Experimental Study Of The Color Of Stainless Steel Arch Wire And Bracket Of Biological Safety

Part 1The short-term systemic toxicity test(oral route) of the colored orthodontic stainless steel wire and bracketObjective: To estimate the potential systemic toxicity of the colored orthodontic stainless steel wire and bracket applying chemical coloration technology, and to provide the evidence for clinical application.Methods: Twenty 150～200g Sprague-Dawley rats, half of which were male, were randomly divided into the negative control group and the experimental group, 10 rats in each group, half of which were male. The negative control group was taken the artificial saliva, and the experimental group was taken the extraction of the colored orthodontic stainless steel wire and bracket dipped in artificial saliva, 5mL/kg per day for 7 days and then were observed for 7 days. To evaluate the clinical toxicity symptom, to record the weight and the food consumption, to calculate the food use ratio, the weight relatively increasing ratio and the important viscera coefficient, and to take statistics.Results: During the 14 days, none of the rats showed the clinical toxicity symptom. There was no statistically significant difference about the weight, the weight relatively increasing ratio and the important viscera coefficient between the experimental group and the negative control group(P＞0.05). The food use ratio of the experimental group was approximately consistent with the control group.Conclusion: There was no short-term systemic toxicity of the extraction of the colored orthodontic stainless steel wire and bracket applying chemical coloration technology dipped in artificial saliva.Part 2The oral mucous membrane irritation test of the colored orthodontic stainless steel wire and bracketObjective: To estimate the potential oral mucous membrane irritation of the colored orthodontic stainless steel bracket applying chemical coloration technology, and to provide the evidence for clinical application.Methods: To choose ten male hamsters, aged 60～70 days. The colored stainless steel brackets and the negative control materials(gutta-percha) were respectively fixed on the right and left oral mucous membrane of the hamsters' cheek pouches. The hamsters were killed after 14 days. To observe the tissues contacting the materials and to evaluate the oral mucous membrane irritation reaction of the materials with the Hematoxylin and Rosin Staining.Results: During the 14 days, all the hamsters were normal. The oral mucous membrane contacting the colored brackets and the negative control materials showed no engorgement, tumidness, erosion, or ulceration. The histopathological findings were also normal. There was no significant difference between the experimental sides and the negative control sides.Conclusion: There was no oral mucous membrane irritation of the colored orthodontic stainless steel bracket applying chemical coloration technology.Part 3The sensitization test of the colored orthodontic stainless steel wire and bracketObjective: To estimate the potential sensitization of the colored orthodontic stainless steel wire and bracket applying chemical coloration technology, and to provide the evidence for clinical application.Methods: Thirty 200～300g male white guinea pigs, were randomly divided into the experimental group, the negative control group and the positive control group, 10 animals in each group. The experimental group were used the extraction of the colored orthodontic stainless steel wire and bracket dipped in artificial saliva. After the inducement phase and the excitation phase, to respectively evaluate the sensitization reaction 24h and 48h after removing the excitation slips.Results: 24h and 48h after removing the excitation slips, the experimental group and the negative control group showed no sensitization reaction, and there was no erythema or oedema. The positive control group showed sensitization reaction with severe erythema and oedema.Conclusion: There was no sensitization of the extraction of the colored orthodontic stainless steel wire and bracket applying chemical coloration technology dipped in artificial saliva.Part 4The Ames mutagenicity test of the colored orthodontic stainless steel wire and bracketObjective: To estimate the potential mutagenicity of the colored orthodontic stainless steel wire applying chemical coloration technology, and to provide the evidence for clinical application.Methods: To use the plate incorporation test, with S-9 or not, 37℃and 48h, and to calculate the average numbers of spontaneous revertants of TA97, TA98, TA100, TA102 of Salmonella typhimurium under 4 concentrations of the extraction of the colored orthodontic stainless steel wire dipped in artificial saliva.Results: Whether added S-9 or not, the numbers of induced revertants of the 4 concentrations of the extraction of the colored wire, compared to that of spontaneous revertants, did not increase statistically significantly. The numbers of induced revertants of the positive control materials increased statistically significantly, which were many times than the numbers of spontaneous revertants. The result of the Ames test was negative.Conclusion: There was no mutagenicity of the extraction of the colored orthodontic stainless steel wire applying chemical coloration technology dipped in artificial saliva.