Effect of two erosive protocols using acidic beverages on the shear bond strength of orthodontic brackets to bovine enamel

Abstract

Objective: To assess the short-term effect of two in vitro erosive challenge protocols on the bond strength of metal orthodontic brackets on bovine enamel. Methods: Sixty bovine incisors were selected and randomly divided into six groups: AS7 (artificial saliva - 7 days, Control Group); CC7 (Coca-Cola™ - 7 days); LJ7 (lime juice - 7 days); AS30 (artificial saliva - 30 days, Control Group); CC30 (Coca-Cola™ - 30 days); LJ30 (lime juice - 30 days). Microhardness testing was performed prior to the erosive challenge to verify the standardization of samples. Immersion was performed 4x/day for five minutes, for either 7 or 30 days. After immersions were concluded, the brackets were bonded and shear bond strength was assessed after 48 hours. The Adhesive Remnant Index (ARI) was also assessed. Data were analyzed by two-way ANOVA, followed by Tukey’s post-hoc and Student’s t test for paired samples, and the Kruskal-Wallis non-parametric test (α = 5%). Results: The mean and standard deviation of microhardness testing of total samples were 281.89 ± 44.51 KHN. There was no statistically significant difference in shear bond strength for the time factor (7 or 30 days; F5.54= 0.105; p = 0.901). However, there was a statistically significant difference for the solution factor (F5.54= 6.671; p = 0.003). These differences occurred among solutions of Saliva x Coca-Cola™ (p = 0.003) and Coca-Cola™ x Lime Juice (p = 0.029). The assessment of the Adhesive Remnant Index showed no significant difference between groups. Conclusions: The immersion time used in the erosion protocols did not affect the bond strength of brackets to teeth. Coca-Cola™ induced significantly higher shear bond strength values than lime juice and artificial saliva. However, the short term effects of 7/30 days in this in vitro study may not be extrapolated for in vivo ones. Clinical studies should be conducted, substantiating the laboratory results.

Assessment of the Erosive Potential of Mineral Waters in Bovine Dental Enamel

“…The progression of erosive lesions is also related to the failure of the protective properties of saliva performed by proteins and by the buffering system, which neutralises acid attacks resulting from food and other extrinsic means [13,35,36] Artificial saliva compared to human saliva has differences in its composition that can cause the appearance of an eroded surface more easily [37]. However, Baumann et al [38] evaluated different formulations of artificial saliva and natural human saliva concluding that the efficacy between them is equivalent, in terms of protective activity, and is closely related to the proportions of components present.…”

“…Formulations that do not have mucin as a remineralising agent can favour the onset of enamel lesions, as it is an important component of the salivary pellicle and acts to reduce erosive demineralization [36,39]. Several studies have indicated the effects of artificial saliva in erosion models [19, 36 -38, 40].…”

Effects of Acidic Environments on Dental Structures after Bracket Debonding

“…Composite resins are frequently used for bonding brackets due to their good aesthetic and bond strength [ 4 ]. However, to bond with composite resins we need a completely dry surface, and the patient’s compliance is essential [ 5 ]. Due to the fixed appliance, and depending on the behavior of the patient regarding oral hygiene, the prevalence of plaque accumulation tends to increase during orthodontic treatment [ 6 ].…”

“…Enamel demineralization is a severe complication of orthodontic treatment and is the result of a decrease in salivary pH [ 5 ]. If its pH is lower than 5, saliva is sub-saturated in fluoroapatite and hydroxyapatite, and this creates a medium for demineralization.…”

“…If its pH is lower than 5, saliva is sub-saturated in fluoroapatite and hydroxyapatite, and this creates a medium for demineralization. Behavioral factors, such as the pH of drinks consumed, and buffering of saliva can result in enamel demineralization and dental erosion [ 5 ];in such cases, the bond between bracket and enamel will be affected and the success of the treatment will be compromised.…”