Assessment of different types of intra oral scanners and 3D printers on the accuracy of printed models : an in vitro study

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 comparis

Effects of sandblasting of prosthetic abutment surfaces on the tensile strength of cement-retained crowns, using a cementing technique: an in vitro study

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

Accuracy of self-perforating impression tray for maxillary dental implant

Objectives: To analyze the accuracy of a pre-fabricated self-perforating tray for implant impression in an edentulous maxilla. Methods: Four implants (13, 16, 23, 26) were placed in an acrylic resin model of an edentulous maxilla. Implant impressions (n = 7) were taken using a customized open tray (Control Group) and a pre-fabricated self-perforating tray (Test Group). A metal bar was fabricated and screw-retained on implant 13 and the vestibular gap between the framework and implants was measured by stereomicroscopy on implants 16, 23, and 26. Data were analyzed by ANOVA repeated measures and Tukey tests with a significance level (α) of 0.05. Results: There was no statistical difference between self-perforating and customized open tray groups. Control group showed a gap of 73.31± 26.01 for I1; 149.16± 53.90 for I2; and 115.46± 73.34 for I3. Whereas Test Group showed a gap of 154.41± 74.64 for I1; 159.45± 87.64 for I2; and 109.28± 49.18 for I3. Conclusion: The pre-fabricated self-perforating and custom trays showed a similar accuracy for implant impression of edentulous maxilla.Objetivos: Analisar a precisão de uma moldeira autoperfurante de impressão pré-fabricada para implantes na maxila edêntula. Métodos: Quatro implantes (13, 16, 23, 26) foram colocados em um modelo de resina acrílica de uma maxila edêntula. As impressões dos implantes (n = 7) foram tiradas com uma moldeira aberta customizada (Grupo Controle) e uma moldeira autoperfurante pré-fabricada (Grupo Teste). Uma barra de metal foi fabricada e aparafusada no implante 13, e o gap vestibular entre a estrutura e os implantes foi medido por estereomicroscopia nos implantes 16, 23 e 26. Os dados foram analisados por Anova de medidas repetidas e teste de Tukey, com um nível de significância (α) de 0,05. Resultados: Não houve diferença estatística entre os grupos de moldeiras, tanto autoperfurante quanto aberta customizada. O grupo controle apresentou gaps de 73,31 ± 26,01 para I1; 149,16 ± 53,90 no I2; e 115,46 ± 73,34 para o I3. Ao passo que o Grupo Teste apresentou gaps de 154,41 ± 74,64 no I1; 159,45 ± 87,64 no I2; e 109,28 ± 49,18 para o I3. Conclusão: A moldeira autoperfurante pré-fabricada e a moldeira customizada apresentaram precisão similar na impressão de implantes da maxila edêntula

Acurácia de Modelos Impressos obtidos a partir de Escaneamento Intra-oral

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), bem como menores valores de distância linear. Conclusões: Quando comparados aos modelos de gesso, os modelos impressos em resina diferiram muito do modelo mestre, indicando a necessidade de padronização do protocolo de impressão, pois suas variáveis podem influenciar no nível de acurácia dos modelos impressos.Objectives: To compare the accuracy of two methods for the manufacturing of physical models: I) intraoral scanning and resin-printed models; and II) addition silicone impression and gypsum model. Materials and methods: A dental manikin was used as the master model and compared with five gypsum models (g1) and five resin printed models (g2) by analyzing linear measurements at four sites (M1, M2, M3, and M4) using an image measuring instrument. The mean values of the experimental models were compared to those of the master model using one-sample t-test. The samples of each group at the same site were compared with an independent t-test. For all tests, a significance level of 5% (0.05) was considered. Results: The confidence intervals from M1, M2, and M4 sites for both gypsum and resin models presented statistically lower linear distance when compared to the reference values. At m3, the mean value for the gypsum models was not statistically different from the reference mean value (p > 0.05); however, resin-printed models presented a statistically different mean value (p < 0.05), as well as lower values of linear distance. Conclusions: When compared to gypsum models, resin- printed models differed greatly from the master model, indicating the need for standardizing the printing protocol, for its variables may influence printed models accuracy

Trabecular Bone Assessment Using Magnetic-Resonance Imaging: A Pilot Study

The aim of this study was to assess trabecular bone morphology via magnetic-resonance imaging (MRI) using microcomputed tomography (µCT) as the control group. Porcine bone samples were scanned with T1-weighted turbo spin echo sequence imaging, using TR 25 ms, TE 3.5 ms, FOV 100 × 100 × 90, voxel size 0.22 × 0.22 × 0.50 mm, and scan time of 11:18. µCT was used as the control group with 80 kV, 125 mA, and a voxel size of 16 µm. The trabecular bone was segmented on the basis of a reference threshold value and morphological parameters. Bone volume (BV), Bone-volume fraction (BvTv), Bone specific surface (BsBv), trabecular thickness (TbTh), and trabecular separation (TbSp) were evaluated. Paired t-test and Pearson correlation test were performed at p = 0.05. MRI overestimated BV, BvTv, TbTh, and TbSp values. BsBv was the only parameter that was underestimated by MRI. High statistical correlation (r = 0.826; p < 0.05) was found for BV measurements. Within the limitations of this study, MRI overestimated trabecular bone parameters, but with a statistically significant fixed linear offset

Bone defect rehabilitation using lyophilized bone preshaped on a stereolithographic model

Bone grafting provides ideal conditions to the patient′s rehabilitation with dental implants. In addition, prototyped tridimensional models allow the surgical procedure to be simulated and enable important anatomic structures to be visualized. To present a bone defect rehabilitated with xenogenic bone preshaped on a stereolithographic model and the follow-up after 7 years of treatment. The present case report describes a bone defect rehabilitated with a lyophilized bone block preshaped on a stereolithographic model. The patient, a 56-year-old woman, was referred to the dental office presenting a bone defect in the anterior maxilla. Bone regeneration intervention was performed with xenogenic grafting and barrier membrane. The follow-up of the postoperative period and after 7 years is presented. After 7 years, the tomographic exam showed the maintenance of bone at the grafted site, representing the long-term success of the treatment