author = {Theerasopon, Pornpat. and Kosuwan, Weerachai. and Charoemratrote, Chairat.}, title = {{Stress assessment of mandibular incisor intrusion during initial leveling in continuous arch system with different archwire shapes of superelastic nickel-titanium: A three-dimensional finite element study}}, journal ={International Journal of Health & Allied Sciences}, volume ={8}, number ={2}, pages = {92-97}, doi = {10.4103/ijhas.IJHAS_3_19}, year = {2019}, abstract ={ INTRODUCTION: Orthodontic leveling of mandibular teeth with deep curve of Spee usually creates an intrusive force on mandibular incisors with labial tipping. After placing an archwire, a deactivation force causes tooth movement within the periodontal space which induces the first step and is the first signal for further remodeling processes. This study aimed to investigate stress distribution and types of mandibular incisor movement after initial leveling with different nickel-titanium (Ni-Ti) archwires using finite element analysis. MATERIALS AND METHODS: A three-dimensional finite element model of well-aligned mandibular teeth with a deep curve of Spee was created to investigate intrusive force on mandibular incisors within the periodontal ligament (PDL) space. Round, square, and rectangular superelastic Ni-Ti archwires of 0.016” in height were tested to compare stress magnitude and the pattern of distribution on the root surface and PDL as well as the pattern of tooth displacement between the archwires. RESULTS: Intrusive force by an archwire within the PDL space caused the highest stress at both labial and lingual cervical roots, but much higher stress was found at the labial than the lingual cervical roots. The highest labial stress was more cervical than lingual in all models. Round wires showed much higher stress than either square- or rectangular-shaped archwires. Displacement in the labial direction of round wires moved the farthest, whereas square and rectangular wires showed less labial displacement. CONCLUSIONS: Lower incisor intrusion with round wires produced more stress at the labial cervical root and tipped more labially compared to square and rectangular archwires. }, URL ={https://www.ijhas.in/article.asp?issn=2278-344X;year=2019;volume=8;issue=2;spage=92;epage=97;aulast=Theerasopon;t=6}, eprint ={https://www.ijhas.in/article.asp?issn=2278-344X;year=2019;volume=8;issue=2;spage=92;epage=97;aulast=Theerasopon;t=6} }