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Int. J. Mol. Sci. 2017, 18(10), 2096; https://doi.org/10.3390/ijms18102096
Spot-Bonding and Full-Bonding Techniques for Fiber Reinforced Composite (FRC) and Metallic Retainers
Unit of Orthodontics and Paediatric Dentistry, Section of Dentistry, Department of Clinical, Surgical, Diagnostic and Paediatric Sciences, University of Pavia, 27100 Pavia, Italy
Department of Biomaterial Science and Turku Clinical Biomaterials Centre—TCBC, Institute of Dentistry, University of Turku, 20100 Turku, Finland
Welfare Division, 20100 Turku, Finland
Author to whom correspondence should be addressed.
Received: 19 September 2017 / Accepted: 2 October 2017 / Published: 4 October 2017
Fiber reinforced Composite (FRC) retainers have been introduced as an aesthetic alternative to conventional metallic splints, but present high rigidity. The purpose of the present investigation was to evaluate bending and fracture loads of FRC splints bonded with conventional full-coverage of the FRC with a composite compared with an experimental bonding technique with a partial (spot-) resin composite cover. Stainless steel rectangular flat, stainless steel round, and FRC retainers were tested at 0.2 and 0.3 mm deflections and at a maximum load. Both at 0.2 and 0.3 mm deflections, the lowest load required to bend the retainer was recorded for spot-bonded stainless steel flat and round wires and for spot-bonded FRCs, and no significant differences were identified among them. Higher force levels were reported for full-bonded metallic flat and round splints and the highest loads were recorded for full-bonded FRCs. At the maximum load, no significant differences were reported among spot- and full-bonded metallic splints and spot-bonded FRCs. The highest loads were reported for full bonded FRCs. The significant decrease in the rigidity of spot-bonded FRC splints if compared with full-bonded retainers suggests further tests in order to propose this technique for clinical use, as they allow physiologic tooth movement, thus presumably reducing the risk of ankylosis.
Keywords:dentistry; orthodontics; prosthodontics; fiber reinforced composite; FRCs; three-point bending; bend; strength
Fiber reinforced composites (FRCs) were introduced in dentistry over 40 years ago. The reinforcement of dental resins with short or long fibers has been described in alternative to the widely used particulate reinforcements [1,2]. FRCs allow a high strength/weight and stiffness/weight if compared with other materials . Firstly, dental composites have been reinforced with polyethylene, carbon, and aramid fibers . Subsequently, glass fibers  have been introduced and, more recently, nanofilled glass FRCs  have been presented.
FRCs showed meaningful improvements in properties over unreinforced resins, and usually the clinicians found them easy to manipulate and customize [1,2]. Consequently, during the last years, FRCs have been proposed for many clinical applications . Fixed dental prostheses [8,9], root canal anchoring systems [10,11,12], fillings and core-built ups [13,14,15,16], removable devices [17,18], periodontal and trauma splints , orthodontic retainers , and orthodontic anchorage units  have been reported to be realized with FRCs. Even if FRCs’ high stiffness (33 and 44 N under 0.1 and 0.2 mm deflections, respectively)  can be useful for prosthodontic uses, this characteristic could be unwanted for splint and retainer purposes. Some studies have demonstrated that FRC splints presented increased deflection values if compared with metallic wires  and conventional stainless steel splints [23,24]. Excessive rigidity can be in contrast with physiologic tooth movement, thus increasing the risk of ankylosis [25,26].
The rigidity of an FRC splint is due to composite and fiber characteristics  and can be magnified by the FRC application technique. In fact after enamel etching, the tooth is dried and a thin layer of adhesive resin is applied. The FRC retainer is then located on the enamel surface and a small amount of resin paste is placed to cover the entire retainer and then light cured, as per the manufacturer’s instructions [4,20]. The total composite coverage of an FRC retainer is in contrast with conventional stainless steel splint preparation, which allows the retainer to be covered with resin only in correspondence of each tooth. This fabrication design could enhance the structural elasticity of metallic splints, due to the lack of composite coverage in the interproximal zones of the retainer . On the basis of these considerations, a spot-bonding technique, if applied to FRC splint construction, could decrease FRC rigidity, thus increasing similarity with stainless steel mechanical behaviour.
To our knowledge, bending and fracture loads of FRCs have been tested in the literature [29,30,31], but there is no report that has compared FRCs, prepared with the spot- or full-bonding technique.
Therefore, the purpose of the present investigation was to evaluate and compare stainless steel (round and rectangular) and FRC splints bonded with full- or spot-composite coverage. The load required to bend the retainer of various deflections was measured (Figure 1).
Strengths were measured at 0.2 and 0.3 mm deflections and at a maximum load (Table 1). The null hypothesis of the present report was that there is no significant difference in deflection values among the various groups tested.
The descriptive statistics of the loads (N) recorded in the 18 groups including the mean, standard deviation, median, minimum, and maximum are shown in Table 2.
The results of ANOVA indicated significant differences among the various groups (p < 0.001).
A post-hoc test pointed out that, both at 0.2 mm (Figure 2—groups 1 to 6) and at 0.3 mm (Figure 3—groups 7 to 12) deflections, the lowest strengths were recorded for spot-bonded stainless steel flat (groups 1 and 7) and round (groups 3 and 9) wires and for spot bonded FRCs (groups 5 and 11), and no significant differences were observed among them (p < 0.05). Significantly higher force levels were reported for full bonded metallic flat (groups 2 and 8) and round (groups 4 and 9) splints if compared with spot bonded flat (groups 1 and 7) and round (groups 3 and 9) retainers, respectively (p < 0.05). The highest strengths were recorded for full bonded FRCs (groups 6 and 12) (p < 0.001).
On the other hand, at maximum load (Figure 4—groups 13 to 18), no significant differences were reported among spot- and full-bonded metallic flat and round splints (groups 13 to 16) and spot-bonded FRCs (group 17) (p > 0.05). Significantly higher loads were reported for full bonded FRCs (group 18) if compared with all other groups tested at maximum deflection (p < 0.001).
The null-hypothesis of the study has been rejected. Significant differences in deflection values were reported among the various groups tested.
Full-bonded groups showed significantly higher strength values than spot-bonded groups for flat splints, round splints, and FRCs, at both 0.2 and 0.3 mm deflections. No significant differences among spot-bonded groups (both splints and FRCs) were reported. Therefore, in this study, the spot-bonded technique significantly decreased FRC rigidity, thus allowing a mechanical behaviour similar to flat and round stainless steel splints after 0.2 and 0.3 deflections. A possible reason could be related to the presence of a composite distributed all along the fiber in full bonded groups that could increase the rigidity if compared with the spot-bonded group, in which the composite structure is interrupted between teeth. Another explanation could be related to other variables, such as the internal arrangement of the FRCs. In fact, unidirectional or woven fiber orientation has been reported to influence their mechanical behaviour [3,5,13]. Moreover, the presence of micro- and nano-fillers could also change the FRC characteristics . However, as the spot-bonding technique has not yet been tested, further tests are needed to understand the phenomenon.
Moreover, in the present report, at maximum load, no significant differences between spot and full bonded splints were recorded, whereas significantly higher load values were reported for full-bonded FRCs if compared with spot-bonded FRCs. Therefore, the maximum resistance before the fracture of flat and round splints has been shown to be similar. Maximum load values were reported in the full-bonded FRCs group.
Previous studies have evaluated the load values of conventional and nanofilled FRCs, showing values ranging from 10 to 50 N [6,22,23,30,32,33]. These values are in agreement with the results reported in the present investigation with full-bonded FRCs. To our knowledge, there are no studies that measured the deflection values of FRCs prepared with the spot-bonded technique. In fact, in the literature, previous studies only evaluated spot-bonded metallic splints and full-bonded FRC retainers. To our knowledge, there are no studies that evaluated full-bonded metallic splints. In the present investigation, after 0.2 and 0.3 mm deflections, full-bonded stainless steel retainers showed significantly higher load values than spot-bonded splints (both metallic and FRC) and statistically lower load values than full-bonded FRCs. Therefore, full-bonded metallic splints (both flat and round) exhibited an intermediate mechanical behaviour between spot bonded retainers and full bonded FRCs. Moreover, at maximum load, full-bonded stainless steel retainers showed similar load values to spot-bonded splints (both metallic and FRC) and significantly lower load values than full-bonded FRCs.
The use of multi-stranded spot-bonded wires for the construction of the fixed retainers has been proposed based on their ability to allow the physiological movement of teeth. Moreover, a braided surface offers increased mechanical retention during bonding . Metallic splints presented some disadvantages, mainly related to their aesthetic and the necessity of removal if the patient has to undergo nuclear magnetic resonance exams. Moreover, they cannot be used in patients allergic to metals . For these reasons, FRC retainers have been introduced as a completely aesthetic and metal-free alternative to conventional metallic splints . On the other hand, FRC splints present some disadvantages, in the form of higher costs and the difficulty to repair if debonded . Moreover, the mechanical behaviour of FRC retainers has been reported to be significantly different when compared with metallic ones. Previous studies showed that full-bonded FRC retainers exhibited higher rigidity if compared with metallic wires  and splints [23,24,30]. This is in agreement with the present report, as full-bonded FRCs showed significantly higher deflection strengths if compared with flat and round metallic splints.
Some reports showed that the higher rigidity of full-bonded FRC splints could be associated with tooth ankylosis [25,26]. Therefore, the reduction of load values in spot-bonded FRC groups reported in the present investigation could prevent the risk of ankylosis assimilating FRCs behaviour to metallic splints, even if further studies are needed on this topic.
Other studies showed that the clinical durability of an FRC full-bonded splint is over 85% after one year [20,34] and over 65% after two years  from bonding. No significant differences were reported between the survival rates of metallic splints and FRC retainers [20,34,35]. These studies support the clinical reliability of full-bonded FRC splints. However, no studies have tested the clinical reliability of spot-bonded FRCs.
When the FRC is left as such in the approximal areas of teeth, oxygen inhibits the free radical polymerization form the surface of the FRC. Therefore, the diameter of the well polymerized FRC is somewhat less than the actual outer diameter of the FRC. The thickness of the oxygen inhibition layer is ca. 0.1 mm which means that the effective diameter (polymerized part of the FRC) of the FRC is not 0.8 mm but ca. 0.6 mm. Such a reduction in the diameter of the retainer causes considerably lower strength and rigidity for the retainer. This may have had an influence on the results with the spot-bonding technique. Therefore, it is advised to add adhesive resin to the surface of an FRC at the approximal areas so that the oxygen inhibition of polymerization occurs in the adhesive rather that in the FRC [36,37].
Bond strengths of full-bonded FRCs have been reported both for new  and repaired  fibers. Also, the influence of different adhesive systems  and polymerization methods  has been tested. All these reports showed clinically acceptable bond strength values of conventional full-bonded FRCs, but no studies have been carried out for spot-bonded FRCs.
On the bases of the results of the present investigation, in order to reduce the rigidity of FRC splints, a spot-bonded preparation technique could be proposed. This is the first study that evaluated the spot-bonding technique for FRCs, and in the literature, no other studies have been conducted on such a concern. Therefore, before being routinely used, spot-bonded FRCs should also be tested for other important variables, such as other physical properties, mechanical behaviour, shear bond strength values, biocompatibility, and microbial colonization characteristics.
4. Materials and Methods
Rectangular metallic splint wires (Bond-A-Braid, Reliance Orthodontic Products Inc., Itasca, IL, USA), round metallic splint wires (Penta-one 0155, Masel Orthodontics, Carlsbad, CA, USA), and FRCs (Everstick Ortho, StickTech, Turku, Finland) were tested in the present investigation (Table 1).
After a sample size calculation test, all materials were divided into coded groups of 10 specimens each (length: 28 mm), according to different bonding techniques:
- -SFS: Stainless steel Flat Spot-bonded
- -SFF: Stainless steel Flat Full-bonded
- -SRS: Stainless steel Round Spot-bonded
- -SRF: Stainless steel Round Full-bonded
- -FS: FRC Spot-bonded
- -FF: FRC Full-bonded
All specimens were then prepared to be bonded to an acrylic mandible model, simulating a canine-to-canine splint. Element 3.1 was removed from the model before bonding, in order to allow the force to be directly applied to the retainer (Figure 1). The span length between element 3.2 and 4.1 was 8 mm. The two metallic splints (flat and round) and the FRCs were bonded to the elements 3.3, 3.2, 4.1, 4.2 and 4.3 of the mandible model with a one-step, self-etch 7th generation bonding agent (G-aenial Bond, GC America, Alsip, IL, USA) and fixed with flow composite (G-aenial Universal Flo, GC America, Alsip, IL, USA). The composite coverage was complete in the full-bonded splints (Codes: SFS, SRS and FS). In the spot-bonded groups (Codes: SFF, SRF and FF), the composite covered the retainer only in correspondence of each tooth, leaving the splint exposed in interproximal spaces.
All specimens were light-cured (wavelength range of 430–480 nm and light intensity of 1200 mW/cm2) by hand with a halogen curing unit (Elipar S10, 3M, Monrovia, CA, USA) for 40 s.
All the stainless steel wires and FRC samples were subsequently tested according to a modified three-point bending test in order to measure the load required to bend the retainer. The load was applied with a universal testing machine (Lloyd LRX; Lloyd Instruments, Fareham, UK) to the middle of the distance between elements 3.2 and 4.1. The strength values were recorded with Nexygen MT software (Lloyd Instruments). The crosshead speed was 1.0 mm per minute [22,32]. Ten specimens for each coded groups were tested at deflections of 0.2 mm (groups 1 to 6), 0.3 mm (groups 7 to 12), and at maximum load (groups 13 to 18). Loads were recorded in newton.
Statistical analysis was performed with a software (R version 3.1.3, R Development Core Team, R Foundation for Statistical Computing, Wien, Austria). Descriptive statistics (mean, standard deviation, minimum, median, maximum, lower confidence interval, and upper confidence interval) were calculated for all the 18 groups tested. The normality of the data was calculated using the Kolmogorov-Smirnov test. As the data were demonstrated to be normal (gaussian distribution), a parametric test was performed. A multi-factor analysis of variance (ANOVA) was performed. Subsequently, a Tukey test was applied as post-hoc, to determine whether there were significant differences among the deflection values of the various groups. Significance for all statistical tests was predetermined at p < 0.05.
The present study demonstrated that both at 0.2 and at 0.3 mm deflections, the lowest loads required to bend the retainer were recorded for spot-bonded stainless steel flat and round wires and for spot-bonded FRCs. Moreover, at maximum load, no significant differences were reported among spot- and full-bonded metallic splints and spot-bonded FRCs.
The significant decrease in the rigidity of spot-bonded FRC splints if compared with full-bonded retainers suggests further tests in order to propose this technique for clinical use.
We thank GC America, Masel Orthodontics, Reliance Orthodontic Products, and StickTech—GC Group for providing the materials tested in the present study.
Andrea Scribante: Statistics and manuscript preparation; Paola Gandini: Overall orthodontic supervision; Paola Tessera: Tests execution; Pekka K. Vallittu: Overall Laboratory supervision, manuscript preparation; Lippo Lassila: Tests supervision; Maria Francesca Sfondrini: Study Design, manuscript preparation.
Conflicts of Interest
The authors declare no conflict of interest.
- Goldberg, A.J.; Burstone, C.J. The use of continuous fiber reinforcement in dentistry. Dent. Mater. 1992, 8, 197–202. [Google Scholar] [CrossRef]
- Vallittu, P.K.; Lassila, V.P. Reinforcement of acrylic resin denture base material with metal or fibre strengtheners. J. Oral Rehabil. 1992, 19, 225–230. [Google Scholar] [CrossRef] [PubMed]
- Nayar, S.; Ganesh, R.; Santhosh, S. Fiber reinforced composites in prosthodontics—A systematic review. J. Pharm. Bioallied Sci. 2015, 7 (Suppl. 1), S220–S222. [Google Scholar] [CrossRef] [PubMed]
- Freilich, M.A.; Karmaker, A.C.; Burstone, C.J.; Goldberg, A.J. Development and clinical applications of a light-polymerized fiber-reinforced composite. J. Prosthet. Dent. 1998, 80, 311–318. [Google Scholar] [CrossRef]
- Kanie, T.; Arikawa, H.; Fujii, K.; Ban, S. Light-curing reinforcement for denture base resin using a glass fiber cloth pre-impregnated with various urethane oligomers. Dent. Mater. J. 2004, 23, 291–296. [Google Scholar] [CrossRef] [PubMed]
- Scribante, A.; Massironi, S.; Pieraccini, G.; Vallittu, P.; Lassila, L.; Sfondrini, M.F.; Gandini, P. Effects of nanofillers on mechanical properties of fiber-reinforced composites polymerized with light-curing and additional postcuring. J. Appl. Biomater. Funct. Mater. 2015, 13, e296–e299. [Google Scholar] [CrossRef] [PubMed]
- Sewón, L.A.; Ampula, L.; Vallittu, P.K. Rehabilitation of a periodontal patient with rapidly progressing marginal alveolar bone loss: 1-year follow-up. J. Clin. Periodontol. 2000, 27, 615–619. [Google Scholar] [CrossRef] [PubMed]
- Perea, L.; Matinlinna, J.P.; Tolvanen, M.; Lassila, L.V.; Vallittu, P.K. Fiber-reinforced composite fixed dental prostheses with various pontics. J. Adhes. Dent. 2014, 16, 161–168. [Google Scholar] [PubMed]
- Vallittu, P.K.; Sevelius, C. Resin-bonded, glass fiber reinforced composite fixed partial dentures—A clinical study. J. Prosthet. Dent. 2000, 84, 413–418. [Google Scholar] [CrossRef] [PubMed]
- Saker, S.; Özcan, M. Retentive strength of fiber-reinforced composite posts with composite resin cores: Effect of remaining coronal structure and root canal dentin conditioning protocols. J. Prosthet. Dent. 2015, 114, 856–861. [Google Scholar] [CrossRef] [PubMed][Green Version]
- Le Bell, A.-M.; Tanner, J.; Lassila, L.V.J.; Kangasniemi, I.; Vallittu, P.K. Depth of light initiated polymerization of glass fiber reinforced composite in a simulated root canal. Int. J. Prosthodont. 2003, 16, 403–408. [Google Scholar] [PubMed]
- LeBell, A.-M.; Tanner, J.; Lassila, L.V.J.; Kangasniemi, I.; Vallittu, P.K. Bonding of composite resin luting cement to fibre-reinforced composite root canal post. J. Adhes. Dent. 2004, 6, 319–325. [Google Scholar]
- Abouelleil, H.; Pradelle, N.; Villat, C.; Attik, N.; Colon, P.; Grosgogeat, B. Comparison of mechanical properties of a new fiber reinforced composite and bulk filling composites. Restor. Dent. Endod. 2015, 40, 262–670. [Google Scholar] [CrossRef] [PubMed]
- Garoushi, S.; Vallittu, P.K.; Lassila, L.V.J. Fracture toughness, compressive strength and load-bearing capacity of short glass fiber-reinforced composite resin. Chin. J. Dent. Res. 2011, 14, 15–19. [Google Scholar] [PubMed]
- Garoushi, S.; Lassila, L.V.J.; Vallittu, P.K. Influence of nanometer scale particulate fillers on some properties of microfilled composite resin. Dent. Mater. 2011, 22, 1645–1651. [Google Scholar] [CrossRef] [PubMed]
- Garoushi, S.; Kaleem, M.; Shinya, A.; Vallittu, P.K.; Satterwaite, J.D.; Watts, D.C.; Lassila, L.V.J. Static and dynamic creep of experimental short fiber-reinforced composite resin. Dent. Mater. J. 2012, 31, 737–741. [Google Scholar] [CrossRef] [PubMed]
- Akin, H.; Turgut, M.; Coskun, M.E. Restoration of an anterior edentulous space with a unique glass fiber-reinforced composite removable partial denture: A case report. J. Esthet. Restor. Dent. 2007, 19, 193–197. [Google Scholar] [CrossRef] [PubMed]
- Narva, K.; Vallittu, P.K.; Yli-Urpo, A. Clinical survey of acrylic resin removable denture repairs with glass-fiber reinforcement. Int. J. Prosthodont. 2001, 14, 219–224. [Google Scholar] [PubMed]
- Chafaie, A.; Dahan, S.; Le Gall, M. Fiber-reinforced composite anterior bridge in pediatric traumatology: Clinical considerations. Int. Orthod. 2013, 11, 445–456. [Google Scholar]
- Sfondrini, M.F.; Fraticelli, D.; Castellazzi, L.; Scribante, A.; Gandini, P. Clinical evaluation of bond failures and survival between mandibular canine-to-canine retainers made of flexible spiral wire and fiber-reinforced composite. J. Clin. Exp. Dent. 2014, 6, e145–e149. [Google Scholar] [CrossRef] [PubMed]
- Bayani, S.; Heravi, F. Application of fiber reinforced composites in adjunctive orthodontics. Int. J. Orthod. 2012, 23, 11–13. [Google Scholar]
- Cacciafesta, V.; Sfondrini, M.F.; Lena, A.; Scribante, A.; Vallittu, P.K.; Lassila, L.V. Force levels of fiber-reinforced composites and orthodontic stainless steel wires: A 3-point bending test. Am. J. Orthod. Dentofac. Orthop. 2008, 133, 410–413. [Google Scholar] [CrossRef] [PubMed]
- Sfondrini, M.F.; Gandini, P.; Tessera, P.; Vallittu, P.K.; Lassila, L.; Scribante, A. Bending properties of fiber reinforced composites (FRC) retainers bonded with spot-composite coverage. Biomed. Res. Int. 2017, 2017, 8469090. [Google Scholar]
- Annousaki, O.; Zinelis, S.; Eliades, G.; Eliades, T. Comparative analysis of the mechanical properties of fiber and stainless steel multistranded wires used for lingual fixed retention. Dent. Mater. 2017, 33, e205–e211. [Google Scholar] [CrossRef] [PubMed]
- Oshagh, M.; Heidary, S.; Dehghani Nazhvani, A.; Koohpeima, F.; Koohi Hosseinabadi, O. Evaluation of histological impacts of three types of orthodontic fixed retainers on periodontium of rabbits. J. Dent. 2014, 15, 104–111. [Google Scholar]
- Angelopoulou, M.V.; Koletsi, D.; Vadiakas, G.; Halazonetis, D.J. Induced ankylosis of a primary molar for skeletal anchorage in the mandible as alternative to mini-implants. Prog. Orthod. 2015, 16, 18. [Google Scholar] [CrossRef] [PubMed]
- Qi, Y.; Fang, H.; Liu, W. Experimental Study of the Bending Properties and Deformation Analysis of Web-Reinforced Composite Sandwich Floor Slabs with Four Simply Supported Edges. PLoS ONE 2016, 11, e0149103. [Google Scholar] [CrossRef] [PubMed]
- Zhu, Y.; Chen, H.; Cen, L.; Wang, J. Influence of abutment tooth position and adhesive point dimension on the rigidity of a dental trauma wire-composite splint. Dent. Traumatol. 2016, 32, 225–230. [Google Scholar] [CrossRef] [PubMed]
- Schmage, P.; Nergiz, I.; Platzer, U.; Pfeiffer, P. Yield strength of fiber-reinforced composite posts with coronal retention. J. Prosthet. Dent. 2009, 101, 382–387. [Google Scholar] [CrossRef]
- Alavi, S.; Mamavi, T. Evaluation of load-deflection properties of fiber-reinforced composites and its comparison with stainless steel wires. Dent. Res. J. 2014, 11, 234–239. [Google Scholar]
- Chen, J.H.; Li, W.; Zheng, Y.P. Study on relationship between bent angles of dental fiber reinforced composites posts and their flexural properties. Zhonghua Kou Qiang Yi Xue Za Zhi 2006, 41, 331–332. [Google Scholar] [PubMed]
- Cacciafesta, V.; Sfondrini, M.F.; Lena, A.; Scribante, A.; Vallittu, P.K.; Lassila, L.V. Flexural strengths of fiber-reinforced composites polymerized with conventional light-curing and additional postcuring. Am. J. Orthod. Dentofac. Orthop. 2007, 132, 524–527. [Google Scholar] [CrossRef] [PubMed]
- Sfondrini, M.F.; Massironi, S.; Pieraccini, G.; Scribante, A.; Vallittu, P.K.; Lassila, L.V.; Gandini, P. Flexural strengths of conventional and nanofilled fiber-reinforced composites: A three-point bending test. Dent. Traumatol. 2014, 30, 32–35. [Google Scholar] [CrossRef] [PubMed]
- Scribante, A.; Sfondrini, M.F.; Broggini, S.; D'Allocco, M.; Gandini, P. Efficacy of Esthetic Retainers: Clinical Comparison between Multistranded Wires and Direct-Bond Glass Fiber-Reinforced Composite Splints. Int. J. Dent. 2011, 2011, 548356. [Google Scholar] [CrossRef] [PubMed]
- Sobouti, F.; Rakhshan, V.; Saravi, M.G.; Zamanian, A.; Shariati, M. Two-year survival analysis of twisted wire fixed retainer versus spiral wire and fiber-reinforced composite retainers: A preliminary explorative single-blind randomized clinical trial. Korean J. Orthod. 2016, 46, 104–110. [Google Scholar] [CrossRef] [PubMed]
- Vallittu, P.K. Unpolymerized surface layer of autopolymerizing polymethyl methacrylate resin. J. Oral Rehabil. 1999, 26, 208–212. [Google Scholar] [CrossRef] [PubMed]
- Bijelic-Donova, J.; Garoushi, S.; Vallittu, P.K.; Lassila, L.V.J. Oxygen inhibition layer of composite resins: The effect of layer thickness and surface layer treatmenton the interlayer bond strength. Eur. J. Oral Sci. 2015, 123, 53–60. [Google Scholar] [CrossRef] [PubMed]
- Foek, D.L.; Yetkiner, E.; Ozcan, M. Fatigue resistance, debonding force, and failure type of fiber-reinforced composite, polyethylene ribbon-reinforced, and braided stainless steel wire lingual retainers in vitro. Korean J. Orthod. 2013, 43, 186–192. [Google Scholar] [CrossRef] [PubMed][Green Version]
- Frese, C.; Decker, C.; Rebholz, J.; Stucke, K.; Staehle, H.J.; Wolff, D. Original and repair bond strength of fiber-reinforced composites in vitro. Dent. Mater. 2014, 30, 456–462. [Google Scholar] [CrossRef] [PubMed]
- Scribante, A.; Cacciafesta, V.; Sfondrini, M.F. Effect of various adhesive systems on the shear bond strength of fiber-reinforced composite. Am. J. Orthod. Dentofac. Orthop. 2006, 130, 224–227. [Google Scholar] [CrossRef] [PubMed]
- Yanagida, H.; Tanoue, N.; Minesaki, Y.; Kamasaki, Y.; Fujiwara, T.; Minami, H. Effects of polymerization method on flexural and shear bond strengths of a fiber-reinforced composite resin. J. Oral Sci. 2017, 59, 13–21. [Google Scholar] [CrossRef] [PubMed]
Figure 1. FRC tested with the conventional Full-bond technique (A) and with the experimental Spot-bond technique (B).
Figure 2. Box plot of load values (N) of the various groups tested at 0.2 mm deflection.
Figure 3. Box plot of load values (N) of the various groups tested at 0.3 mm deflection.
Figure 4. Box plot of load values (N) of the various groups tested at maximum deflection.
Table 1. Materials tested.
|Name||Flat Stainless Steel Wire||Round Stainless Steel Wire||Fiber Reinforced Composite|
|Bond-a-Braid||Penta One 0155||FRC Ortho|
|Material||Stainless steel||Stainless steel||E-glass fiber 15 μm|
|Dimensions||0.673 mm (w) × 0.268 mm (h)||Diameter: 0.394 mm||Diameter: 0.75 mm|
|Unit Amount||8 wires||5 wires||1000 fibers|
|Design||Ribbon arch||Coaxial||Unidirectional fibre bundle|
Table 2. Descriptive statistics (N) of the load values of the 18 groups tested (each group consisted of 10 specimens).
|Group||Code||Material||Shape||Bonding||Deflection (mm)||Mean||SD||Min||Mdn||Max||Lower CI||Upper CI||Post-Hoc *|
|1||SFS||Stainless steel||Flat||Spot bonded||0.2||8.20||1.03||6.57||7.93||9.94||7.48||9.23||A|
|2||SFF||Stainless steel||Flat||Full bonded||0.2||30.18||8.91||17.43||29.17||45.41||24.01||39.10||B, I|
|3||SRS||Stainless steel||Round||Spot bonded||0.2||4.60||0.86||3.60||4.59||6.43||4.00||5.46||A|
|4||SRF||Stainless steel||Round||Full bonded||0.2||21.79||5.88||16.83||19.90||33.93||17.71||27.67||B|
|5||FS||FRC||-||Spot bonded||0.2||11.13||2.16||6.37||11.50||13.69||9.63||13.28||A, C|
|6||FF||FRC||-||Full bonded||0.2||61.70||8.75||49.72||62.53||73.40||55.64||70.45||D, G, H|
|7||SFS||Stainless steel||Flat||Spot bonded||0.3||9.34||1.00||7.63||9.12||10.59||8.65||10.35||A, C|
|8||SFF||Stainless steel||Flat||Full bonded||0.3||29.37||11.16||19.12||24.84||44.43||21.64||40.53||B, I|
|9||SRS||Stainless steel||Round||Spot bonded||0.3||6.89||1.79||4.98||6.30||10.00||5.66||8.68||A|
|10||SRF||Stainless steel||Round||Full bonded||0.3||26.35||8.74||18.33||24.93||44.29||20.30||35.09||B, C, J|
|12||FF||FRC||-||Full bonded||0.3||64.78||16.29||45.52||59.42||95.02||53.49||81.08||D, E, H|
|13||SFS||Stainless steel||Flat||Spot bonded||Maximum Load||46.44||18.21||23.50||38.88||73.62||33.82||64.64||F, G, I|
|14||SFF||Stainless steel||Flat||Full bonded||Maximum Load||36.17||11.33||21.66||34.12||49.32||28.32||47.50||F, I, J|
|15||SRS||Stainless steel||Round||Spot bonded||Maximum Load||41.67||11.40||24.68||43.45||60.47||33.77||53.06||F, I, J|
|16||SRF||Stainless steel||Round||Full bonded||Maximum Load||37.25||10.00||25.38||34.15||50.71||30.32||47.26||F, I, J|
|17||FS||FRC||-||Spot bonded||Maximum Load||52.20||16.55||32.30||51.48||79.19||40.74||68.75||F, G|
|18||FF||FRC||-||Full bonded||Maximum Load||81.86||12.56||58.81||81.15||100.51||73.16||94.42||E|
*: Mean with same letters are not significantly different.
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