ABSTRAK Nama : Aula Aqrama Fakultas : Kedokteran Gigi ProgramStudi : Pendidikan Dokter Gigi Judul : Pengaruh Penambahan Hidroksiapatit 5% dari Cangkang Kerang Darah terhadap Perubahan Dimensi Glass Ionomer Cement(GIC)setelah Perendaman Kopi Arabika Gayo Glass ionomer cement (GIC) merupakan material restorasiyang bersifat biokompatibel. Namun,material ini bersifat rapuh dan memiliki daya tahan terhadap keausan yang rendah, sehingga dimodifikasi dengan penambahan hidroksiapatit (HAp) pada powder GIC untuk memperbaiki sifat mekanis tersebut karena berdampak pada sifat fisiknya.Hidroksiapatit adalah biomaterial yang mempunyai struktur kristal mirip apatit pada gigi dan tulang manusia.Pada penelitian ini, HAp disintesis dari cangkang kerang darah (Anadara granosa) sebagai sumber kalsium untuk sintesis HAp dengan metode solid state reaction.Tujuan: melihat pengaruh penambahan hidroksiapatit 5% dari cangkang kerang darah terhadap perubahan dimensi GICsetelah perendaman kopi arabika gayo. Metode: spesimen dibagi menjadi 2 kelompok, kelompok GIC tanpa penambahan HAp(n=4) dan kelompok GIC dengan penambahan 5% HAp (n=4). Jumlah keseluruhan spesimen sebanyak 8 spesimen berbentuk silinder berdiameter 5mm dan tinggi 2mm. Perubahan dimensi GIC dihitung menggunakan rumus perubahan dimensi yaitu dengan menghitung selisih berat sebelum dan sesudah perendaman spesimen dalam kopi arabika gayo selama 4 hari dengan suhu 55oC menggunakan timbangan analitik dan dibagi dengan luas permukaan spesimen yang diukur dengan jangka sorong digital. Hasil: rata-rata perubahan dimensiGIC tanpa penambahan HAp adalah sebesar 0.2 ± 0.179 dan GIC dengan penambahan HAp sebesar 0.122 ± 0.1. Hasil ujiMann Whitney pada data tersebut menunjukkan tidak terdapat perbedaan yang signifikan antar kedua kelompok (p>0,05).Kesimpulan: tidak terdapat pengaruh yang signifikan penambahan HAp terhadap perubahan dimensi GIC setelah perendaman kopi arabika gayo walaupun terdapat perbedaan rata-rata antara kelompok perlakuan dan kontrol. Kata Kunci: Glass ionomer cement (GIC), hidroksiapatit, perubahan dimensi   ABSTRACT Name : Aula Aqrama Faculty : Dentistry Study Program : Dentistry Title : Effect of Addition of 5% Hydroxyapatite from Blood Clam Shells to Dimensional Change of Glass Ionomer Cement (GIC) after Immersion of Gayo Arabica Coffee Glass ionomer cement (GIC) is a biocompatible restorative material. However, the material is brittle and low resistance to wear, so it is modified by adding hydroxyapatite (HAp) in to GIC powder to improve the mechanical properties because it will have an impact on their physical properties. Hydroxyapatite is a biomaterial that has a crystal structure which are similar to the apatite in human dental structures and skeletal system. In this study, HAp was synthesized from blood clam shells (Anadara granosa) as a calcium source to synthesis of HAp by using solid state reaction method. Purpose: to determine the effect of additional of 5% hydroxyapatite from blood clam shells to dimensional change of GIC after immersion of gayo arabica coffee. Method: the specimens were divided into 2 groups, which are GIC group without the addition of HAp (n=4) and the GIC group with addition of HA (n=4). Total of specimens were 8 specimens with 5mm and 2mm cylindrical shapes in diameter and height, respectively. Dimensional change of GIC were calculated by using a dimensional change formula, by calculating the weight difference before and after immersion of specimens in gayo arabica coffee for 4 days with a 55oC temperature by using analytical scale and were divided by the surface area of the specimen as measured by digital caliper. Results: the mean of dimensional change was 0.2 ± 0.179 for GIC without the addition of HAp and 0.122 ± 0.1 for GIC with the addition of HAp. The result of Mann Withneytest in the data showed no significant difference between the two groups (p >0,05). Conclusion: there was no significantly effect of adding HAp to dimensional change of GIC after immersion of gayo arabica coffee although there was an average difference between experimental and control groups. Keywords: Glass ionomer cement (GIC), hydroxyapatite, dimensional change