Comparison of MI Paste Plus and Resin Infiltration in Improvement of White Spot Lesions Following Fixed Orthodontic Treatment: A Randomized Controlled Trial

White spot lesion (WSL) is the first clinical sign of enamel caries that presents itself as a milky-white opacity non-cavitated when located on smooth surfaces. These surfaces are rougher than sound enamel, and they can be arrested or progressed. WSLs are more commonly seen on the outer surface of teeth after orthodontics treatment. Causing unaesthetic appearance on the anterior teeth and increasing chance of dental caries progression.

Different interventions have been introduced to manage WSL as preventing demineralization and biofilm formation, and promoting remineralization with fluoride varnish, casein phosphopeptides-amorphous calcium phosphate (CPP-ACP)- a nano-complex derived from milk casein that significantly increases salivary calcium and phosphate levels9 .

The remineralization of enamel subsurface lesions by CPP-ACP has been demonstrated in several in vitro studies. The potential of CPP-ACP to prevent enamel demineralization and promote lesion remineralization has also been successfully demonstrated in human in situ models. In the presence of fluoride, CPP-ACP has been shown to promote the formation of fluorapatite-like minerals deep in the subsurface lesion. Clinical studies evaluating the effect of CPP-ACP/ACFP on WSLs after debonding report significant regression of WSL numbers, size, and activity in comparison to fluoride or substances without fluoride. Consequently, CPP-ACP has been incorporated into minimally invasive products for the remineralization of WSLs. Nevertheless, other studies state significant change showing improvements in WSLs with remineralization products but no superiority of CPP-ACP .

Multiple studies have tested the efficacy of CPP-ACP on post-orthodontic WSLs but only a limited number of prospective clinical studies have examined the effect of CPP-ACP and fluoride + etch on WSLs developed during orthodontic treatment. It is during therapy with fixed appliances that patients are most susceptible to forming WSLs and WSLs are most active. Recently, treatment with resin infiltration has been developed by the dentistry equipe at Charité University of Berlin, Germany and was first proposed to halt the interproximal early stage non-cavitated caries lesions. It represents a new concept in dentistry that offers valuable clinical applicability for clinicians and high acceptance by patients and is an alternative method to treat early caries lesions that are not expected to remineralize or arrest by non-invasive measures when the infiltration is performed with low-viscosity light-curing resins.

The refractive index (RI) of enamel lesions is effective in arresting and stabilizing the progress of WSLs. Paris et al noted that lesions infiltrated by resin infiltration took on the appearance of the surrounding sound enamel masking the whitish appearance by filling the lesion's body with resin, which results in a rise of the refractive index (RI) of the lesion from 1-1. to 1.42-1.44 with resin infiltration, which is closer to a healthy enamel (1.62-1.63). Thus, a restoration with enamel-like optical characteristics is obtained. This technique is considered micro-invasive and may bridge the gap between the non-invasive and minimally invasive treatment of WSLs, postponing the need for a restoration as long as possible.