| |
|
|
| Year : 2016 | Volume
: 27
| Issue : 4 | Page : 383-387 |
|
| Can 10% hydrofluoric acid be used for reconditioning of orthodontic brackets? |
|
|
Daniela D Pompeo1, Henrique D Rosário1, Beatriz MV Lopes1, Paulo F Cesar2, Luiz Renato Paranhos3
1 Health Sciences Center, Sacred Heart University, Bauru, SP, Brazil
2 Department of Biomaterials and Oral Biology, University of Sao Paulo, São Paulo, SP, Brazil
3 Department of Dentistry, Federal University of Sergipe, Lagarto, SE, Brazil
Click here for correspondence address and email
| Date of Submission | 27-Oct-2015 |
| Date of Decision | 17-Nov-2015 |
| Date of Acceptance | 18-Jul-2016 |
| Date of Web Publication | 10-Oct-2016 |
|
|
 |
|
 Abstract | | |
Context: Bracket debonding is a common problem during orthodontic treatment. This type of failure is associated to masticatory forces, poor adhesion, and the need for repositioning the piece.
Aims: The objective of this work was to compare the shear bond strength of debonded brackets that were reconditioned using different protocols (alumina blasting versus hydrofluoric etching).
Settings and Design: This was an in vitro experimental study with 45 stainless steel orthodontic brackets.
Subjects and Methods: They were randomly divided into three groups: (1) New brackets (n = 15), (2) brackets reconditioned using 10% hydrofluoric acid for 60 s (n = 15), and (3) brackets reconditioned by aluminum oxide blasting until complete removal of the remaining resin (n = 15). In Groups 2 and 3, the insertion of composite resin proceeded in two stages to simulate a type of bracket failure in which the bonding resin was left at the bracket base. For the shear test, the assembly composed by the metallic support, and specimen was taken to the Instron universal testing machine in which the specimens were loaded using a semicircle-shaped active tip in the region of the bonding interface parallel to the surface of the bracket at a speed of 0.5 mm/min.
Statistical Analysis Used: The data were subjected to D'Agostino's normality test to have their distribution checked. Analysis of variance and Tukey's test (P < 0.01) were used to compare the findings between groups.
Results: The results indicated that Group 1 (new brackets) showed higher bond strength than that obtained for the group treated with hydrofluoric acid (Group 2, P < 0.01). The bond strength value obtained for the group treated with alumina blasting (Group 3) was statistically similar to those obtained for Groups 1 and 2.
Conclusions: The aluminum oxide blasting technique was effective for the reconditioning of orthodontic brackets. Nevertheless, the reconditioning technique using 10% fluoridric acid for 60 s was not efficient for clinical use. Keywords: Aluminum oxide, hydrofluoric acid, orthodontics
How to cite this article:
Pompeo DD, Rosário HD, Lopes BM, Cesar PF, Paranhos LR. Can 10% hydrofluoric acid be used for reconditioning of orthodontic brackets?. Indian J Dent Res 2016;27:383-7 |
How to cite this URL:
Pompeo DD, Rosário HD, Lopes BM, Cesar PF, Paranhos LR. Can 10% hydrofluoric acid be used for reconditioning of orthodontic brackets?. Indian J Dent Res [serial online] 2016 [cited 2023 Jun 9];27:383-7. Available from: https://www.ijdr.in/text.asp?2016/27/4/383/191886 |
Bracket failure or loss is a common clinical problem faced during orthodontic treatment,[1],[2],[3] and accounts for 4.7-6% of the patients' complaints over a treatment period of 2 years.[4] This type of clinical problem may occur due to accidental displacement related to occlusal trauma,[5] excessive overbite, or substrate contamination during bonding.[6] Other factors related to these failures are bracket base design and type of adhesive.[6] The brackets failure rates are also related to the type of tooth and its position in the arch, as it has been verified that incisors and canines show lower failure rates than premolars.[7] Furthermore, lower canines are likely to present higher failure rates than those of their upper counterparts.[8]
Studies with metallic brackets evaluating bracket/resin/tooth boding have reported that fracture usually occurs at the bracket/resin interface due to the weak bonding existing in this region.[9],[10] Higher fracture rates at the resin/tooth interface have been reported as a result of surface treatment before bonding[3],[11] or application of self-curing adhesive system.[5]
In some cases, the clinician needs to decide how to proceed in cases of debonded and/or improperly positioned brackets.[12] In such clinical situations, one needs to choose between using the original debonded bracket or a new one.[5] If the debonded bracket is to be reused, it should go through a process known as reconditioning or recycling.[13]
The primary goal of the reconditioning process is to remove the adhesive layer from the bracket retentive base without causing damages or distortions to the piece.[12] This procedure can be done chairside (immediate method) or the bracket may be sent out to specialized companies, a procedure also known as commercial reconditioning (mediate method).[4],[12] One of the most popular and efficient chairside bracket reconditioning techniques is the aluminum oxide micromechanical blasting,[12],[13],[14],[15],[16],[17],[18] and specific equipment needs to be acquired by the dentist for this technique. Commercial reconditioning has some disadvantages such as increased susceptibility to corrosion and the fact that it is time-consuming for routinely clinical practices.[13]
Occasionally, in the absence of specific equipment and given the need for reconditioning the orthodontic bracket, the practitioner is supposed to find alternative methods to carry out this procedure. Hydrofluoric acid (HF) is a chemical agent that affects the composite surface morphology,[19],[20] and it is used in many procedures in dentistry. In repairs performed on resin composite restorations, HF is applied to create microretentions at the restoration surface to improve bonding between the old and the new composite materials.[20]
HF has shown promising results when used in the repair of resin composites or cementation of indirect resin restorations.[20] However, there are doubts in relation to the use of HF to improve the bonding of debonded brackets to dental enamel. Thus, the effectiveness of HF etching on the bond strength of debonded metallic brackets needs to be further investigated. The objective of this work was to compare the shear bond strength of debonded brackets that were reconditioned using different protocols (alumina blasting versus HF etching). Our hypothesis was that HF etching would result in higher bond strength values than alumina blasting for debonded brackets.
| Subjects and Methods | |  |
Preparation of specimens
This was an in vitro experimental study with 45 stainless steel orthodontic brackets designed for right maxillary central incisors, Roth prescription (3M Abzil, São José do Rio Preto, SP, Brazil), which were divided into three groups:
Group 1: Fifteen new brackets (control group); Group 2: Fifteen brackets reconditioned with a porcelain conditioner, 10% fluoridric acid (Porcelain Conditioner, Dentsply® , Petrópolis, RJ, Brazil); Group 3: Fifteen brackets reconditioned by aluminum oxide blasting (Jat bracket, VH Equipment® , Araraquara, SP, Brazil).
Specimens were prepared using a cylindrical polyvinyl chloride (PVC) tube (Tigre® , Joinville, SC, Brazil) measuring Ύ inch in diameter and 3 cm in height to serve as a matrix, allowing for the formation of resin cylinders as described in a previous study by Mondelli and Feitas.[10]
The brackets were positioned on a tape with their base (retentive mesh) facing the sticky side. After placing the bracket on the tape, the PVC tube was positioned over it so that the bracket was at the center of the pipe, as shown in [Figure 1]a. Chemically activated acrylic resin (JET® , São Paulo, SP, Brazil) was then poured into the pipe. After the setting time of acrylic resin was completed, the adhesive tape was removed, resulting in a specimen containing the bracket base available for the bonding procedure. | Figure 1: (a) Polyvinyl chloride pipe centralized in relation to the bracket. (b) Self-sticking adhesive on the specimen surface. (c) Metallic support with Teflon mold adapted. Note the central hole, which has dimensions equal to those of the self-sticking adhesive in the specimen. (d) Specimen undergoing the shear test. Note the semicircle-shaped active tip adapted to the specimen to exert continued strength aimed to break down the specimen
Click here to view |
Before the experimental tests, the brackets bases were subjected to prophylaxis using Robson brush with pumice in a low-speed micromotor. These were washed with jets of air and water for 30 s and then dried with jets of air for the same time.[10]
Test groups
Each experimental group was submitted to one of the following treatments. In Group 1, after the brackets had been stabilized and cleaned, a self-sticking adhesive with a central hole of 3 mm in diameter was applied on the specimen surface so that only the bracket base was exposed [Figure 1]b. For standardization of the application of composite resin on the bracket base, a metallic device and a split Teflon mold were adapted to the PVC cylinder, as shown in [Figure 1]c. This device consists of a metallic structure with a lateral screw and a split Teflon mold, having a central hole with a diameter of 3 mm and 2 mm in height. A commercial composite resin (3M Unitek® -Transbond XT, Monrovia, CA, USA) was then applied to the bracket base and photoactivated by a light-emitting diode (LED) device (SDI® - Radii™, Bayswater, Victoria, Australia) for 40 s with intensity of 400 mW/cm2 , as measured by a radiometer (Gnatus® , Ribeirão Preto, SP, Brazil) for LED devices. All specimens were carefully removed from the Teflon mold and metallic bases. The prepared specimens were stored in distilled water for 24 h at 37°C.[19]
In Groups 2 and 3, the insertion of composite resin proceeded in two stages to simulate a type of bracket failure in which the bonding resin was left at the bracket base. The applied resin composite covered the entire bracket base surface with a uniform thickness of 1 mm.
Specimens were stored in a container with distilled water for 24 h, as proposed by Endo et al.[19] Subsequently, the reconditioning process was preceded as described below:
Group 2: Removal of the composite resin from the bracket base by means of a silicon carbide abrasive flap disc, without hitting the metallic mesh. The bracket base was washed and dried with a jet of air and water using a triple syringe for 30 s. After that, 10% hydrofluoric acid was applied for 60 s, with subsequent washing and drying for 30 s.
Group 3: Reconditioning was made with aluminum oxide blasting with 90 μm particles placed 10 mm away from the bracket base. The blasting pressure was set at 80 psi. After that, the brackets were washed with water and air-sprayed for 30 s and then completely dried.
After the reconditioning stage, the resin composite was applied using a metallic support and Teflon mold, as described for Group 1, for subsequent shear testing.
Shear test
Each specimen was placed individually on a metallic support containing a hole, which had two screws used to adjust the cylinder and keep it still. The assembly composed by the metallic support, and specimen was taken to the Instron universal testing machine (Instron Corp.® , Model 4444, Canton, MA, USA), in which the specimens were loaded using a semicircle-shaped active tip in the region of the bonding interface parallel to the surface of the bracket at a speed of 0.5 mm/min [Figure 1]d. The values were recorded in kilonewtons, and bond strength (megapascal [MPa]) was calculated thereafter.
Statistical analysis
Data were submitted to statistical analysis with the software BioEstat 5.0 (BioEstat® Software, Belém, PA, Brazil). The sample size was calculated considering a 5% alpha error, significant differences between groups of 2.0 MPa, and standard deviation of 2.03 MPa. These values were obtained from a previous study[10] and confirmed with the present investigation. Therefore, with a sample size of 13 specimens, the power of this study was calculated to be 95%. Intergroup values were submitted to a normality test (D'Agostino test). As values were found to have a normal distribution, they were analyzed by one-way analysis of variance (ANOVA test, P < 0.0001) followed by Tukey-Kramer multiple comparison test (P < 0.01) between groups.
| Results | | |
The mean shear strength values and standard deviations for the three experimental groups are shown in [Table 1] and [Figure 2]. The results indicated that Group 1 (new brackets) showed higher bond strength than that obtained for the group treated with hydrofluoric acid (Group 2, P < 0.01). The bond strength value obtained for the group treated with alumina blasting (Group 3) was statistically similar to those obtained for Groups 1 and 2. | Figure 2: Comparison of the values in megapascal of shear strength in different groups *Significance of 5%. Analysis of variance test - ANOVA (one-criteria). Same letters indicate no statistical differences between groups (Tukey's test, P < 0.01)
Click here to view |
 | Table 1: Distribution of values (mean±standard deviation) expressed as megapascal regarding shear strength in different groups
Click here to view |
| Discussion | | |
The shear test performed in this study has been also described by other authors,[1],[21],[22],[23],[24] and the load was applied in the occlusogingival direction since a greater resistance would be expected if this test had been carried out in the mesiodistal direction because of the greater dimension of the bracket. Moreover, the load applied on the occlusogingival direction seems to better simulate the way, these brackets are loaded in the oral cavity.
Several studies[9],[10],[11] have shown that considering the bracket/resin/tooth interrelationship; fracture normally occurs at the bracket/resin interface because the adhesive bonding existing in this area is weak. However, studies investigating bracket reconditioning commonly assess bond strength to the tooth structure.[1],[2],[3],[6],[25] In the present study, the methodology used allowed for the evaluation of the bracket/resin interface. With regard to the bracket reconditioning process, a more critical clinical situation was simulated, for example, permanence of remaining resin on the base of the orthodontic accessory. Hence, the findings reported here in should be interpreted carefully when compared to those of other studies.
The bond strength results found for Group 1 (control) and Group 3 (aluminum oxide blasting) are in the range compatible with clinical use because to withstand the forces exerted by the arch on the tooth during orthodontic treatment, there should be a minimum shear strength varying from 5 to 8 MPa.[4],[26],[27] On the other hand, the brackets that were reconditioned using hydrofluoric acid showed a statistically lower performance than those of other groups. In addition, these etched brackets showed shear strength values below the threshold for a good clinical performance, contradicting the hypothesis of this study. This finding could be explained due to the large amount of remaining resin on the bracket base. When there is a significant amount of resin composite left on the bracket base after debonding (as simulated in the current investigation before reconditioning), there are lower chances of achieving good bond strength results.[28] In addition, the contact time between the hydrofluoric acid and the remaining resin may have been insufficient to cause microretentions in the resin surface.
A number of studies have shown that aluminum oxide blasting is the most effective technique to remove the remaining resin from the bracket base. Accordingly, this surface treatment has been the most indicated technique for reconditioning[12],[13],[14],[15],[16],[17],[18] corroborating the results found in the current study. Quick et al.[13] found shear strength values of 7.28 MPa (±1.58) for brackets reconditioned using this technique. In the present study, a slightly higher shear strength values 8.83 (±1.21) MPa was found.
Techniques that employ abrasive tips or multilaminated drills to remove the remaining resin from the bracket base should be analyzed carefully. Quick et al.[13] did not find good bond strength results for these techniques. In the current investigation, the remaining resin was partially removed by means of a silicon carbide abrasive tip before etching. As a result, a resin layer remained on the bracket mesh with the purpose of preventing its base to be altered by the abrasive tip. Egan et al.[6] proposed that these techniques may have clinical effects on the brackets torque, rotation, and "in/out" parameters. The magnitude of these changes due to the additional resin layer should be evaluated along with the magnitude of natural variation in the structure of the buccal surfaces of the teeth.
In the present study, brackets that underwent reconditioning showed shear strength values lower than those obtained for new brackets, confirming the findings of other studies.[5],[12],[25] Quick et al.[13] had similar results for various reconditioning approaches, but when using aluminum oxide blasting, they observed no significant decrease in shear strength values. Likewise, Montasser et al.[3] observed no difference in the clinical performance of three adhesive systems in reconditioning procedures.
Although hydrofluoric acid has been proven to be effective in repairing composite resin and to prepare indirect restorations,[20],[29],[30] this acid was not effective in the reconditioning of orthodontic brackets. Therefore, its use is not indicated for this purpose at a concentration of 10% for 60 s because it may result in clinical failures for reused orthodontic brackets, as these accessories would not have sufficient strength to withstand masticatory loads and forces applied during orthodontic movements.
Thus, in case of bracket bonding failure, it is recommended as first-choice of clinical protocol to use a new bracket, but if this is not possible, one should consider the reconditioning with aluminum oxide blasting. Further studies are needed to test this technique using different concentrations of hydrofluoric acid as well as different time protocols.
| Conclusions | | |
According to the conditions and shortcomings of this in vitro study, it could be concluded that the aluminum oxide blasting technique was effective for the reconditioning of orthodontic brackets. Nevertheless, the reconditioning technique using 10% hydrofluoric acid for 60 s was not efficient for clinical use.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
| References | | |
| 1. | Bishara SE, Laffoon JF, Vonwald L, Warren JJ. The effect of repeated bonding on the shear bond strength of different orthodontic adhesives. Am J Orthod Dentofacial Orthop 2002;121:521-5.  [ PUBMED] |
| 2. | Eminkahyagil N, Arman A, Cetinsahin A, Karabulut E. Effect of resin-removal methods on enamel and shear bond strength of rebonded brackets. Angle Orthod 2006;76:314-21. |
| 3. | Montasser MA, Drummond JL, Evans CA. Rebonding of orthodontic brackets. Part I, a laboratory and clinical study. Angle Orthod 2008;78:531-6. [ PUBMED] |
| 4. | Wendl B, Muchitsch P, Pichelmayer M, Droschl H, Kern W. Comparative bond strength of new and reconditioned brackets and assessment of residual adhesive by light and electron microscopy. Eur J Orthod 2011;33:288-92. [ PUBMED] |
| 5. | Mui B, Rossouw PE, Kulkarni GV. Optimization of a procedure for rebonding dislodged orthodontic brackets. Angle Orthod 1999;69:276-81. [ PUBMED] |
| 6. | Egan FR, Alexander SA, Cartwright GE. Bond strength of rebonded orthodontic brackets. Am J Orthod Dentofacial Orthop 1996;109:64-70. [ PUBMED] |
| 7. | Romano FL, Correr AB, Correr-Sobrinho L, Magnani MB, Ruellas AC. Clinical evaluation of the failure rates of metallic brackets. J Appl Oral Sci 2012;20:228-34. [ PUBMED] |
| 8. | Kinch AP, Taylor H, Warltier R, Oliver RG, Newcombe RG. A clinical trial comparing the failure rates of directly bonded brackets using etch times of 15 or 60 seconds. Am J Orthod Dentofacial Orthop 1988;94:476-83. [ PUBMED] |
| 9. | Buzzitta VA, Hallgren SE, Powers JM. Bond strength of orthodontic direct-bonding cement-bracket systems as studied in vitro. Am J Orthod 1982;81:87-92. [ PUBMED] |
| 10. | Mondelli AL, Feitas MR. Comparative study of the shear bond strength of the resin/bracket interface, using three different resin composites and three different treatments in the base of the bracket. Rev Dent Press Ortod Ortop Facial 2007;12:11-25. |
| 11. | Pignata LM, Lugato IC, Bertoz FA, Santos EC. Evaluation of Adhesive Remnant Index using conventional mesh bases and sandblasted orthodontic bracket bases and three bonding systems. Rev Dent Press Ortod Ortop Facial 2009;14:117-23. |
| 12. | Basudan AM, Al-Emran SE. The effects of in-office reconditioning on the morphology of slots and bases of stainless steel brackets and on the shear/peel bond strength. J Orthod 2001;28:231-6. [ PUBMED] |
| 13. | Quick AN, Harris AM, Joseph VP. Office reconditioning of stainless steel orthodontic attachments. Eur J Orthod 2005;27:231-6. [ PUBMED] |
| 14. | Ahrari F, Basafa M, Fekrazad R, Mokarram M, Akbari M. The efficacy of Er, Cr: YSGG laser in reconditioning of metallic orthodontic brackets. Photomed Laser Surg 2012;30:41-6. [ PUBMED] |
| 15. | Halwai HK, Kamble RH, Hazarey PV, Gautam V. Evaluation and comparision of the shear bond strength of rebonded orthodontic brackets with air abrasion, flaming, and grinding techniques: An in vitro study. Orthodontics (Chic.) 2012;13:e1-9. |
| 16. | Ishida K, Endo T, Shinkai K, Katoh Y. Shear bond strength of rebonded brackets after removal of adhesives with Er, Cr: YSGG laser. Odontology 2011;99:129-34. [ PUBMED] |
| 17. | Sharma-Sayal K, Rossouw PE, Kulkarni GV, Titley KC. The influence of orthodontic bracket base design on shear bond strength. Am J Orthod Dentofacial Orthop 2003;124:74-82. |
| 18. | Tavares SW, Consani S, Nouer DF, Magnani MB, Nouer PR, Martins LM. Shear bond strength of new and recycled brackets to enamel. Braz Dent J 2006;17:44-8. [ PUBMED] |
| 19. | Endo T, Ozoe R, Shinkai K, Aoyagi M, Kurokawa H, Katoh Y, et al. Shear bond strength of brackets rebonded with a fluoride-releasing and -recharging adhesive system. Angle Orthod 2009;79:564-70. [ PUBMED] |
| 20. | Hori S, Minami H, Minesaki Y, Matsumura H, Tanaka T. Effect of hydrofluoric acid etching on shear bond strength of an indirect resin composite to an adhesive cement. Dent Mater J 2008;27:515-22. [ PUBMED] |
| 21. | Bezerra GL, Torres CR, Tonetto MR, Borges AH, Kuga MC, Bandeca MC, et al. Shear bond strength of orthodontic brackets fixed with remineralizing adhesive systems after simulating one year of orthodontic treatment. ScientificWorldJournal 2015;2015:903451. [ PUBMED] |
| 22. | Menezes-Silva R, Reis LA, Tostes BO, Douglas de Oliveira DW, Santos MH. Bond strength of brackets bonded with chemically and light activated materials after thermal cycling. Adv Mater Phys Chem 2015;5:351-60. |
| 23. | Naidu E, Stawarczyk B, Tawakoli PN, Attin R, Attin T, Wiegand A. Shear bond strength of orthodontic resins after caries infiltrant preconditioning. Angle Orthod 2013;83:306-12. [ PUBMED] |
| 24. | Kanashiro LK, Robles-Ruíz JJ, Ciamponi AL, Medeiros IS, Dominguez GC, de Fantini SM. Effect of adhesion boosters on indirect bracket bonding. Angle Orthod 2014;84:171-6. |
| 25. | Regan D, van Noort R, O′Keeffe C. The effects of recycling on the tensile bond strength of new and clinically used stainless steel orthodontic brackets: An in vitro study. Br J Orthod 1990;17:137-45. [ PUBMED] |
| 26. | Abe R, Endo T, Shimooka S. Effects of tooth bleaching on shear bond strength of brackets rebonded with a self-etching adhesive system. Odontology 2011;99:83-7. [ PUBMED] |
| 27. | Reynolds IR, von Fraunhofer JA. Direct bonding in orthodontics: A comparison of attachments. Br J Orthod 1977;4:65-9. [ PUBMED] |
| 28. | Eslamian L, Borzabadi-Farahani A, Tavakol P, Tavakol A, Amini N, Lynch E. Effect of multiple debonding sequences on shear bond strength of new stainless steel brackets. J Orthod Sci 2015;4:37-41. [ PUBMED] |
| 29. | Sobreira FM, Acevedo CR, Freitas Filho LH, Vidal AP, Barros LF, Ferreira MP. Methods of repair in composed resin: A revision. Odontol Clín Cient 2008;7:123-8. |
| 30. | Yamamoto ET, Souza AC, Cunha LA, Gallo FT, Pagani C. Evaluation of three methods of surface treatment in an indirect composite resin. Odontol Clín Cient 2009;8:331-5. |
Correspondence Address:
Prof. Luiz Renato Paranhos
Department of Dentistry, Federal University of Sergipe, Lagarto, SE
Brazil
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/0970-9290.191886
[Figure 1], [Figure 2]
[Table 1] |
|
| This article has been cited by | | 1 |
Comparison of shear bond strength of orthodontic brackets bonded to human teeth with and without fluorotic enamel: A systematic review and meta-analysis of experimental in vitro studies |
|
| Daniela Alvarez, Abdul Basir Barmak, Paul Emile Rossouw, Dimitrios Michelogiannakis | | Orthodontics & Craniofacial Research. 2022; | | [Pubmed] | [DOI] | | | 2 |
Aspects and Principles of Material Connections in Restorative Dentistry—A Comprehensive Review |
|
| Zbigniew Raszewski, Dariusz Brzakalski, Lukasz Derpenski, Marek Jalbrzykowski, Robert E. Przekop | | Materials. 2022; 15(20): 7131 | | [Pubmed] | [DOI] | |
|
|
|
|
|
|
|
|
|
|
|
|
| Article Access Statistics | | | Viewed | 7640 | | | Printed | 514 | | | Emailed | 0 | | | PDF Downloaded | 79 | | | Comments | [Add] | | | Cited by others | 2 | | |
|
|
Users online:
