## 1 Introduction  
Dental caries is one of the most prevalent diseases affecting humans worldwide. As technology advances, white spot lesions must be treated with non-invasive techniques to prevent further disease progression and preserve the integrity of tooth structure [1; 2; 3]. Remineralization of tooth enamel is defined as the process whereby calcium and phosphate ions are supplied from an external source to promote ion-deposition-demineralized enamel crystals to produce mineral gain [4]. Speaking about mineralization, it is fundamental to use the term biomineralization when referring to its formation. In particular, there are two kinds of dental hard tissue: enamel, which covers the tooth crown, and dentin, which constitutes the whole body of the tooth. Hard tissue formation involves two main processes: a biological one with cell signaling and a biochemical one with the interaction of biomolecules in crystal apatite formation [5]. Fluoride is the cornerstone of remineralization, but its ability to promote remineralization is limited by the availability of calcium and phosphate ions [4]. Recently, new alternatives that purport to be better than fluoride have appeared in the dentistry market. These include a calcium-phosphate-based delivery system and low-level lasers (LLLs). A laser is a device consisting of solid, liquid, or gas substances that produce a light beam when excited by a source of energy. This device can be classified into two categories: high-power lasers or surgical lasers, featuring thermal effects with cutting, vaporization, and hemostasis properties, and low-power lasers or therapeutic lasers, with analgesic, anti-inflammatory, and biostimulation properties [6]. The manufacturers claim that these products provide a new option for the remineralization of non-cavitated dental lesions. It has been reported that laser irradiation on enamel causes crystalline changes promoting significant acid resistance of dental hard tissue [7]. Producers of varnish based calcium and phosphate state that the crystalline system showed the potential to deliver calcium and phosphorous to enamel lesion. This tricalcium phosphate system is encapsulated in sodium lauryl sulfate. This is more efficient than using only fluoride on the lesion [4; 8; 9; 10]. Similarly, LLLs have been proposed as a remineralization treatment when combined with fluoride to maximize their effects. It has been demonstrated that the application of a high-power lasers, such as CO\({}_{2}\) and erbium lasers (erbium:yttrium-aluminium-garnet (Er:YAG) and erbium, chromium:yattrium-scandium-gallium-garnet (Er, Cr:YSGG)), are effective in white spot lesion prevention. These lasers absorb water from the hydroxyapatite of tooth tissues and can modify the crystalline structure, acid solubility, and permeability of the tooth surface to increase resistance against demineralization. However, high-power lasers are costly and not readily available in every practice [11; 12; 13; 14]. LLLs are relatively inexpensive, small, and portable and have multiple applications in several areas of dentistry. Equally, their application in the prevention or arrestment of tooth caries is interesting. However, the efficacy of these lasers in remineralization has not yet been sufficiently studied. Dental researchers have utilized several analytical techniques to quantify changes in the mineral content of enamel during white spot lesion formation. The most common are the Knoop and Vickers micro-hardness, polarized light microscopy, confocal laser scanning microscopy, and light-induced fluorescence. In the present study, we primarily used the Vickers microhardness followed by UV-Vis spectroscopy to quantify the absence or presence of phosphorus. Atomic absorption spectroscopy was used to measure calcium. Bovine enamel was used as a model for human teeth. This model offers a large surface area and more uniform enamel thickness; previous studies have shown that they are very similar to human teeth [15; 16; 17].