الفهرس 
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Abstract
This in vitro study aimed at evaluating the mechanical and chemical characteristics of sound, demineralized and remineralized enamel by creating subsurface caries lesions in bovine samples and subjecting them to a well- established pH-cycling regimen. The samples were studied using surface microhardness (SMH), cross sectional microhardness (CSMH), energy dispersive x-ray spectroscopy (EDAX) and microleakage score at restorations/tooth interface.
The results were analyzed and compared based on the effect of different remineralizing approaches; biomimetic and remineralizing using professionally applied products and patient applied ones. (Patient applied casein phosphopeptide-amorphous calcium phosphate with fluoride paste (MI paste plus), Professionally applied casein phosphopeptide-amorphous calcium phosphate with fluoride varnish (MI varnish), Professionally applied self-assembling peptide (Curodont repairTM), Patient applied self-assembling peptide (Curodont protectTM) and artificial saliva (as a control agent) on previously restored (with composite resin and conventional glass ionomer) demineralized enamel margins.
In our study, all remineralizing agents showed remineralization after the different treatments. Although the microhardness didn’t attain the value of baseline samples, but this could be attributed to the length of treatment since more time is required to achieve better results specially for the self-assembling peptides of both types (professionally applied and patient applied). However, it can be also seen that remineralization obviously needs considerable time to consolidate the entire subsurface lesion, and lesions were not completely remineralized after 30 days. Thus, it can be presumed that the surface layer of the lesion as well as the lesion body are both preferred sites of mineral gain as well as loss (depending on the storage solution). Furthermore, even longer storage periods might be of interest when evaluating the possibility of a complete remineralization of subsurface lesions219. The acid challenge in the present study was obviously too strong for complete remineralization, as shown by the decreased microhardness and enamel fluoride content after the experimental period.
Microleakage test results has shown that conventional glass ionomer resulted in higher microleakage score compared to nanohybrid resin composite. Additionally, demineralized groups have shown the highest microleakage scores compared to the remineralizing agents groups which may indicate the enhancement in the quality of the interface following the use of remineralizing agents.
The limitations of this in vitro study include difficulty to precisely simulate the biological aspects of caries and the multitude of intraoral conditions that contribute to dental caries, the role of enzymes is not accounted for. Since solutions are composed of inorganic ions only, the effects of salivary proteins, pellicle and plaque on mineralization inhibition are not taken into consideration. Other confounding factors involve the possibility of experimental errors and dissimilarities in the micro-structure of the enamel between samples62. Other limitations include the lack of studies that have assessed the efficacy of some of these remineralizing agents239.