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.
Although various surface modification technologies have been developed to enhance the bioactivity and osseointegration capability of titanium, no consensus has been reached on an effective method. Since the surface wettability of implants plays an important role in the initial adhesion and subsequent behavior of the cells, this study aimed to clarify the effect of surface treatments, including surface topography and surface chemical modification, on the surface wettability （contact angle） of titanium. Several kinds of surface topography were produced by alumina blasting and acid etching, and then surface chemical modification was carried out with oxygen plasma （O2 plasma）, ultraviolet light （UV）, or hydrogen peroxide （H2O2） treatment. Surface contact angle was then evaluated against distilled water. In addition, the sustainability of hydrophilicity of these surface-modified titanium specimens was evaluated for various storage conditions.
The blasted and acid-etched surfaces showed super-hydrophilicity with a water contact angle of almost zero degrees. Super-hydrophilicity was also obtained by O2 plasma and UV treatment regardless of the surface topography. Though this hydrophilicity rapidly decreased over time in air atmosphere, this property was maintained by storage in distilled water. These results were influenced by the amounts of hydrocarbon and hydroxyl group on the titanium surfaces.
From the results of the present study, surface treatments that regulate the surface topography and surface chemical modification for enhancing the hydrophilicity of titanium and storage methods for sustaining the hydrophilicity were obtained.
Idiopathic thrombocytopenic purpura (ITP) is characterized by a marked decrease in platelet count in the absence of factors such as a systemic disease and an inducing drug. In cases where patients with ITP undergo surgery for an oral disease, the platelet count should be adequately maintained. Here, we report a case of peri-implantitis in a patient with severe ITP who underwent extraction of dental implants after high-dose γ-globulin therapy.
The patient was an 81-year-old woman who had been treated with dental implants for missing teeth at a certain dental clinic about 20 years earlier. The dental implants had become loose over the past few years, eventually developing into peri-implantitis and requiring extraction of the implants. The patient was referred to our hospital for stabilizing the platelet count within the normal range before extraction. At the first visit, the platelet count was 1.3×104/mm3; it increased to 14.2×104/mm3 after high-dose γ-globulin therapy (20 g/day for 5 days). As a result, extraction of the dental implants was performed safely with satisfactory hemostasis.
This indicates that high-dose γ-globulin therapy can be administered to patients with ITP who are about to undergo oral surgery. Moreover, we suggest that patients with dental implants should be followed-up regularly for checking not only the general oral condition but also systemic diseases arising concurrently.