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Objetivos: Comparar a acurácia de dois métodos de fabricação de modelos físicos: I) escaneamento intra-oral e modelos impressos em resina; e II) moldagem de silicone de adição e modelo de gesso. Materiais e métodos: Utilizou-se um manequim odontológico como modelo mestre, o qual foi comparado a cinco modelos de gesso (g1) e cinco modelos impressos em resina (g2) por meio de análises de medições lineares em quatro sítios de medição (M1, M2, M3 e M4) com um instrumento de medição por imagem. Os valores médios dos modelos experimentais foram comparados aos do modelo mestre utilizando-se o Teste-t. Para um mesmo local, as amostras de cada grupo foram comparadas por meio do Teste-t para amostras independente. Para todos os testes, foi adotado o nível de significância de 5% (0,05). Resultados: Os intervalos de confiança dos sítios M1, M2, e M4 para os modelos de gesso e resina apresentaram distância linear estatisticamente menor quando comparados aos valores do modelo de referência. Em M3, o valor médio dos modelos de gesso não foi estatisticamente diferente do valor médio da referência (p > 0,05); entretanto, os modelos impressos em resina apresentaram valor médio estatisticamente diferente (p 0.05); however, resin-printed models presented a statistically different mean value (p

Background 3D printing technology is a reality in Dentistry and presents several ways to obtain a printed model. The aim of this study was to verify the influence of different types of intraoral scanners and 3D printers on the accuracy of printed models in comparison to plaster models obtained from conventional impressions. Material and Methods A dental study model was used as the reference model and was molded with polyvinyl siloxane to produce the plaster models. It was also scanned with two types of intraoral scanners and the digital files were printed by two types of 3D printers. The plaster and printed models formed five groups (n=50), which were analyzed using linear measurements at six dimension sites. In order to test the equivalence in the precision of the measurements made in the reference model and in the different models of the experimental groups, the Schuirmann Two-One Sided t-test was applied. The trueness of the measurements of the experimental models was tested in comparison to those of the reference model by applying tests for paired data. In all statistical tests, the significance level of 5% (α = 0.05) was adopted. Results In relation to precision, all five groups presented similar and acceptable results. The trueness analysis indicated that both the printed and the plaster models had average measurements that were different from the reference model. Conclusions It was concluded that the accuracy of printed and plaster models was impaired due to the trueness of the models. The type of printer influenced the accuracy of the printed models, while the type of scanner did not. The standardization of the method of obtaining printed models must be carried out in order to provide the production of quality models. However, there will be differences between the technologies. Key words:Dental models, three-dimensional printing, dimensional accuracy.

Aim: The aim of this systematic review was to compare the survival rate and the marginal bone loss between short implants (≤7 mm) placed in the atrophic area and longer implants placed in the augmented bone area of posterior regions of maxillaries. Methods: Electronic search using three databases was performed up to May 2017 to identify Randomized Controlled Trials (RCT) assessing short implants survival with a minimal follow-up of 12 months post-loading. For the meta-analysis, a Risk Difference (RD) with the 95% Confidence Interval (CI) was used to pool the results of implant failure rate for each treatment group. For the marginal bone changes, Mean Differences (MD) with 95% CI were calculated. Results: Seven randomized controlled trials met the inclusion criteria, being included in qualitative and quantitative analyses. The RD between the short implant group and the control group was -0.02 (95% CI: -0.04 to 0.00), I2=0 and Chi2=3.14, indicating a favorable survival rate for short implant, but with no statistical significance (p=0.09). Discussion: For marginal bone loss, the mean difference was -0,13 (95%CI: -0.22 to -0.05), favoring the test group with statistical significance (p=0.002). The studies showed more heterogeneity for bone loss compared to survival rate. Short and longer implants showed similar survival rates after one year of loading, however the marginal bone loss around short implants was lower than in longer implants sites. Conclusion: Placement of implants ≤7 mm of length was found to be a predictable alternative for the rehabilitation of atrophic posterior regions, avoiding all the disadvantages intrinsic to bone augmentation procedures.

Objetivo: El propósito de este estudio fue evaluar el uso de un jig de verificación para corregir la posición de los implantes dentales en un modelo impreso en 3D y comparar su precisión con los modelos dentales obtenidos por impresión convencional. Materiales y Métodos: Se instalaron tres implantes dentales en un modelo maxilar dentado parcial y se obtuvieron moldes dentales (n = 10) mediante impresiones convencionales y digitales. Se usó una plantilla de verificación para determinar la posición del implante en el modelo impreso en 3D y su precisión se comparó con el molde convencional. Resultados: Los datos se analizaron mediante ANOVA y prueba post hoc a un nivel de significancia de p ≤ 0.05. Se encontró un error de medición estadísticamente mayor (p≤ 0.05) para los modelos impresos en 3D en comparación con los modelos convencionales, con una diferencia media de 47 µm. Conclusión: El uso de un jig de verificación para colocar implantes dentales en un modelo impreso en 3D mostró mayores discrepancias en comparación con las impresiones convencionales.

A confecção de trabalhos protéticos em um fluxo digital é possível a partir do escaneamento intra-oral e confecção da Prótese via CAD/CAM. A tecnologia atual de impressão 3D permite a obtenção de um modelo impresso, para a realização de determinados procedimentos. Entretanto, é necessário analisar e comparar estes modelos com os modelos de gesso, uma vez que existe uma diferença significativa na forma de obtenção, assim como, nos custos de cada tipo de modelo. O presente estudo teve como objetivo realizar uma análise da acurácia entre modelos impressos, obtidos por meio de escaneamento intra-oral e impressão 3D, e modelos de gesso obtidos pelo método de moldagem convencional. Foi utilizado um manequim odontológico como modelo mestre e foram confeccionados dez modelos de gesso (n= 10), pela técnica de moldagem da dupla impressão com silicone de adição. Foram utilizados dois tipos de escâneres intra-orais e dois tipos de impressoras 3D, que formaram quatro grupos experimentais com dez modelos por grupo (n= 10). Os modelos físicos de gesso e impressos foram comparados com o modelo mestre por meio de análises de medições lineares em seis sítios de medições, com o uso de uma máquina de medição por imagem (Quick Scope, Mitutoyo®). A análise dos modelos impressos incluiu as possíveis interações entre os fatores principais tipo de impressora, tipo de escâner e sítios de medições. Os resultados mostraram que em relação ao modelo mestre, no geral, as discrepâncias dos modelos de gesso foram menores que as discrepâncias dos modelos impressos. A análise das interações dos fatores principais indicou que o tipo de impressora exerceu a maior influência na acurácia dos modelos impressos, seguido do fator sítio de medição e tipo de escâner. Pôde-se concluir que os modelos de gesso apresentaram uma acurácia superior quando comparados com os modelos impressos. O acabamento superficial dos modelos impressos exerceu influência na sua acurácia. The preparation of prosthetic restoration in a digital flow is possible using intraoral scanning and confection of the prosthesis via CAD/CAM. The current 3D printing technology allows the making of a printed cast, for performing certain laboratory procedures. However, it is necessary to analyze and compare these casts with the gypsum casts, since there is a significant difference in the form of obtaining, as well as, in the costs of each type of cast. The objective of the present study was to perform a comparative study of the accuracy of printed casts, obtained through intraoral scanning and 3D printing, and gypsum casts, obtained through the conventional impression. A dental mannequin was used as the master model and ten gypsum casts (n=10) were obtained, using double impression technique with polyvinyl siloxane. Two types of intraoral scanners and two types of 3D printers were used, which formed four experimental groups with ten models per group (n=10). The real gypsum and printed casts were compared to the master model by linear measurements in six sites, using an image-measuring machine (Quick Scope, Mitutoyo®). The analysis of the printed models included possible interactions between the factors type of printer, type of scanner and measurement sites. The results showed that, in relation to the master model, in general, the discrepancies of the gypsum casts were smaller than the discrepancies of the printed casts. The interactions of the factors analysis indicated that the type of printer exerted the greatest influence on the accuracy of the printed casts, followed by the site measurement and type of scanner. It was conclude that the gypsum casts presented superior accuracy when compared to the printed casts. The surface finish of the printed casts exerted influence in its accuracy.

Objective: The tensile strength effects on the sandblasting of the abutment associated with a cementing technique are not well documented. The objective of this study is to analyze the tensile strength of prosthetic crowns cemented on standard and sandblasted abutments, using a cementing technique. Methods: Experimental groups were formed according to ce­menting technique (control and practice abutment technique) and prosthetic abutment roughness (standard and sandblas­ted), totaling forty specimens. The crowns were cemented with Zinc Phosphate cement. Statistical analysis was conducted with an α at 0.05. Results: Considering the cementation techniques analysis, there were no statistically significant differen­ces between the groups, with mean tensile strength values of 157.83±22.16 N for the control technique, and 159.95±46.40 N for the practice abutment technique on the standard surface. Result analysis of the control technique (626.23±34.80 N) and practice abutment technique (642.62±94.00 N) indicated no significant differences on the sandblasted surface. Consi­dering the surface roughness analysis, significant differences were observed, with values of 157.83±22.16 N for the control technique/standard surface group and 626.23±34.80 N for the control technique/sandblasted surface group. Significant differences were observed in the practice abutment technique/standard surface group with 159.95±46.40 N values, compa­red to the 642.62±94.00 N value for the practice abutment technique/sandblasted group. Conclusions: The practice abut­ment cementing technique showed no significant differences with the control technique, regarding to the tensile strength, in the two surfaces (standard and sandblasted) used in the study. The sandblasting of prosthetic abutments led to a signifi­cant increase on the tensile strength considering the two studied cementation techniques. Objetivos: Os efeitos de resistência à tração no jateamento do pilar associado a uma técnica de cimentação não estão bem documentados. O objetivo deste estudo é analisar a resistência à tração de coroas protéticas cimentadas em munhões padrões e asperizados, utilizando uma técnica de cimentação. Métodos: Os grupos experimentais foram formados de acordo com a técnica de cimentação (técnica de controle e prática de pilares) e a rugosidade do pilar protético (padrão e asperizado), totalizando quarenta espécimes. As coroas foram cimentadas com cimento de fosfato de zinco. A análise estatística foi conduzida a um valor de α=0,05. Resultados: Na análise das técnicas de cimentação não houve diferenças estatisticamente significativas entre os grupos, com valores médios de resistência à tração de 157,83±22,16 N para a técnica controle e 159,95±46,40 N para a técnica practice abutment na superfície padrão. A análise dos resultados na técnica controle (626,23±34,80 N) e na técnica practice abutment (642,62±94,00 N), na superfície jateada, também não indicaram diferenças significativas. Na análise da rugosidade da superfície, observaram-se diferenças significativas, com valores de 157,83±22,16 N para o grupo técnica controle/superfície padrão e 626,23±34,80 N para o grupo técnica controle/superfície asperizada. Foram observadas diferenças significativas no grupo técnica Practice abutment/ superfície padrão com valores de 159,95±46,40 N comparado com o grupo técnica Practice abutment/grupo jateado, com valores de 642,62±94,00 N. Conclusões: A técnica de cimentação Practice abutment não mostrou diferenças significativas com a técnica controle, em relação à resistência à tração, nas duas superfícies (padrão e asperizada) usadas no estudo. O jateamento dos munhões protéticos levou a um aumento significativo da resistência à tração nas duas técnicas de cimentação estudadas.

Aim: The aim of this systematic review was to compare the survival rate and the marginal bone loss between short implants (≤7 mm) placed in the atrophic area and longer implants placed in the augmented bone area of posterior regions of maxillaries. Methods: Electronic search using three databases was performed up to May 2017 to identify Randomized Controlled Trials (RCT) assessing short implants survival with a minimal follow-up of 12 months post-loading. For the meta-analysis, a Risk Difference (RD) with the 95% Confidence Interval (CI) was used to pool the results of implant failure rate for each treatment group. For the marginal bone changes, Mean Differences (MD) with 95% CI were calculated. Results: Seven randomized controlled trials met the inclusion criteria, being included in qualitative and quantitative analyses. The RD between the short implant group and the control group was -0.02 (95% CI: -0.04 to 0.00), I2=0 and Chi2=3.14, indicating a favorable survival rate for short implant, but with no statistical significance (p=0.09). Discussion: For marginal bone loss, the mean difference was -0,13 (95%CI: -0.22 to -0.05), favoring the test group with statistical significance (p=0.002). The studies showed more heterogeneity for bone loss compared to survival rate. Short and longer implants showed similar survival rates after one year of loading, however the marginal bone loss around short implants was lower than in longer implants sites. Conclusion: Placement of implants ≤7 mm of length was found to be a predictable alternative for the rehabilitation of atrophic posterior regions, avoiding all the disadvantages intrinsic to bone augmentation procedures.

Since the dental implant/abutment interface cannot totally seal the passage of microorganisms, the interior of implant becomes a reservoir of pathogenic microorganisms that produce and maintain chronic inflammation in the tissues around implants. Silver nanoparticles (nano-Ag) are potent and broad-spectrum antimicrobial agents. The aim of this study was to evaluate the capacity of the nano-Ag to prevent the contamination of the implant internal surface byCandida albicans, caused by the implant/abutment microgap infiltration. Thirty-six implants were used in this experiment. Three study groups were performed: experimental group (implants receiving an application of nano-Ag in their inner cavity before installation of the abutment); positive-control group (implants receiving sterile phosphate buffer saline application instead of nano-Ag) and negative-control group (implants receiving the application of nano-Ag in the inner cavity and immersed in a sterile medium). In the positive-control and experimental groups, the implants were immersed in a Candida albicans suspension. The abutments of all three groups were screwed with a 10 N torque. After 72 h of immersion inC. albicans suspension or sterile medium, the abutments were removed and the inner surface of the implants was sampled with absorbent paper cone for fungal detection. No C. albicans contamination was observed in the negative-control group. The positive-control group showed statistically higher values of colony forming units (CFUs) of C. albicans compared with the experimental group. In conclusion, silver nanoparticles reduced C. albicans colonization inside the implants, even with low torque screw abutment. Resumo: A interface implante/pilar não pode ser totalmente selada para passagem de microrganismos, com isso o interior do implante torna-se um reservatório de microrganismos patogênicos que promovem e mantêm a inflamação crônica nos tecidos em volta dos implantes. Nanopartículas de prata são agentes antimicrobianos potentes e de amplo espectro. O objetivo deste estudo foi avaliar a capacidade das nanopartículas de prata em evitar a contaminação porCandida albicans do interior de implantes, originada da infiltração do fungo através da interface implante/pilar. 36 implantes foram utilizados neste experimento. Três grupos de estudo foram estabelecidos: grupo experimental (os implantes receberam aplicação de nanopartículas de prata na sua cavidade interna, antes da instalação do pilar); grupo controle positivo (os implantes receberam PBS estéril em vez das nanopartículas de prata) e grupo controle negativo (implantes receberam aplicação de nanopartículas de prata na cavidade interna, mas os implantes foram imersos em meio estéril). Nos grupos controle positivo e experimental, os implantes foram imersos em suspensão deCandida albicans. Os pilares protéticos de todos os grupos foram parafusados com torque de 10 N. Após 72 h imersos na suspensão deC. albicans ou em meio estéril, os pilares foram removidos e amostras da superfície interna dos implantes foram coletadas com cone de papel absorvente para a detecção de Candida. No grupo controle negativo não foi observada contaminação por C. albicans. O grupo-controle positivo mostrou valores de unidades formadoras de colônia deCandida estatisticamente maiores quando comparado com o grupo experimental. Conclui-se que nanopartículas de prata reduzem a colonização de C. albicans dentro dos implantes, mesmo quando o pilar é parafusado com torque baixo.