en Health Improvement Strategies Health Improvement Strategies مقاله پژوهشی Original Research Article <p style="text-align: justify;"><span style="font-size:16px;"><span style="font-family:Times New Roman;"><b><span style="background:#2d7f8f"><span style="color:white">Background & Objective:</span></span>&nbsp;</b><span style="color:black">Fixed retainer success is reported to increase with passive adaptation of the retainer wire to the tooth surface, reducing saliva contamination during bonding. Flexible wires minimize bond failures by reducing stress concentration inside the bonding compound; therefore, the ideal fixed orthodontic retainer should be passive and semi-rigid. This<i> in-vitro</i> study aimed to evaluate the deflection load of different orthodontic fixed lingual retainers, and evaluate the bending properties of a chain type stainless steel fixed retainer comparing it with the other types.</span><br> <b><span style="background:#2d7f8f"><span style="color:white"><span style="letter-spacing:-.1pt">&nbsp;Materials & Methods:</span></span></span></b> <span style="color:black"><span style="letter-spacing:-.1pt">Five types of fixed bonded lingual retainers were flat metallic wire (FMW), round metallic wire (RMW), braided chain wire (BCW), and Fiber-reinforced composite with spot (SF) and full (FF) techniques were used to be tested. A three-point bending test was done at 0.1, 0.2, and 0.3 mm, and maximum deflection with an acrylic Frasaco mandibular model. These forces were measured using a Universal Instron testing machine.</span></span><br> <b><span lang="EN-IN"><span style="background:#2d7f8f"><span style="color:white">Results: </span></span></span>&nbsp;</b><span style="color:black"><span style="letter-spacing:-.1pt">The FF retainer showed significantly higher load deflection values than other retainer types at 0.1, 0.2, and 0.3 mm and at the maximum load deflection. On the other hand, there were no significant differences between the remaining types of fixed retainers, except for the significant differences between FMW and RMW, SF groups at 0.2 and 0.3 mm.</span></span><br> <b><span style="background:#2d7f8f"><span style="color:white">Conclusion: </span></span>&nbsp;</b><span style="color:black">The FMW retainer showed the lowest load deflection values, the BCW retainer would be an e</span><span dir="RTL" lang="AR-IQ"><span style="color:black">xcellent choice for retaining tooth position </span></span><span style="color:black">as it had an intermediate load deflection values compared with other retainer types; and the FF retainer had the largest values of load deflection.</span></span></span></p> Lingual, Wire, Relapse, Retention, Deflection Load, Chain Type Stainless Steel 68 80 http://journal.zums.ac.ir/browse.php?a_code=A-10-7432-1&slc_lang=en&sid=1 Noor A. Hussain raadmuslim7@gmail.com 5200319475328460087553 5200319475328460087553 Yes College of Dentistry, University of Baghdad, Baghdad, Iraq Mustafa M. AL-Khatieeb MustafaAL-Khatieeb@gmail.com 5200319475328460087554 5200319475328460087554 No Department of Orthodontics, College of Dentistry, University of Baghdad, Baghdad, Iraq