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Original Article
6 (
1
); 12-17
doi:
10.4103/2321-1407.173724

Effect of fluoridated casein phospopeptide-amorphous-calcium phosphate complex, chlorhexidine fluoride mouthwash on shear bond strength of orthodontic brackets: A comparative in vitro study

Department of Orthodontics and Dentofacial Orthopaedics, A. J. Institute of Dental Sciences, Mangalore, Karnatakay, India
Address for Correspondence: Dr. Anurag D. Mahale, Department of Orthodontics and Dentofacial Orthopaedics, A. J. Institute of Dental Sciences, Mangalore, Karnataka, India. E-mail: dranuragmahale@gmail.com
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How to cite this article: Abdul Shahariyar CA, Mahale AD, Kumar K, Rai R. Effect of fluoridated casein phospopeptide-amorphous-calcium phosphate complex, chlorhexidine fluoride mouthwash on shear bond strength of orthodontic brackets: A comparative in vitro study. APOS Trends Orthod 2016;6:12-7.

Abstract

Objective

The aim of the current study was to determine the effects of casein phosphopeptide amorphous calcium-phosphate (CPP-ACP) complex, chlorhexidine fluoride mouthwash on shear bond strengths (SBSs) of orthodontic brackets.

Materials and Methods

About sixty extracted healthy human premolar teeth with intact buccal enamel were divided into two equal groups to which brackets were bonded using self-etching primers (SEPs) and conventional means respectively. These were further equally divided into three subgroups - (1) control (2) CPP-ACP (3) chlorhexidine fluoride mouthwash. The SBSs were then measured using a universal testing machine.

Results

SBS of the conventional group was significantly higher than the self-etching group. The intragroup differences were statistically insignificant.

Conclusion

CPP-ACP, chlorhexidine fluoride mouthwash did not adversely affect SBS of orthodontic brackets irrespective of the method of conditioning. Brackets bonded with conventional technique showed greater bond strengths as compared to those bonded with SEP.

Keywords

Bonding
casein phosphopeptide amorphous calcium-phosphate
shear bond strength

INTRODUCTION

The bonding of orthodontic attachments has become an integral part of orthodontics.

The bonding of various adhesives to enamel and dentin has developed leaps and bounds over the past 50 years in

all areas of dentistry. Buonocore, initially demonstrated the adhesions of acrylic filling materials to enamel, following acid etching with phosphoric acid.[1] It was Newman in 1965, who suggested that this technique can be applied for orthodontic bonding.[2]

There are different adhesive systems for bonding, mainly the conventional etching and self-etching systems. Conventional adhesive systems comprise an enamel conditioner, a primer solution and an adhesive resin. When using conventional bonding, the acid etching brings about dissolution of enamel crystals in the prism structure, which produces a permeable enamel surface layer which ranges in depth from 5 to 50 µ[3] The irregular enamel surface formed helps in micromechanical retention. The amount of dissolution of enamel surface depends upon the type of acid and its concentration.

In self-etching primers (SEPs), the methacrylate group and phosphoric acid ester are combined into a molecule that helps in etching and priming at the same time during the process of bonding. The main advantage of SEP is that two steps are combined and made into a single step. Etching and priming are simultaneously done which helps in eliminating the unwanted effects of unfiltered resin which brings about demineralization.[4]

Loss of surface enamel notably in the gingival third of the crown is being increasingly seen in patients undergoing fixed orthodontic therapy. These enamel decalcifications are also known as white spot lesions (WSLs) due to change in the refractive index of enamel leading to scattering of light and a chalky white appearance.

Several studies have shown that WSLs have a high incidence rate varying from 75.6% in Indians[5] to 96% in Europeans[6] undergoing orthodontic therapy. Several methods have been suggested to counteract the development and progression of WSL ranging from complete appliance removal to topical application of fluoride and recently used titanium oxide coated stainless steel brackets. The use of casein phosphopeptide amorphous calcium-phosphate (CPP-ACP) a milk protein derivative has shown favorable results in decreasing WSLs. Maintenance of oral hygiene with the use of fluoridated toothpaste, mouthwash, etc., has also been recommended as the method to prevent WSLs. However, the presence of fluoride in these products undermines the bond strength of orthodontic brackets by interfering with the binding mechanisms of resins by the formation of fluorapatites suggested by some studies.[7] Hence, it is important to determine the effect of CPP- ACP and fluoridated chlorhexidine (CHX) mouthwash on the shear bond strength (SBS) of orthodontic brackets.

The objectives of the study were:

  1. To investigate the effect of fluoride containing CPP-ACP complex on the SBS of brackets bonded with SEP

  2. To investigate the effect of fluoride containing CPP-ACP complex on the SBS of brackets bonded with conventional etching primer

  3. To investigate the effect of CHX + fluoride mouthwash on the SBS of brackets bonded with SEP

  4. To investigate the effect of CHX + fluoride mouthwash on the SBS of brackets bonded with conventional acid etching primer.

MATERIALS AND METHODS

Sixty extracted healthy human premolar teeth with intact buccal enamel, extracted for orthodontic therapy were included in the study. Teeth with caries or any other morphological abnormality were excluded. The teeth were then stored in distilled water. The teeth were mounted vertically group wise using self-cure acrylic, such that the crowns were exposed. The buccal surfaces of the teeth were cleaned and polished with a rubber cup and slurry with nonfluoridated pumice and water, followed by rinsing with a water spray and drying with compressed air.

The sixty extracted teeth were divided into two groups. The first group (Group 1) consisted of 30 teeth bonded with SEP (Transbond Plus, 3M Unitek, Monrovia, CA, USA). The group was further divided into equal subgroups consisted of 10 teeth each. The three subgroups were an untreated control Group (1A), teeth pretreated with fluoridated CPP-ACP paste (MI Paste Plus, GC America, Alsip, Il.) to which brackets were immediately bonded (1B) and teeth pretreated with CHX and fluoride mouthwash to which brackets were bonded 7 days after application (Chlohex-plus, Dr. Reddy’s Laboratories, Hyderabad, India) (1C).

The second group (Group 2) consisted of 30 teeth bonded with conventional etching system (35% phosphoric acid and Transbond XT primer, 3M Unitek, Monrovia, CA, USA). It was further divided into subgroups similar to the first group (Group 2A, 2B and 2C, respectively) [Figure 1].

Figure1: Investigation design

The premolar stainless steel brackets (0.022 slot, MBT prescription, Ormco, Orange, CA, USA) were then bonded to the buccal surfaces of these teeth using a light cured adhesive (Transbond XT, 3M Unitek, Monrovia, CA, USA). The SBS was then measured using a universal testing machine (Model no. 3366, Instron, Norwood, MA, USA).

All data was summarized by mean and standard deviation values. One-factor analysis of variance (ANOVA) was used to compare conventionally and SEP. Multiple comparisons were also performed with Tukey’s test when ANOVA yielded significant results indicating that there was difference between the primers.

RESULTS

Tables 1 and 2 show the bond strength of individual groups and the comparison of the six subgroups between the groups and within the groups using ANOVA test. In Group 1, self-etching group, Group 1A had mean SBS of 9.90 ± 2.29 MPa. Group 1B had a mean SBS of 9.83 ± 4.83 MPa compared to Group 1C with a mean SBS of 8.22 ± 2.12 MPa [Figure 2].

Table 1: Shear bond strengths of self-etching primer group (Group 1)
Sub-group No. of specimens Minimum* Maximum* Mean* SD*
1 A 10 5.74 12.66 9.9036 2.29466
1 B 10 2.76 20.98 9.8303 4.83438
1 C 10 4.31 10.89 8.2228 2.12168
Value in Mega Pascals (Mpa). SD=Standard Deviation
Table 2: Shear bond strengths of conventional group (Group 2)
Sub-group No. of specimens Minimum* Maximum* Mean* SD*
2 A 10 4.31 10.89 8.2228 2.12168
2 B 10 4.54 21.81 12.4971 5.88858
2 C 10 6.47 16.50 11.4852 3.58934
Value in Mega Pascals (Mpa). SD=Standard Deviation
Figure 2: Graphic representation of mean shear bond strength of all the six groups

In Group 2, the conventional etching group, Group 2A had a mean SBS of 14.10 ± 5.56 MPa. In Group 2B teeth the mean bond SBS was 12.49 ± 5.88 MPa, whereas in Group 2C the mean SBS was 11.48 ± 3.58 MPa [Figure 2]. Between the two main groups, the P value was statistically significant (P > 0.05) showing that the self-etching group had a lesser bond strength than conventional acid-etch group [Tables 3 and 4].

Table 3: Inter-group comparisons using analysis of variance
ANOVA
Bond strength Sum of squares df Mean square F Significant
Inter group 224.297 5 44.859 2.410 0.048*
Intra groups 1005.003 54 18.611
Total 1229.300 59
The mean difference is significant at the 0.05 level
Table 4: Tukey honest significant difference test for multiple comparisons
Multiple comparisons
Shear bond strength Tukey HSD SE Significant 95% CI
Material (I) Material (J) Mean difference (I-J) Lower bound Upper bound
1a 1b 1.08500 28.55377 1.000 −83.2765 85.4465
1c 24.87600 28.55377 0.952 −59.4855 109.2375
2a −62.25000 28.55377 0.264 −146.6115 22.1115
2b −38.38400 28.55377 0.759 −122.7455 45.9775
2c −23.40800 28.55377 0.963 −107.7695 60.9535
1b 1a −1.08500 28.55377 1.000 −85.4465 83.2765
1c 23.79100 28.55377 0.960 −60.5705 108.1525
2a −63.33500 28.55377 0.247 −147.6965 21.0265
2b −39.46900 28.55377 0.737 −123.8305 44.8925
2c −24.49300 28.55377 0.955 −108.8545 59.8685
1c 1a −24.87600 28.55377 0.952 −109.2375 59.4855
1b −23.79100 28.55377 0.960 −108.1525 60.5705
2a −87.12600* 28.55377 0.039* −171.4875 −2.7645
2b −63.26000 28.55377 0.248 −147.6215 21.1015
2c −48.28400 28.55377 0.544 −132.6455 36.0775
2a 1a 62.25000 28.55377 0.264 −22.1115 146.6115
1b 63.33500 28.55377 0.247 −21.0265 147.6965
1c 87.12600* 28.55377 0.039* 2.7645 171.4875
2b 23.86600 28.55377 0.959 −60.4955 108.2275
2c 38.84200 28.55377 0.750 −45.5195 123.2035
2b 1a 38.38400 28.55377 0.759 −45.9775 122.7455
1b 39.46900 28.55377 0.737 −44.8925 123.8305
1c 63.26000 28.55377 0.248 −21.1015 147.6215
2a −23.86600 28.55377 0.959 −108.2275 60.4955
2c 14.97600 28.55377 0.995 −69.3855 99.3375
2c 1a 23.40800 28.55377 0.963 −60.9535 107.7695
1b 24.49300 28.55377 0.955 −59.8685 108.8545
1c 48.28400 28.55377 0.544 −36.0775 132.6455
2a −38.84200 28.55377 0.750 −123.2035 45.5195
2b −14.97600 28.55377 0.995 −99.3375 69.3855
The mean difference is significant at the 0.05 level. HSD – Honest significant difference; SE – Standard error; CI – Confidence interval

DISCUSSION

The present study compared the SBS of orthodontic brackets bonded to teeth using SEP and conventional techniques which were pretreated with casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) or a chlorhexidine and fluoride mouthwash.

Introduction of bonding revolutionized dentistry in general and orthodontics in particular. It has helped to improve treatment, increase patient comfort, and at the same time eliminate the ill-effects usually associated with banding of teeth. The introduction of SEP in the 1990s further reduced chair side time. However, there has always been disagreement regarding its bond strength as compared to conventional primers. It has been suggested that the bond strength attained using SEP was inferior. There is a large body of evidence supporting as well as refuting the claim.

Previous studies concluded[8-10] that the conventional primer consistently showed better bond strength than SEP.

However, Moule et al.[11] reported contrasting findings suggesting that SEP had greater bond strengths than conventional primers.

Bishara et al.[12] as well as Buyukyilmaz et al.[13] reported that that SBSs of both the systems were not significantly different.

Similarly, Ireland et al.[14] from their investigations concluded that there was weak evidence to suggest that bond failures with an SEP were higher than those with conventional etching and priming. They suggested the increased likelihood of bond failure had to be weighed against the time advantage of the SEP when used at the initial bonding appointment.

However, the current study found that there was a statistically significant difference between the two groups. It was observed that the conventional primer group consistently had greater SBS than the SEP group. This included the subgroups where CPP-ACP and CHX with fluoride were used, respectively. These differences can be attributed to different mechanisms of action of the two systems and not the presence of CPP-ACP or CHX.

WSLs are a commonly seen sequela of orthodontic treatment. A number of methods have been suggested to prevent this. These range from topical fluoride applications, dentifrices, mouthwashes, etc.

CPP-ACP is a milk-derived product, a more recent introduction to tackle WSLs. It is claimed that CPP-ACP remineralizes teeth and help prevent caries. Casein phosphopeptides derived from the major milk protein have the ability to stabilize calcium, phosphate and fluoride ions as water-soluble amorphous complexes. These complexes remineralize early stages of tooth decay by replacing calcium and phosphate ions lost due to decay.[15] Presently, CPP- ACP can be administered via sugar-free gum, medicated tooth mousse and fortified dairy milk.

Current literature has contrasting reports of the effect of CPP-ACP on SBS of orthodontic brackets. A number of previous investigations[16-18] have mentioned that CPP-ACP had no detrimental effects on the SBS of orthodontic brackets. However, Dunn[19] reported that ACP-containing composite material failed at significantly lower forces than brackets bonded to teeth with the conventional resin-based composite orthodontic cement. On the other, Adebayo et al.[20,21] reported that use of SEP along with CPP-ACP enhanced SBS.

Investigators of the current study did not observe any significant differences in the between the CPP-ACP subgroups (Groups 1b and 2b) and other subgroups in either the conventional or SEP groups.

Hence, on the basis of these findings and previous investigations,[16-18] it can be safely concluded that CPP-ACP did not adversely affect the SBS of brackets bonded with either conventional or SEP.

Chlorhexidine is often used as an active ingredient in commonly prescribed mouthwashes designed to reduce dental plaque and oral bacteria. It actions and efficacy is well documented.[22] However, its role in preventing tooth decay is controversial as clinical data has not been convincing.[23] In addition, there are no clear evidence of its effects on SBS of orthodontic brackets.

Cacciafesta et al.[24] assessed the effect of chlorhexidine application on the SBS and concluded that chlorhexidine application immediately before bonding significantly lowered the bond strength values of resin-modified glass ionomer cement (RM-GIC) but did not affect its bond strength when applied 1 week before bonding.

The teeth (Groups 1c and 2c) in the current study were also bonded 1 week after CHX application. It was observed that there were no significant differences between these sub-groups and other sub-groups in either the conventional or SEP groups.

The present study differed from the previously mentioned study in two ways. Firstly, this study used extracted human teeth as opposed to bovine teeth. Second, unlike RM-GIC used in the previous study, the investigators used a light cured composite adhesive. Light cured adhesives have been proven to be more amenable to orthodontic bonding and are also used more widely. These two factors enabled the investigators of this study to provide a more accurate picture of real-time clinical scenarios.

In addition to CHX, additional fluoride supplements are routinely prescribed during orthodontic therapy. Hence, it is also important to consider the effect of fluoride in addition to the CHX mouthwash on SBS of brackets.

Previous investigations, for the most part, have studied these two separately and have not considered their effects when acting simultaneously.

The novelty of the current study was that the CHX mouthwash used had incorporated fluoride. Thus, the effects of CHX and fluoride on brackets acting simultaneously on the SBS of orthodontic brackets could be studied.

According to the results, it can be safely concluded that bonding of brackets 1-week post-CHX application did not adversely affect the bracket strength. In addition, the current study concluded that the concurrent use of CHX mouthwash with incorporated with fluoride or other fluoride supplements did not have a detrimental effect on SBS of orthodontic brackets regardless of the method of etching.

CONCLUSION

From the findings of the current study it can be concluded that:

The fluoride containing CPP-ACP had no adverse effect on the SBS of brackets bonded with SEP

  1. The fluoride containing CPP-ACP had no adverse effect on the SBS of brackets bonded with conventional primers

  2. CHX + fluoride mouthwash had no adverse effects on the SBS of brackets bonded with SEP

  3. CHX + fluoride mouthwash had no adverse effects on the SBS of brackets bonded with conventional primer

  4. Higher SBS was consistently observed in brackets bonded using a conventional primer as compared to SEP.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

  1. . A simple method of increasing the adhesion of acrylic filling materials to enamel surfaces. J Dent Res. 1955;34:849-53
    [Google Scholar]
  2. . Epoxy adhesives for orthodontic attachments: Progress report. Am J Orthod. 1965;51:901-12
    [Google Scholar]
  3. , , . In vivo effect of a self-etching primer on dentin. Am J Dent. 1999;12:167-71
    [Google Scholar]
  4. , , , , , . Effects of a self-etching primer on enamel shear bond strengths and SEM morphology. Am J Dent. 1997;10:141-6
    [Google Scholar]
  5. , , , . Prevalence of white spot lesion in a section of Indian population undergoing fixed orthodontic treatment: An in vivo assessment using the visual international caries detection and assessment system II criteria. J Conserv Dent. 2012;15:104-8
    [Google Scholar]
  6. , , , . The incidence of caries and white spot lesions in orthodontically treated adolescents with a comprehensive caries prophylactic regimen–A prospective study. Eur J Orthod. 2012;34:633-9
    [Google Scholar]
  7. , , . Bond strength with APF applied after acid etching. Am J Orthod Dentofacial Orthop. 1998;114:510-3
    [Google Scholar]
  8. , , , , . An evaluation and comparison of orthodontic bracket bond strengths achieved with self-etching primer. Am J Orthod Dentofacial Orthop. 2004;126:213-9
    [Google Scholar]
  9. , , , , . Shear bond strength of metallic orthodontic brackets bonded to enamel prepared with self-etching primer. Angle Orthod. 2005;75:849-53
    [Google Scholar]
  10. , . Scanning electron microscopy evaluation of the bonding mechanism of a self-etching primer on enamel. Angle Orthod. 2006;76:132-6
    [Google Scholar]
  11. , , , , , , et al. Resin bonding using an all-etch or self-etch adhesive to enamel after carbamide peroxide and/or CPP-ACP treatment. Aust Dent J. 2007;52:133-7
    [Google Scholar]
  12. , , , . Comparison of the shear bond strength of 2 self-etch primer/adhesive systems. Am J Orthod Dentofacial Orthop. 2004;125:348-50
    [Google Scholar]
  13. , , . Effect of self-etching primers on bond strength–are they reliable. ? Angle Orthod. 2003;73:64-70
    [Google Scholar]
  14. , , . An in vivo investigation into bond failure rates with a new self-etching primer system. Am J Orthod Dentofacial Orthop. 2003;124:323-6
    [Google Scholar]
  15. , . Clinical efficacy of casein derivatives: A systematic review of the literature. J Am Dent Assoc. 2008;139:915-24
    [Google Scholar]
  16. , , , , . Effects of a fluoride-containing casein phosphopeptide-amorphous calcium phosphate complex on the shear bond strength of orthodontic brackets. Eur J Orthod. 2012;34:193-7
    [Google Scholar]
  17. , , . Effect of fluoride-releasing light-cured resin on shear bond strength of orthodontic brackets. Am J Orthod Dentofacial Orthop. 2009;135:14.e1-6
    [Google Scholar]
  18. , , , . Effect of acidulated phosphate fluoride and casein phosphopeptide-amorphous calcium phosphate application on shear bond strength of orthodontic brackets. Angle Orthod. 2008;78:129-33
    [Google Scholar]
  19. . Shear bond strength of an amorphous calcium-phosphate-containing orthodontic resin cement. Am J Orthod Dentofacial Orthop. 2007;131:243-7
    [Google Scholar]
  20. , , . Bond strength test: Role of operator skill. Aust Dent J. 2008;53:145-50
    [Google Scholar]
  21. , , . Effects of conditioners on microshear bond strength to enamel after carbamide peroxide bleaching and/or casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) treatment. J Dent. 2007;35:862-70
    [Google Scholar]
  22. . Essentials of Preventive Community Dentistry (2nd ed). New Delhi: Arya (Medi) Publishing House.
  23. . The role of chlorhexidine in caries prevention. Oper Dent. 2008;33:710-6
    [Google Scholar]
  24. , , , , . Effect of chlorhexidine application on shear bond strength of brackets bonded with a resin-modified glass ionomer. Am J Orthod Dentofacial Orthop. 2006;129:273-6
    [Google Scholar]
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