<![CDATA[Background: Dental caries is a major oral health problem with a prevalence of 43.44% in Indonesia. Commonly used remineralizing agents such as CPP-ACP may trigger allergic reactions in patients with Cow's Milk Allergy (CMA). A combined gel of haruan fish scale chitosan (Channa striata) and hydroxyapatite was developed as a safe and effective alternative remineralization agent. Objective: To analyze the effect of combined gel of haruan fish scale chitosan (Channa striata) and hydroxyapatite on enamel Crystallinity Index (CI) as an indicator of remineralization potential. Methods: A true experimental laboratory study was conducted using 12 maxillary first premolar samples divided into four groups: negative control, combined gel of 5% chitosan and 10% hydroxyapatite, combined gel of 10% chitosan and 10% hydroxyapatite, and positive control (CPP-ACP). Demineralization was performed with 37% phosphoric acid for 15 seconds. CI was measured using ATR-FTIR. Data were analyzed using One Way ANOVA followed by Bonferroni post hoc test. Results: The highest CI was observed in the 10% chitosan and 10% hydroxyapatite group (mean 4.18±0.76), followed by 5% chitosan and 10% hydroxyapatite (2.94±0.16), CPP-ACP (2.57±0.37), and the lowest in the negative control (1.62±0.43). One Way ANOVA revealed statistically significant differences between groups (p=0.003). Conclusion: The combined gel of haruan fish scale chitosan (Channa striata) and hydroxyapatite significantly increased enamel Crystallinity Index compared to the untreated group. The combination of 10% chitosan and 10% hydroxyapatite demonstrated the highest CI improvement, surpassing CPP-ACP, indicating its potential as an alternative topical remineralizing agent in preventive dentistry.Keywords : Channa striata fish scale chitosan, Crystallinity Index, demineralization, enamel remineralization, hydroxyapatite.]]>
