Shear Bond Strength of Composite Resin Attachments in Clear Aligner Orthodontic Appliances with Different Adhesive Systems
Objectives: Orthodontic treatments with clear aligners are popular. Loss of composite resin attachments during treatment remains a concern. Self-adhesive composite resins were introduced to simplify bonding. This study compared the shear bond strength (SBS) and evaluated the failure modes of self-adhesive and conventional composite resin.
Methods: Eighty-four intact upper first premolars were used, 80 were randomly allocated into five groups with different bonding protocols: Group 1 (etch and rinse + conventional flowable composite resin), Group 2 (self-etching + conventional flowable composite resin), Group 3 (self-adhesive composite resin), Group 4 (etching + self-adhesive composite resin), and Group 5 (self-etching + self-adhesive composite resin). After thermocycling, the SBS was tested using a universal testing machine and analyzed with one-way ANOVA (p<0.05). Failure modes were determined under a stereomicroscope. The enamel surface of four unallocated teeth with different preparations were assessed by a scanning electron microscope.
Results: 62.5% of attachments in Group 3 dislodged after thermocycling. The mean SBS (MPa) was significantly higher in Group 1 (17.72±5.37), Group 2 (19.13±5.37), Group 4 (19.03±6.91), and Group 5 (13.21±4.87) than in Group 3 (3.69±1.30); (p<0.05). Most failures in Groups 1, 2, 4, and 5 were mixed, while Group 3 exhibited only adhesive failure.
Conclusions: Self-adhesive composite resin alone had the lowest SBS. Pretreatment with 37% phosphoric acid or a self-etching primer significantly improved the SBS.
References
1. Weir T. Clear aligners in orthodontic treatment. Aust Dent J. 2017;62:58-62.
2. Jedliński M, Mazur M, Greco M, Belfus J, Grocholewicz K, Janiszewska-Olszowska J. Attachments for the orthodontic aligner treatment-state of the art-a comprehensive systematic review. Int J Environ Res Public Health. 2023;20(5):4481.
3. Yaosen C, Mohamed AM, Jinbo W, Ziwei Z, Al-Balaa M, Yan Y. Risk factors of composite attachment loss in orthodontic patients during orthodontic clear aligner therapy: a prospective study. Biomed Res Int. 2021. 2021:6620377.
4. Alshammari RR, Alshihah N, Aldweesh A. Mechanical properties of different types of composite resin used as clear aligner attachments: an in vitro study. Saudi Dent J. 2025;37(4-6):12.
5. Ocak I, Gorucu-Coskuner H, Aksu M. Wear resistance of orthodontic attachments: a comparative analysis of different composite resins in clear aligner therapy. Clin Oral Investig. 2025;29(5):242.
6. Dasy H, Dasy A, Asatrian G, Rózsa N, Lee HF, Kwak JH. Effects of variable attachment shapes and aligner material on aligner retention. Angle Orthod. 2015;85(6):934-40.
7. Nucera R, Dolci C, Bellocchio AM, Costa S, Barbera S, Rustico L, et al. Effects of composite attachments on orthodontic clear aligners therapy: a systematic review. Materials (Basel). 2022;15(2):533.
8. Bayram M, Yeşilyurt C, Kuşgöz A, Ülker M, Nur M. Shear bond strength of orthodontic brackets to aged resin composite surfaces: effect of surface conditioning. Eur J Orthod. 2010;33(2):174-9.
9. Al Noor HSS, Al-Joubori SK. Retention of different orthodontic aligners according to their thickness and the presence of attachments. Int J Med Res Health Sci. 2018;7(11):115-21.
10. Reynolds IR. A Review of direct orthodontic bonding. Br J Orthod. 1975;2(3):171-8.
11. Ozer F, Blatz MB. Self-etch and etch-and-rinse adhesive systems in clinical dentistry. Compend Contin Educ Dent. 2013;34(1):12-4, 16, 18; quiz 20, 30.
12. Valizadeh S, Alimohammadi G, Nik TH, Etemadi A, Tanbakuchi B. In vitro evaluation of shear bond strength of orthodontic metal brackets to aged composite using a self-adhesive composite: effect of surface conditioning and different bonding agents. Int Orthod. 2020;18(3):528-37.
13. Tosun G, Sener Y, Sengun A. Effect of storage duration/ solution on microshear bond strength of composite to enamel. Dent Mater J. 2007;26(1):116-21.
14. Lee JJ, Nettey-Marbell A, Cook A, Jr., Pimenta LA, Leonard R, Ritter AV. Using extracted teeth for research: the effect of storage medium and sterilization on dentin bond strengths. J Am Dent Assoc. 2007;138(12):1599-603.
15. Goracci C, Margvelashvili M, Giovannetti A, Vichi A, Ferrari M. Shear bond strength of orthodontic brackets bonded with a new self-adhering flowable resin composite. Clin Oral Investig. 2013;17(2):609-17.
16. Årtun J, Bergland S. Clinical trials with crystal growth conditioning as an alternative to acid-etch enamel pretreatment. Am J Orthod. 1984;85(4):333-40.
17. Chen W, Qian L, Qian Y, Zhang Z, Wen X. Comparative study of three composite materials in bonding attachments for clear aligners. Orthod Craniofac Res. 2021;24(4):520-7.
18. Sabbagh J, Dagher S, El Osta N, Souhaid P. Randomized clinical trial of a self-adhering flowable composite for Class I restorations: 2-year results. Int J Dent. 2017;2017:5041529.
19. Elraggal A, Raheem IA, Holiel A, Alhotan A, Alshabib A, Silikas N, et al. Bond strength, microleakage, microgaps, and marginal adaptation of self-adhesive resin composites to tooth substrates with and without preconditioning with universal adhesives. J Adhes Dent. 2024;26:53-64.
20. Veli I, Akin M, Kucukyilmaz E, Uysal T. Shear bond strength of a self-adhering flowable composite when used for lingual retainer bonding. J Orofac Orthop. 2014;75(5):374-83.
21. Talan J, Gupta S, Nikhil V, Jaiswal S. Effect of mechanical alteration of enamel surface on shear bond strength of different bonding techniques. J Conserv Dent. 2020;23(2):141-4.
22. Dunnett CW. Pairwise multiple comparisons in the unequal variance case. J Am Stat Assoc. 1980;75(372):796-800.
23. Lamper T, Ilie N, Huth KC, Rudzki I, Wichelhaus A, Paschos E. Self-etch adhesives for the bonding of orthodontic brackets: faster, stronger, safer?. Clin Oral Investig. 2014;18(1):313-9.
24. Sandhu SV, Tiwari R, Bhullar RK, Bansal H, Bhandari R, Kakkar T, et al. Sterilization of extracted human teeth: a comparative analysis. J Oral Biol Craniofac Res. 2012;2(3):170-5.
25. Kohn WG, Collins AS, Cleveland JL, Harte JA, Eklund KJ, Malvitz DM. Guidelines for infection control in dental health-care settings-2003. MMWR Recomm Rep. 2003;52(RR-17):1-61.
26. Sibai N, El Mourad A, Al Suhaibani N, Al Ahmadi R, Al Dosary S. Shear bond strength of self-adhesive flowable resin composite. Int J Dent. 2022;2022:1-8.
27. Meharry MR, Moazzami SM, Li Y. Comparison of enamel and dentin shear bond strengths of current dental bonding adhesives from three bond generations. Oper Dent. 2013;38(6):E237-45.