## 4 Discussion
evaluated the remineralizing efficacy of four different types of products on artificially demineralized elements by evaluating surface microhardness. From their evaluations they conclude that the nano-hydroxyapatite compound creates a resistant surface by remineralizing residual enamel. These observations are consistent with previous studies that have emphasized the importance of fluoride and other remineralizing agents in dental care [16; 36; 63]. Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) is widely used for stabilizing calcium and phosphate ions on enamel surfaces, creating a supersaturated environment that promotes mineral deposition. However, research by [PERSON] et al. and [PERSON] et al. indicates that, while CPP-ACP effectively remineralizes outer enamel, its penetration into deeper lesions is limited compared to nHA [41; 64]. This study found HA treatments to yield results comparable to CPP-ACP in terms of improving surface hardness but with the added benefits of deeper remineralization, making HA a practical option for managing both early-stage and advanced demineralization with minimal invasiveness. The analyses by [PERSON] et al. [43] are consistent with our results. Also, SEM studies indicate that, following treatment, the enamel structure was nearly fully remineralized, resembling smooth, sound enamel in both the CPP-ACP and synthetic nHA groups. Another study [42] also utilized SEM analysis to evaluate the remineralizing efficacy of CPP-ACP by assessing morphological changes in artificially demineralized dental enamel. The findings evaluated how the CCP-ACP paste regenerated a homogeneous and compact surface layer, which agreed with our SEM analysis despite using another product. Erosive wear, often exacerbated by acidic diets and lifestyle factors, poses a significant risk to enamel integrity, especially in younger individuals or patients with gastroesophageal reflux disease (GERD). [PERSON] et al. observed that acidic environments accelerate enamel loss, particularly when combined with mechanical wear [65]. HA-based treatments offer a unique solution by forming a resistant layer on the enamel surface that mitigates acid attacks and mechanical wear. In this study, HA-treated enamel displayed smoother surfaces, indicating enhanced resistance to erosive wear. This aligns with findings by [PERSON], who demonstrated that nHA forms a barrier against acid erosion, thus preserving enamel integrity over time [18]. Aging impacts the enamel's mineral composition, reducing its resilience and increasing susceptibility to demineralization. [PERSON] et al. and [PERSON] et al. observed that aging enamel exhibits reduced thickness and mineral density, which can accelerate demineralization due to lower fluoride content [13; 66]. By preventing caries and erosion-related complications, HA's ability to replenish minerals offers a preventive strategy suitable for all age groups, aligning with the Caries Management by Risk Assessment (CAMBRA) philosophy, which advocates for minimally invasive, risk-based caries management [67; 26]. Saliva plays a crucial role in natural remineralization by supplying essential ions that buffer pH and promote mineral deposition on enamel. [PERSON] et al. reported that saliva's buffering capacity is essential for maintaining a neutral pH conducive to remineralization [11]. However, natural salivary remineralization may be insufficient to reverse advanced lesions, as its effect is mostly limited to surface enamel. HA-based treatments can enhance the function of saliva by supplying extra calcium and phosphate ions that penetrate the enamel, helping to restore its mineral density. This study indicates that HA works harmoniously with saliva, especially benefiting patients who experience reduced salivary flow, such as those with xerostomia. Minimally invasive dentistry focuses on preserving tooth structure through preventive and therapeutic methods that avoid invasive procedures.