In vitro retention capacity of two overdenture attachment systems: Locator® and Equator®.

BACKGROUND: It is necessary to know the in vitro behavior of different attachment systems to be used clinically. The evolution of retention capacity over 10 years (14,600 insertion/de-insertion cycles) was determined in vitro, evaluating two overdenture attachment systems (Locator® and OT Equator®). MATERIAL AND METHODS: The study used an implant replica compatible with the abutments of both systems. 10 Locator® and 10 OT Equator® attachments were screwed to the abutments. Nylon inserts were attached and tested, subjecting them to 14,600 insertion and de-insertion cycles (representing 10 years functional life) in axial direction. The universal test machine crosshead speed was 50 mm/min with a de-insertion range of 2 mm. RESULTS: The initial retention of Locator® was 17.02 N and of Equator® 16.36 N. After 14,600 cycles, Locator® suffered a mean loss of retention of 50.89%, while Equator® lost 69.28%. Both systems showed retention increases up to the first 1,000 cycles, which decreased thereafter up to 14.600 cycles. Statistically significant differences between the systems were found after 7,500 cycles. CONCLUSIONS: Both systems presented acceptable retention capacities after 14,600 cycles. Significant differences in retention force between the systems evolved after 7,500 cycles (5 years in vitro use). These results should be treated with caution and should be verified clinically. Key words:Denture, mandibular prosthesis implantation, attachment, dental implant-abutment connection, denture retention.

In vitro experimental study of bonding between aluminium oxide ceramicsand resin cements

To evaluate bond strengths of different resin cements to two aluminum oxide-based ceramics. Methods: Onehundred ten ceramic cylinders were produced and given four different surface treatments. Resin cement cylinderswere then bonded to the ceramic cylinders using different resin cements and the bond strength was determinedby shear testing to the breaking point. We were thus able to obtain results for the different combinations of porcelain,surface treatments and cements. All data was analyzed using the Kruskal-Wallis test for more than twoindependent samples and the Bonferroni correction applied (a=0.01). An optical microscopy study was carriedout to analyze the type of failure, and an electronic microscopy examination was carried out in order to evaluatethe changes produced in the ceramic by the different surface treatments. Results: The best values correspondedto the control group, composed of silicate ceramics combined with Variolink II resin cement. In-Ceram Aluminashowed no significant differences with respect to the type of cement applied. Procera AllCeram obtained the bestvalues when silica coated using the CoJet System and applying Variolink II, or when sandblasted and applyingClearfil SE Bond + Porcelain Bond Activator and Panavia F cement. Significance: Surface treatment modifies theceramic surface and influences the bond strength, as does the type of cement used. Silica coating is recommendedto improve adhesion to Procera AllCeram, applying Variolink II, or sandblasting plus resin cement containingMDP (Panavia F) (AU)

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In vitro experimental study of bonding between aluminium oxide ceramics and resin cements.

UNLABELLED: To evaluate bond strengths of different resin cements to two aluminum oxide-based ceramics. METHODS: One hundred ten ceramic cylinders were produced and given four different surface treatments. Resin cement cylinders were then bonded to the ceramic cylinders using different resin cements and the bond strength was determined by shear testing to the breaking point. We were thus able to obtain results for the different combinations of porcelain, surface treatments and cements. All data was analyzed using the Kruskal-Wallis test for more than two independent samples and the Bonferroni correction applied (a=0.01). An optical microscopy study was carried out to analyze the type of failure, and an electronic microscopy examination was carried out in order to evaluate the changes produced in the ceramic by the different surface treatments. RESULTS: The best values corresponded to the control group, composed of silicate ceramics combined with Variolink II resin cement. In-Ceram Alumina showed no significant differences with respect to the type of cement applied. Procera AllCeram obtained the best values when silica coated using the CoJet System and applying Variolink II, or when sandblasted and applying Clearfil SE Bond + Porcelain Bond Activator and Panavia F cement. SIGNIFICANCE: Surface treatment modifies the ceramic surface and influences the bond strength, as does the type of cement used. Silica coating is recommended to improve adhesion to Procera AllCeram, applying Variolink II, or sandblasting plus resin cement containing MDP (Panavia F).