PENGARUH DEFLEKSI BERULANG TERHADAP GAYA UNLOADING DAN HISTERESIS PADA KAWAT BUSUR INISIAL NIKEL TITANIUM (NiTi) DAN COPPER NIKEL TITANIUM (CuNiTi) (Penelitian In Vitro)

LIDYA N ARFIADI, drg. Darmawan Sutantyo, SU., Sp.Ort(K); drg. Prihandini Iman, MS., Sp. Ort(K)

2016 | Tesis-Spesialis | SP ORTODONSIA

Kawat busur Nikel Titanium (NiTi) memiliki sifat shape memory effect dan superelastisitas sehingga kawat dapat kembali ke bentuk semula setelah dilakukan defleksi. Kedua sifat ini berpengaruh terhadap gaya loading dan gaya unloading yang dihasilkan kawat busur. Perbedaan antara kedua gaya tersebut disebut histeresis. Kawat busur ortodontik dengan penambahan tembaga (CuNiTi) akan menghasilkan sifat mekanis kawat yang lebih baik. Tujuan dari penelitian ini adalah untuk membandingkan gaya loading dan unloading yang dihasilkan kawat busur NiTi dan CuNiTi diameter 0,012 inci baru dengan kawat busur yang sudah pernah digunakan (defleksi berulang). Three-point bending test dilakukan pada lima kawat busur NiTi 0,012 inci dan lima kawat busur CuNiTi 0,012 inci baru dengan menggunakan Universal Testing Machine. Kawat busur yang telah diuji tersebut kemudian dipasang pada tiga bracket edgewise standar dengan defleksi 7 mm dan direndam dalam saliva buatan (suhu 37ºC). Three-point bending test diulang pada 3 minggu dan 6 minggu. Hasil penelitian menunjukkan bahwa baik kawat NiTi maupun CuNiTi menghasilkan gaya unloading lebih kecil dibandingkan gaya loading. Gaya unloading yang dihasilkan kawat busur busur baru tidak berbeda signifikan (p>0,05) dibandingkan kawat 3 minggu, namun berbeda signifikan dibandingkan kawat busur 6 minggu. Histeresis kawat busur CuNiTi baru, 3 minggu, dan 6 minggu berbeda signifikan (p<0,05) dibandingkan kawat busur NiTi. Kesimpulan dari penelitian ini adalah gaya unloading yang dihasilkan kawat busur setelah 6 minggu lebih rendah daripada kawat busur baru, dan kawat busur CuNiTi memiliki histeresis yang lebih kecil daripada NiTi.

ABSTRACT Shape memory effect and superelasticity properties of Nickel Titanium (NiTi) archwires ensures the archwire to revert its former shape after deflection. Both properties effect the loading and unloading forces exerted by the archwire. The disparity between the two forces forms the hysteresis loop. Copper added to the orthodontic archwire (CuNiTi) generates a better mechanical property. This study aims to evaluate the loading and unloading force exerted by a new 0.012 inch diameter NiTi and CuNiTi wire compared to a used redeflected wire. Three point bending test was perfomed on five new 0.012 inch NiTi wires and five new 0.012 inch CuNiTi using a Universal Testing Machine. After testing, both groups of wires were mounted on three standard edgewise brackets with the deflection of 7 mm and incubated in artificial saliva (37ºC). Three point bending tests were done on the third and sixth week. Result of this research shows that both NiTi and CuNiTi wire exert a lower unloading force compared to its loading force. The unloading force exerted by new wires is not statistically significant compared to the three-week used wires, however it is statistically signficant compared to the six-week used wires (p<0.05). The hysteresis of CuNiTi wires (new, three-week, six-week) is statictically significant compared to NiTi wires. This study concludes that the unloading force exerted by six-week used archwires is lower than a new archwires, and CuNiTi archwires produces lower hysteresis than NiTi archwires.

Kata Kunci : kawat busur, NiTi, CuNiTi, gaya loading-unloading, histeresis, defleksi berulang/archwires, NiTi, CuNiTi, loading-unloading force, hysteresis, redeflection