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"ABSTRAKLatar Belakang: Kasus kehilangan gigi molar pertama yang disertai dengan mesial tipping dari gigi molar kedua sering ditemui, sehingga penegakan gigi merupakan salah satu mekanika yang sering dilakukan oleh klinisi. Namun, sebagian besar literatur yang tersedia mengenai penegakan gigi merupakan laporan kasus yang memaparkan mengenaihasil perawatan dengan mekanika tertentu, sesuai dengan pengalaman masing-masing klinisi. Efisiensi dalam perawatan ortodonti, khususnya penegakan gigi, dapat dicapai apabila pergerakan gigi dapat diprediksi. Tujuan: Menganalisis gambaran distribusi stress pada ligamen periodontal gigi molar kedua, pada model 3D mandibula, serta menganalisis perpindahan inisial gigi molar kedua (dalam arah bukolingual, vertikal, dan mesiodistal) ketika diaplikasikan gaya penegakan gigi dengan menggunakan initial archwire, helical uprighting spring, T-loop, serta dengan retromolar miniscrew. Metode:Konstruksi model tiga dimensi mandibula dilakukan dalam satu kuadran, dengan konfigurasi kehilangan gigi molar pertama dan gigi molar kedua tipping 30º. Empat buah model kerja dibuat sesuai dengan metode penegakan gigi yang akan diuji yaitu dengan initial archwire, helical uprighting spring, T-loop, serta dengan retromolar miniscrew.Hasil: Terdapat perbedaan bermakna intensitas stress dan perpindahan inisial pada keempat kelompok mekanika yang diuji. Distribusi stress dan perpindahan inisial gigi molar kedua pada penggunaan initial archwire sangat kecil dibandingkan dengan ketiga mekanika lain yang diuji. Pada penggunaan T-loop, helical uprighting spring, dan retromolar miniscrew, area tension terbentuk paling besar di area servikal akar mesial, sedangkan area compression terbentuk pada area servikal akar distal. Pada analisis perpindahan inisial gigi molar kedua, penggunaan helical uprighting spring menunjukkan ekstrusi yang paling besar, diikuti oleh T-loop, dan retromolar miniscrew. Selain itu,terlihat adanya pergerakan akar pada penggunaan retromolar miniscrew, yang tidak ditemukan pada penggunaan mekanika lainnya. Kesimpulan: Intensitas stress ekuivalen paling besar dihasilkan dari penggunaan helical uprighting spring, T-loop, dan retromolar miniscrew secara berurutan. Analisis perpindahan inisial gigi menunjukkan penggunaan retromolar miniscrew menyebabkan mesial root movement, dibandingkan dengan distal tipping mahkota gigi pada mekanika lain.

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ABSTRACTIntroduction: One of the most frequently encountered clinical situation in adult patients would be the tipping of mandibular second molar which normally occurred due to early loss of the first molar. Previous studies reported different uprighting mechanics were mainly case report and only a few that aimed to describe the efficacy of the variousavailable mechanics. A profound understanding of the efficacy and predictability of the various mechanics would improve tooth movement and prevent unwanted side effects that may arise. The aim of this study was to analyse and compare the stress distribution as well as initial displacement of mandibular second molar using various uprightingmechanics. Methods: A three-dimensional model was constructed and analysed using Finite Element Analysis (FEA) with tipped mandibular second molar set at 30º. Four mandibular models were assembled according to different uprighting mechanics, as follows: initial continuous archwire, helical uprighting spring, T-loop and retromolarminiscrew. Results: Stress distribution and initial displacement resulted from the use of initial archwire were insignificant compared to other mechanics tested. The highest tensile stress were observed on the cervical area of mesial root and the highest compressive stress were observed on the cervical area of distal root on the application ofT-loop, helical uprighting spring, and retromolar miniscrew mechanics. Analysis of initial tooth displacement showed that helical uprighting spring caused the largest degree of extrusion, followed by T-loop, and retromolar miniscrew. Root movement was observed on the usage of retromolar miniscrew. Conclusion: Greatest equivalent stress wereobserved on the usage of helical uprighting spring, T-loop, and retromolar miniscrew in consecutive order. Analysis of initial displacement of the second molar showed that the application of retromolar miniscrew caused mesial root movement, while other mechanics showed distal tipping of the crown."

"Latar Belakang: Ekspresi penuh dari preskripsi torque bracket dipengaruhi oleh faktor yang berkaitan dengan bracket, kawat, torque play, dan faktor klinis. Hingga saat ini belum ada penelitian yang membandingkan kemampuan ekspresi torque antara berbagai ukuran kawat pada penggunaan bracket passive self-ligating (PSL) dan konvensional melalui simulasi finite element, serta menganalisis interaksi dari faktor-faktor tersebut, sekaligus memberikan gambaran pergerakan gigi dan respon jaringan periodontal. Penelitian ini bertujuan untuk mengukur besar torque play dan menganalisis pola perpindahan inisial gigi, serta distribusi stress antara berbagai ukuran kawat pada penggunaan bracket PSL dan konvensional melalui simulasi finite element. Metode: Model 3D dikonstruksi dengan skenario kasus yang membutuhkan pencabutan premolar pertama dan retraksi masse gigi anterior maksila, menggunakan penjangkaran temporary anchorage device dan gaya retraksi 150 g. Simulasi finite element dilakukan untuk mengukur torque play antara penggunaan kawat stainless steel 0.016 x 0.022", 0.017 x 0.025" dan 0.019 x 0.025", serta mengukur perpindahan inisial pada tepi insisal dan apeks akar insisif sentral maksila, serta distribusi stress pada PDL dan tulang alveolar antara penggunaan ketiga ukuran kawat pada kedua jenis bracket. Hasil: Pada penggunaan kawat 0.019 x 0.025", 0.017 x 0.025", dan 0.016 x 0.022" didapatkan torque play sebesar 7.6º, 11.6º, dan 18.7º untuk bracket PSL, dan 9.5º, 14º, dan 18º untuk bracket konvensional. Retraksi dan ekstrusi tepi insisal terbesar dihasilkan oleh kawat 0.016 x 0.022", sedangkan perpindahan palatal dari apeks terbesar dihasilkan oleh kawat 0.019 x 0.025". Konsentrasi stress terbesar terletak pada area 1/3 servikal pada sisi palatal dan 1/3 apikal pada sisi labial, yang menunjukkan pola perpindahan uprighting atau lingual crown tipping. Penggunaan kawat dengan diameter terbesar dan bracket konvensional menghasilkan stress terbesar pula.Kesimpulan: Torque play antara kawat dan bracket berbanding terbalik dengan ukuran kawat. Besarnya lingual crown tipping berbanding lurus terhadap torque play antara kawat dan bracket, dan dikonfirmasi oleh pola distribusi stress di PDL dan tulang alveolar. Kendali torque yang paling baik didapatkan oleh penggunaan kawat stainless steel 0.019 x 0.025". Perbedaan metode ligasi dan geometri bracket konvensional dan PSL kemungkinan menyebabkan adanya perbedaan besar moment yang dihasilkan.

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Introduction: The full expression of torque prescription of a bracket is influenced by bracket-related factors, wire-related factors, torque play and clinical factors. Finite element analysis (FEA) could be utilized to deepen our understanding and study the interaction between these factors, as well as to produce a simulation of the predicted tooth movement and tissue response. This study aims to measure the amount of torque play, and to analyse the pattern of initial tooth displacement, among different wire sizes and between passive self-ligating and conventional brackets using FEA.

Methods: A 3D model was constructed simulating a case which required first premolar extractions and en masse anterior retraction using temporary anchorage device and 150 g of retraction force on each side. Finite element simulation was performed to measure torque play, to investigate the pattern of initial tooth displacement at the incisal tip and of apex of the central maxillary incisor, as well as to analyse the pattern of stress distribution at the periodontal ligament (PDL) and alveolar bone, among different stainless steel wire diameters (0.016 x 0.022", 0.017 x 0.025" and 0.019 x 0.025") and between PSL and conventional brackets.

Results: The use of 0.019 x 0.025", 0.017 x 0.025", and 0.016 x 0.022" wires on PSL brackets produced a torque play of 7.6º, 11.6º, and 18.7º, respectively. While the use of the same wire sizes on conventional brackets produced a play of 9.5º, 14º, dan 18º, respectively. The use of 0.016 x 0.022 produced the farthest retraction and extrusion of the incisal tip. However, the greatest apex retraction was produced when 0.019 x 0.025" was used. The largest stress concentration was observed at the 1/3 cervical area on the palatal side and at the 1/3 apical area on the labial side. This shows that there is a pattern of uprighting or lingual crown tipping of the teeth. The use of 0.019 x 0.025" and conventional brackets yielded the greatest amount of stress on the PDL and alveolar bone.

Conclusion: The degree of torque play between wire and bracket was inversely proportional to the wire size, and the amount of lingual crown tipping was directly proportional to the degree of play. This pattern of tooth movement was confirmed by the pattern of stress distribution on the PDL and alveolar bone. Torque expression was better achieved using the 0.019 x 0.025" wire. Differences in the geometry and method of ligation between PSL and conventional brackets possibly generated different force magnitudes."