engleski

Corrosion properties of orthodontic mini-implants

AIM: To examine to what extent the oral hygiene agents affect corrosion of the head of mini-implant thereby increasing roughness. This could allow higher retention of plaque and propagation of mucositis and peri-implatitis instead of preventing them. MATERIALS AND METHODS: Three types of commercially available mini-implants were tested: those made of stainless steel and titanium alloys Ti-6Al-4V, grade 5 and 23. They were immersed in the experimental solution: artificial saliva with a pH 4.8, saliva with probiotic bacteria Lactobacillus reuteri and saliva with oral antiseptic chlorhexidine (CHX). Immersion lasted 28 days and solutions were replaced once a week. In order to simulate intraoral conditions, samples were thermocycled through 2500 cycles from 5-50°C the first 5 days, after which they were stored in an incubator at a temperature of 37°C until the 28th day. Atomic force microscopy was used to analyse surface topolography before and after immersion using parameters: roughness average (Ra), root mean square (Rms) and maximum height (Mh). The measurement of microhardness was conducted by the Vickers method. RESULTS: Corrosion of mini-implants depends on the type of material and corrosive media, and it is reflected more in the change of the surface roughness of the head than in microhardness. Exposure of titanium implant grade 5 to probiotic significantly increased roughness in parameters Mh, Ra i Rms compared to CHX, artificial saliva and unexposed implants (p<0.005). Exposure to CHX significantly increased the roughness of steel implants in comparison to other experimental conditions (p<0.05). Exposure of titanium implant grade 23 to media increased roughness only in parameter Mh after exposure to artificial saliva and probiotic, but not after CHX (p=0.003). Exposure of mini-implants to saliva, probiotics and CHX did not change microhardness of titanium implants significantly. However in steel implants exposure to CHX and probiotics decreased microhardness compared to unexposed implants (p<0.031), but not in comparison to saliva. CONCLUSION: Probiotics increase roughness of titanium mini-implants, while CHX of steel mini-implants.Therefore, in prevention of mucositis and peri-implatitis in patients undergoing orthodontic treatment with temporary anchorage units the usage of CHX could be recommended for titanium, and probiotics for steel mini-implants for oral-hygiene.

mini-implants; orthodontic; corrosion

Potpora istraživanju PREDIKTIVNI ČIMBENICI USPJEHA ORTODONTSKE TERAPIJE U DJECE I ADOLESCENATA (13.06.2.1.53) financirano od Sveučilišta u Rijeci