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Abstrak :
Paduan Nitinol adalah salah satu paduan yang paling banyak digunakan untuk pemakaian paduan ingat bentuk karena mempunyai sifat mekanik sangat baik dan efek ingat bentuk yang stabil. Telah dilakukan penelitian pengaruh laku panas terhadap struktur mikro dan karaktristik sifat ingat bentuk paduan Nitinol. Paduan Nitinol dengan komposisi Ti-50,04% at.Ni sebagai paduan ingat bentuk diberikan perlakuan pelarutan pada 1000°C selama 1 jam dan dicelupkan kedalam air kemudian dilakukan proses penuaan pada temperatur 500°C, 550°C, 600°C, 650°C dan 700°C selama 10 jam. Struktur mikro diteliti dengan menggunakan Mikroskop Optik (MO) dan Scanning Electron Microscopy (SEM). Temperatur transformasi ditentukan dengan pengukuran resistansi dan sifat mekanik yaitu kekerasan diukur dengan metoda Vickers. Hasil pengamatan menunjukkan bahwa fasa martensit yang terbentuk tersusun oleh pelat-pelat Iamelar yang cenderung menjadi besar sedangkan kekerasan menurun pada penuaan 600°C ---700°C. Temperatur transformasi martensit menunjukkan kenaikan sekitar 4 °C setelah penuaan pada 500°C selama 10 jam. Akan tetapi penuaan dari 500°C - 700 °C tidak menunjukkan perubahan yang berarti terhadap ukuran butir dan temperatur transformasi. ......Nitinol is one of the most of alloys used for the shape memory applications because they have good mechanical properties and stable shape memory effect. In this investigation, the influence of heat treatment on the microstructure and characteristic of Nitinol shape memory alloy were studied.The shape memory Nitinol alloy with Ti-50.04 % at.Ni composition was solution treated at 1000°C for 1 hour and quenched in water, then aged at temperature 500°C, 550°C, 600°C, 650°C and 700°C for 10 hours, respectively. Microstructures were investigated by using optical microscopy and Scanning Electron Microscopy (SEM). Transformation temperature were measured using resistance measurement technique, whereas the mechanical property such as hardness was measured by Vickers method. The results of observation show that martensitic phase were arranged by large lamellar plates which in addition the hardness values were found to decease within the temperature range of 600°C - 700°C of aging. The martensite transformation temperature increased about 4°C after aging process at 500°C for 10 hours. However, in the aging temperature of 500°C --700°C there were no significant change observed in the grain size and the transformation temperature.

Abstrak :
Latar Belakang: Preparasi saluran akar gigi dengan file endodontik Ni-Ti umum digunakan saat ini dalam praktik klinis maupun institusi pendidikan karena karakteristik bahan yang baik. File perlu melalui sterilisasi autoklaf sebelum digunakan kembali. Namun, setelah siklus preparasi dan sterilisasi terlihat perubahan morfologi dan belum ada kesepakatan batas penggunaan untuk menghindari hal tersebut. Tujuan: Menganalisis efek frekuensi preparasi dan sterilisasi terhadap perubahan morfologi file endodontik Ni-Ti hand-use. Metode: File ProTaper® Universal hand-use (Dentsply Maillefer) digunakan untuk preparasi 135 gigi premolar akar tunggal, sebanyak 5 kali (kelompok 1) dan 10 kali (kelompok 2), antar tiap preparasi file dibersihkan dengan larutan enzimatik, scouring sponge, ultrasonic cleaner dan sterilisasi autoklaf. Kemudian sampel diamati dengan stereomicroscope (Nikon® SMZ800, Japan). Data dianalisis dengan uji Kruskal-wallis dan Mann-Whitney (p<0,05). Hasil Penelitian: Terdapat perbedaan bermakna antara perubahan morfologi file setelah 5 dan 10 kali preparasi dan sterilisasi (p<0,05). Tidak terdapat perbedaan bermakna antara perubahan morfologi file F1 setelah 5 dan 10 siklus (p>0,05). Terdapat perbedaan bermakna antara perubahan morfologi file F2 setelah 5 dan 10 siklus (p<0,05) dan antara perubahan morfologi file F1 dan F2 setelah 5 siklus (p<0,05). Tidak terdapat perbedaan bermakna antara perubahan morfologi file F1 dan F2 melalui 10 siklus (p>0,05). Kesimpulan: Frekuensi preparasi dan sterilisasi file endodontik Ni-Ti hand use memiliki efek terhadap perubahan morfologi pada file. ......Background: Root canal preparation using Ni-Ti endodontic file was generally used today, due to its more elastic characteristic. In clinical setting, file requires autoclave sterilization before next usage. However, morphological changes could be seen after cycles of preparation and sterilization and there is still no agreement on safe usage limits for the re-use of these files. Objective: To analyze the effect of preparation and sterilization frequency on Ni-Ti endodontic hand-use files by their morphological changes. Method: ProTaper® Universal Hand-use files (PTU) (Dentsply Maillefer, Switzerland) were used on 135 single-rooted canal premolars for 5 times (1st group), 10 times (2nd group), then after every use, files are cleaned with enzymatic solution, scouring sponge, ultrasonic cleaner and sterilized by autoclave. Afterward, F1 and F2 files observed with stereomicroscope. Data was analyzed using Kruskal-Wallis and Mann-Whitney tests (p<0.05). Result: There were statistically significant differences of file morphological changes after 5 and 10 cycles (p<0.05). There were no statistically significant differences of F1 files morphological changes after 5 and 10 cycles (p>0.05). There were statistically significant differences of F2 files morphological changes after 5 and 10 cycles (p<0.05). There were statistically significant differences of F1 and F2 files morphological changes after 5 cycles (p<0.05). There were no statistically significant differences of F1 and F2 files morphological changes after 10 cycle (p>0.05). Conclusion: The frequency of preparation and sterilization on Ni-Ti endodontic hand-use files had effect on its morphological changes.