Comparison of the Accuracy of Different Transfer Impression Techniques for Osseointegrated Implants.

The aim of this study was to evaluate 3 transfer techniques used to obtain working casts of implant-supported prostheses through the marginal misfit and strain induced to metallic framework. Thirty working casts were obtained from a metallic master cast, each one containing 2 implant analogs simulating a clinical situation of 3-unit implant-supported fixed prostheses according to the following transfer impression techniques: group A, squared transfers splinted with dental floss and acrylic resin, sectioned, and re-splinted; group B, squared transfers splinted with dental floss and bis-acrylic resin; and group N, squared transfers not splinted. A metallic framework was made for marginal misfit and strain measurements from the metallic master cast. The misfit between the metallic framework and working casts was evaluated with an optical microscope following the single-screw test protocol. In the same conditions, the strain was evaluated using strain gauges placed on the metallic framework. The data were submitted to one-way analysis of variance followed by the Tukey test (α = 5%). For both marginal misfit and strain, there were statistically significant differences between groups A and N (P < .01) and groups B and N (P < .01), with greater values for group N. According to the Pearson test, there was a positive correlation between the misfit and strain variables (r = 0.5642). The results of this study showed that the impression techniques with splinted transfers promoted better accuracy than the nonsplinted technique, regardless of the splinting material used.

The influence of master cast technique on the cast precision of implant-retained fixed prostheses.

The aim of this study was to evaluate the precision of three different mold filling techniques in order to obtain a cast simulating a three-unit, implant-retained, fixed prosthesis. Thirty casts (n = 10) were obtained using three different mold filling techniques. Group 1 used a unique fulfillment technique, Group 2 used a two-step fulfillment technique, and Group 3 used a latex cylinder technique. Using a metallic matrix, a titanium substructure was created to simulate a three-unit fixed prosthesis used as reference to evaluate the marginal misfit and tension forces in each cast. The vertical misfit was measured by an optical microscope with an increase of 120X and by an analysis unit using the one-screw test. The tension was quantified using strain gauges. The strain results showed a statistical difference between Group 3 and the other groups. The Tukey test showed no difference between the different treatment groups (p = 0.05). All three techniques were deemed efficient; however, considering that the cylinder latex technique induced less force toward the implants, it is the preferable technique for daily clinical practice.

Análise da influência de diferentes técnicas de preenchimento do molde com gesso na precisão de modelos de próteses fixas implanto-retidas / Evaluation of master cast techniques influence of implant fixed prostheses cast precision

Objetivo: Este estudo teve por objetivo avaliar a precisão de três técnicas de preenchimento do molde com gesso para obtenção de modelos de trabalho a partir de um modelo mestre simulando uma situação clínica de uma prótese fixa implanto-retida de três elementos. Materiais e métodos: Foram obtidos trinta modelos (n = 10) a partir do modelo mestre, por meio de três técnicas de preenchimento do molde com gesso. Assim, o Grupo 1 foi obtido pela técnica de preenchimento único (PU); o Grupo 2, pelo preenchimento do molde com gesso em duas porções (DP); o Grupo 3, utilizando-se a técnica do cilindro de latex (CL). Sobre a matriz metálica foi obtida uma infraestrutura fundida em titânio comer-cialmente puro simulando uma prótese fixa implanto-retida de três elementos, utilizada como referência para a avaliação de desajustes verticais em cada modelo. O desajuste vertical foi avaliado segundo a técnica do parafuso único. Para a análise dos resultados foi aplicada a análise de variância, seguida do teste de Tukey. Resultados: De acordo com os resultados obtidos, observou-se maior valor médio entre as amostras do grupo em que o molde foi preenchido com gesso pela técnica do preenchimento único (média = 0,14), ao passo que as amostras dos grupos 2 e 3 apresentaram os mesmos valores médios (média = 0,10). Porém, de acordo com o teste de Tukey, não houve diferença estatística entre os três diferentes grupos de tratamento. Conclusão: Assim, pode-se afirmar que as três técnicas foram eficientes, sendo, de acordo com a praticidade, a mais indicada a técnica de preenchimento único.