## 4 Discussion
Likewise, the fact that toothpastes were applied during a 7-day pH cycle in our study may have prevented us from sufficiently observing the remineralization effect of theobromine reported in previous studies. Additionally, we did not know the amount of theobromine contained in the toothpaste. However, the remineralizing effect of theobromine should be noted, considering the SEM images and the increase in microhardness values after the remineralization stage. The toothpastes in the study groups contain agents associated with maintaining oral, dental, and gum health, providing freshness throughout the day, helping to prevent tooth decay, and exhibiting antibacterial, anti-inflammatory, antispasmodic, and analgesic effects, as promoted by the manufacturers of these toothpastes (Table 1). Upon reviewing the studies, it can be observed that plant extracts, such as aloe vera gel, chamomile, licorice root, grape seed, green tea, miswak, tea tree, propolis, peppermint oil, and eucalyptus oil are noted for their antimicrobial effects. However, research on the effectiveness of these agents for remineralization is limited [54, 55, 56, 57, 58, 59]. In addition, some studies indicate that licorice root, grape seed extracts, and aloe vera may effectively promote teeth remineralization [54, 55, 58]. The cavity-preventive effect of xylitol, a natural sugar alcohol, is explained by its impact on saliva and plaque bacteria [60]. Arginine, a semi-essential amino acid, is metabolized by oral commensal _Streptococcus_ species, resulting in ammonia that increases the pH of the environment and shifts the balance towards remineralization at the tooth-plaque interface [61]. Although there are studies evaluating the effects of Castera-Verduzan thermal spring water in oral spray preparations for patients with xerostomia and its antibacterial activity, no research has been found regarding its remineralization efficacy [62, 63] In our study, the effectiveness of the evaluated toothpastes may also be attributed to the effects of the other ingredients they contain or to their combined effects with remineralization agents. SEM analysis revealed a homogeneous distribution of distinct enamel prisms on healthy surfaces. In artificially carious enamel, prisms appeared with intact peripheries and dissolved bodies and displayed a honeycomb appearance. These findings are parallel to the observations reported by [PERSON] et al. [45]. Although pores and surface irregularities were observed in the prism body in the SEM images of enamel samples from Group 1 (Splat), they appeared to be filled compared to the demineralized state. In a study where the same toothpaste was evaluated using SEM-EDX, remineralization of the enamel surface was observed, and calcium fluoride deposits were noted [64]. On the surface of the enamel samples from Group 2, irregular deposits were noticeable. In the enamel samples from Group 3, although there were voids in the prism bodies, the interiors of the honeycomb-like prisms appeared to be filled. In a study evaluating the remineralization efficacy of fluoride-containing toothpaste, nano-hydroxyapatite-containing toothpaste, and toothpaste solutions containing theobromine at two different concentrations (100 and 200), SEM analyses showed surface coatings filling the pores. However, no significant differences between the groups were reported [65]. In the enamel samples from Group 4 (Naturalive), although small fillings were observed, the honeycomb appearance was noticeable. This result was confirmed in an in vitro study that examined the effect of toothpaste containing nano-calcium carbonate on the surface roughness of demineralized enamel. The study supported the finding of reduced surface roughness of enamel samples after application of this toothpaste, as well as the appearance of white spots on the enamel surface, and an increase in calcium and phosphate on the enamel surface, as observed in SEM-EDS analysis, indicating that it also enhanced remineralization [66].