Pendahuluan: Cangkang kerang hijau (Perna viridis) mengandung 95% kalsium karbonat amorf murni yang berfungsi sebagai prekursor hidroksiapatit. Hidroksiapatit berperan dalam proses remineralisasi gigi. Efektifitas penggunaan sintesis hidroksiapatit sangat dipengaruhi oleh bentuk sediaan yang diberikan. Tujuan penelitian ini menganalisis pengaruh aplikasi ekstrak cangkang kerang hijau (Perna Viridis) konsentrasi 20% dalam sediaan mousse terhadap kadar kalsium email gigi sulung. Metode: penelitian eksperimental semu dengan menggunakan 16 gigi insisivus desidui anterior yang dibagi menjadi 4 kelompok penelitian. Sebelum diberikan perlakuan, dilakukan demineralisasi menggunakan asam fosfat 37%. Kelompok perlakuan diaplikasikan mousse cangkang kerang hijau konsentrasi 20%, kelompok kontrol positif diaplikasikan CPP-ACP, kelompok kontrol negatif tidak diberikan perlakuan dan kelompok basis diaplikasikan mousse ke permukaan labial gigi. Keseluruhan sampel dimasukkan ke dalam inkubator bersuhu 37˚C dan diambil sesuai dengan waktu retensinya yaitu 30 menit, setelah pemaparan bahan remineralisasi. Pengukuran kadar kalsium gigi dilakukan menggunakan Spektrofotometri Serapan Atom (SSA). Analisis data dilakukan dengan menggunakan uji Anova dan post hoc. Hasil: Kelompok mousse cangkang kerang hijau memiliki kadar kalsium tertinggi, diikuti dengan kelompok kontrol positif, basis mousse dan kelompok kontrol negatif. Hasil One Way ANOVA menunjukkan adanya perbedaan kadar kalsium yang bermakna antara kelompok perlakuan (p=0,001). Hasil uji Post Hoc LSD menunjukkan adanya perbedaan yang signifikan (p<0,05) antara kelompok kontrol negatif dengan kelompok kontrol positif (p=0,001) dan kelompok mousse kerang hijau (p=0,001). Simpulan: Pemberian aplikasi mousse ekstrak cangkang kerang hijau konsentrasi 20% dapat meningkatkan kadar kalsium email gigi sulung.Effect of 20% green mussel (Perna viridis) shell extract in mousse formulation on the calcium content of deciduous tooth enamel: an experimental studyIntroduction: Green mussel shells (Perna viridis) contain 95% amorphous calcium carbonate (CACO3), which serves as a precursor for hydroxyapatite, which plays an important role in the tooth remineralization process. The effectiveness of hydroxyapatite synthesis application is greatly influenced by the formulation and form of the preparation. This study aimed to determine the effect of a 20% green mussel shell extract in mousse formulation on the calcium content of deciduous tooth enamel. Methods: This was a quasi-experimental study using 16 anterior deciduous incisor teeth divided into four experimental groups. Before treatment, demineralization was performed using 37% phosphoric acid. The treatment group received mousse containing 20% green mussel shell extract, the positive control group received CPP-ACP, the negative control group received no treatment, and the base group received plain mousse applied to the labial tooth surface. All samples were placed in an incubator at a temperature of 37˚C and collected according to their retention time, i.e., 30 minutes after exposure to the remineralizing agents. Measurement of enamel calcium levels was performed using Atomic Absorption Spectrophotometry (AAS). Data were analyzed using one-way ANOVA followed by a post hoc LSD test. Results: The group treated with 20% green mussel shell mousse showed the highest calcium levels followed by the positive control group, mousse base group, and negative control group. The one-way ANOVA results showed a significant difference in calcium levels between treatment groups (p=0.001). The Post Hoc LSD test results showed a significant difference (p<0.05) between the negative control group and both the positive control (p=0.001) and green mussel mousse group (p=0.001). Conclusion: Application of 20% green mussel shell extract mousse effectively increases the calcium content of deciduous tooth enamel.