Fracture toughness of bleached enamel: Effect of applying three different nanobiomaterials by nanoindentation test

Abstract

Background:Despite the absence of dispute about the efficacy of bleaching agents, a prime concern is about their compromising effect on the enamel structure. This in vitro study investigated whether the addition of three different biomaterials, including nano-bioactive glass (n-BG)/nano-hydroxy apetite (n-HA)/nano-amorphous calcium phosphate (n-ACP), to bleaching agents can affect the fracture toughness (FT) and vickers hardness number (VHN) of bovine enamel.Materials and Methods:The crowns of the newly extracted permanent bovine incisors teeth were separated from the root and sectioned along their central line; one half serving as the control specimen and the other half as the test specimen. After mounting and polishing procedure, all the control specimens (C) were subjected to nano-indentation test to obtain the baseline values of FT. Then, the control specimens were exposed to a 38% hydrogen peroxide for four times, each time for 10 min. The test specimens were divided into three groups and treated as follows, with the same protocol used for the control specimens: Group 1; ACP + hydrogen peroxide (HP) mixed gel; Group 2 BG + HP mixed gel; and Group 3 HA + HP mixed gel. FT measurements with nano-indentation were carried out subsequent to bleaching experiments. Data were analyzed using SPSS and Kruskal–Wallis test (α = 0.05).Results:A significant difference in young's modulus (YM), VHN, and FT at baseline and subsequent to bleaching in control group was observed. However, no significant differences were found in YM, VHN, and FT between the test groups, compared to the respective baseline values.Conclusion:Under the limitations of the current study, it can be concluded that the n-HA, n-ACP, and n-BG could be potential biomaterials used to reduce the adverse effects of tooth bleaching.

Prevention and treatment of white spot lesions in orthodontic patients

“…showed in an in vitro study that a gentle, noninvasive bleaching procedure by incorporating three different biomaterials, including nano-BAG, nano-hydroxyapatite, and nano-amorphous calcium phosphate, into bleaching agents might mitigate the negative effects of tooth bleaching and prevent the irreversible changes in the enamel surface. [ 99 100 ] This treatment modality should be reserved for patients with good oral hygiene to mask inactive lesions when natural remineralization is not complete. [ 92 ]…”

Effects of Different Bleaching Agents on the Surface Topography and the Microhardness of Artificial Carious Lesions

“…It was already demonstrated that adding remineralizing agents such as CPP-ACP paste, fluoride, and nano-biomaterials to bleaching gels enhances the mineral deposition, induces fluoride acquisition and prevents irreversible changes on enamel without altering the whitening efficacy. 16 24 26 27 28 29 30 While, in GI (35% HP Whiteness HP Maxx) the microhardness increase is thought to be related to the short application time of the bleaching gel and the early contact with saliva. Artificial saliva, following the literature, can boost the remineralization and increase enamel microhardness subsequently.…”

Controlled clinical trial addressing teeth whitening with hydrogen peroxide in adolescents: a 12-month follow-up

“…Moreover, it should be stressed that such materials are generally employed with no follow-up or technical supervision, raising concerns in the scientific community. This is especially true when considering the abrasiveness of these products and their possible morphological changes and negative effects, such as increased toothsensitivity and compromised enamel structure 4 , 7 - 10 . Furthermore, patients with severe discoloration, such as tetracycline staining and fluorosis, may believe that the products will solve their problem instead of seeking professional help.…”