Corrosion behavior of 2205 duplex stainless steel

The corrosion of 2205 duplex stainless steel was compared with that of AISI type 316L stainless steel. The 2205 stainless steel is a potential orthodontic bracket material with low nickel content (4 to 6 wt%), whereas the 316L stainless steel (nickel content: 10 to 14 wt%) is a currently used bracket material. Both stainless steels were subjected to electrochemical and immersion (crevice) corrosion tests in 37 degrees C, 0.9 wt% sodium chloride solution. Electrochemical testing indicates that 2205 has a longer passivation range than 316L. The corrosion rate of 2205 was 0.416 MPY (milli-inch per year), whereas 316L exhibited 0.647 MPY. When 2205 was coupled to 316L with equal surface area ratio, the corrosion rate of 2205 reduced to 0.260 MPY, indicating that 316L stainless steel behaved like a sacrificial anode. When 316L is coupled with NiTi, TMA, or stainless steel arch wire and was subjected to the immersion corrosion test, it was found that 316L suffered from crevice corrosion. On the other hand, 2205 stainless steel did not show any localized crevice corrosion, although the surface of 2205 was covered with corrosion products, formed when coupled to NiTi and stainless steel wires. This study indicates that considering corrosion resistance, 2205 duplex stainless steel is an improved alternative to 316L for orthodontic bracket fabrication when used in conjunction with titanium, its alloys, or stainless steel arch wires.

Soldiers' dental complaints compared with clinical findings in the Military Hospital in Bologna, Italy

There is no previous data published on the frequency and reasons for dental emergencies in the Italian Army. In this study, all the 329 soldiers who sought dental help during a 5-month period in the Military Hospital in Bologna were investigated. Prior to clinical examination, the soldiers filled out a questionnaire concerning their subjective perception about their dental treatment needs. Data from the questionnaire were then compared with the actual status findings. The results showed that endodontic problems comprised the majority of the cases (37.1%), followed by surgical problems as the second most frequent emergency (33.1%). The subjects' own perceptions showed good agreement with the clinical record in cases with endodontal or surgical problems, excluding problems related to wisdom teeth, while those related to caries and periodontal disease were less frequently correctly assessed by the soldiers.