Journal of Baghdad College of Dentistry, Vol. 34, No. 4 (2022), ISSN (P): 1817-1869, ISSN (E): 2311-5270 51 Review Article Force degradation of orthodontic elastomeric chains: A literature review Ali Rahman Issa1* , Ammar Salim Kadhum2 1 Master Student, Department of Orthodontics, College of Dentistry, University of Baghdad, Iraq. 2 Assistant Professor, Department of Orthodontics, College of Dentistry, University of Baghdad, Iraq *Correspondence Email: ali.hassan1902@codental.uobaghdad.edu.iq Abstract: Background: Elastomeric chains are used to generate force in many orthodontic procedures, but this force decays over time, which could affect tooth movement. This study aimed to study the force degradation of elastomeric chains. Data and Sources: An electronic search on Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, LILACS, and PubMed was made, only articles written in English were included, up to January 2022.Study selection: Fifty original articles, systematic reviews, and RCTs were selected. Conclusion: Tooth movement, salivary enzymes, alcohol-containing mouthwash, whitening mouthwash, and alkaline and strong acidic (pH <5.4) solutions all have a significant impact on elastomeric chain force degradation. The force level of elastomeric chains degrades rapidly over time; however, the force degradation rate is slower in thermoset chains than in thermoplastic ones. An efficient tooth movement could be achieved by using a thermoset chain type with monthly replacement. Ethylene oxide and gamma sterilization methods are preferred to avoid the risk of cytotoxicity. Keywords: Orthodontic, Elastomeric chain, Force degradation, Tooth movement. Introduction Elastomeric chains are polyurethane-based polymers synthesized through chemical reactions between polyether or polyester with bi-functional iso-cyanates (1). They have been introduced in orthodontic treatment since the 1960s. A variety of forms is available depending on the distance between the rings. Since they are reasonably hygienic, affordable, simple to use, and don't require patient cooperation, they are widely used (2). However, there are some disadvantages to consider including the time-limited mechanical efficiency which necessitates their regular replacement. This efficiency is affected by both internal and external influences, which determine their permanent deformation. Material composition, production methods, and physical morphology are all internal influences, while temperature, pH, and moisture absorption are external influences (3). This review investigated the effects of the internal and external influences on force degradation in orthodontic elastomeric chains. Effect of time Several authors (4-16) showed that the tested elastomeric chains were incapable of generating continuous force over time. According to their research, the greatest amount of force degradation (20 50% depending on the study and chain type) happened on day one (particularly the first hour), followed by a considerably slower rate of degradation over the next four weeks, providing an average degradation of 50 to 85% (5,7,9-16). Andreasen and Bishara (4) advocated additional chain extension to produce a higher initial force to compensate for this rapid force degradation. However, this led to enormous patient discomfort and could lead to complications like root resorption (17). Received date: 12-03-2022 Accepted date: 03-04-2022 Published date: 15-12-2022 Copyright: © 2022 by the authors. The article is published under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org /licenses/by/4.0/). https://doi.org/10.26477/jbcd. v34i4.3276 mailto:ali.hassan1902@codental.uobaghdad.edu.iq https://creativecommons.org/licenses/by/4.0/ https://creativecommons.org/licenses/by/4.0/ https://doi.org/10.26477/jbcd.v34i3.3214 https://doi.org/10.26477/jbcd.v34i3.3214 J. Bagh. Coll. Dent. Vol. 34, No. 4. 2022 Issa and Kadhum 52 Hershey and Reynolds (5) increased the study time to six weeks and included simulated tooth motions at a rate of 0.25 and 0.5 mm per week. After four weeks, all modules sustained an average of 40% of their initial force, and a similar level after six weeks was recorded. The rate of force loss increased as the teeth were moved about in a virtual environment. Only 33% of the initial force persisted after four weeks at a rate of 0.25 mm, while 25% remained at a rate of 0.5 mm over the same period. More recently, Evans et al. (18) have published a clinical trial that tested elastomeric chain (3M) ability to produce sufficient force for orthodontic tooth movement over 16 weeks. This study had a split-mouth design, with the chain being removed after four weeks on one side but kept in for the entire 16 weeks on the other side. They found a difference in the rate of space closure between the altered and unaltered sides which was insignificant statistically. Clinically the chains were capable of moving teeth after 16 weeks although the generated force was 86 gm (the minimum suggested force level is 100 gm). Effect of internal factors The method of manufacturing may affect the mechanical properties of the material. Hershey and Reynolds (5), in an in vitro setting, found that die-cut stamped elastomers maintained higher levels of force than the injection-molded ones. However, clinical findings in canine retraction for both types were similar with no statistically significant difference (2,8). Different elastomeric chain configurations are available depending on the distance between the rings in their passive state. Generally, the continuous chains were reported to deliver greater initial force and less deterioration than the chains with a longer distance between the rings (19). The amount of force generated by the elastomeric chain varies from one brand to another. Rock et al. (20) found that the initial force generated by different brands of closed elastomeric chains stretched to 100% was 403 to 625 gm. They considered this a high amount of force and recommended extending the elastomeric chain to only 50-75% of its original length (regardless of the number of links) to achieve the desired force of approximately 300 gm. Aldrees et al. (12) studied 19 clear elastomeric chains with different varieties (closed, short, and long) from eight manufacturers (Ormco/Sybron, 3M/Unitek, Dentaurum, Dentsply/GAC, Ortho-Organizers, American Orthodontics, Rocky Mountain Orthodontics, and TP Orthodontics) and found significant differences in the mean percentage of force degradation between them. In light of these variations, a cautious practitioner should use a force gauge to define the needed initial force level compatible for efficient tooth movement. In 1985, Killiany and Duplessis (7) conducted a study about the new elastomeric chain (Energy Chain) from Rocky Mountain Orthodontics and compared it to the conventional elastomeric chain (thermoplastic) from American Orthodontics. At the time, it was not known that the Rocky Mountain elastomeric chain was a thermoset type. Force degradation testing revealed that the American Orthodontics plastic chain initially applied 375 gm of force, whereas the Rocky Mountain Orthodontics chain produced 330 gm of force. After four weeks, the Rocky Mountain Orthodontics chain retained 65.8% of its initial force, while the American Orthodontics chain retained 33.4% only. In an in-situ stetting, Baratieri et al. (21) discovered that only thermoset type maintained force levels over 100 gm after three weeks. Masoud et al. (22) investigated two types of elastomeric chains (thermoset and thermoplastic). They tested one of each type from American Orthodontics and ORMCO. They came to the conclusion that thermoset chains generated lower initial force and degraded at a much slower rate than thermoplastic chains, prompting them to recommend that a clear distinction should be made between the two during application. Additionally, Subroto et al. (23) found that the thermoset elastomeric chain color stability is superior to the thermoplastic type. Thermoset elastomeric chains are marketed under various brand names that imply memory or low force decay (14). These elastics have grown in favor of other materials in recent years as a result of J. Bagh. Coll. Dent. Vol. 34, No. 4. 2022 Issa and Kadhum 53 manufacturer claims regarding their "memory," a reduced force deterioration with time, a lighter initial force, and ease of usage; and being compliance-free, smooth, and more affordable than NiTi springs (24). Khanemasjedi et al. (25) reported that by using a thermoset elastomeric chain and replacing it every month, the canine can be retracted at speeds comparable to those achieved with a NiTi coil spring. However, thermoset chains needed more stretching than thermoplastic chains to achieve the desired forces (12). Cheng et al. (3) attempted to enhance the physical properties of elastomeric chains by nanoimprinting their surface during manufacturing. Nanopillars are nanostructures created on the surface of elastomeric chains as a part of the treatment. The results were promising, as this procedure transformed them from hydrophilic to hydrophobic, reducing the problems associated with these force-generating auxiliaries. The effect of external factors (environmental factors) David et al. (6) evaluated the effects of thermo-cycling on the force degradation pattern. They found that the thermo-cycled group (15-45°C) had significantly lower force degradation than the group maintained at a constant temperature of 37°C. However, this difference was reported as only 7-10 gm after three weeks of elastomeric chain stretching. Sulaiman et al. (26) tested the effect of temperature on the elastomeric chain by immersing them in artificial saliva at different temperatures (4°C, 23°C, 37°C, 55°C) for 210 minutes. The force degradation of the elastomeric chain stored at 23°C was statistically significantly higher, while other groups have a similar value of force degradation (no statistically significant difference). There is a controversy in literature when evaluating the effects of artificial saliva on force degradation versus water. Von Fraunhofer et al. (27) found that elastomeric chains in artificial saliva needed more stretching to achieve the desired force, while other researchers (4,19) reported no statistically significant difference between the two. However, the condition is different in the oral cavity as enzymes (especially esterase) in saliva can contribute to polyurethane degradation (28). Andhare et al. (29) reported higher force degradation in vivo studies than in vitro studies in a systematic review and meta-analysis. Ramazanzadeh (30), Javanmardi and Salehi (31), and Mirhashemi et al. (14) investigated the effects of fluoride on elastomeric chains. They concluded that using sodium fluoride (NaF) on a daily basis did not affect the force delivery capabilities of orthodontic elastomeric chains. Behnaz et al. (15,16) evaluated the effect of whitening kinds of toothpaste and mouthwash on the elastomeric chain force delivery. It was concluded that ordinary toothpaste (from Crest) had a lower negative impact on chains than whitening toothpaste and that regular toothpaste had the least negative influence on chains when compared to Sensodyne toothpaste (15). On the other hand, it was found that both fluoridated and whitening mouthwash might produce force degradation, with a stronger effect for the whitening mouthwash (16). The effect of different chlorhexidine concentrations on the force delivery of elastomeric chains was studied by Pithon et al. (10), who found a nonsignificant effect after four weeks. Their findings were in agreement with Mirhashemi et al. (14). In contrast, Omidkhoda et al. (13) reported a significant effect of chlorhexidine on the force degradation of the elastomeric chain, which could be attributed to ethanol content (13.65%) of the studied mouthwash; as the deleterious effect of alcohol on the elastomeric chains force delivery was reported by Larrabee et al. (9) and Mahajan et al. (32). J. Bagh. Coll. Dent. Vol. 34, No. 4. 2022 Issa and Kadhum 54 Teixeira et al. (33) evaluated the effect of phosphoric acid, citric acid, light Coke®, and artificial saliva on the elastomeric chain. Following three weeks of immersion, there was no statistically significant difference in force degradation pattern when compared to immersion in artificial saliva. Lacerda dos Santos et al. (34) had the same conclusion for weak acidic and neutral pH (5.0, 6.0, and 7.5 pH). In contrast, other studies (35, 36) found that Coke® (35) and citric acid (36) resulted in an increased force degradation of elastomeric chains, while Ferriter et al. (37) reported that the acidic fluoride environment improved force delivery of elastomeric chains. Pureprasert et al. (38) found that exposure to Sodium Hydroxide (NaOH), a strong alkaline solution, lowered the maximum forces and delivery forces of various elastic bands. Sufarnap (39) reported that polyurethane material can be hydrolyzed when exposed to a strongly acidic pH (pH <5.4) or alkaline pH (pH >8.0). The effect of Sterilization Traditional sterilization procedures (like dry heat sterilization) are not feasible due to the heat- sensitive nature of elastomeric chains, and autoclaving them resulted in force deterioration (40). When elastomeric chains were immersed in glutaraldehyde-containing solutions for 30 minutes (disinfection protocol), force degradation was found to be non-significant, until immersion time was increased up to 10 hours (sterilization protocol) when the effect became significant (41, 42). Immersion in 0.12% chlorhexidine for 10 minutes (disinfection protocol) and peracetic acid for 30 minutes was found to be non-significant (11). Pithon et al. (43) analyzed the effect of different methods of sterilization (70% alcohol, glutaraldehyde, ethylene oxide, autoclave, microwave, ultraviolet (UV), and gamma rays) on the cytotoxicity of elastomeric chains. They found that sterilizing elastics with ethylene oxide, UV, and gamma rays had no effect on their cytotoxicity; nevertheless, cytotoxicity was raised by autoclaving, glutaraldehyde, 70% alcohol, and microwaving. One of the significant flaws in this study is that they did not examine the mechanical impacts of these sterilization techniques. So, Pithon et al. (44) in 2015 studied the mechanical influence of these sterilization methods; they found no significant effect on elastomeric chain force delivery. They also reported that the UV is not completely efficient for the sterilization of elastomeric chains. Effects of pre-stretching Kim et al. (17) studied the effect of pre-stretching on transparent closed elastomeric chains (from Ormco company). They compare experimental group being pre-stretched to 100% of their initial length with non-stretched control group. The initial force was significantly lower in pre-stretched group; one hour later, both experimental and control groups had similar readings. The rate and pattern of force degradation were very similar from one hour to four weeks. Baty et al. (19) concluded in their literature review that the improvements were minor (although statistically significant) and unlikely to be clinically relevant, given that the pre-stretching resulted in a 5% less force degradation at three weeks. With a force reduction of 50 to 75%, a 5% change is unlikely to be clinically significant. A similar conclusion was reached by Halimi et al. (40) in a systematic review. However, Chang et al. (45) reported that the pre-stretching has no disadvantages like permanent deformation of the elastomeric chain, which could affect its force recovery ability, and considered it a beneficial technique that should be practiced. Clinical efficacy of elastomeric chains Andrew L. Sonis (46) compared NiTi coil springs to elastic. He sought to avoid the initial force degradation of elastics by using a material that delivers selectable tooth moving forces with the desired effects. This study showed that NiTi coil springs were superior to elastomeric chains as they delivered J. Bagh. Coll. Dent. Vol. 34, No. 4. 2022 Issa and Kadhum 55 a constant force over a wide range of lengths without permanent deformation, which nearly produced twice the rate of tooth movement. Santos et al.(47) and Pires et al. (48), in in vitro studies, concluded that NiTi closed coil springs are more suitable for dental movement than elastomeric chains. However, a more recent study (as mentioned earlier) by Khanemasjedi et al. (25) reported that monthly replacement of thermoset elastomeric chain gave a comparable speed of tooth movement to that with NiTi coil spring; this is consistent with earlier studies done by Nightingale and Jones (49), and Bokas and Woods (50). In a split-mouth trial, Barsoum et al. (51) reported no significant difference in canine retraction when employing elastomeric chins, other than the patient experiencing increased pain for longer days. On the other hand, another study by Evans et al. (18) found that elastomeric chains were capable of producing efficient tooth movement for nearly up to 16 weeks, as compared to those changed every four weeks. This shows a considerable improvement in the manufacturing process as well as the continued development of the chain material. Conclusions 1. Generally, the force level of elastomeric chains degrades rapidly over time, with the majority of degradation occurring during the first 24 hours, after which the rate reduces by time. 2. Differences in elastomeric chains configurations, manufacturer, and especially their types (either thermoset or thermoplastic) affect their initial force and degradation pattern over time, so a clear distinction between them is recommended. 3. The initial force and force degradation rate is lower in thermoset type than the thermoplastic ones. 4. It may be recommended to stretch the thermoplastic elastomeric chains to 50-75% of their original length to achieve an initial force around 300 gm, whereas the thermoset type needs more stretching, to achieve the same force. 5. The pre-stretching to decrease force degradation appears to be of minimal clinical value; however, no clinical disadvantages are present. 6. Environmental factors like tooth movement, salivary enzymes, alcohol-containing mouthwash, whitening mouthwash, and alkaline and strong acidic pH (<5.4) all have a significant impact on elastomeric chain force degradation, whereas sodium fluoride and chlorhexidine mouthwashes (in different concentrations) and temperature changes within the oral cavity (4-55°C) have no negative impact. 7. Cold disinfection protocol is recommended. Ethylene oxide and gamma rays are preferred to avoid the risk of cytotoxicity. Conflict of interest: None. References 1. Oertel G, Polyurethane Handbook, second ed., Germany, Hanser Publications, 1994. 2. Bousquet JA, Tuesta O, Flores-Mir C. In vivo comparison of force decay between injection molded and die-cut stamped elastomers. Am J Orthod Dentofacial Orthop. 2006;129(3):384-389. 3. Cheng HC, Chen MS, Peng BY, Lin WT, Shen YK, Wang YH. Surface treatment on physical properties and biocompatibility of orthodontic power chains. Biomed Res Int. 2017 Apr 30;2017. 4. Andreasen GF, Bishara SE. Relaxation of orthodontic elastic chains and midules in vitro and in vivo. Angle Orthod. 1970;40(3):151-8. 5. Hershey HG, Reynolds WG. The plastic module as an orthodontic tooth-moving mechanism. Am J Orthod Dentofacial Orthop. 1975;67(5):554-562. 6. David C, McInnes-Ledoux P, Weinberg R, Shaye R. Force degradation of orthodontic elastomeric chains—a product comparison study. Am J Orthod. 1985 May 1;87(5):377-84. J. Bagh. Coll. Dent. Vol. 34, No. 4. 2022 Issa and Kadhum 56 7. Killiany DM, Duplessis J. Relaxation of elastomeric chains. J Clin Orthod: JCO. 1985 Aug;19(8):592-3. 8. Eliades T, Eliades G, Silikas N, Watts DC. In vitro degradation of polyurethane orthodontic elastomeric modules. J Oral Rehabil. 2005;32(1):72-7. 9. Larrabee TM, Liu SS, Torres-Gorena A, Soto-Rojas A, Eckert GJ, Stewart KT. The effects of varying alcohol concentrations commonly found in mouth rinses on the force decay of elastomeric chain. Angle Orthod. 2012;82(5):894-9. 10. Pithon MM, Santana DA, Sousa KH, Farias IM. Does chlorhexidine in different formulations interfere with the force of orthodontic elastics?. Angle Orthod. 2013;83(2):313-8. 11. Losito KA, Lucato AS, Tubel CA, Correa CA, Santos JC. Force decay in orthodontic elastomeric chains after immersion in disinfection solutions. Braz J Oral Sci. 2014 Oct;13:266-9. 12. Aldrees AM, Al-Foraidi SA, Murayshed MS, Almoammar KA. Color stability and force decay of clear orthodontic elastomeric chains: An in vitro study. Int Orthod. 2015 Sep 1;13(3):287-301. 13. Omidkhoda M, Rashed R, Khodarahmi N. Evaluation of the effects of three different mouthwashes on the force decay of orthodontic chains. Dent Res J. 2015;12(4):348. 14. Mirhashemi A, Farahmand N, Saffar Shahroudi A, Ahmad Akhoundi MS. Effect of four different mouthwashes on force- degradation pattern of orthodontic elastomeric chains. Orthod Waves. 2017;76(2):67-72. 15. Behnaz M, Dalaie K, Hosseinpour S, Namvar F, Kazemi L. The effect of toothpastes with bleaching agents on the force decay of elastomeric orthodontic chains. Eur J Dent. 2017;11:427. 16. Behnaz M, Namvar F, Sohrabi S, Parishanian M. Effect of Bleaching Mouthwash on Force Decay of Orthodontic Elastomeric Chains. J Contemp Dent. 2018;19:221-225. 17. Kim KH, Chung CH, Choy K, Lee JS, Vanarsdall RL. Effects of prestretching on force degradation of synthetic elastomeric chains. Am J Orthod Dentofacial Orthop. 2005 Oct 1;128(4):477-82. 18. Evans KS, Wood CM, Moffitt AH, Colgan JA, Holman JK, Marshall SD, Pope DS, Sample LB, Sherman SL, Sinclair PM, Trulove TS. Sixteen-week analysis of unaltered elastomeric chain relating in-vitro force degradation with in-vivo extraction space tooth movement. Am J Orthod Dentofacial Orthop. 2017 Apr 1;151(4):727-34. 19. Baty DL, Storie DJ, von Fraunhofer JA. Synthetic elastomeric chains: a literature review. Am J Orthod Dentofacial Orthop. 1994;105(6):536–542. 20. Rock WP, Wilson HJ, Fisher SE. A laboratory investigation of orthodontic elastomeric chains. Br J Orthod. 1985;12(4):202- 207. 21. Baratieri C, Mattos CT, Alves Jr M, Lau TC, Nojima LI, Souza MM, Araujo MT, Nojima MD. In situ evaluation of orthodontic elastomeric chains. Brazilian dental journal. 2012;23:394-8. 22. Masoud AI, Tsay TP, BeGole E, Bedran-Russo AK. Force decay evaluation of thermoplastic and thermoset elastomeric chains: A mechanical design comparison. Angle Orthod. 2014 Nov;84(6):1026-33. 23. Subroto MI, Putri AP, Putri LS, Hidayati L. Generation I and Generation II Elastomeric Chains Characteristics Comparison in Artificial Saliva Immersion. Brazilian Dental Science. 2021;24(1):9-P. 24. Kanuru RK, Azaneen M, Narayana V, Kolasani B, Indukuri RR, Babu PF. Comparison of canine retraction by in vivo method using four brands of elastomeric power chain. J Int Soc Prev Community Dent. 2014 Nov;4(Suppl 1):S32. 25. Khanemasjedi M, Moradinejad M, Javidi P, Niknam O, Jahromi NH, Rakhshan V. Efficacy of elastic memory chains versus nickel–titanium coil springs in canine retraction: a two-center split-mouth randomized clinical trial. Int Orthod. 2017 Dec 1;15(4):561-74. 26. Sulaiman TH, Eriwati YK, Indrani DJ. Effect of temperature on tensile force of orthodontics power chain in artificial saliva solution. J Phys Conf Ser. 2018 Aug 1 (Vol. 1073, No. 6, p. 062006). IOP Publishing. https://doi.org/10.1088/1742-6596/1073/6/062006 J. Bagh. Coll. Dent. Vol. 34, No. 4. 2022 Issa and Kadhum 57 27. Von Fraunhofer JA, Coffelt MP, Orbell GM. The effects of artificial saliva and topical fluoride treatments on the degradation of the elastic properties of orthodontic chains. Angle Orthod. 1992 Dec;62(4):265-74. 28. Kemona A, Piotrowska M. Polyurethane recycling and disposal: Methods and prospects. Polymers. 2020 Aug;12(8):1752. 29. Andhare P, Datana S, Agarwal SS, Chopra SS. Comparison of in vivo and in vitro force decay of elastomeric chains/modules: a systematic review and meta analysis. J World Fed Orthod. 2021 Dec;10(4):155-162. 30. Ramazanzadeh BA, Jahanbin A, Hasanzadeh N, Eslami N. Effect of sodium fluoride mouth rinse on elastic properties of elastomeric chains. Journal of Clinical Pediatric Dentistry. 2009;34:189-192. 31. Javanmardi Z, Salehi P. Effects of Orthokin, Sensikin and Persica mouth rinses on the force degradation of elastic chains and NiTi coil springs. J Dent Res Dent Clin Dent Prospects. 2016;10(2):99. 32. Mahajan V, Singla A, Negi A, Jaj HS, Bhandari V. Influence of Alcohol and Alcohol-free Mouthrinses on Force Degradation of Different Types of Space Closure Auxiliaries used in Sliding Mechanics. J Indian Orthod Soc. 2014;48(4_suppl4):546-51. 33. Teixeira L, Pereira Bdo R, Bortoly TG, Brancher JA, Tanaka OM, Guariza-Filho O. The environmental influence of Light Coke, phosphoric acid, and citric acid on elastomeric chains. J Contemp Dent Pract. 2008;9:17-24. 34. Lacerda dos Santos R, Pithon MM, Romanos MT. The influence of pH levels on mechanical and biological properties of nonlatex and latex elastics. Angle Orthod. 2012;82(4):709-14. 35. Nattrass C, Ireland AJ, Sherriff M. The effect of environmental factors on elastomeric chain and nickel titanium coil springs. Eur J Orthod. 1998 Apr 1;20(2):169-76. 36. Khaleghi A, Ahmadvand A, Sadeghian S. Effect of citric acid on force decay of orthodontic elastomeric chains. Dental Research Journal. 2021;18. 37. Ferriter JP, Meyers Jr CE, Lorton L. The effect of hydrogen ion concentration on the force-degradation rate of orthodontic polyurethane chain elastics. Am J Orthod Dentofacial Orthop. 1990;98(5):404-10. 38. Pureprasert T, Anuwongnukroh N, Dechkunakorn S, Loykulanant S, Kongkaew C, Wichai W. Comparison of Mechanical Properties of Three Different Orthodontic Latex Elastic Bands Leached with NaOH Solution. Key Eng Mater. 2017; (Vol. 730, pp. 135-140). Trans Tech Publications Ltd. 39. Sufarnap E, Harahap KI, Terry T. Effect of sodium fluoride in chlorhexidine mouthwashes on force decay and permanent deformation of orthodontic elastomeric chain. Padjadjaran Journal of Dentistry. 2021 Mar 31;33(1):74-80. 40. Halimi A, Benyahia H, Doukkali A, Azeroual MF, Zaoui F. A systematic review of force decay in orthodontic elastomeric power chains. Int Orthod. 2012; 10(3):223-240. 41. Jeffries CL, Von Fraunhofer JA. The effects of 2% alkaline gluteraldehyde solution on the elastic properties of elastomeric chain. Angle Orthod. 1991 Mar;61(1):26-30. 42. Martins MM, Lima TA, Areas AC. Influence of glutaraldehyde solutions 2% in the forces generated by orthodontic elastic chains. Cienc Odontol Bras. 2008;11:49-57. 43. Pithon MM, dos Santos RL, Martins FO, Romanos MT, Araújo MT. Cytotoxicity of orthodontic elastic chain bands after sterilization by different methods. Orthod Waves. 2010 Dec 1;69(4):151-5. 44. Pithon MM, Ferraz CS, Rosa FC, Rosa LP. Sterilizing elastomeric chains without losing mechanical properties. Is it possible?. Dental press journal of orthodontics. 2015 May;20:96-100. 45. Chang JH, Hwang CJ, Kim KH, Cha JY, Kim KM, Yu HS. Effects of prestretch on stress relaxation and permanent deformation of orthodontic synthetic elastomeric chains. Korean J Orthod. 2018 Nov;48(6):384-394. 46. Sonis AL. Comparison of NiTi coil springs vs. elastics in canine retraction. J Clin Orthod. 1994 May;28(5):293. https://doi.org/10.15171/joddd.2016.016 https://doi.org/10.5005%2Fjp-journals-10021-1313 J. Bagh. Coll. Dent. Vol. 34, No. 4. 2022 Issa and Kadhum 58 47. Santos AC, Tortamano A, Naccarato SR, Dominguez-Rodriguez GC, Vigorito JW. An in vitro comparison of the force decay generated by different commercially available elastomeric chains and NiTi closed coil springs. Brazilian oral research. 2007 Mar;21(1):51-7. 48. Pires BU, de Souza RE, Vedovello Filho M, Degan VV, dos Santos JC, Tubel CA. Force degradation of different elastomeric chains and nickel titanium closed springs. Brazilian Journal of Oral Sciences. 2011;10(3):167-70. 49. Nightingale C, Jones SP. A clinical investigation of force delivery systems for orthodontic space closure. Journal of orthodontics. 2003 Sep;30(3):229-36. 50. Bokas J, Woods M. A clinical comparison between nickel titanium springs and elastomeric chains. Australian Orthodontic Journal. 2006 May;22(1):39-46. 51. Barsoum HA, ElSayed HS, El Sharaby FA, Palomo JM, Mostafa YA. Comprehensive comparison of canine retraction using NiTi closed coil springs vs elastomeric chains. Angle Orthod. 2021 Jul 1;91(4):441-448. العنوان: تضاؤل قوة السالسل المرنة التقويمية: مراجعة النتاج الفكري , عمار سالم كاظم الباحثون: علي رحمن عيسى الملخص بمرور الوقت، مما قد يؤثر على تتضاءلاهداف البحث: تُستخدم السالسل المرنة لتوليد القوة في العديد من إجراءات تقويم األسنان، لكن هذه القوة ة.القوة في السالسل المرن تضاؤلحركة األسنان. هدفت هذه الدراسة إلى دراسة وتم تضمين (CENTRAL ،MEDLINE ، LILACS ،PubMed) البيانات االلكترونية في قواعد البيانات والمصادر: تم إجراء بحث إلكتروني .2022حتى يناير فقط،المقاالت المكتوبة باللغة اإلنجليزية . سريرية شوائيةعمقالة أصلية ومراجعات منهجية وتجارب خمسين اختيار الدراسة: تم اختيار األسنان، حركة الكحول، وغسولاللعابية، واإلنزيماتاالستنتاجات: على المحتوي المبيض، وغسول الفم عالية والفم العالية القلويمحاليل أو ة معدل مستوى قوة السالسل المرنة بسرعة بمرور الوقت؛ ومع ذلك فإن يتضاءلالمرنة. في السالسل تضاؤل القوة كلها لها تأثير كبير على الحمضية السالسل المتصلبة . يمكن تحقيق حركة أسنان فعالة باستخدام السالسل اللدنة بالحرارةمنه في السالسل المتصلبة بالحراراةأبطأ في تضاؤل القوة .مخاطر السمية الخلويةالغاما لتجنب واشعةثيلين يفضل استخدام طرق التعقيم بأكسيد األشهري. الستبدال المع ابالحرارة