Pengaruh Jarak dan Lama Peregangan Terhadap Besar dan Penurunan Gaya Tarik Closed Coil Spring Nikel Titanium

Abstract

     Closed coil spring NiTi telah banyak digunakan dan dikembangkan karena besar gaya ringan dan konstan dalam jangka panjang untuk pergerakan gigi, kesehatan jaringan periodontal terjaga, penutupan ruang terjadi secara
cepat dan konsisten. Penelitian ini dilakukan untuk mengetahui pengaruh jarak dan lama peregangan terhadap besar gaya tarik dan penurunan gaya tarik closed coil spring NiTi dalam simulasi retraksi gigi kaninus, dengan rerata
kecepatan retraksi gigi kaninus sebesar 2 mm/bulan.
     Penelitian eksperimental dilakukan pada 25 closed coil spring NiTi yang terbagi menjadi 5 kelompok jarak peregangan awal yaitu 21 mm (kelompok A), 23 mm (kelompok B), 25 mm (kelompok C), 27 mm (kelompok D), dan 29 mm (kelompok E). Sampel direndam dalam saliva buatan pH normal (6,75) yang disimpan pada inkubator dengan suhu 37°C. Masing-masing sampel diukur besar gaya tariknya menggunakan Tensile Testing Machine pada minggu ke-0, minggu ke-4, minggu ke-8 dan minggu ke-12. Pengurangan jarak peregangan pada tiap kelompok sebesar 2 mm dilakukan pada minggu ke-4 dan ke-8. Besar penurunan gaya tarik diketahui dari selisih pengukuran gaya awal dan gaya akhir pada 0-4 minggu, 4-8 minggu dan 8-12 minggu. Data dianalisis menggunakan uji statistik
Analisis Variansi Dua Jalur dan dilanjutkan uji Post Hoc Multiple Comparisons (LSD) (p<0,05).
      Hasil penelitian menunjukkan terdapat pengaruh jarak dan lama peregangan terhadap besar gaya tarik dan penurunan gaya tarik closed coil spring NiTi (p<0.05). Kesimpulan : Besar gaya tarik closed coil spring nikel titanium
meningkat dengan bertambah panjang jarak peregangan, dan menurun dengan makin lamanya waktu peregangan dalam 4 minggu. Jarak peregangan tertentu menghasilkan penurunan gaya tarik yang konstan. Jarak peregangan makin panjang melebihi superelastis NiTi akan mengalami penurunan gaya tarik semakin besar.

ABSTRACT
     NiTi closed coil springs have been widely developed and used because of the light and constant forces they produced in the long term for teeth movement, periodontal tissue health, space closure occurs rapidly and
consistently. This study was to determine the effect of stretching distance and duration of the NiTi closed coil springs to the tensile force and decreased tensile strength of the NiTi closed coil spring in simulated canine retraction, with rate of canines retracted by 2 mm/month.
     The experimental study was involving 25 NiTi closed coil springs, divided into 5 groups with initial stretching distances of 21 mm (group A), 23 mm (group B), 25 mm (group C), 27 mm (group D) and 29 mm (group E). Samples
were immersed in neutral artificial saliva at pH 6.75 which was stored in an incubator at 37° C. Each sample was measured using Tensile Testing Machine at initial week, 4th week, 8th week and 12th week. Reducing the distance stretch of 2 mm each group performed at 4th week and 8th . Large reduction of the difference in tensile force measurement known initial and end force at 0-4 weeks, 4-8 weeks and 8-12 weeks. Data were analized by two-way Analysis of Variance test followed by Post Hoc Multiple Comparisons (LSD) test (p<0,05).
     The results showed there was an effect of stretching distance and duration of the NiTi closed coil springs to the tensile force and decreased tensile strength (p<0.05). Conclusion : The tensile force increased by longer stretching distance of NiTi and and decreased by longer stretching duration in 4 weeks. Certain stretching distance resulted in a constant decreased tensile force and stretching distance longer than the superelasticity of NiTi resulted to the greater decreased of tensile force.