a table in Excel format (Microsoft Office Excel, Redmond, WA, USA) and submitted to SigmaPlot software (SigmaPlot, San Jose, CA, USA) version 12.0. All data were initially analyzed using descriptive statistics. Then, data for intrusion (positive values), extrusion (negative values), initial detorque, final detorque, and debonding were analyzed in relation to dist determination of normality (Shapiro-Wilk test and equality of variance) and, later, the one-way Analysis of Variance (ANOVA) was adopted (Different material groups: G1 to G4), when there was normality of the data, the Tukey post test was adopted for multiple comparisons, when a normal distribution was not identified, the Kruskall-Wallis test and Dunn's or Tukey post-test were used, similarly the specific analysis of the pillar variables (UCLA and Universal Pillar) and systems retainer (Screwed and Cemented). For all tests, a significance level of 5% (α=0.05) was applied. The graphical analysis was considered through a bar graph for the data that presented normality with mean and standard deviation values, and the other analyzes that did not present normality was considered the creation of a boxplot for each comparative group. Implant prostheses using zirconia abutments have gained more and more space, in addition to the in vitro study, a systematic review was performed to compare marginal bone loss and prosthetic complications of rehabilitations using cemented and screwed zirconia abutments. Regarding cemented and screw-retained prostheses, due to conflicting evidence and the presence of many systematic reviews on the subject, an overview of systematic reviews was performed, with the objective of compiling the available information and evaluating the methodological quality of these studies regarding complications present in cemented or screw-retained implant prostheses(AU)

Patient Satisfaction and Pink Esthetics of PEEK Versus Zirconium Abutments in the Esthetic Zone (A Randomized Controlled Trial) / Satisfação do paciente e estética rosa dos pilares PEEK versus Zircônia na zona estética (um ensaio clínico randomizado)

Objective: This study was performed to evaluate the use of PEEK abutments versus zirconium abutments with lithium disilicate superstructure on the esthetic acceptance and peri-implant clinical parameters. Zirconium abutments were found to have high surface roughness even after polishing. This causes a remarkable collapse of the soft tissue papilla that is a primary factor in the Pink Esthetic Score(PES), resulting in failed esthetic restoration in the anterior esthetic zone. Material and Methods:Twenty patients who needed a single implant restoration in the esthetic zone were included in this study. Eighteen patients completed screening, baseline, three-month, six-month, and twelve-month follow-up visits. At the screening visit, the patients were randomly allocated into two groups: Zirconia abutments (A) Group, and PEEK abutments (B) Group, both of which were restored with IPS e.max CAD superstructure. Patients Satisfaction was assessed by visual analogue scale (VAS). Pink esthetics score (PES), modified plaque index (mPI) and modified gingval index (mGI) were also assessed. Results: All implants were successfully osseo-integrated with a 100% survival rate over one year. Patient satisfaction was significantly higher for the PEEK group than the zirconium group. The pink esthetic score showed no statistical significance between both groups. The modified plaque index was significantly lower for the PEEK group than the zirconium group. The modified gingival index showed no statistical difference between both groups. Conclusion: PEEK revealed to be a versatile material to replace zirconium for implant abutments, due to its lower plaque affinity and higher patient satisfaction (AU)

Objetivo: Este estudo foi realizado para avaliar o uso de pilares PEEK versus pilares de zircônia com estrutura de dissilicato de lítio quanto a aceitação estética e parâmetros clínicos peri-implantares. Os pilares de zircônia apresentam alta rugosidade superficial, mesmo após o polimento. Isso causa um colapso notável da papila do tecido mole, que é um fator primário no índice estético rosa (Pink Esthetic Score - PES), resultando em falha na restauração estética na zona estética anterior. Materiais e Métodos:Vinte pacientes que precisavam de um implante unitário na zona estética foram incluídos neste estudo. Dezoito pacientes completaram a triagem, a consulta inicial e as visitas de acompanhamento de três, seis e doze meses. Durante a triagem, os pacientes foram aleatoriamente divididos em dois grupos: Grupo Pilares de Zircônia (A) e Grupo de Pilares PEEK (B), ambos foram restaurados com IPS e.max CAD. A satisfação dos pacientes foi avaliada pela escala visual analógica (VAS). O PES, o índice de placa modificado (mPI) e o índice gengival modificado (mGI) também foram avaliados. Resultados: Todos os implantes foram osseointegrados com sucesso, com uma taxa de sobrevivência de 100% ao longo de um ano. A satisfação do paciente foi significativamente maior para o grupo PEEK quando comparado com o grupo de pilares de zircônia. O índice da estética rosa não apresentou significância estatística entre os dois grupos. O índice de placa modificado foi significativamente menor para o grupo PEEK quando comparado com o grupo de pilares de zircônia. Conclusão: O PEEK revelou-se um material versátil para substituir a zircônia em pilares de implante, devido a sua menor afinidade de placa e maior satisfação do paciente. (AU)

Implant volume loss, misfit, screw loosening, and stress in custom titanium and zirconia abutments

Abstract The aim of this study was to verify the effect of the implant volume loss, vertical misfit between abutment and prosthetic platform, prosthetic screw loosening torque, and screw stress distribution in titanium and zirconia abutments. Ten CAD/CAM system custom abutments of each material were milled and attached to the titanium implants. The implant volume loss was evaluated by microtomography, the vertical misfit with optical microscopy, and digital torque wrench measured the prosthetic screw loosening. All experimental analyses were performed before and after mechanical cycle (1,000,000 cycles, 100 N/2 Hz). Virtual models of the structures were created for finite element analysis, and the stress on the screw obtained with von Mises procedure. Data were analyzed using an independent t-test, two-way ANOVA for repeated measures, and Tukey's HSD test (a=0.05). There was no significant difference in the implant volume loss for the two abutment materials (p=0.662). Titanium abutments provided higher loosening torque values after mechanical cycling (p<0.001). Lesser marginal misfit was obtained with titanium abutments before and after mechanical cycling (p<0.001). The stress distribution on the screw was similar between abutment materials. In conclusion, CAD/CAM custom titanium abutment reduced the marginal misfit and increased the torque maintenance of prosthetic screws when compared to CAD/CAM custom zirconia abutment.

Resumo O objetivo neste estudo foi verificar o efeito da diminuição de volume do implante, desajuste vertical entre o pilar e plataforma protética, torque de afrouxamento do parafuso protético e distribuição da tensão no parafuso em pilares de titânio e zircônia. Dez pilares personalizados de cada material foram fresados e conectados aos implantes de titânio. A diminuição de volume do implante foi avaliada com microtomografia, o desajuste vertical com microscopia óptica e o torque de afrouxamento do parafuso protético com chave de torque digital. Todas as análises experimentais foram realizadas antes e após aplicação do ciclo mecânico (1.000.000 ciclos, 100 N/2 Hz). Modelos virtuais das estruturas foram criados para análise por elementos finitos e a tensão no parafuso obtida com valores de von Mises. Os dados foram analisados usando teste t independente, análise de varância dois fatores para medidas repetidas e teste de Tukey HSD (a=0,05). Não houve diferença significativa na diminuição de volume do implante para os dois materiais do pilar (p= 0,662). Os pilares de titânio proporcionaram maiores valores de torque de afrouxamento após o ciclo mecânico (p<0,001). O menor desajuste marginal foi obtido com os pilares de titânio antes e após o ciclo mecânico (p<0,001). A distribuição da tensão no parafuso foi similar entre os materiais. Em conclusão, os pilares personalizados de titânio reduziram o desajuste marginal e aumentaram a manutenção do torque dos parafusos protéticos quando comparados aos pilares de zircônia.

Prótesis sobre implantes: ¿atornillada o cementada? / Implant supported prosthesis: screw retained or bonded?

El objetivo de este artículo es revisar la evidencia científica existente acerca de los tipos de retención protética fija sobre implantes: atornillada, cementada y cemento-atornillada. Fueron evaluadas sus ventajas y desventajas a fin de facilitar al clínico la elección del sistema de retención en el tratamiento rehabilitador con implantes. Si bien la evidencia científica no es concluyente, la prótesis atornillada presentaría más complicaciones técnicas, y las cementadas, más complicaciones biológicas. Por ello, las prótesis cemento-atornilladas podrían ser en la actualidad una opción de elección, por su versatilidad en la rehabilitación implanto-soportada, combinando las ventajas de cada tipo de retención (AU)

The objective of this article is to review the existing scientific evidence about the different types of retention of fixed prosthetic on implants: screwed, cemented and cement-screwed. The advantages and disadvantages of them were evaluated in order to facilitate the clinician's choice of the retention system in the rehabilitation treatment with implants. Although the scientific evidence is inconclusive, the screwed prosthesis would present more technical complications, while the cemented, more biological complications. Therefore, cement-screwed prostheses could be an option of choice, due to their versatility when rehabilitating an implant, combining the advantages of each type of retention (AU)

Internal and marginal fit and fracture strength of narrow diameter dental implant-abutment assembly

Abstract The aim of this study was to assess the internal and vertical marginal fit of metallic copings to abutments and the fracture strength of different narrow diameter dental implant/abutments, either submitted to thermomechanical cycling or not. Sixty-four implant/abutments (n=16) were divided into 4 groups according to diameter and abutment type: G3.5-UAC (morse taper implant Ø3.5mm + universal abutment with beveled chamfer finish); G2.9-UAS (morse taper implant Ø2.9mm + universal abutment with shoulder finish); G2.8-AA (morse taper friction implant Ø2.8mm + anatomical abutment) and G2.5-HP (one-piece implant Ø2.5mm with indexed hexagonal platform). Each group was divided into two subgroups (n=8): submitted and not submitted to thermomechanical cycling (TMC). To assess internal and vertical marginal fit of metallic copings, the assemblies were scanned using microtomography (micro-CT) (n=5). The samples were subjected to the compressive strength test on a universal test machine. Group G3.5-UAC showed the highest marginal misfit regardless of TMC (p<0.05). All other groups were similar after TMC. Group G2.8-AA showed the lowest internal misfit both with and without TMC (p<0.05). Group G2.8-AA showed the highest fracture strength, similar only to G2.5-HP without TMC and G3.5-UAC with TMC. The type of abutment affects the internal and marginal fit of metallic copings and the anatomical abutment led to the best internal and marginal coping fit. The narrow diameter dental implant/abutments differ in terms of fracture strength, the strongest assembly was that composed by implant of type V grade titanium without internal threads (friction implant).

Resumo O objetivo deste estudo foi avaliar a adaptação marginal e interna de cópings metálicos em pilares sobre implantes, e a resistência a fratura de diferentes conjuntos de implantes/pilares de diâmetro reduzido, submetidos à ciclagem termomecânica ou não. Sessenta e quatro implantes/pilares (n=16) foram divididos em 04 grupos de acordo com o tipo de pilar e diâmetro do implante: G3.5-UAC (implante cone morse Ø3.5mm + munhão universal com término em chanfro); G2.9-UAS (implante cone morse Ø2.9mm + munhão universal com término em ombro); G2.8-AA (implante cone morse friccional Ø2.8mm + munhão anatômico); e G2.5-HP (implante de corpo único de Ø2.5mm com plataforma hexagonal indexada). Cada grupo foi dividio em dois subgrupos (n=8): submetidos ou não à ciclagem termomecânica (TMC). As amostras foram escaneadas por microtomografia (micro-CT) para avaliar a adaptação interna e marginal vertical dos copings metálicos. As amostras foram submetidas à resistência à compressão em uma maquina de ensaios universal. O grupo G3.5-UAC apresentou os maiores valores de desadaptação marginal independentemente da TMC (p<0,05). Todos os outros grupos foram similares entre si após TMC. O grupo G2.8-AA demonstrou o menor desajuste interno independentemente de TMC (p<0,05). O grupo G2.8-AA demonstrou a maior resistência à fratura, similar apenas ao grupo G2.5-HP sem TMC e G3.5-UAC com TMC. O tipo de pilar influencia a adaptação interna e marginal vertical de copings metálicos. O grupo do pilar anatômico (sem entalhes na superfície) levou à melhor adaptação, enquanto o grupo com plataforma expandida hexagonal e os grupos com munhão universal (com entalhes na superfície) proporcionaram os maiores desajustes (especialmente com termino em chanfro). Os implantes/pilares de diâmetro reduzido diferem em termos de resistencia à fratura, sendo que o conjunto mais resistente foi aquele composto por titânio tipo V e sem roscas internas (implante friccional).

Comparison of residual cement between CAD/CAM customized abutments and stock abutments via digital measurement in vitro / 北京大学学报(医学版)

OBJECTIVE@#To compare the residual cement between computer aided design/computer aided manufacturing customized abutments (CCA) and stock abutments (SA), and to evaluate the feasibility of digital measurement for residual cement volume by three-dimensional scanning.@*METHODS@#Twenty master models needed in this study were all taken from one 47-year-old patient with arrested periodontitis, who had already had an implant placed at his right upper central incisor site in the Department of Periodonto-logy, Peking University School and Hospital of Stomatology. After 4 weeks of soft tissue conditioning by means of customized healing abutment, the height of peri-implant soft tissue was measured, from the implant platform to mucosal margin, as 5 mm. Using customized impression coping, the impression was taken and twenty models were fabricated and allocated to 4 groups according to the type of abutments: CCA1 (5 mm transmucosal height CCA, with margin at tissue level), CCA2 (4 mm transmucosal height CCA, with 1 mm submucosal margin), SA1 (3 mm transmucosal height SA, with 2 mm submucosal margin) and SA2 (1 mm transmucosal height SA, with 4 mm submucosal margin). Crowns were cemented to the abutments, which were seated on the working models. Excess cement was removed by a prosthodontic specialist. Thereafter, the volume of residual cement was evaluated by using three-dimensional scanning technique. The area proportion of residual cement was calculated on photographs taken by a single lens reflex camera. The weight of residual cement was weighed by an analytical balance. And the correlation of residual cement volume data with residual cement area proportion or weight of residual cement acquired by traditional methods was analyzed.@*RESULTS@#Residual cement was observed on all the experiment samples. The residual cement volume of CCA was significantly less than that of SA [(0.635 3±0.535 4) mm3 vs. (2.293 8±0.943 8) mm3, P < 0.001]. Consistently, CCA had less residual cement area proportion and weight than those of SA [area proportion: 7.57%±2.99% vs. 22.68%±10.06%, P < 0.001; weight: (0.001 5±0.001 0) g vs. (0.003 7±0.001 4) g, P < 0.001]. The residual cement volume was strongly correlated with the residual cement area proportion and residual cement weight (r>0.75, P < 0.001).@*CONCLUSION@#These in vitro results suggest that CCA minimized the residual cement more effectively than SA. The method to digitally evaluate the residual cement volume is feasible, but its validity and reliability need to be further studied.

Three-dimensional misfit between Ti-Base abutments and implants evaluated by replica technique

Abstract An important factor affecting the biomechanical behavior of implant-supported reconstructions is the implant-abutment misfit. Objective: This study evaluated the misfit between Ti-Base abutments and implants by means of polyvinyl siloxane replica technique using microcomputed tomography (μCT). Methodology: Volumetric and linear (central and marginal) gaps of four Ti-base abutments (n=10/group): (i) Odontofix LTDA (OD), (ii) Singular Implants (SING), (iii) EFF Dental Components (EFF), and (iv) Control Group (S.I.N implants) compatible with an implant system (Strong SW, S.I.N Implants) were measured using μCT reconstructed polyvinyl siloxane replicas. Results: The results showed significantly lower volume gap for Control S.I.N (0.67±0.29 mm3) and SING (0.69±0.28 mm3) Ti-base abutments relative to OD (1.42±0.28 mm3) and EFF groups (1.04±0.28 mm3) (p<0.033), without significant difference between them (p=0.936). While gap values were homogenous in the central region, EFF presented a significantly higher marginal gap. Accordingly, the Control S.I.N and Singular Ti-base abutments showed improved volumetric and marginal fit relative to Odontofix and EFF. Conclusion: The method of manufacturing abutments influenced the misfit at the implant-abutment interface.

Prótese Parcial Fixa em Cantilever, uma opção de tratamento: Revisão da Literatura / Fixed Partial Denture with Cantilever an option for therapeutic: Literature Review

Hoje em dia no consultório a indicação de uma prótese fixa em cantilever, ainda gera muitas dúvidas, levando o clinico inseguro, muitas vezes a sua contra indicação. Com intuito de esclarecer as características relacionadas à prótese parcial fixa em cantilever realizou- -se uma revisão de literatura. Uma busca foi realizada nas bases de dados Scielo e Pubmed usando-se as palavras-chaves: Prótese fixa, cantilever, dentes suportes. Os artigos dentro do escopo do estudo foram selecionados e pode-se concluir que estas próteses são uma excelente alternativa conservadora para restabelecimento de dentes perdidos, porém para obtenção de resultados satisfatórios com boa longevidade, especial atenção deve ser desprendida aos princípios biomecânicos dos preparos e um controle rigoroso de placa bacteriana deve ser estabelecido.

Actuality the use of Fixed Partial Denture with Cantilever until causes many doubts, making de dentist do not indicate this treatment. To making clear the characteristics relation to this prosthesis, was done a literature review. A search was performed in the Scielo and Pubmed databases using the keywords: Fixed prosthesis, cantilever, supporting teeth. The articles within the scope of the study were selected and it can be concluded that these were an alternative excellent to reestablish the follow teeth, therefore to obtain the good results with respect long-term prosthetic appliances, special attention should be dispensed to the biomechanics principles and optimal hygiene with plaque control should be established.

A technique to design the framework of removable partial denture by multi-stage expert system / 华西口腔医学杂志

This study aims to apply a new expert system to design removable partial denture (RPD) framework. The RPD design is completed in three steps, namely, "selecting missing teeth", "selecting abutment condition", and "selecting personalized clasp". The system can help auxiliary dentists develop personalized treatment plans to reduce their clinical workload. It can also generate a dental preparation guideline for clinical preparation, which can prevent tooth preparation mistakes. By generating the standard electronic drawings of the framework design, the system can reduce the inconvenience caused by manual drawing, thereby facilitating dentist-technician communication and reducing the rate of remade.

Manejo de tejidos blandos en implantes con carga inmediata del sector anterosuperior: reporte de caso clínico / Handling of soft tissues of an immediate loading implant on the upper anterior sector: report of a clinical case

Los implantes dentales se han colocado en sitios de extracción cicatrizados mediante un procedimiento quirúrgico en dos etapas para un periodo de tres a seis meses sin carga. Sin embargo, los pacientes esperan ser rehabilitados lo antes posible, especialmente los pacientes sometidos a restauraciones estéticas en el maxilar anterior. Después de la colocación del implante, la fabricación de la restauración temporal y la carga del implante dentro de las 48 horas se denominan carga inmediata. Esto acorta el tiempo del tratamiento, ya que requiere menos intervenciones quirúrgicas, reduce la pérdida ósea crestal periimplantaria, conduce a la preservación de la morfología de los tejidos blandos y mejora la estética. En este artículo se hablará del caso clínico de un paciente femenino de 44 años de edad que presentaba pérdida del órgano dentario 21. Se realizó valoración periodontal, radiográfica y tomográfica de este órgano dentario, se colocó implante con la utilización de guía quirúrgica y protésica acrílica termocurable, se realizó carga inmediata, el provisional fue conformado con contorno subgingival cóncavo y se toman en cuenta criterios de contorno crítico y subcrítico para el desarrollo ideal del perfil de emergencia. En las citas de valoración se encontraron los tejidos periimplantales estables y la paciente no refirió sintomatología (AU)

Dental implants have been placed in scarred extraction sites by a twostage surgical procedure for a period of three to six months without load. However, patients expect to be rehabilitated as soon as possible, especially patients undergoing esthetic restorations in the anterior maxilla. After implant placement, the fabrication of the temporary restoration and implant loading within 48 hours are called immediate loading. This shortens the time of treatment, beacause it requires fewer surgical interventions, reduces peri-implant crestal bone loss, leads to the preservation of soft tissue morphology and improves aesthetics. In this article we will discuss the clinical case of a 44-year-old female patient who had lost the dental organ 21. Periodontal, radiographic and tomographic assessment of this dental organ was performed, an implant was placed with the use of surgical guide and acrylic prosthesis thermocurable, immediate loading was performed, the provisional was formed with a concave subgingival contour and critical and subcritical contour criteria were taken into account for the ideal development of the emergence profile. In the assessment appointments stable periimplant tissues were found and the patient did not report symptoms (AU)

Influence of abutment collar height and implant length on stress distribution in single crowns

Abstract This in silico study evaluated the influence of the abutment collar height and implants length on the biomechanical behavior of morse taper single dental implants with different crown-to-implant ratio. Six virtual models were constructed (S11, M11, L11, S13, M13 and L13) by combining short (S: 2.5 mm), medium (M: 3.5 mm) or long (L: 4.5 mm) abutment collar heights with different implant lengths (11 or 13-mm). An upper central incisor of 11-mm height was constructed on top of each abutment. Each set was positioned in a virtual bone model and exported to analyze mathematically. A 0.60-mm mesh was created after convergence analysis and a 49 N load was applied to the cingulum of the crown at an angle of 45°. Load-generated stress distribution was analyzed in the prosthetic components according to von Mises stress criteria (σvM) and in the cortical and cancellous bone by means of shear stress (εmax). The use of longer collar abutments (L11) increased the stress on the abutment by 250% and resulted in 40% higher stresses on the screw and 92% higher cortical shear stresses compared to short collared abutments (S11). Increasing the implant length produced a slight stress reduction on cortical bone. Cancellous bone was not affected by the crown-to-implant ratio. Longer abutment collars concentrate stresses at the implant level and cortical bone by increasing the crown-to-implant ratio.

Resumo Este estudo avaliou a influência da altura da porção transmucosa do pilar protético com junção cone morse e do comprimento dos implantes no comportamento biomecânico coroas unitárias com diferentes proporção coroa-implante. Seis modelos virtuais (S11, M11, L11, S13, M13 e L13) foram construídos combinando pilares protéticos com transmucoso considerado: curto (S: 2,5 mm), médio (M: 3,5 mm) ou longo (L: 4,5 mm) com diferentes comprimentos de implantes (11 ou 13 mm). Um incisivo central superior de 11 mm de altura foi construído para cada pilar. Cada conjunto foi posicionado em um modelo de osso virtual e exportado para análise matemática. Uma malha de 0,60 mm foi criada após análise de convergência e uma carga de 49 N foi aplicada ao cíngulo da coroa em um ângulo de 45°. A distribuição de estresse gerada por carga foi analisada nos componentes protéticos de acordo com o critério de tensão de von Mises (σvM) e no osso cortical e medular por meio da tensão de cisalhamento (εmax). O uso de pilares com porção transmucosa mais longa (L11) aumentou a tensão no pilar protético em 250%, e resultou em tensões 40% maiores no parafuso e 92% no osso cortical em relação aos pilares com transmucoso curto (S11). O aumento do comprimento do implante produziu uma ligeira redução da tensão de cisalhamento no osso cortical. O osso medular não foi afetado pela relação coroa-implante. Pilares protéticos com porção transmucosa mais longa concentram tensões no implante e no osso cortical, quando a proporção coroa-implante é aumentada.

Failure probability, stress distribution and fracture analysis of experimental screw for micro conical abutment

Abstract The aim of this study was to evaluate the failure probability of two types of abutment screws after compressive load and to analyze the stress distribution with finite element method. Sixty (60) single-tooth implant restorations were assembled on titanium implants (e-fix, A.S. Technology - Titanium Fix). The groups were divided into Conventional screw (Screw neck 1.5 ø mm) and Experimental screw (Screw neck constricted with 1.2 ø mm). Specimens were subjected to single load to failure with compressive test according ISO 14801. The fractured specimens were subjected to stereomicroscopy for measurement of remaining screws inside the implant and characterization of fracture origin. Representative specimens were analyzed by scanning electronic microscopy. For finite element method (FEM), an identical 3D model of the two in vitro test groups were used with similar conditions (30º, 100 N load). The stress in the abutment screw was analyzed by von-Mises criteria. The results of strength means were 4132.5 ± 76 MPa and 4528.2 ± 127.2 for conventional and experimental groups, respectively. During microscopy, the mean (mm) of the remaining screw piece inside the implants were 0.97 ± 0.23 and 1.32 ± 0.12 for conventional and experimental groups, respectively. In FEM, the conventional group showed stress concentered in an unfavorable region (peak of 39.23 MPa), while the experimental group showed more stress areas but less concentration than the conventional group (36.6 MPa). In using the tested experimental geometry, the abutment screw can have its strength improved, and the origin of failure can be more favorable to clinical resolution.

Resumo O objetivo deste estudo foi avaliar a probabilidade de falha de dois tipos de parafusos para pilar protético após a compressão e analisar a distribuição da tensão com o método dos elementos finitos. Sessenta (60) restaurações unitárias foram montadas em implantes de titânio (e-fix, A.S. Technology - Titanium Fix). Os grupos foram divididos em parafusos convencionais (parafuso de pescoço 1,5 ø mm) e parafuso experimental (parafuso de pescoço estreitado com 1,2 ø mm). As amostras foram sujeitas ao teste de compressão de acordo com ISO 14801. Os espécimes fraturados foram submetidos a estereomicroscopia para a mensuração dos parafusos restantes dentro do implante e caracterização da origem da fratura. Os espécimes representativos foram analisados ​​por microscopia eletrônica de varredura. Para o método de elementos finitos (FEM), utilizou-se um modelo 3D idêntico dos dois grupos de teste in vitro com condições semelhantes (30º, 100 N). A tensão no parafuso do pilar foi analisada pelo critério de von-Mises. Os resultados de resistência a compressão foram 4132,5 ± 76 MPa e 4528,2 ± 127,2 para grupos convencionais e experimentais, respectivamente. Durante a microscopia, a média do remanescente do parafuso restante dentro dos implantes foi de 0,97 ± 0,23 e 1,32 ± 0,12 mm para os grupos convencionais e experimentais, respectivamente. Em FEM, o grupo convencional mostrou tensão concentrada em uma região desfavorável (pico de 39,23 MPa), enquanto o grupo experimental apresentou mais áreas de tensão, porém menor concentração do que o grupo convencional (36,6 MPa). Ao usar a geometria experimental testada, o parafuso do pilar pode ter sua resistência melhorada e a origem da falha pode ser mais favorável à resolução clínica.

Does the implant-abutment interface interfere on marginal bone loss? A systematic review and meta-analysis

Abstract The objective of this systematic review was to compare the conical internal connection (IC) with the external hexagonal connection (EH) on the occurrence of marginal bone loss (ΔMBL). Different databases were used to carry out the selection of the elected studies. The studies were judged according to the risk of bias as "high", "low" and "unclear" risk. For the meta-analysis we included only studies that could extract the data of ΔMBL, survival rate (SR) and probing depth (PD). No statistically significant differences were found for ΔMBL data at one, three- and five-year survival rates between implant connections (p <0.05), however statistically significant differences were found for PD between EH and IC implants (1-year follow-up) -0.53 [95%CI -0.82 to -0.24, p = 0.0004]. This present systematic review demonstrated that there are no significant differences between IC and EH implants for both ΔMBL and SR at 1, 3 e 5 years after functional loading, although better PD values were observed for implants pertaining to the IC connections. Considering the high heterogeneity, more well-delineated, randomized clinical trials should be conducted.

Traitement par la technique de Latarjet des instabilités antérieures de l'épaule au centre hospitalier de l'Ordre Malte de Dakar

Introduction : Le but de cette étude était d'évaluer les résultats cliniques et radiologiques des patients ayant une instabilité antérieure traitée par la technique de Latarjet. Patients et méthodes : Dans cette étude rétrospective 14 patients (15 épaules) ont été opérés entre janvier 2013 et décembre 2016 pour une luxation récidivante de l'épaule selon la technique de Latarjet à foyer ouvert. La fonction de l'épaule a été appréciée selon les cotations de Rowe, Duplay , et WOSI (the Western Ontario ShoulderInstability). Les résultats radiographiques ont concerné la consolidation du greffon et la position de la butée. Résultats : Le recul moyen était de 34 mois (7- 64). Douze patients étaient très satisfaits de la stabilité et de la fonction de leur épaules. il n'y avait pas de récidive. Selon la cotation de Walch et Duplay les résultats étaient bons (n=13) et moyen (n=1). Selon Rowe ils étaient bons (n=13) et mauvais ( n=1). Selon la cotation WOSI ils étaient excellents ( n=8), bons ( n=4), et moyens (n=2). Toutes les butées ont consolidées. Elles étaient sous l'équateur. Elles étaient affleurantes (n=14), médiale (n=1). Conclusion : Ce travail suggère que la technique de Latarjet réalisée à foyer ouvert offre aux patients une stabilisation de l'épaule, des mobilités quasi-normales, et la possibilité de reprendre dans de bonnes conditions des activités professionnelles et sportives

Expert consensus on biomechanical research of dental implant / 华西口腔医学杂志

Current biomechanical research of dental implants focuses on the mechanical damage and enhancement mechanism of the implant-abutment interface as well as how to obtain better mechanical strength and longer fatigue life of dental implants. The mechanical properties of implants can be comprehensively evaluated by strain gauge analysis, photo elastic stress analysis, digital image correlation, finite element analysis, implant bone bonding strength test, and measurement of mechanical properties. Finite element analysis is the most common method for evaluating stress distribution in dental implants, and static pressure and fatigue tests are commonly used in mechanical strength test. This article reviews biomechanical research methods and evaluation indices of dental implants. Results provide methodology guidelines in the field of biomechanics by introducing principles, ranges of application, advantages, and limitations, thereby benefitting researchers in selecting suitable methods. The influencing factors of the experimental results are presented and discussed to provide implant design ideas for researchers.

Bruxismo e implantes dentales / Bruxism and dental implants

En ausencia de guías clínicas que permitan ponderar factores de riesgo para el manejo del paciente bruxista, respecto a los índices de supervivencia de los implantes dentales y restauraciones que soporta, se realiza esta revisión bibliográfi ca a través de una búsqueda electrónica, indagando cómo un incremento en la función muscular pudiera signifi car un factor de riesgo para el implante mismo o para sus diferentes componentes y tipos de diseño protésico. Fue encontrada una diversidad de información contrastante en cuanto a los efectos que tiene el bruxismo en pacientes que han recibido un tratamiento de implantes, respecto a diagnóstico, manejo y adecuaciones o compensaciones que pudieran ser requeridas. En este reporte se ofrecen algunas recomendaciones respecto a la valoración clínica de los individuos con historial de bruxismo para mejor estimar los riesgos de colocación de implantes en sus bocas y poder reducirlos o sobrepasarlos (AU)

The lack of clinical guides to assess the risk factor for the treatment of a patient with bruxism and its relationship with the survival rate of the dental implants and its restoration has motivated a literature review on the subject. This examination was done through an electronic search, looking for the possible association between an increased muscular function as a risk factor and the damage possibility to dental implants or their diff erent prosthetic components. The obtained information was rather contrasting regarding the eff ects that bruxism may lead on dental implant treatment, as well as on diagnosis, management, and treatment plan modifi cations. A number of recommendations are given regarding evaluations of individuals with bruxism to better estimate risk factors to control or overpass them in benefi t of the patients seeking rehabilitation through the use of dental implants (AU)

One Abutment at One Time Concept for Platform-Switched Morse Implants: Systematic Review and Meta-Analysis

Abstract The aim of this systematic review and meta-analysis was to compare the peri-implant vertical bone loss of immediate loading of implant crowns using the one abutment at one time (AOT) protocol and implants with abutment removal (AR). This systematic review with meta-analysis was reported according to the PRISMA statement, with guidance from the Cochrane Collaboration Handbook. A total of 103 publications were identified in the PubMed database and reference lists of examined articles. After the screening of titles and abstracts, the eligibility of eight full-text articles was assessed. Five studies published between 2010 and 2015 were included in the meta-analysis. There was less peri-implant vertical bone loss at implants using an AOT protocol than at implants using AR protocol (WMD -0.19, 95% CI -0.26 to -0.13; p<0.0001; random-effects model). In conclusion, the use of the AOT protocol with platform-switched Morse implants results in less bone loss than do AR procedures, but this effect may not be clinically relevant. The preservation of marginal bone level achieved with the AOT protocol may not enhance the aesthetics. These results should be interpreted with caution.

Resumo O objetivo desta revisão sistemática e meta-análise foi comparar a perda óssea vertical em implantes de carga imediata usando o protocolo de um pilar em um único momento (AOT) e implantes com remoção de pilar (AR). Esta revisão sistemática com meta-análise foi relatada de acordo com a declaração PRISMA, com orientação do Cochrane Collaboration Handbook. Foram identificadas 103 publicações na base de dados PubMed e nas listas de referência dos artigos examinados. Após a triagem de títulos e resumos, avaliou-se a elegibilidade de oito artigos de texto completo. Cinco estudos publicados entre 2010 e 2015 foram incluídos na meta-análise. Houve menos perda óssea vertical peri-implante em implantes usando o protocolo AOT do que nos implantes usando o protocolo AR (WMD -0,19, 95% IC -0,26 a -0,13; p <0,0001, modelo de efeitos aleatórios). Em conclusão, o uso do protocolo AOT com implantes Cone Morse associados a pilares com plataforma switching resulta em menos perda óssea do que os procedimentos AR, mas esse efeito pode não ser clinicamente relevante. A preservação do nível ósseo marginal alcançado com o protocolo AOT pode não melhorar a estética. Estes resultados devem ser interpretados com cautela.