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OBJECTIVES: To evaluate the peri-implant tissue changes and esthetic outcomes of cemented and screw-retained crowns of single-tooth implants in the esthetic zone using zirconia abutments. MATERIAL AND METHODS: An electronic search was performed on nine databases. The risk-of-bias was assessed by the revised Cochrane risk-of-bias tool for randomized (RoB 2) and non-randomized (ROBINS-I) clinical trials. Marginal bone level change, soft tissue thickness, bleeding on probing, probing depth, survival rates of implants and crowns, complications, plaque and papilla indexes, and pink esthetic score data were extracted and analyzed. The certainty of evidence was accessed through the GRADE approach. RESULTS: Nine records were included and 7 were used in the meta-analyses. Screw-retained crowns presented greater marginal bone level change (MD -0.04 [-0.08, -0.00] p = 0.04, I2  = 0%) compared to cemented crowns up to 1-year. At 3 and 4 years no significant differences (p > 0.05) were observed. Soft tissue thickness did not differ between groups (p > 0.05). The bleeding on probing was higher in cemented group than in screw-retained crowns at 1-year (MD 0.17 [0.08, 0.27] p = 0.0005, I2  = 0%), at medium-term periods (3 and 4 years) no statistically significant differences (p > 0.05) were observed for this outcome. Probing depth, survival rates of implants and crowns, complications, and plaque index, as well as esthetic analysis using the papilla index and pink esthetic score did not differ statistically (p > 0.05) between both retention systems at short and medium-term periods. CONCLUSION: The connection system considering zirconia abutments presented no influence on peri-implant parameters and esthetics evaluation for medium-term periods (3 and 4 years).

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RESUMEN: Introducción: Los implantes dentales se han transformado en una opción de tratamiento de suma relevancia para pacientes parcial o totalmente desdentados. El éxito del tratamiento puede verse afectado por la elección del tipo de retención de estos (cementada o atornillada). A pesar que ambas presentan ventajas, aún no existe consenso sobre el mejor tipo de retención para restauraciones fijas implantosoportadas. Métodos: Realizamos una búsqueda en Epistemonikos, la mayor base de datos de revisiones sistemáticas en salud, la cual es mantenida mediante el cribado de múltiples fuentes de información, incluyendo MEDLINE, EMBASE, Cochrane, entre otras. Extrajimos los datos desde las revisiones identificadas, analizamos los datos de los estudios primarios, realizamos un metanálisis y preparamos una tabla de resumen de los resultados utilizando el método GRADE. Resultados y conclusiones: Identificamos 14 revisiones sistemáticas que en conjunto incluyeron 43 estudios primarios, de los cuales cinco corresponden a ensayos aleatorizados. De estos, solamente dos ensayos responden a la pregunta de interés de manera directa. Concluimos que las coronas atornilladas podrían aumentar levemente el riesgo de pérdida de implante a largo plazo, podrían resultar en nula o poca diferencia en el riesgo de pérdida de implante a mediano plazo, reabsorción ósea y periimplantitis, pero la certeza de evidencia ha sido evaluada como baja. Por otro lado, no es posible establecer con claridad si las coronas cementadas disminuyen el riesgo de complicaciones estéticas y protésicas, ya que la certeza de la evidencia existente ha sido evaluada como muy baja.

ABSTRACT: Introduction: Dental implants have become a highly relevant treatment option for partially or totally edentulous patients. Implant retention systems (cemented or screwed) can influence the treatment success. Although both have advantages, there is still no consensus on the best type of retention for implant-supported fixed restorations. Methods: We searched in Epistemonikos, the largest database of systematic reviews in health, which is maintained by screening multiple information sources, including MEDLINE, EMBASE, Cochrane, among others. We extracted data from the systematic reviews, reanalyzed data of primary studies, conducted a meta-analysis and generated a summary of findings table using the GRADE approach. Results and conclusions: We identified 14 systematic reviews including 43 primary studies overall, of which five were randomized trials. Of these, only two trials answer the question of interest. We concluded that screw-retained crowns may increase long-term implant loss, may make little or no difference in the risk of medium-term implant loss, bone resorption, and peri-implantitis, but the certainty of the evidence has been assessed as low. On the other hand, it is not possible to clearly establish whether cemented crowns reduce the risk of cosmetic and prosthetic complications, since the certainty of the evidence has been assessed as very low.

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PURPOSE: To evaluate the fatigue survival, fracture loads and failure modes of monolithic lithium disilicate screw-retained crowns, attached to titanium insert, and cement-retained crowns. MATERIALS AND METHODS: Internal tapered connection implants, embedded in acrylic resin at 30° inclination, were restored with lithium disilicate restorations, simulating a maxillary premolar (n = 20), with different designs: screw-retained titanium base abutment-crowns, and cement-retained crowns. The specimens were submitted to cyclic mechanical loading (1.2 × 106 cycles with a load of 0-250 N at 2 Hz). Surviving specimens were subjected to single load to fracture in a universal testing machine and failure modes were determined with the aid of an optical microscope. Maximum load values were analyzed statistically using the t-test and differences in failure modes were analyzed using the chi-squared test (α = 0.05). RESULTS: All specimens survived the cyclic mechanical loading. Fracture load was significantly higher for screw-retained crowns (821.69 ±196.71 N) than the cement-retained crowns (577.03 ± 137.75 N) (p = 0.005). Ceramic failure was the predominant mode, with no statistical difference between groups. CONCLUSIONS: Screw-retained and cement-retained lithium disilicate crowns survived the cyclic mechanical loading. The use of titanium inserts to support a monolithic restoration enhances the fracture strength of the crown/abutment system.

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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)

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ABSTRACT Rehabilitation of the partially edentulous anterior maxilla is considered one of the most difficult challenges for the restorative dentist due to the esthetic, functional and psychological implications. Implant-supported restorations provide an appealing treatment alternative that responds to today's patient expectations. The gold standard for this scenario has been the use of an implant-supported fixed partial denture with pontics that masks the soft tissue deficiencies, with acceptable esthetic results. However, nowadays patients are looking for individual single crowns since they believe that this type of restorations resemble the natural dentition, are easy to clean and floss. From the dentist perspective, they are easy to maintain and in case of prosthetic complications they can be repaired or changed without compromising the adjacent restorations. Three parameters have been identified that could guide the decision-making process when multiple adjacent implant supported restorations (MAISR) are selected as the treatment of choice: 1) Smile line 2) Inter-implant distance and tooth-implant distance 3) Patient's expectations and ability to clean.

RESUMEN La rehabilitación del maxilar anterior parcialmente edéntulo se considera uno de los retos más difíciles para el dentista restaurador debido a las implicaciones estéticas, funcionales y psicológicas. Las restauraciones apoyadas por implantes proporcionan una alternativa de tratamiento atractiva que responde a las expectativas actuales de los pacientes. El patrón de referencia en este contexto ha sido el uso de una prótesis parcial fija con implantes con pónticos para enmascarar las deficiencias de tejido blando, el cual ha tenido resultados estéticos aceptables. Sin embargo, hoy en día los pacientes están buscando coronas individuales ya que creen que este tipo de restauraciones se asemejan a la dentición natural y son fáciles de limpiar con cepillado e hilo dental. Desde la perspectiva del dentista, son fáciles de mantener y en caso de complicaciones protésicas pueden ser reparadas o cambiadas sin comprometer las restauraciones adyacentes. Se han identificado tres parámetros que podrían guiar el proceso de toma de decisiones cuando se seleccionan varias restauraciones compatibles con implantes adyacentes como el tratamiento de elección: 1) Línea de sonrisa 2) Distancia entre implantes y distancia de implante dental 3) Las expectativas del paciente y la facilidad de limpieza.

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Abstract The purpose of this study was to evaluate different retention systems (cement- or screw-retained) and crown designs (non-splinted or splinted) of fixed implant-supported restorations, in terms of stress distributions in implants/components and bone tissue, by 3-dimensional (3D) finite element analysis. Four 3D models were simulated with the InVesalius, Rhinoceros 3D, and SolidWorks programs. Models were made of type III bone from the posterior maxillary area. Models included three 4.0-mm-diameter Morse taper (MT) implants with different lengths, which supported metal-ceramic crowns. Models were processed by the Femap and NeiNastran programs, using an axial force of 400 N and oblique force of 200 N. Results were visualized as the von Mises stress and maximum principal stress (σmax). Under axial loading, there was no difference in the distribution of stress in implants/components between retention systems and splinted crowns; however, in oblique loading, cemented prostheses showed better stress distribution than screwed prostheses, whereas splinted crowns tended to reduce stress in the implant of the first molar. In the bone tissue cemented prostheses showed better stress distribution in bone tissue than screwed prostheses under axial and oblique loading. The splinted design only had an effect in the screwed prosthesis, with no influence in the cemented prosthesis. Cemented prostheses on MT implants showed more favorable stress distributions in implants/components and bone tissue. Splinting was favorable for stress distribution only for screwed prostheses under oblique loading.

Resumo O objetivo deste estudo foi avaliar diferentes sistemas de retenção (cimentada x parafusada) e configuração da coroas (unitárias x esplintadas) de próteses fixas implantossuportadas em relação a distribuição de tensões nos implantes/componentes e tecido ósseo pela análise de elementos finitos 3D. Quatro modelos 3D foram simulados com auxílio dos programas Invesalius, e Rhinoceros 3D, e SolidWorks. Os modelos foram confeccionados simulando bloco ósseo de região posterior da maxila (tipo ósseo III), com 3 implantes cone Morse com 4,0 mm de diâmetro e diferentes comprimentos, suportando prótese metalocerâmica de 3 elementos. Os modelos foram processados pelos programas FEMAP e NEiNastran sob força axial de 400 N e oblíqua de 200N. Os resultados foram plotados através de mapas de tensão de von Mises (vM) (implantes e componentes) e tensão máxima principal (TMP) (tecido ósseo). Sobre o carregamento axial, não foi observada diferenças entre os diferentes sistemas de retenção e tipo de prótese na distribuição das tensões nos implantes/componentes, porém, sobre o carregamento oblíquo as próteses cimentadas apresentaram melhor distribuição de tensões em comparação com as próteses parafusadas, enquanto que as próteses esplintadas apresentou uma tendência de redução das tensões no implante do primeiro molar. No tecido ósseo as próteses cimentadas apresentaram melhor distribuição das tensões em comparação com as próteses parafusadas, independente do carregamento. A esplintagem foi favorável somente para as próteses parafusadas, não havendo influência sobre as próteses cimentadas. As próteses cimentadas sobre implantes cone Morse apresentam melhor comportamento biomecânico nos implantes/componentes e tecido ósseo. A esplintagem foi efetiva somente nas próteses parafusadas sob carregamento oblíquo.

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Abstract The purpose of this study was to assess the influence of sealing of the screw access hole (SAH) on the fracture resistance of metal-ceramic implant-supported restorations. UCLA abutments were used to make 30 implant-retained mandibular molar restorations and divide equally into three groups: Group SRS: screw-retained restorations with SAH sealed; Group SRNS: screw-retained restorations with SAH not sealed; Group CR: cement-retained restorations. The following protocol was adopted to restore the SAH: the ceramic surface of the SAH was air-abraded with aluminum oxide; etched with 10% hydrofluoric acid; a silane coupling agent and a bonding agent were applied; cotton pellets were used as filling material and P-60 resin composite as restoring material. The cement-retained restorations were cemented with Rely-X U100. A metal rod with a spherical tip of 6.0 mm diameter was used to apply a vertical static load, simultaneously on the buccal and lingual incline cusps, at a crosshead speed of 0.5 mm/min until the fracture of the specimens. Data were analyzed using one-way ANOVA and Dunnet test (p<0.05) for multiples comparisons. The mode of failure was evaluated by a scanning electron microscopy (SEM). No significant difference between screw-retained restorations was found. The highest mean fracture resistance values were observed with CR group. Therefore, it was shown that SAH sealing did not influence the fracture resistance of the screw-retained restorations.

Resumo O objetivo deste estudo foi avaliar a influência do selamento do orifício de acesso ao parafuso (OAP) na resistência à fratura de coroas metalocerâmicas implantossuportadas aparafusadas. Pilares UCLA foram utilizados para fazer 30 molares inferiores implantossuportados e divididos igualmente em três grupos: Grupo AS: coroas aparafusadas com o OAP selado; Grupo ANS: coroas aparafusadas com o OAP não selado; Grupo CC: coroas cimentadas. O seguinte protocolo foi utilizado para selar o OAP: a superfície de cerâmica do OAP foi jateada com óxido de alumínio; condicionada com ácido fluorídrico a 10%; um agente silano e um adesivo dentinário foram aplicados; bolinhas de algodão foram utilizadas como material de preenchimento e a resina composta P-60 como material de restauração. As coroas cimentadas foram cimentadas com Rely-X U100. Uma haste de metal com uma ponta esférica de 6.0 mm de diâmetro foi usada para aplicar uma carga estática vertical, simultaneamente nas vertentes triturantes das cúspides linguais e vestibulares, com 0,5 mm/min velocidade do atuador até a fratura das coroas. Os dados foram analisados através de ANOVA um fator e teste de Dunnett (p<0,05) para as comparações múltiplas. O modo de falha foi avaliado por um microscópio eletrônico de varredura (MEV). Não houve diferença significativa entre restaurações aparafusadas. Os maiores valores médios de resistência à fratura foram observados com o Grupo CC. Portanto, observou-se que o selamento do OAP não influenciou a resistência à fratura das coroas aparafusadas.

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A Implantodontia tem demonstrado que a colocação de implantes não é uma tarefa das mais difíceis. A dificuldade reside em posicionar os implantes adequadamente para instalação, de maneira que o clínico possa optar pelo melhor sistema de retenção, de acordo com sua opinião: parafusada, cimentada ou cimentada-parafusada. Os problemas gerados por implantes malposicionados têm trazido muitas complicações na hora de confeccionar as próteses. Na tentativa de ilustrar uma forma de resolução desses problemas, o presente trabalho descreve um caso clínico de prótese unitária parafusada por lingual. Na região do primeiro molar inferior esquerdo, um implante – que havia sido instalado com inclinação vestibular – teve sua posição corrigida por meio desse sistema de retenção de prótese. Assim, conferiu-se ao trabalho protético estética vestibular sem aparecimento de cinta metálica, estética oclusal semelhante à das coroas cimentadas e, ao mesmo tempo, reversibilidade.

Implantology has shown that the insertion of implants is not one of the most difficult task. The difficulty lies in properly positioning the implant to be installed so that the clinician can choose the best retention system, according to his opinion: screwed, cemented or screwed-cemented. The problems caused by misplaced implants have brought many complications at the time of manufacturing the prosthesis. In an attempt to illustrate one way of solving these problems, this paper describes a clinical case of a single crow prosthesis screwed by lingual. In the region of the lower left first molar, an implant - which had been installed with vestibular inclination - had its position adjusted by means of this prosthesis retention system. Thus, it was given to prosthetic work buccal aesthetics appearance without showing the metallic collar, occlusal esthetics similar to that of cemented crowns and, at the same time, reversibility.

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Com a previsibilidade e longevidade relacionadas à osseointegração, o tratamento com implantes dentários tornou-se uma realidade na clínica odontológica, proporcionando uma significativa melhora no restabelecimento da saúde bucal, da função e da estética nos tratamentos odontológicos. A fim de alcançar um sucesso mais duradouro da restauração protética, é de fundamental importância a seleção adequada do sistema de retenção da prótese sobre implante. Dessa forma, é imprescindível o conhecimento de fatores como a passividade na adaptação da restauração protética, aspectos oclusais, espaço interoclusal, requisitos estéticos, saúde dos tecidos moles peri-implantares, necessidade de manutenção, reversibilidade da restauração e fator financeiro, a fim de fornecer um embasamento científico suficiente aos cirurgiões dentistas para a escolha mais adequada do tipo de sistema de retenção nas mais variadas situações clínicas. Dessa forma, o objetivo do presente estudo foi discorrer, baseado na literatura, as vantagens, desvantagens, indicações, contra-indicações e dificuldades técnicas relacionadas a cada modalidade restauradora sobre implante (parafusada e cimentada).

With the previsibility and longevity related to the osseointegration, the treatment with dental implants became a reality in the dental clinic, providing a significant improvement in the restoration of the buccal health, of the function and of the aesthetics in the dental treatments. In order to reach a prosthetic restoration more successfull, it is very important the appropriate selection of the retention system of the implant-supported prosthesis. By this way, it is indispensable the knowledge of factors as the passivity in the prosthetic restoration adaptation, occlusal aspects, interocclusal space, aesthetic requirements, peri-implant soft tissue health, maintenance necessity, reversibility and financial factor, in order to provide a satisfactory scientific support to the dentists in the most appropriate retention system choice during the several clinical situations. In that way, the aim of the current study was to discourse, based on the literature, the advantages, disadvantages, indications, contraindications and technical difficulties related to each restoring modality implant-supported screwed and cemented.

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