Mechanical behavior of laser welded titanium implant abutments

ABSTRACT Mechanical Behavior of Laser Welded Titanium Implant Abutments The aim of this study was to describe the effect of Cresco-Ti laser welding conditions on the mechanical properties of the material and to analyze stresses on the weld joint and titanium screw through finite element models of different prosthesis designs. Grade III Titanium specimens described in EN10002-1 were divided into two groups often. While control group specimens were used in solid form, those in test group were sectioned and laser welded by conditions provided by the Cresco- Ti system. All specimens were subjected to tensile and Knoop hardness test. The fractographic analysis was performed under scanning electron microscope. Mann Whitney-U and student-t test were used to describe the effect of laser welding procedure on the material properties at 0.05 significance level. Three-dimensional finite element models(MSC/Marc2003Beta) simulated 5-impiant-supported fixed distal extension(Ml) and 2-impiant-supported partial(M2) prosthetic designs. An oblique load of 400N with 15° lingual-axial inclination was applied to both models at various locations separately. The control group specimens failed with necking. The failure in laser- welded specimens was at heat-affected sone and no porosities were observed at ail fracture surfaces. Control group mean values for elastic modulus, ultimate tensile strength (UTS), percentage of elongation and hardness were 129.7±3.0GPa,574±113N/mm2, 11.2±0.4%,269.6±16.8 and laser-welded group's were 251.6±23.3GPa,776±72 N/mm2, 4.8±0.7%,352.S±23.3 respectively. The differences between the groups were statistically significant for all properties. In Ml, maximum principle stresses did not exceed UTS of the weld-joint, but von Mises stress values in titanium screws were higher than its' strength. In M2, stresses in both were below their strength values. Laser welding conditions provided non-porous and sound joint structure, decrease in ductility and increase in tensile strength at joint Within in the constraints of the model, monotonic mechanical failure of the welded joint may not be expected under biomechankal conditions simulated in this study. Key Words: Passive Fit, Laser Welding, Finite Element Analysis, Titanium