Mechanical Properties of Titanium and Titanium Alloys for Dental Implants

Abstract

One cause of fractures of dental implant bodies placed in the oral cavity is considered to be that manufacturers of implant bodies and clinicians do not sufficiently understand the relationship between the mechanical characteristics and structure of implant bodies to their strength.
Therefore, we examined the mechanical characteristics of the following as-received titanium materials for implants: types 1, 2, 3, and 4 JIS pure titanium, and Ti-6Al-4V and Ti-6Al-7Nb titanium alloys.
Because we were concerned that a material with a nonhomogeneous distortion could be evaluated only by the uniaxial tensile test, we performed a loading test from the 30-degree direction in conformity with ISO14801. The following conclusions were obtained.
1. Tensile strength, proof stress, and hardness were the highest in the Ti-6Al-7Nb titanium alloy, and the lowest in type 1 JIS pure titanium.
2. Elongation was the highest in type 1 JIS pure titanium, and the lowest in Ti-6Al-4V titanium alloy, in which the elongation percentage was over 20% in all titanium materials.
3. Although all the titanium materials satisfied the values of JIS standards, their values did not necessarily show sufficient strength for dental implants.
4. The maximum load in the 30-degree direction of the titanium materials differed from that expected from the data of mechanical properties (tensile strength, proof strength, and hardness). Therefore, manufacturers of dental implant bodies should conduct a bending test from 30 degrees for every lot.
5. As for using small-diameter implants, it should be noted that pure titanium lacks strength. Therefore, using the stronger titanium alloy, the diameter of implants and implant position should be considered by both the manufacturer and surgical operator.