- Email: [email protected]
Effect of fluoride-releasing light-cured resin on shear bond strength of orthodontic brackets
ONLINE ONLY
Effect of fluoride-releasing light-cured resin on shear bond strength of orthodontic brackets Cumhur Tuncer,a Burcu Balos¸ Tuncer,b and Çag˘rı Ulusoyb Ankara, Turkey Introduction: The aim of this study was to analyze the effect of an enamel-protective resin on the shear bond strength (SBS) of orthodontic brackets bonded with self-etching primer. Methods: Eighty extracted premolars were randomly divided into 4 groups of 20, and metal brackets were bonded. Group 1 specimens were bonded with Transbond Plus self-etching primer (3M Unitek, Monrovia, Calif) and no fluoride resin; in group 2, a fluoride-releasing resin (Ortho-Coat, Pulpdent, Watertown, Mass) was used with the Transbond Plus self-etching primer; group 3 teeth were bonded with a new antimicrobial self-etching primer (Clearfil Protect Bond, Kuraray Medical, Osaka, Japan) with no fluoride resin; and the same protocol was used in group 4 with an application of Ortho-Coat. A universal testing machine was used to determine the SBS, and the adhesive remaining after debonding was assessed. Results: There was no difference in SBS whether fluoride-releasing resin was used. Groups 3 and 4 had higher SBS values than the other groups (P ⬍0.001). The Kruskal-Wallis test showed no significant differences in the adhesive remnant index (chi-square ⫽ 0.019, P ⫽ 0.990). Conclusions: The application of enamel-protective resin did not affect the bond strength of orthodontic brackets to enamel with self-etching primer systems. (Am J Orthod Dentofacial Orthop 2009;135: 14.e1-14.e6)
O
ver the years, much attention has been paid to improving bonding techniques and materials to decrease decalcification during fixed orthodontic treatment, especially in patients with poor oral hygiene.1,2 The oral environment changes in patients treated with fixed orthodontic appliances by the low resting pH value in the dental plaque around the brackets, and the increase of Streptococcus mutans.3,4 The risk of white spot lesions and dental caries still exists because of more retentive sites and greater accumulations of dental plaque.4,5 Various preventive approaches have been reported in the literature.4,6-9 Investigations were mainly carried out on the demineralization-inhibiting effects of fluoride applications such as toothpastes and gels,7 varnishes and sealants,6,10 topical fluoride preparations,11 fluoride-releasing elastomeric modules and chains12 or fluoride-releasing bonding materials,7 antimicrobial agents mixed with orthodontic adhesives,1,13 or combinations of self-etching primer and fluoride-releasing adhesives.14 The efficacy of fluoride varnish to prevent white From the Department of Orthodontics, Faculty of Dentistry, Gazi University, Ankara, Turkey. a Assistant professor. b Research assistant. Reprint requests to: Cumhur Tuncer, Gazi University, Faculty of Dentistry, Department of Orthodontics, 8.cadde 82.sokak, 06510 EMEK, Ankara, Turkey; e-mail, [email protected]. Submitted, July 2008; revised and accepted, September 2008. 0889-5406/$36.00 Copyright © 2009 by the American Association of Orthodontists. doi:10.1016/j.ajodo.2008.09.016
spot lesions was evaluated.15,16 Derks et al7 stated that fluoride-releasing bonding materials had almost no demineralization-inhibiting effect, since the low-pH environment inhibits the remineralization phase. Therefore, Buyukyilmaz and Øgaard17 suggested combining fluoride and antimicrobials to improve the cariostatic effect of fluoride at low pH. It was shown that chlorhexidine inhibits acid production in dental plaque.18 Although rinses with fluoride or chlorhexidine are excellent methods of prevention, patient compliance has been shown to be low—about 13%.19 Methods that eliminate patient compliance would be beneficial in preventing white spot lesions around brackets and at the gingival margins. New materials incorporate antimicrobial and fluoride-releasing agents, such as Clearfil Protect Bond (Kuraray Medical, Okayama, Japan) and OrthoCoat (Pulpdent, Watertown, Mass). The former contains 12-methacryloyloxydodecypyridinium bromide, an antimicrobial agent with strong antibacterial activity,20,21 and the latter is a fluoride-releasing light-cured resin. OrthoCoat coats the enamel under and around the brackets and prevents food and bacteria from collecting there and, thus, decalcification that can develop as early as 4 weeks after placement.22 In addition, this material is hydrophilic and allows bonding of resin to moist enamel. The findings of in-vitro studies about bond strength of orthodontic brackets bonded to fluoride-treated and nonfluoride-treated enamel surfaces have shown con14.e1
14.e2 Tuncer, Tuncer, and Ulusoy
tradicting results.23-25 The effect of the new fluoridereleasing light-cured resin (Ortho-Coat) on the shear bond strength (SBS) of orthodontic brackets is untested. Therefore, our aim in this in-vitro study was to evaluate the effect of Ortho-Coat on the SBS of brackets bonded with a self-etching primer system (Transbond Plus, 3M Unitek, Monrovia, Calif) and a new antimicrobial, fluoride-releasing bonding system (Clearfil Protect Bond). MATERIAL AND METHODS
We used 80 caries-free maxillary premolars, extracted for orthodontic reasons. The teeth were stored in distilled water with thymol crystals (1% wt/vol) added to inhibit bacterial growth at room temperature. The criteria for tooth selection included intact buccal enamel that had not been pretreated with chemical agents, no visible cracks, and no enamel irregularities. The teeth were cleaned and polished with a fluoridefree pumice slurry and rubber cups for 10 seconds and thoroughly washed and dried with an oil-free air stream. They were examined under a light stereomicroscope at 10 times magnification to ensure the absence of caries and enamel cracks. The sample was randomly divided in 4 groups of 20 teeth, by using a random numbers table. All were embedded vertically in coldcuring acrylic (Orthocryl, Dentaurum, Ispringen, Germany) with metal ring molds. Premolar metal orthodontic brackets (Victory Series, 3M Unitek GmbH, Seefeld, Germany) were used. The average base surface areas of the brackets were calculated with measurements made by a digital caliper (Mitutoyo, Miyazaki, Japan). The mean base surface area was 10.53 mm2 for the metal brackets. The bonding procedures were performed as follows. Group 1 received conventional bonding with Transbond Plus self-etching primer. The primer was rubbed with pressure onto the enamel surface of each teeth for 5 seconds and dried with an oil- and moisture-free air stream. The brackets were coated with Transbond XT adhesive paste (3M Unitek) and positioned at the center of the buccal surface. The excess adhesive was removed from the margins of bracket base with a scaler before polymerization. All brackets were light-cured for 40 seconds with a halogen curing unit (Hilux Ultra Plus, Benliog˘lu Dental, Ankara, Turkey), 10 seconds each from the mesial, distal, gingival, and occlusal margins. In group 2, the same bonding procedure was performed as in group 1, but after using Transbond self-etching primer and adhesive, a fluoride-releasing light-cured resin, Ortho-Coat, was applied around the bracket and the entire enamel surface extending to the
American Journal of Orthodontics and Dentofacial Orthopedics January 2009
gingival margin and light-cured from the mesial and distal sides for 20 seconds. In group 3, Clearfil Protect Bond self-etching primer was applied as suggested by the manufacturer. First, the enamel surfaces were etched for 10 seconds with 37% phosphoric acid gel (Gel Etch, 3M Unitek). Then the teeth were washed with water for 20 seconds and air-dried with an oil-free air stream. The Clearfil Protect Bond primer was applied with a brush on the etched enamel surfaces in a thin uniform layer, left for 20 seconds, and sprayed with an air stream to evaporate the solvent. Later, the bonding agent was applied and light-cured for 10 seconds. The brackets were bonded with Transbond XT adhesive paste, placed on the center of the buccal surfaces and, after removal of excess adhesive, light-cured for 40 seconds. Group 4 received the same adhesive system as in group 3, except that Ortho-Coat was used around the bracket and the enamel margin and light-cured from the mesial and distal sides for 20 seconds. The enamel surfaces were etched with the same 37% phosphoric acid for 10 seconds, rinsed for 20 seconds, and air dried with an oil-free air stream. Clearfil Protect Bond primer was applied to the etched enamel surfaces, left for 20 seconds, and air sprayed to evaporate the solvent. The bonding agent was applied and light-cured for 10 seconds. Then Transbond adhesive was placed on the brackets, positioned on the center of the buccal surfaces, and light-cured for 40 seconds. Later, Ortho-Coat was applied around the brackets and the entire enamel surface to the gingival margin and light-cured for 20 seconds. All specimens were stored in distilled water at room temperature for 24 hours. Shear peel testing was performed with a universal testing machine (Instron, Canton, Mass). The specimens were stressed in an occlusogingival direction with a crosshead speed of 1 mm per minute. The maximum load necessary to debond each bracket was recorded in Newtons and then converted into megapascals (MPa). The debonded enamel surfaces were examined under a stereomicroscope (Nikon, Osaka, Japan) at 20 times magnification to assess the residual adhesive on the tooth surface by a blinded examiner (Ç.U.). A modified adhesive remnant index (ARI) was used to quantify the amount of remaining adhesive on the tooth surface. The following scale was used: 1, all adhesive remained on the tooth; 2, more than 90% of the adhesive remained on the tooth; 3, 10% to 90% of the adhesive remained on the tooth; 4, less than 10% of the adhesive remained on the tooth; and 5, no adhesive remained on the tooth.
Tuncer, Tuncer, and Ulusoy 14.e3
American Journal of Orthodontics and Dentofacial Orthopedics Volume 135, Number 1
Table I.
Materials used in the study
Material
Components
Ingredients
Transbond Plus self-etching primer (3M) Ortho-Coat (Pulpdent) Clearfil Protect Bond (Kuraray Medical)
Primer and bond Light-cured resin Primer and bond
Transbond XT (3M)
Light-cured adhesive
Primer: fluoride, no filler; bond: methacrylate ester derivative Uncured acrylate resins, silica, amorphous hydrofluoric acid Self-etching primer: adhesive phosphate monomer (MDP), 2-hydroxyethylmethacrylate (HEMA), water, initiators, monomer 12-methacryloyloxydodecyl pyridinium bromide (MDPB); bonding agent: MDP, HEMA, comonomers, initiators, functionalized sodium fluoride Quartz silica, bisphenol A diglycidyl ether dimethacrylate, bisphenol A bis (2-hydroxyethyl) dimethacrylate
Table II.
Descriptive statistics related to SBS and results of 2-way ANOVA comparing the effect of fluoride-releasing resin on in-vitro bond strength of brackets with self-etching primer systems 95% Confidence interval Group
n
Mean (MPa)
SD
Minimum
Maximum
Lower bound
Upper bound
1 2 3 4
20 20 20 20
8.21 8.18 13.48 13.34
0.93 1.06 1.78 1.69
6.87 6.31 10.85 10.75
10.05 10.30 16.85 16.85
7.77 7.69 12.65 12.55
8.64 8.68 14.31 14.13
Group 1, Transbond Plus self-etching; group 2, Transbond Plus self-etching plus Ortho-Coat; group 3, Clearfil Protect Bond; group 4, Clearfil Protect Bond plus Ortho-Coat. Interaction not significant (P ⫽ 0.841) and main effect of fluoride were not significant (P ⫽ 0.798). Main effect of adhesive type was significant (P ⬍0.001).
Statistical analysis
Statistical evaluation was performed by SPSS for Windows software (version 10.0, SPSS, Chicago, Ill). Descriptive statistics including means, standard deviations, and minimum and maximum values were calculated for each group. The 1-sample Kolmogorov-Smirnov test was used to evaluate the normal distribution of variances. Comparisons of bond strength data were performed with 2-way analysis of variance (ANOVA) to test for differences between groups and statistical interactions between the fluoride-releasing resin and adhesive groups. Follow-up analyses were performed by the post-hoc Tukey honestly significant difference multiple comparison test. The Kruskal-Wallis test was used to determine significant differences in the ARI scores among the groups. The level of significance was established at P ⬍0.05. RESULTS
Materials used in the study are shown in Table I. The descriptive statistics for SBS including means, standard deviations, minimum and maximum values, and 95% confidence intervals for mean values of SBS data are shown in Table II. Two-way ANOVA comparing the SBS of self-etching primer systems with and without fluoride-releasing resin showed no significant
interaction (P ⫽ 0.841). There was no difference in SBS whether the fluoride-releasing resin was used (P ⫽ 0.798). SBS values of the brackets in groups 3 and 4 were significantly higher than in the other groups (P ⬍0.001). The distribution of the ARI scores is shown in Table III. The Kruskal-Wallis test showed no significant differences in the ARI scores of the groups (chi-square ⫽ 0.019, P ⫽ 0.990). DISCUSSION
Since caries, enamel decalcification, and gingival inflammation during fixed orthodontic treatments could jeopardize the final esthetic results, preventive regimens must be taken seriously. Even patients with good hygiene can have difficulty cleaning around brackets, because plaque builds up easily under brackets, where it is extremely difficult to clean, and decalcification and staining can result; these are long-term concerns for orthodontists. Methods to protect the susceptible areas beneath and adjacent to brackets, independent of patient compliance, would be extremely beneficial. The new light-cured reinforced resin, Ortho-Coat, prevents decalcification, microleakage, and discoloration of teeth under orthodontic brackets. The soft tissues are also protected from irritation caused by
14.e4 Tuncer, Tuncer, and Ulusoy
Table III.
American Journal of Orthodontics and Dentofacial Orthopedics January 2009
Frequency distribution of ARI scores
Group
n
1
2
3
4
5
1 2 3 4
20 20 20 20
— — — —
1 (5%) 2 (10%) 2 (10%) 2 (10%)
4 (20%) 3 (15%) 2 (10%) 3 (15%)
6 (30%) 5 (25%) 7 (35%) 3 (15%)
9 (45%) 10 (50%) 9 (45%) 12 (60%)
Group 1, Transbond Plus self-etching; group 2, Transbond Plus self-etching plus Ortho-Coat; group 3, Clearfil Protect Bond; group 4, Clearfil Protect Bond plus Ortho-Coat.
rough or sharp surfaces of brackets. It can be placed around the bracket to seal it, immediately after seating the bracket or at a follow-up visit. Fluoride ions encourage the formation of calcium fluoride and fluorapatite, which enhances remineralization of the etched enamel.26 Fluoride deposits in hydroxyapatite to form fluorapatite, but fluorapatite can affect bond strength.27 Meng et al28 found that the application of acidulated phosphate fluoride after acid etching has an adverse effect on orthodontic bond strength of enamel. However, several studies showed that fluoride application did not negatively affect bond strength.29,30 Our results agreed with previous studies, suggesting that fluoride-releasing light-cured resin has no adverse effect on enamel bond strength. Self-etching systems have become an accepted bonding technique, since they reduce chair time and increase cost effectiveness for orthodontists. There are significant differences in the in-vitro SBS among the self-etching adhesive materials.31,32 It has been stated that the bond strength of a stainless steel bracket should be more than 6 MPa to permit adequate adhesion.33 Additionally, bond strength should be high enough to resist accidental debonding during treatment, but low enough to remove the bracket without harming the periodontium.33,34 Bond strengths between 8 and 9 MPa have been recommended.35 One study reported significantly higher bond strengths with Clearfil SE Bond,32 and another found lower bond strength values than that of conventional systems.36 Buyukyılmaz et al31 declared that Clearfil SE Bond produced bond strength values with a mean of 11.5 ⫾ 3.3 MPa. Another study showed a mean SBS of 26.4 ⫾ 4.2 MPa after 24 hours of Clearfil SE Bond application.32 Lower SBS values were found when self-etching primers were bonded to intact enamel surfaces.37 The chemical composition of Clearfil Protect Bond has a significant inhibitory effect against growth of bacteria in plaque.14,20,21 Bishara et al38 compared the effect of this new adhesive on the SBS of orthodontic brackets with conventional adhesive systems and found higher SBS values with Clearfil Protect Bond. Accordingly, our results showed significantly higher bond
strength values in the Clearfil Protect Bond group when compared with the other groups. The mean SBS value in this study was 13.48 MPa, which was similar to the results of a previous study.39 As suggested by the manufacturer, the enamel was etched for 10 seconds before applying Clearfil Protect Bond. However, Arhun et al39 suggested that etching might not be necessary, since they achieved acceptable bond strengths without this procedure. Also, acid etching increases clinical steps and chair time. With respect to the ARI scores, indicating that most of the adhesive remained on the bracket surfaces, the predominant mode of bracket failure was at the enameladhesive resin interface in all groups. Although groups 3 and 4 had the statistically highest SBS values, they also had less composite resin remaining on the teeth. There were no statistical differences in any group. Littlewood et al40 declared that the failure in the bracket-adhesiveenamel complex can occur in the bracket, between the bracket and the adhesive, in the adhesive, and between the tooth surface and the adhesive. A basic opinion on the remaining adhesive on teeth after debonding involves the bracket-adhesive interface failure.41 The other option involves failure at the enamel-adhesive resin interface.42 Although several studies supported the first option, our findings supported the second.43-45 These findings were similar to a previous report.14 Some studies showed conflicting results about the amount of residual adhesive on teeth with self-etching primers.43,46 The inconsistency might be due to differences in bracket-base areas, different bonding regimens, or the classification system of ARI. We believe that high SBS during treatment and shorter chair time for residual resin removal during debonding would be beneficial in clinical situations. The results of this in-vitro study showed that all SBS values were adequate and consistent with studies that reported adequate bond strengths with self-etching systems.39,47 Although the combined application of self-etching primer systems and the fluoride-releasing resin (Ortho-Coat) had lower scores, the SBS values were not significantly reduced. This finding agreed with previous studies.30,48
American Journal of Orthodontics and Dentofacial Orthopedics Volume 135, Number 1
However, in-vitro testing of bond strength cannot completely predict clinical efficiency, because of the limitations of laboratory assessments and the different intraoral factors, but these results should help in the planning of further clinical studies. CONCLUSIONS
The results from this in-vitro study suggest that the new fluoride-releasing light-cured resin with self-etching primer system does not have an adverse effect on bond strength. The demineralization and microleakageinhibiting effects and the simple application of this product might be considered for clinical use in orthodontic patients especially with inadequate oral hygiene. Further in-vivo studies are required to evaluate its clinical performance.
REFERENCES 1. Bishara SE, VonWald L, Zamtua J, Damon PL. Effects of various methods of chlorhexidine application on shear bond strength. Am J Orthod Dentofacial Orthop 1998;114:150-3. 2. Mitchell L. Decalcification during orthodontic treatment with fixed appliances—an overview. Br J Orthod 1992;19:199-205. 3. Scheie AA, Arnesberg P, Krogstad O. Effect of orthodontic treatment on prevalence of Streptococcus mutans in plaque and saliva. Scand J Dent Res 1984;92:211-7. 4. Øgaard B, Larsson E, Henriksson T, Birkhed D, Bishara SE. Effects of combined application of antimicrobial and fluoride varnishes in orthodontic patients. Am J Orthod Dentofacial Orthop 2001;120:28-35. 5. Gorelick L, Geiger AM, Gwinnett AJ. Incidence of white spot formation after bonding and banding. Am J Orthod 1982;81: 93-8. 6. Stecksen-Blicks C, Renfors G, Oscarson ND, Bergstrand F, Twetman S. Caries-preventive effectiveness of a fluoride varnish: a randomized controlled trial in adolescents with fixed orthodontic appliances. Caries Res 2007;41:455-9. 7. Derks A, Katsaros C, Frencken JE, van’t Hof MA, KuijpersJagtman AM. Caries-inhibiting effect of preventive measures during orthodontic treatment with fixed appliances. A systematic review. Caries Res 2004;38:413-20. 8. Twetman S, Hallgren A, Petersson LG. Effect of an antibacterial varnish on mutans streptococci in plaque from enamel adjacent to orthodontic appliances. Caries Res 1995;29:188-91. 9. Twetman S, Petersson LG. Effect of different chlorhexidine varnish regimens on mutans streptococci levels in interdental plaque and saliva. Caries Res 1997;31:189-93. 10. Wenderoth CJ, Weinstein M, Borislow AJ. Effectiveness of a fluoride-releasing sealant in reducing decalcification during orthodontic treatment. Am J Orthod Dentofacial Orthop 1999;116: 629-34. 11. Chadwick BL, Roy J, Knox J, Treasure ET. The effect of topical fluorides on decalcification in patients with fixed orthodontic appliances: a systematic review. Am J Orthod Dentofacial Orthop 2005;128:601-6. 12. Banks PA, Chadwick SM, Asher-McDade C, Wright JL. Fluoride-releasing elastomerics—a prospective controlled clinical trial. Eur J Orthod 2000;22:401-7.
Tuncer, Tuncer, and Ulusoy 14.e5
13. Karaman AI, Uysal T. Effectiveness of a hydrophilic primer when different antimicrobial agents are mixed. Angle Orthod 2004;74:414-9. 14. Korbmacher HM, Huck L, Kahl-Nieke B. Fluoride-releasing adhesive and antimicrobial self-etching primer effects on shear bond strength of orthodontic brackets. Angle Orthod 2006;76: 845-50. 15. Demito CF, Vivaldi-Rodrigues G, Ramos AL, Bowman SJ. The efficacy of a fluoride varnish in reducing enamel demineralization adjacent to orthodontic brackets: an in vitro study. Orthod Craniofac Res 2004;7:205-10. 16. Todd MA, Staley RN, Kanellis MJ, Doly KJ, Wefel JS. Effect of a fluoride varnish on demineralization adjacent to orthodontic brackets. Am J Orthod Dentofacial Orthop 1999;116:159-67. 17. Buyukyilmaz T, Øgaard B. Caries preventive effects of fluoridereleasing materials. Adv Dent Res 1995;9:377-83. 18. Rolla G, Melsen B. On the mechanisms of the plaque inhibition by chlorhexidine. J Dent Res 1975;54:57-62. 19. Geiger AM, Gorelick L, Gwinnett AJ, Benson BJ. Reducing white spot lesions in orthodontic populations with fluoride rinsing. Am J Orthod Dentofacial Orthop 1992;101:403-7. 20. Imazato S, Kinomoto Y, Tarumi H, Torii M, Russell RR, McCabe JF. Incorporation of antibacterial monomer MDPB into dentin primer. J Dent Res 1997;76:768-72. 21. Imazato S, Kuramoto A, Takahashi Y, Ebisu S, Peters MC. In vitro antibacterial effects of the dentin primer of Clearfil Protect Bond. Dent Mater 2006;22:527-32. 22. Øgaard B, Rolla G, Arends J. Orthodontic appliances and enamel demineralization. Part I. Lesion development. Am J Orthod Dentofacial Orthop 1988;94:68-73. 23. Bryant S, Reteif DH, Bradley EL, Denys FR. The effect of topical fluoride treatment on enamel fluoride uptake and the tensile bond strength of an orthodontic bonding resin. Am J Orthod 1985;87:294-302. 24. Branstrom M, Nordenvall KJ, Malmgren O. The effect of various pretreatment methods of the enamel in bonding procedures. Am J Orthod 1978;74:522-30. 25. McCourt JW, Cooley RL, Barnwell S. Bond strength of lightcure fluoride-releasing base-liners as orthodontic bracket adhesives. Am J Orthod Dentofacial Orthop 1991;100:47-52. 26. Kimura T, Dunn WJ, Taloumis LJ. Effect of fluoride varnish on the in vitro bond strength of orthodontic brackets using a self-etching primer system. Am J Orthod Dentofacial Orthop 2004;125:351-6. 27. Aasenden R, DePaola PF, Brudevold F. Effects of daily rinsing and ingestion of fluoride solutions upon dental caries and enamel fluoride. Arch Oral Biol 1972;17:1705-14. 28. Meng CL, Li CH, Wang WN. Bond strength with APF applied after acid etching. Am J Orthod Dentofacial Orthop 1998;114: 510-3. 29. Wang WN, Sheen DH. The effect of pretreatment with fluoride on the tensile strength of orthodontic bonding. Angle Orthod 1991;61:31-4. 30. Bishara SE, Chan D, Abadir EA. The effect on the bonding strength of orthodontic brackets of fluoride application after etching. Am J Orthod Dentofacial Orthop 1989;95:259-60. 31. Buyukyılmaz T, Usumez S, Karaman AI. Effect of self-etching primers on bond strength—are they reliable? Angle Orthod 2003;73:64-70. 32. Naughton WT, Latta MA. Bond strength of composite to dentin using self-etching adhesive systems. Quintessence Int 2005;36: 259-62.
14.e6 Tuncer, Tuncer, and Ulusoy
33. Özcan M, Vallittu PK, Peltomaki T, Huysmans MC, Kalk W. Bonding polycarbonate brackets to ceramic: effects of substrate treatment on bond strength. Am J Orthod Dentofacial Orthop 2004;126:220-7. 34. Faltermeier A, Behr M, Müssig D. A comparative evaluation of bracket bonding with 1-, 2-, and 3-component adhesive systems. Am J Orthod Dentofacial Orthop 2007;132:144.e1-5. 35. Reynolds IR. A review of direct orthodontic bonding. Br J Orthod 1975;2:171-8. 36. Cehreli ZC, Kecik D, Kocadereli I. Effect of self-etching primer and adhesive formulations on the shear bond strength of orthodontic brackets. Am J Orthod Dentofacial Orthop 2005;127: 573-9. 37. Kanemura N, Sano H, Tagami J. Tensile bond strength to and SEM evaluation of ground and intact enamel surfaces. J Dent 1999;27:523-30. 38. Bishara SE, Soliman M, Laffoon J, Warren JJ. Effect of antimicrobial monomer-containing adhesive on shear bond strength of orthodontic brackets. Angle Orthod 2005;75:397-9. 39. Arhun N, Arman A, Sesen C, Karabulut E, Korkmaz Y, Gokalp S. Shear bond strength of orthodontic brackets with 3 self-etch adhesives. Am J Orthod Dentofacial Orthop 2006; 129:547-50. 40. Littlewood SJ, Mitchell L, Greenwood DC, Bubb NL, Wood DJ. Investigation of a hydrophilic primer for orthodontic bonding: an in vitro study. J Orthod 2000;27:181-6.
American Journal of Orthodontics and Dentofacial Orthopedics January 2009
41. Bishara SE, Oonsombat C, Ajlouni R, Laffoon JF. Comparison of the shear bond strength of 2 self-etch primer/adhesive systems. Am J Orthod Dentofacial Orthop 2004;125:348-50. 42. Bishara SE, VonWald L, Laffoon JF, Jakobsen JR. Effect of altering the type of enamel conditioner on the shear bond strength of a resin-reinforced glass ionomer adhesive. Am J Orthod Dentofacial Orthop 2000;118:288-94. 43. Bishara SE, VonWald L, Laffoon JF, Warren JJ. Effect of a self-etch primer/adhesive on the shear bond strength of orthodontic brackets. Am J Orthod Dentofacial Orthop 2001;119:621-4. 44. Eminkahyagil N, Korkmaz Y, Gokalp S, Baseren M. Shear bond strength of orthodontic brackets with newly developed antibacterial self-etch adhesive. Angle Orthod 2005;75:843-8. 45. Romano FL, Tavares SW, Nouer DF, Consani S, Borges de Araujo Magnani MB. Shear bond strength of metallic orthodontic brackets bonded to enamel prepared with self-etching primer. Angle Orthod 2005;75:849-53. 46. Bishara SE, Gordan VV, VonWald L, Jacobsen JR. Shear bond strength of composite, glass ionomer and an acidic primer adhesive systems. Am J Orthod Dentofacial Orthop 1999;115: 24-8. 47. Arnold RW, Combe EC, Warford JH Jr. Bonding of stainless steel brackets to enamel with a new self-etching primer. Am J Orthod Dentofacial Orthop 2002;122:274-6. 48. Damon PL, Bishara SE, Olsen ME, Jakobsen JR. Effects of fluoride application on shear bond strength of orthodontic brackets. Angle Orthod 1996;66:61-4.
Effect of fluoride-releasing light-cured resin on shear bond strength of orthodontic brackets Cumhur Tuncer,a Burcu Balos¸ Tuncer,b and Çag˘rı Ulusoyb Ankara, Turkey Introduction: The aim of this study was to analyze the effect of an enamel-protective resin on the shear bond strength (SBS) of orthodontic brackets bonded with self-etching primer. Methods: Eighty extracted premolars were randomly divided into 4 groups of 20, and metal brackets were bonded. Group 1 specimens were bonded with Transbond Plus self-etching primer (3M Unitek, Monrovia, Calif) and no fluoride resin; in group 2, a fluoride-releasing resin (Ortho-Coat, Pulpdent, Watertown, Mass) was used with the Transbond Plus self-etching primer; group 3 teeth were bonded with a new antimicrobial self-etching primer (Clearfil Protect Bond, Kuraray Medical, Osaka, Japan) with no fluoride resin; and the same protocol was used in group 4 with an application of Ortho-Coat. A universal testing machine was used to determine the SBS, and the adhesive remaining after debonding was assessed. Results: There was no difference in SBS whether fluoride-releasing resin was used. Groups 3 and 4 had higher SBS values than the other groups (P ⬍0.001). The Kruskal-Wallis test showed no significant differences in the adhesive remnant index (chi-square ⫽ 0.019, P ⫽ 0.990). Conclusions: The application of enamel-protective resin did not affect the bond strength of orthodontic brackets to enamel with self-etching primer systems. (Am J Orthod Dentofacial Orthop 2009;135: 14.e1-14.e6)
O
ver the years, much attention has been paid to improving bonding techniques and materials to decrease decalcification during fixed orthodontic treatment, especially in patients with poor oral hygiene.1,2 The oral environment changes in patients treated with fixed orthodontic appliances by the low resting pH value in the dental plaque around the brackets, and the increase of Streptococcus mutans.3,4 The risk of white spot lesions and dental caries still exists because of more retentive sites and greater accumulations of dental plaque.4,5 Various preventive approaches have been reported in the literature.4,6-9 Investigations were mainly carried out on the demineralization-inhibiting effects of fluoride applications such as toothpastes and gels,7 varnishes and sealants,6,10 topical fluoride preparations,11 fluoride-releasing elastomeric modules and chains12 or fluoride-releasing bonding materials,7 antimicrobial agents mixed with orthodontic adhesives,1,13 or combinations of self-etching primer and fluoride-releasing adhesives.14 The efficacy of fluoride varnish to prevent white From the Department of Orthodontics, Faculty of Dentistry, Gazi University, Ankara, Turkey. a Assistant professor. b Research assistant. Reprint requests to: Cumhur Tuncer, Gazi University, Faculty of Dentistry, Department of Orthodontics, 8.cadde 82.sokak, 06510 EMEK, Ankara, Turkey; e-mail, [email protected]. Submitted, July 2008; revised and accepted, September 2008. 0889-5406/$36.00 Copyright © 2009 by the American Association of Orthodontists. doi:10.1016/j.ajodo.2008.09.016
spot lesions was evaluated.15,16 Derks et al7 stated that fluoride-releasing bonding materials had almost no demineralization-inhibiting effect, since the low-pH environment inhibits the remineralization phase. Therefore, Buyukyilmaz and Øgaard17 suggested combining fluoride and antimicrobials to improve the cariostatic effect of fluoride at low pH. It was shown that chlorhexidine inhibits acid production in dental plaque.18 Although rinses with fluoride or chlorhexidine are excellent methods of prevention, patient compliance has been shown to be low—about 13%.19 Methods that eliminate patient compliance would be beneficial in preventing white spot lesions around brackets and at the gingival margins. New materials incorporate antimicrobial and fluoride-releasing agents, such as Clearfil Protect Bond (Kuraray Medical, Okayama, Japan) and OrthoCoat (Pulpdent, Watertown, Mass). The former contains 12-methacryloyloxydodecypyridinium bromide, an antimicrobial agent with strong antibacterial activity,20,21 and the latter is a fluoride-releasing light-cured resin. OrthoCoat coats the enamel under and around the brackets and prevents food and bacteria from collecting there and, thus, decalcification that can develop as early as 4 weeks after placement.22 In addition, this material is hydrophilic and allows bonding of resin to moist enamel. The findings of in-vitro studies about bond strength of orthodontic brackets bonded to fluoride-treated and nonfluoride-treated enamel surfaces have shown con14.e1
14.e2 Tuncer, Tuncer, and Ulusoy
tradicting results.23-25 The effect of the new fluoridereleasing light-cured resin (Ortho-Coat) on the shear bond strength (SBS) of orthodontic brackets is untested. Therefore, our aim in this in-vitro study was to evaluate the effect of Ortho-Coat on the SBS of brackets bonded with a self-etching primer system (Transbond Plus, 3M Unitek, Monrovia, Calif) and a new antimicrobial, fluoride-releasing bonding system (Clearfil Protect Bond). MATERIAL AND METHODS
We used 80 caries-free maxillary premolars, extracted for orthodontic reasons. The teeth were stored in distilled water with thymol crystals (1% wt/vol) added to inhibit bacterial growth at room temperature. The criteria for tooth selection included intact buccal enamel that had not been pretreated with chemical agents, no visible cracks, and no enamel irregularities. The teeth were cleaned and polished with a fluoridefree pumice slurry and rubber cups for 10 seconds and thoroughly washed and dried with an oil-free air stream. They were examined under a light stereomicroscope at 10 times magnification to ensure the absence of caries and enamel cracks. The sample was randomly divided in 4 groups of 20 teeth, by using a random numbers table. All were embedded vertically in coldcuring acrylic (Orthocryl, Dentaurum, Ispringen, Germany) with metal ring molds. Premolar metal orthodontic brackets (Victory Series, 3M Unitek GmbH, Seefeld, Germany) were used. The average base surface areas of the brackets were calculated with measurements made by a digital caliper (Mitutoyo, Miyazaki, Japan). The mean base surface area was 10.53 mm2 for the metal brackets. The bonding procedures were performed as follows. Group 1 received conventional bonding with Transbond Plus self-etching primer. The primer was rubbed with pressure onto the enamel surface of each teeth for 5 seconds and dried with an oil- and moisture-free air stream. The brackets were coated with Transbond XT adhesive paste (3M Unitek) and positioned at the center of the buccal surface. The excess adhesive was removed from the margins of bracket base with a scaler before polymerization. All brackets were light-cured for 40 seconds with a halogen curing unit (Hilux Ultra Plus, Benliog˘lu Dental, Ankara, Turkey), 10 seconds each from the mesial, distal, gingival, and occlusal margins. In group 2, the same bonding procedure was performed as in group 1, but after using Transbond self-etching primer and adhesive, a fluoride-releasing light-cured resin, Ortho-Coat, was applied around the bracket and the entire enamel surface extending to the
American Journal of Orthodontics and Dentofacial Orthopedics January 2009
gingival margin and light-cured from the mesial and distal sides for 20 seconds. In group 3, Clearfil Protect Bond self-etching primer was applied as suggested by the manufacturer. First, the enamel surfaces were etched for 10 seconds with 37% phosphoric acid gel (Gel Etch, 3M Unitek). Then the teeth were washed with water for 20 seconds and air-dried with an oil-free air stream. The Clearfil Protect Bond primer was applied with a brush on the etched enamel surfaces in a thin uniform layer, left for 20 seconds, and sprayed with an air stream to evaporate the solvent. Later, the bonding agent was applied and light-cured for 10 seconds. The brackets were bonded with Transbond XT adhesive paste, placed on the center of the buccal surfaces and, after removal of excess adhesive, light-cured for 40 seconds. Group 4 received the same adhesive system as in group 3, except that Ortho-Coat was used around the bracket and the enamel margin and light-cured from the mesial and distal sides for 20 seconds. The enamel surfaces were etched with the same 37% phosphoric acid for 10 seconds, rinsed for 20 seconds, and air dried with an oil-free air stream. Clearfil Protect Bond primer was applied to the etched enamel surfaces, left for 20 seconds, and air sprayed to evaporate the solvent. The bonding agent was applied and light-cured for 10 seconds. Then Transbond adhesive was placed on the brackets, positioned on the center of the buccal surfaces, and light-cured for 40 seconds. Later, Ortho-Coat was applied around the brackets and the entire enamel surface to the gingival margin and light-cured for 20 seconds. All specimens were stored in distilled water at room temperature for 24 hours. Shear peel testing was performed with a universal testing machine (Instron, Canton, Mass). The specimens were stressed in an occlusogingival direction with a crosshead speed of 1 mm per minute. The maximum load necessary to debond each bracket was recorded in Newtons and then converted into megapascals (MPa). The debonded enamel surfaces were examined under a stereomicroscope (Nikon, Osaka, Japan) at 20 times magnification to assess the residual adhesive on the tooth surface by a blinded examiner (Ç.U.). A modified adhesive remnant index (ARI) was used to quantify the amount of remaining adhesive on the tooth surface. The following scale was used: 1, all adhesive remained on the tooth; 2, more than 90% of the adhesive remained on the tooth; 3, 10% to 90% of the adhesive remained on the tooth; 4, less than 10% of the adhesive remained on the tooth; and 5, no adhesive remained on the tooth.
Tuncer, Tuncer, and Ulusoy 14.e3
American Journal of Orthodontics and Dentofacial Orthopedics Volume 135, Number 1
Table I.
Materials used in the study
Material
Components
Ingredients
Transbond Plus self-etching primer (3M) Ortho-Coat (Pulpdent) Clearfil Protect Bond (Kuraray Medical)
Primer and bond Light-cured resin Primer and bond
Transbond XT (3M)
Light-cured adhesive
Primer: fluoride, no filler; bond: methacrylate ester derivative Uncured acrylate resins, silica, amorphous hydrofluoric acid Self-etching primer: adhesive phosphate monomer (MDP), 2-hydroxyethylmethacrylate (HEMA), water, initiators, monomer 12-methacryloyloxydodecyl pyridinium bromide (MDPB); bonding agent: MDP, HEMA, comonomers, initiators, functionalized sodium fluoride Quartz silica, bisphenol A diglycidyl ether dimethacrylate, bisphenol A bis (2-hydroxyethyl) dimethacrylate
Table II.
Descriptive statistics related to SBS and results of 2-way ANOVA comparing the effect of fluoride-releasing resin on in-vitro bond strength of brackets with self-etching primer systems 95% Confidence interval Group
n
Mean (MPa)
SD
Minimum
Maximum
Lower bound
Upper bound
1 2 3 4
20 20 20 20
8.21 8.18 13.48 13.34
0.93 1.06 1.78 1.69
6.87 6.31 10.85 10.75
10.05 10.30 16.85 16.85
7.77 7.69 12.65 12.55
8.64 8.68 14.31 14.13
Group 1, Transbond Plus self-etching; group 2, Transbond Plus self-etching plus Ortho-Coat; group 3, Clearfil Protect Bond; group 4, Clearfil Protect Bond plus Ortho-Coat. Interaction not significant (P ⫽ 0.841) and main effect of fluoride were not significant (P ⫽ 0.798). Main effect of adhesive type was significant (P ⬍0.001).
Statistical analysis
Statistical evaluation was performed by SPSS for Windows software (version 10.0, SPSS, Chicago, Ill). Descriptive statistics including means, standard deviations, and minimum and maximum values were calculated for each group. The 1-sample Kolmogorov-Smirnov test was used to evaluate the normal distribution of variances. Comparisons of bond strength data were performed with 2-way analysis of variance (ANOVA) to test for differences between groups and statistical interactions between the fluoride-releasing resin and adhesive groups. Follow-up analyses were performed by the post-hoc Tukey honestly significant difference multiple comparison test. The Kruskal-Wallis test was used to determine significant differences in the ARI scores among the groups. The level of significance was established at P ⬍0.05. RESULTS
Materials used in the study are shown in Table I. The descriptive statistics for SBS including means, standard deviations, minimum and maximum values, and 95% confidence intervals for mean values of SBS data are shown in Table II. Two-way ANOVA comparing the SBS of self-etching primer systems with and without fluoride-releasing resin showed no significant
interaction (P ⫽ 0.841). There was no difference in SBS whether the fluoride-releasing resin was used (P ⫽ 0.798). SBS values of the brackets in groups 3 and 4 were significantly higher than in the other groups (P ⬍0.001). The distribution of the ARI scores is shown in Table III. The Kruskal-Wallis test showed no significant differences in the ARI scores of the groups (chi-square ⫽ 0.019, P ⫽ 0.990). DISCUSSION
Since caries, enamel decalcification, and gingival inflammation during fixed orthodontic treatments could jeopardize the final esthetic results, preventive regimens must be taken seriously. Even patients with good hygiene can have difficulty cleaning around brackets, because plaque builds up easily under brackets, where it is extremely difficult to clean, and decalcification and staining can result; these are long-term concerns for orthodontists. Methods to protect the susceptible areas beneath and adjacent to brackets, independent of patient compliance, would be extremely beneficial. The new light-cured reinforced resin, Ortho-Coat, prevents decalcification, microleakage, and discoloration of teeth under orthodontic brackets. The soft tissues are also protected from irritation caused by
14.e4 Tuncer, Tuncer, and Ulusoy
Table III.
American Journal of Orthodontics and Dentofacial Orthopedics January 2009
Frequency distribution of ARI scores
Group
n
1
2
3
4
5
1 2 3 4
20 20 20 20
— — — —
1 (5%) 2 (10%) 2 (10%) 2 (10%)
4 (20%) 3 (15%) 2 (10%) 3 (15%)
6 (30%) 5 (25%) 7 (35%) 3 (15%)
9 (45%) 10 (50%) 9 (45%) 12 (60%)
Group 1, Transbond Plus self-etching; group 2, Transbond Plus self-etching plus Ortho-Coat; group 3, Clearfil Protect Bond; group 4, Clearfil Protect Bond plus Ortho-Coat.
rough or sharp surfaces of brackets. It can be placed around the bracket to seal it, immediately after seating the bracket or at a follow-up visit. Fluoride ions encourage the formation of calcium fluoride and fluorapatite, which enhances remineralization of the etched enamel.26 Fluoride deposits in hydroxyapatite to form fluorapatite, but fluorapatite can affect bond strength.27 Meng et al28 found that the application of acidulated phosphate fluoride after acid etching has an adverse effect on orthodontic bond strength of enamel. However, several studies showed that fluoride application did not negatively affect bond strength.29,30 Our results agreed with previous studies, suggesting that fluoride-releasing light-cured resin has no adverse effect on enamel bond strength. Self-etching systems have become an accepted bonding technique, since they reduce chair time and increase cost effectiveness for orthodontists. There are significant differences in the in-vitro SBS among the self-etching adhesive materials.31,32 It has been stated that the bond strength of a stainless steel bracket should be more than 6 MPa to permit adequate adhesion.33 Additionally, bond strength should be high enough to resist accidental debonding during treatment, but low enough to remove the bracket without harming the periodontium.33,34 Bond strengths between 8 and 9 MPa have been recommended.35 One study reported significantly higher bond strengths with Clearfil SE Bond,32 and another found lower bond strength values than that of conventional systems.36 Buyukyılmaz et al31 declared that Clearfil SE Bond produced bond strength values with a mean of 11.5 ⫾ 3.3 MPa. Another study showed a mean SBS of 26.4 ⫾ 4.2 MPa after 24 hours of Clearfil SE Bond application.32 Lower SBS values were found when self-etching primers were bonded to intact enamel surfaces.37 The chemical composition of Clearfil Protect Bond has a significant inhibitory effect against growth of bacteria in plaque.14,20,21 Bishara et al38 compared the effect of this new adhesive on the SBS of orthodontic brackets with conventional adhesive systems and found higher SBS values with Clearfil Protect Bond. Accordingly, our results showed significantly higher bond
strength values in the Clearfil Protect Bond group when compared with the other groups. The mean SBS value in this study was 13.48 MPa, which was similar to the results of a previous study.39 As suggested by the manufacturer, the enamel was etched for 10 seconds before applying Clearfil Protect Bond. However, Arhun et al39 suggested that etching might not be necessary, since they achieved acceptable bond strengths without this procedure. Also, acid etching increases clinical steps and chair time. With respect to the ARI scores, indicating that most of the adhesive remained on the bracket surfaces, the predominant mode of bracket failure was at the enameladhesive resin interface in all groups. Although groups 3 and 4 had the statistically highest SBS values, they also had less composite resin remaining on the teeth. There were no statistical differences in any group. Littlewood et al40 declared that the failure in the bracket-adhesiveenamel complex can occur in the bracket, between the bracket and the adhesive, in the adhesive, and between the tooth surface and the adhesive. A basic opinion on the remaining adhesive on teeth after debonding involves the bracket-adhesive interface failure.41 The other option involves failure at the enamel-adhesive resin interface.42 Although several studies supported the first option, our findings supported the second.43-45 These findings were similar to a previous report.14 Some studies showed conflicting results about the amount of residual adhesive on teeth with self-etching primers.43,46 The inconsistency might be due to differences in bracket-base areas, different bonding regimens, or the classification system of ARI. We believe that high SBS during treatment and shorter chair time for residual resin removal during debonding would be beneficial in clinical situations. The results of this in-vitro study showed that all SBS values were adequate and consistent with studies that reported adequate bond strengths with self-etching systems.39,47 Although the combined application of self-etching primer systems and the fluoride-releasing resin (Ortho-Coat) had lower scores, the SBS values were not significantly reduced. This finding agreed with previous studies.30,48
American Journal of Orthodontics and Dentofacial Orthopedics Volume 135, Number 1
However, in-vitro testing of bond strength cannot completely predict clinical efficiency, because of the limitations of laboratory assessments and the different intraoral factors, but these results should help in the planning of further clinical studies. CONCLUSIONS
The results from this in-vitro study suggest that the new fluoride-releasing light-cured resin with self-etching primer system does not have an adverse effect on bond strength. The demineralization and microleakageinhibiting effects and the simple application of this product might be considered for clinical use in orthodontic patients especially with inadequate oral hygiene. Further in-vivo studies are required to evaluate its clinical performance.
REFERENCES 1. Bishara SE, VonWald L, Zamtua J, Damon PL. Effects of various methods of chlorhexidine application on shear bond strength. Am J Orthod Dentofacial Orthop 1998;114:150-3. 2. Mitchell L. Decalcification during orthodontic treatment with fixed appliances—an overview. Br J Orthod 1992;19:199-205. 3. Scheie AA, Arnesberg P, Krogstad O. Effect of orthodontic treatment on prevalence of Streptococcus mutans in plaque and saliva. Scand J Dent Res 1984;92:211-7. 4. Øgaard B, Larsson E, Henriksson T, Birkhed D, Bishara SE. Effects of combined application of antimicrobial and fluoride varnishes in orthodontic patients. Am J Orthod Dentofacial Orthop 2001;120:28-35. 5. Gorelick L, Geiger AM, Gwinnett AJ. Incidence of white spot formation after bonding and banding. Am J Orthod 1982;81: 93-8. 6. Stecksen-Blicks C, Renfors G, Oscarson ND, Bergstrand F, Twetman S. Caries-preventive effectiveness of a fluoride varnish: a randomized controlled trial in adolescents with fixed orthodontic appliances. Caries Res 2007;41:455-9. 7. Derks A, Katsaros C, Frencken JE, van’t Hof MA, KuijpersJagtman AM. Caries-inhibiting effect of preventive measures during orthodontic treatment with fixed appliances. A systematic review. Caries Res 2004;38:413-20. 8. Twetman S, Hallgren A, Petersson LG. Effect of an antibacterial varnish on mutans streptococci in plaque from enamel adjacent to orthodontic appliances. Caries Res 1995;29:188-91. 9. Twetman S, Petersson LG. Effect of different chlorhexidine varnish regimens on mutans streptococci levels in interdental plaque and saliva. Caries Res 1997;31:189-93. 10. Wenderoth CJ, Weinstein M, Borislow AJ. Effectiveness of a fluoride-releasing sealant in reducing decalcification during orthodontic treatment. Am J Orthod Dentofacial Orthop 1999;116: 629-34. 11. Chadwick BL, Roy J, Knox J, Treasure ET. The effect of topical fluorides on decalcification in patients with fixed orthodontic appliances: a systematic review. Am J Orthod Dentofacial Orthop 2005;128:601-6. 12. Banks PA, Chadwick SM, Asher-McDade C, Wright JL. Fluoride-releasing elastomerics—a prospective controlled clinical trial. Eur J Orthod 2000;22:401-7.
Tuncer, Tuncer, and Ulusoy 14.e5
13. Karaman AI, Uysal T. Effectiveness of a hydrophilic primer when different antimicrobial agents are mixed. Angle Orthod 2004;74:414-9. 14. Korbmacher HM, Huck L, Kahl-Nieke B. Fluoride-releasing adhesive and antimicrobial self-etching primer effects on shear bond strength of orthodontic brackets. Angle Orthod 2006;76: 845-50. 15. Demito CF, Vivaldi-Rodrigues G, Ramos AL, Bowman SJ. The efficacy of a fluoride varnish in reducing enamel demineralization adjacent to orthodontic brackets: an in vitro study. Orthod Craniofac Res 2004;7:205-10. 16. Todd MA, Staley RN, Kanellis MJ, Doly KJ, Wefel JS. Effect of a fluoride varnish on demineralization adjacent to orthodontic brackets. Am J Orthod Dentofacial Orthop 1999;116:159-67. 17. Buyukyilmaz T, Øgaard B. Caries preventive effects of fluoridereleasing materials. Adv Dent Res 1995;9:377-83. 18. Rolla G, Melsen B. On the mechanisms of the plaque inhibition by chlorhexidine. J Dent Res 1975;54:57-62. 19. Geiger AM, Gorelick L, Gwinnett AJ, Benson BJ. Reducing white spot lesions in orthodontic populations with fluoride rinsing. Am J Orthod Dentofacial Orthop 1992;101:403-7. 20. Imazato S, Kinomoto Y, Tarumi H, Torii M, Russell RR, McCabe JF. Incorporation of antibacterial monomer MDPB into dentin primer. J Dent Res 1997;76:768-72. 21. Imazato S, Kuramoto A, Takahashi Y, Ebisu S, Peters MC. In vitro antibacterial effects of the dentin primer of Clearfil Protect Bond. Dent Mater 2006;22:527-32. 22. Øgaard B, Rolla G, Arends J. Orthodontic appliances and enamel demineralization. Part I. Lesion development. Am J Orthod Dentofacial Orthop 1988;94:68-73. 23. Bryant S, Reteif DH, Bradley EL, Denys FR. The effect of topical fluoride treatment on enamel fluoride uptake and the tensile bond strength of an orthodontic bonding resin. Am J Orthod 1985;87:294-302. 24. Branstrom M, Nordenvall KJ, Malmgren O. The effect of various pretreatment methods of the enamel in bonding procedures. Am J Orthod 1978;74:522-30. 25. McCourt JW, Cooley RL, Barnwell S. Bond strength of lightcure fluoride-releasing base-liners as orthodontic bracket adhesives. Am J Orthod Dentofacial Orthop 1991;100:47-52. 26. Kimura T, Dunn WJ, Taloumis LJ. Effect of fluoride varnish on the in vitro bond strength of orthodontic brackets using a self-etching primer system. Am J Orthod Dentofacial Orthop 2004;125:351-6. 27. Aasenden R, DePaola PF, Brudevold F. Effects of daily rinsing and ingestion of fluoride solutions upon dental caries and enamel fluoride. Arch Oral Biol 1972;17:1705-14. 28. Meng CL, Li CH, Wang WN. Bond strength with APF applied after acid etching. Am J Orthod Dentofacial Orthop 1998;114: 510-3. 29. Wang WN, Sheen DH. The effect of pretreatment with fluoride on the tensile strength of orthodontic bonding. Angle Orthod 1991;61:31-4. 30. Bishara SE, Chan D, Abadir EA. The effect on the bonding strength of orthodontic brackets of fluoride application after etching. Am J Orthod Dentofacial Orthop 1989;95:259-60. 31. Buyukyılmaz T, Usumez S, Karaman AI. Effect of self-etching primers on bond strength—are they reliable? Angle Orthod 2003;73:64-70. 32. Naughton WT, Latta MA. Bond strength of composite to dentin using self-etching adhesive systems. Quintessence Int 2005;36: 259-62.
14.e6 Tuncer, Tuncer, and Ulusoy
33. Özcan M, Vallittu PK, Peltomaki T, Huysmans MC, Kalk W. Bonding polycarbonate brackets to ceramic: effects of substrate treatment on bond strength. Am J Orthod Dentofacial Orthop 2004;126:220-7. 34. Faltermeier A, Behr M, Müssig D. A comparative evaluation of bracket bonding with 1-, 2-, and 3-component adhesive systems. Am J Orthod Dentofacial Orthop 2007;132:144.e1-5. 35. Reynolds IR. A review of direct orthodontic bonding. Br J Orthod 1975;2:171-8. 36. Cehreli ZC, Kecik D, Kocadereli I. Effect of self-etching primer and adhesive formulations on the shear bond strength of orthodontic brackets. Am J Orthod Dentofacial Orthop 2005;127: 573-9. 37. Kanemura N, Sano H, Tagami J. Tensile bond strength to and SEM evaluation of ground and intact enamel surfaces. J Dent 1999;27:523-30. 38. Bishara SE, Soliman M, Laffoon J, Warren JJ. Effect of antimicrobial monomer-containing adhesive on shear bond strength of orthodontic brackets. Angle Orthod 2005;75:397-9. 39. Arhun N, Arman A, Sesen C, Karabulut E, Korkmaz Y, Gokalp S. Shear bond strength of orthodontic brackets with 3 self-etch adhesives. Am J Orthod Dentofacial Orthop 2006; 129:547-50. 40. Littlewood SJ, Mitchell L, Greenwood DC, Bubb NL, Wood DJ. Investigation of a hydrophilic primer for orthodontic bonding: an in vitro study. J Orthod 2000;27:181-6.
American Journal of Orthodontics and Dentofacial Orthopedics January 2009
41. Bishara SE, Oonsombat C, Ajlouni R, Laffoon JF. Comparison of the shear bond strength of 2 self-etch primer/adhesive systems. Am J Orthod Dentofacial Orthop 2004;125:348-50. 42. Bishara SE, VonWald L, Laffoon JF, Jakobsen JR. Effect of altering the type of enamel conditioner on the shear bond strength of a resin-reinforced glass ionomer adhesive. Am J Orthod Dentofacial Orthop 2000;118:288-94. 43. Bishara SE, VonWald L, Laffoon JF, Warren JJ. Effect of a self-etch primer/adhesive on the shear bond strength of orthodontic brackets. Am J Orthod Dentofacial Orthop 2001;119:621-4. 44. Eminkahyagil N, Korkmaz Y, Gokalp S, Baseren M. Shear bond strength of orthodontic brackets with newly developed antibacterial self-etch adhesive. Angle Orthod 2005;75:843-8. 45. Romano FL, Tavares SW, Nouer DF, Consani S, Borges de Araujo Magnani MB. Shear bond strength of metallic orthodontic brackets bonded to enamel prepared with self-etching primer. Angle Orthod 2005;75:849-53. 46. Bishara SE, Gordan VV, VonWald L, Jacobsen JR. Shear bond strength of composite, glass ionomer and an acidic primer adhesive systems. Am J Orthod Dentofacial Orthop 1999;115: 24-8. 47. Arnold RW, Combe EC, Warford JH Jr. Bonding of stainless steel brackets to enamel with a new self-etching primer. Am J Orthod Dentofacial Orthop 2002;122:274-6. 48. Damon PL, Bishara SE, Olsen ME, Jakobsen JR. Effects of fluoride application on shear bond strength of orthodontic brackets. Angle Orthod 1996;66:61-4.