An invitro evaluation of corrosion of stainless steel orthodontic brackets by change in mass: influence of different toothpastes

Introduction: Stainless steel brackets are widely used in orthodontics because of its affordability, mechanical properties, strength and biocompatibility. Among all the components of fixed appliances, brackets are subjected to fluctuations in the oral environment like dietary habits, different oral hygiene practices performed. Previous studies have showed that around 70% of Indian population use toothpastes as common oral hygiene practice technique. In addition to this, orthodontists prescribe different fluoride containing toothpastes during orthodontic treatment. As brackets will be in close association with the toothpastes more than other components, it is very much necessary to evaluate the effectiveness of different toothpastes on the corrosion of stainless steel brackets.
Aims & objectives: To assess corrosion by measuring the change in weight of stainless steel brackets before and after immersion in toothpastes using digital analytical balance.
Materials & method: Thirty six MBT 0.022ʺ slot stainless steel brackets were randomly divided into 3 subgroups of n = 12. The brackets in Group 1 were subjected to Colgate® Total® 12 Toothpaste solution prepared by mixing with artificial saliva at a 1:4 (w/v) ratio. The brackets in Group 2 were subjected to Close Up Deep Action Toothpaste solution prepared by mixing with artificial saliva at a 1:4 (w/v) ratio and the brackets in Group 3 were subjected to GC Tooth Mousse solution prepared by mixing with artificial saliva at a 1:1.14 (w/v) ratio. pH of all the test solutions and toothpastes were individually evaluated on a digital pH meter. The brackets were weighed on a digital analytical balance before immersion in test solutions. The immersion time for the brackets will be 48 hours [simulating the total recommended tooth – brushing time (2 min, twice a day for 2 years) i.e., duration of average orthodontic treatment]. The samples were rinsed with 100ml of distilled water and air dried. All the brackets were weighed again after the immersion in test solutions on a digital analytical balance. Corrosion of the brackets were measured by the change in the weight of the brackets using digital analytical balance.
Results: Among the three groups, weight loss of the brackets immersed in Close Up Deep Action Toothpaste, followed by brackets immersed in GC Tooth Mousse, the least weight loss was seen in those immersed in Colgate® total® 12 toothpaste.
Conclusion: From this study it was concluded that weight loss of the brackets immersed in Close Up Deep Action Toothpaste was the highest owing to the acidic pH of both the toothpaste and the prepared test solution, followed by brackets immersed in GC Tooth Mousse owing to the neutral pH of both the toothpaste and the prepared test solution, the least weight loss was seen in those immersed in Colgate® Total® 12 Toothpaste owing to the basic pH of both the toothpaste and the prepared test solution.