Background: The filler addition to resin based sealers will enhance the physical properties of the polymer. Because of its biological properties, the synthetic hydroxyapatite (HA) has been proposed as filler for dental material such as composite resin. The calcite synthesized HA is the HA produced of calcite minerals that came from many Indonesian mining. Purpose: The aim of study was to determine the effect of different concentration of calcite synthesized HA as the filler of the epoxy-resin-based root canal sealer on the physical properties such as its contact angle, the film thickness and the microhardness. Methods: The crystal of the calcite synthesized hydroxyapatite with the size between 77.721-88.710 nm and the ratio of Ca/P 1.6886 were synthesized at Ceramic Laboratory, Mechanical Engineering, using wet method of hydrothermal microwave. The powders of the epoxy- resin were prepared by added the synthesized hydroxyapatite crystal in 5 different weight ratios (e.g.: HA-10%, HA-20%, HA-30%, HA-40% and HA-50%). Each of these was mixed with the paste of 3:1 ratio using spatula on a glass plate until homogen and then measuring the contact angle and the film thickness. Microhardness test was conducted after the mixture of experimental sealer was stored for 24 hrs at 37 oC to reach perfect polymerization. Results: All of contact angles were <90o and were not significantly different to each other (p= 0.510). All groups had a film thickness in accordance with ISO 6876 (<50 um) and with no statistical difference (p= 0.858). In the HA of 10%, 20%, 30% seen that the microhardness were increased, while in the HA-50% was decreased and in the HA-40% has the same microhardness to the control groups (HA-0%). Conclusion: Calcite synthesized HA as the filler did not affect contact angle and film thickness of the sealer. Microhardness of the epoxy-resin based sealer could be increased using maximum 30% of the calcite synthesized HA as the filler. Latar belakang: Penambahan bahan pengisi pada sealer berbahan dasar resin akan meningkatkan sifat fisik polimer. Karena sifat biologis bagus, hidroksiapatit (HA) sintetis digunakan sebagai bahan pengisi material kedokteran gigi seperti resin komposit. Hidroksiapatit sintesis kalsit merupakan HA yang hasilkan dari mineral kalsit berasal dari berbagai daerah pertambangan di Indonesia. Tujuan: Penelitian ini bertujuan untuk meneliti pengaruh berbagai konsentrasi HA sintesis kalsit sebagai bahan pengisi sealer berbahan dasar resin epoksi terhadap sifat fisiknya yaitu sudut kontak, ketebalan film dan kekerasan mikronya. Metode: Kristal HA sintesis kalsit yang berukuran 7,721-88,710 nm dengan rasio Ca/P 1,6886 diperoleh dari sintesis di Laboratorium Keramik, Teknik Mesin, Universitas Gadjah Mada menggunakan wet method dengan microwave hidrotermal. Serbuk resin epoksi dipersiapkan dengan menambahkan kristal HA sintesis kalsit dalam lima konsentrasi yang berbeda yaitu HA-10%, HA-20%, HA-30%, HA-40% dan HA-50% (dalam berat). Masing-masing serbuk diaduk dengan pasta resin epoksi dengan perbandingan 3:1 menggunakan spatula di atas glassplate hingga homogen, selanjutnya dilakukan pengukuran sudut kontak dan ketebalan film. Pengukuran kekerasan mikro dilakukan setelah sealer disimpan dalam inkubator 37 oC selama 24 jam sehingga mencapai polimerisasi sempurna. Hasil: Semua kelompok menunjukkan bahwa sudut kontak <90o dan menunjukkan tidak ada perbedaan yang signifikan (p=0,510). Semua kelompok menunjukkan bahwa ketebalan filmnya sesuai dengan ISO 6876 (<50 um) dan menunjukkan tidak ada perbedaan yang signifikan (p=0,858). Pada kelompok HA-10%, 20% dan 30% kekerasan mikronya meningkat, sedangkan pada HA-50% menurun dan HA-40% kekerasannya sama dengan kelompok kontrol (HA-0%). Simpulan: Penambahan hingga 50% HA sintesis kalsit sebagai bahan pengisi sealer resin epoksi tidak mempengaruhi sudut kontak dan ketebalan film. Kekerasan sealer dapat ditingkatkan dengan menambahkan HA sintesis kalsit maksimum hingga 30%.