Comparisons of Precision of Fit Between Cast and Computer Numeric Controlled Milled Titanium Implant Frameworks for the Edentulous Mandible

INTRODUCTION: Titanium frameworks have for the last decade been discussed as an option to conventional gold alloy castings in implant dentistry. So far no reports have been made to show milled titanium frameworks and their difference in precision compared to conventional castings, and how laboratory handling andfusing of veneers to the titanium frames affect the precision of fit. PURPOSE: To investigate and compare the precision of fabrication in repeatedly produced Computer Numeric Controlled milled frameworks with conventional castings, and to analyze the distortion from application of different veneering materials (porcelain and acrylic resin veneers). MATERIAL AND METHODS: Twenty identical titanium frameworks were fabricated by means of a Computer Numeric Controlled milling technique for one and the same master model. Five conventional frameworks were cast as a control group to the same model. The frames were measured with regard to fit in a coordinate measuring machine linked to a computer. Measurements were made during different stages of handling of the titanium framework, and after veneering materials had been applied. RESULTS: The Computer Numeric Controlled frameworks showed a statistically (p0.05) affect the fit of the titanium frameworks. CONCLUSION: It is possible to fabricate implant supported titanium frameworks by means of the present Computer Numeric Controlled technique with very high precision and repeatability

Fatigue and microgap behaviour of a three-unit implant-fixed dental prosthesis combining conventional and dynamic abutments

This is an in vitro study composed by a fatigue test followed by an optical microscopy analysis. Dynamic abutments concept, recently introduced on screw-retained implant dental prosthesis, consists on the screw channel customisation according to the individual needs of each rehabilitation. Geometry and tightening torque differences advise the assessment of their mechanical performance. Clarify whether the combination of dynamic and conventional abutments in a three-unit implant-fixed prosthesis has detrimental effects either on the mechanical performance under cyclic loading or on the implant-abutment microgap dimensions. The fatigue test was performed in agreement with the ISO standard 14801. Then on the samples that resisted 5 million cycles, the implant-abutment microgap was measured on dynamic and conventional abutments using optical microscopy. Two unloaded samples were used as control group. The samples supported a load of 1050 N. The implant-abutment microgap measurement did not show statistically significant differences (p=.086) between loaded and unloaded groups, but the loaded conventional abutments showed a significant lower implant-abutment microgap (p=.05) than the loaded dynamic abutments. The combination of conventional and dynamic abutments do not seem to produce a decrease in fatigue resistance to a level below the mastication forces or an increase in the joint dimensions.The study was supported in part by SciTech - Science and Technology for Competitive and Sustainable Industries, and the R&D project was cofinanced by the North Portugal Regional Operational Program ("NORTE2020") and the European Regional Development Fund (FEDER)