Quantitative and qualitative assessment of enamel surface following two composite removal methods after bracket debonding Kundal S, Walia PS, Shokeen T, Bansal A, Janmeda DS,

ORIGINAL ARTICLE

Ahead of print publication

Quantitative and qualitative assessment of enamel surface following two composite removal methods after bracket debonding

Sunegha Kundal¹, Pawanjit Singh Walia², Tulika Shokeen², Anubhav Bansal², Dushyant Singh Janmeda³
¹ Department of Orthodontics and Dentofacial Orthopedics, KD Dental College and Hospital, Mathura, Uttar Pradesh, India
² Private Practice, New Delhi, India
³ Department of Oral and Maxillofacial Surgery, KD Dental College and Hospital, Mathura, Uttar Pradesh, India

Date of Submission	04-Jan-2022
Date of Decision	02-May-2022
Date of Acceptance	30-May-2022
Date of Web Publication	25-Feb-2023

Correspondence Address:
Sunegha Kundal,
Assistant Professor, Department of Orthodontics, K D Dental College and Hospital, Mathura, Uttar Pradesh
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijds.ijds_1_22

Abstract

Aims: To evaluate and compare morphology and roughness of the enamel surface after debonding and polishing by two methods: aluminum oxide disks (Shofu, Super-Snap) and 30-fluted tungsten carbide bur (Strauss and Co.) using a surface roughness tester and a scanning electron microscope (SEM), respectively. Subjects and Methods: For this study, we selected 15 orthodontic patients with bonded metal brackets. After the completion of fixed orthodontic treatment, metal brackets for the maxillary central incisors were removed with a debonding plier. For every patient, teeth were chosen on a random basis to be finished and polished with Super-Snap aluminum oxide disks on one side (n = 15) and with 30-fluted tungsten carbide bur (n = 15) on the other side. Epoxy resin was used to obtain the replicas of maxillary anterior teeth (before and after tooth polishing). SEM analysis was done for five samples from each group. Results: The average roughness after resin removal in the 30-fluted tungsten carbide bur group (0.328 μm ± 0.099) was found to be significantly higher when compared to the Super-Snap aluminum oxide disks (0.299 μm ± 0.109). Conclusions: The Super-Snap aluminum oxide disks resulted in superior finishing and polishing than 30-fluted tungsten carbide bur.

Keywords: Composite removal, debonding, enamel, esthetics, finishing and polishing, orthodontic treatment

How to cite this URL:
Kundal S, Walia PS, Shokeen T, Bansal A, Janmeda DS. Quantitative and qualitative assessment of enamel surface following two composite removal methods after bracket debonding. Indian J Dent Sci [Epub ahead of print] [cited 2023 Sep 30]. Available from: http://www.ijds.in/preprintarticle.asp?id=370599

Introduction

The origination of etch and bond technique for directly bonding the brackets to the tooth surface has revolutionized the orthodontic practice.^[1] At the completion of fixed orthodontic therapy, we are required to remove the brackets and remaining adhesive from the surface of each tooth. Inappropriate finishing and polishing after debonding will certainly result in iatrogenic enamel damage,^[1],[2] increased accumulation of plaque, gingival irritation, and excessive staining of the enamel.^[1],[3]

A multitude of steps are required to return the enamel surface to its original form after orthodontic treatment is completed and the final step involves debonding and removal of all the adhesive from the teeth with subsequent polishing.^[4-6] Various methods have been tested by the researchers for both adhesive removal and polishing to preempt iatrogenic damage to the tooth surface.

Some dentists prefer using the conventional diamond-coated burs for removing the resin fragments from the tooth surface. However, because of the coarse nature of these burs, they tend to leave scratches on the enamel. To avoid such consequences, several devices have been introduced till date for finishing and polishing of the tooth surface.^{[1],[4],[5],[7],[8],[9],[10]} As per the reports, most effective among all is 30-fluted tungsten carbide bur used with a contra-angled handpiece and it is also seen to be the least time-consuming.^{[4],[5],[7],[8]} Other commonly used devices are the abrasive disks.^[4-6] Maximum of these disks being layered with aluminum oxide abrasive are said to provide the best polish.^[1],[3]

Scanning electron microscope (SEM) turned out to be the only method used for assessing the enamel surface morphology for the effectiveness of rotary instruments.^[2],[11] Since such tests are only subjective and using them alone for evaluating the reliability of the cleaning process does not provide quantitative results, other techniques such as surface profilometry emerged as an essential for the assessment of surface roughness.^{[1],[11],[12]}

The prime concern of patients opting for orthodontic treatment is esthetics; thus, it becomes vital for an orthodontist to restore the labial surfaces of the dentition to their original pretreatment form and luster. This is impossible to achieve if the surfaces of the teeth are left rough and unpolished after debonding of brackets.^[5],[13]

Quantitative information relevant to enamel damage after bracket debonding in vivo is limited.^{[9],[14],[15]} Not many studies have been carried out to assess the surface roughness of maxillary central incisors.^[5],[16]

Hence, the objective of our study was to evaluate the bond failure site with adhesive remnant index (ARI) and compare the enamel morphology and roughness following debonding and subsequent polishing by two methods: Super-Snap aluminum oxide disks and 30-fluted tungsten carbide bur using the SEM and surface roughness tester, respectively.

Subjects and Methods

The research plan [Figure 1] was presented to the review board of the institution and ethical approval was taken for carrying out the study. Prior to the selection and involvement of the patients into the study, informed consent was obtained from all. We selected 15 patients who were finishing their fixed orthodontic treatment. The criteria for patient selection included no restorations, caries, bruxism, history of trauma, or fracture lines on the maxillary incisor teeth.

Figure 1: Settings and design of the study

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The standard protocol followed for bonding in the department is explained as follows:

First, cleaning and polishing of the teeth is done using pumice slurry with rubber polishing cups at lower rpm for a duration of 10 s
Rinsing under water and drying with an oil-free air and water spray for 30 s
Etching the middle third portion of the labial surface of each tooth with 37% phosphoric acid (DeTrey, Conditioner 36) for 30 s
Thorough rinsing with air–water spray for 30 s and drying with compressed air
Application of a thin layer of bonding agent (Ormco Ortho Solo-Universal Bond Enhancer)
Adhesive (ENLIGHT Light Cure) is dispensed onto mesh of the stainless steel standard maxillary incisor brackets (0.022” MBT prescription bracket-Ormco, Glendora, California)
Brackets are positioned and firmly bonded to the teeth
Excess adhesive is removed using a sharp explorer
Curing with a light-emitting diode device (SDI Radii, Light intensity-1200–1400 mW/cm²) was used for a total of 40 s (10 s on each side) to polymerize the adhesive completely.

Our study data were fed into the Microsoft Excel 2007 worksheet and evaluated by means of SPSS statistical software 19.0 version. The descriptive statistics included mean and standard deviation. We used paired t-test for the intragroup comparison and Chi-square analysis was used for comparing the intergroup frequencies. The significance level was taken to be 5% and power was kept at 80%. Probabilities < 0.05 (P < 0.05) were considered statistically significant.

Sample Size:

Zα = Level of significance = 5%

Z_1-β = Power of the study = 80%

SD = Standard deviation = 1

d = Effect size = 0.8

From the above formula, it was calculated that minimum sample size required was 12 per group. Therefore, sample size in the study was fixed at 15 per group.

After completion of the treatment, a debonding plier (CAT DB Bracket Remover, Straight) was used to debond the brackets. This was followed by prophylaxis done with pumice and rubber cup at a lower rpm. Subsequently, the teeth were washed, dried, and impression was made with Aquasil Soft Putty/Regular Set (DENTSPLY Caulk) and relined with Aquasil Ultra XLV (DENTSPLY Caulk) using a 2-step impression technique. The molds were cast with epoxy resin (Die Epoxy Type 8000 Resin, American Dental Supply, Inc.).

The examination of epoxy replicas of the debonded teeth (with adhesive remnants) for ARI was done under a stereomicroscope (SALL 1539, Spectro Lab Equipment, India) at a magnification of ×20 using the modified ARI score by Bishara and Trulove.^[17]

Scores for modified adhesive index are as follows:

Score 1 “The entire composite, with an impression of the bracket base remained on the tooth.”

Score 2 “More than 90% of the composite remained on the tooth.”

Score 3 “More than 10% but <90% of the composite remained on the tooth.”

Score 4 “<10% of composite remained on the tooth.”

Score 5 “No composite remained on the tooth.”

For every patient, one-side maxillary central incisor was selected randomly for finishing and polishing with the multistep aluminum oxide disks (Shofu, Super-Snap Kit, Kyoto, Japan) and the other one was finished with one-step 30-fluted tungsten carbide bur (Strauss and Co.). For the disks, we used 4 disks sequentially in the order of decreasing abrasiveness at slow speed (10,000 rpm) with periodic cooling, for 20 s each and bur, on the other hand, was used at a high rpm with water cooling, achieving a clinically smooth and polished tooth surface. Following the finishing procedure, epoxy replicas of the polished teeth were made with the abovementioned procedure.

For the measurement of surface roughness, we tested four sets of epoxy replicas:

Group 1: Aluminum oxide disks – (1a) untouched enamel and (1b) after finishing and polishing
Group 2: 30-fluted tungsten carbide bur – (2a) untouched enamel and (2b) after finishing and polishing.

The measurements of enamel surface roughness were done using the surface roughness tester (Mitutoyo-SJ-210) at a speed of 0.25 mm/s, 2.5 mm length, and 0.25 mm cutoff. We took three measurements all in different directions and mean average roughness (R_a) value was determined for each specimen.

SEM evaluation was done for five samples from each group. Photomicrographs of the representative extents of the replica surfaces were captured at a magnification of ×500.

Results

The statistical analysis of the measurements showed the following results. [Table 1] depicts the results for the ARI scores. For both the groups, majority of the samples depicted a score of 1.

Table 1: Frequency distribution and percentage of adhesive remnant index scores

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[Table 2] depicts the measurements for the surface roughness test (power of statistical test, 80%). The resulting values showed a higher roughness of 0.328 μm for the carbide bur group as compared to 0.299 μm for the aluminum oxide disk group, after resin removal (P < 0.001).

Table 2: Surface roughness (μm) after resin removal

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The surface roughness of aluminum oxide disks for untouched enamel (Group 1a) and after resin removal (Group 1b) was 0.389 ± 0.102 μm and 0.299 ± 0.109 μm, respectively. Similarly, the surface roughness of 30-fluted tungsten carbide bur for untouched enamel (Group 2a) and after resin removal (Group 2b) was 0.363 ± 0.100 μm and 0.328 ± 0.099 μm, respectively [Table 3]. The results of paired t-test revealed that the intragroup comparison of surface roughness after resin removal in both aluminum oxide and carbide bur group was significantly lesser (P < 0.05).

Table 3: Intragroup comparison of surface roughness (μm) before and after resin removal

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Figure 2a-c exhibits the results of SEM examination done under a magnification of × 500 for the tooth surfaces in each of the three groups. Figure 2a depicts the micrograph of the untouched enamel before the resin was removed. Grooves can be seen which were possibly because of the pumice used for prophylaxis. Figure 2b depicts the micrograph of the tooth surface for which the aluminum oxide disks were used for polishing and the grooves seen were nearly negligible. Figure 2c depicts the micrograph of the tooth which was finished with carbide bur exhibiting comparatively more grooves than the aluminum oxide disks and less than the areas of untouched enamel.

Discussion

Evaluation of dental esthetics is primarily reliant on the maxillary central incisor teeth.^[18-20] In this study, we used epoxy replicas of the teeth to evaluate surface roughness of enamel, both pre- and postpolishing of the teeth with different procedures. Since the availability of extracted anterior teeth is limited and it is not always feasible to reproduce the original physical, biologic, chemical, and mechanical conditions of the oral environment with the extracted teeth, the decision of using the dental epoxy replicas was justified.^[5]

When debonding the brackets, the aim is to make fracture at the enamel–adhesive–bracket interface. For our study, we used debonding pliers for the removal of brackets exerting a pulling force as suggested by Fan et al.^[21] Using the debonding pliers for debonding allows the bond to break at either the bracket–adhesive junction or within the adhesive, and breakage at these sites has proven to be beneficial as breakage at enamel–adhesive interface might lead to the fracture of enamel when debonding.

Bishara and Trulove^[17] modified the ARI and gave a system to locate the fracture site. In this study, the result of the ARI came out to be Score 1 for majority of the samples, which indicates that almost all the adhesive was left onto the tooth surface with a definite imprint of the bracket base mesh. Since the ARI was comparable for the two groups, it did not affect the measurements of surface roughness between the groups after tooth surface polishing. The results were comparable to an earlier study done by Faria-Júnior et al.^[5]

As of today, majority of the researches involving the assessment of enamel surface are using SEM as the mode of evaluation, which provides qualitative data only.^[22-24] Since SEM results do not provide any quantitative information regarding the surface roughness, the evaluation is entirely subjective. For quantitative analysis, other techniques such as surface profilometry have proven to give more precise comparative evaluations of various cleanup procedures. Therefore, we used a surface roughness tester to obtain quantitative data in this study.

Tooth enamel, if left rough, will lead to the accumulation of bacterial plaque, decreasing the pH and subsequently resulting in dissolution of hard mineralized tissue which will eventually advance to the formation of carious lesions.^[15],[21] Therefore, smoothening and polishing of the enamel surface is vital, for esthetic motives and for preventing demineralization. The ultimate aim of cleanup procedure is the restoration of original smoothness and luster of the tooth surface after debonding of brackets. In our study, the surface roughness values of aluminum oxide disks obtained after finishing (Group 1b) (0.299 ± 0.109 μm) were lesser as compared to those of the untouched enamel (Group 1a) (0.389 ± 0.102 μm). Thus, the results suggest that the aluminum oxide disks may enhance the brightness of enamel as suggested by Segura et al.^[25]

Disks have been widely used for polishing the enamel surface and providing the highest polish after residual resin removal.^[1] Sequential use of Super-Snap multistep system is necessary, where we start with the coarse grit initially and progressively move to the superfine grit.^[14] The mean value of surface roughness after resin removal for aluminum oxide disks group (0.299 ± 0.109 μm) was less than that for the carbide bur group (0.328 ± 0.099 μm), indicating that the Super-Snap® disks resulted in a polished and even surface of the enamel. This was in accordance with a study done by Ulusoy,^[1] in which the Super-Snap® disks produced the smoother surface as compared to TCB.

The most commonly used TCBs have 8–30 flutes,^[4],[12] and among these, it has been suggested that those with 12 and 30 flutes are comparatively milder to be used on the tooth surface. Zarrinnia et al.^[9] found that for efficient removal of the residual resin, the TCBs are to be used at high speed. Zachrisson and Artun^[26] recommended using TCBs at slow speed. Campbell^[4] and Rouleau et al. (1982)^[7] suggested that TCBs should be worked at higher rpm besides concurrent water cooling, whereas air cooling was recommended by Retief and Denys.^[27] For our study, we preferred using water cooling over air cooling to prevent the rise of intrapulpal temperature. The use of 30-fluted TCBs has proven to be the most effective procedure for the removal of residual resin following debonding procedure as reported by Campbell.^[4]

In our study, the roughness results attained after finishing with carbide bur (Group 2b) (0.328 ± 0.099 μm) were lesser than those of the untouched enamel (Group 2a) (0.363 ± 0.100 μm). The independent t-test revealed a statistically nonsignificant (P > 0.05) difference between the surface roughness of untouched enamel of two groups (Group 1a and 2a) and a statistically significant (P < 0.05) difference between the two groups after resin removal (Group 1b and Group 2b). The results of surface roughness for the samples cleaned and polished with aluminum oxide disks (0.299 ± 0.102 μm) were significantly lower than the values obtained with carbide bur (0.328 ± 0.099 μm). Thus, polishing with aluminum oxide disks showed better results than the carbide bur group.

For our study, we used SEM images for better appreciation of the changes occurring in the surface of enamel after removing adhesive using different methods. SEM of the tooth surface polished with the aluminum oxide disks revealed the least grooves when compared with those finished with the tungsten carbide burs and untouched enamel.

Summary and Conclusions

The following conclusions were drawn from the data and results of our research:

The ARI results showed that the most of the resin was found remaining on the tooth surface after bracket removal in both the groups
The use of multistep aluminum oxide disks methods for finishing and polishing left the enamel surface much smoother as compared to the single-step bur method
The areas polished by aluminum oxide disks and carbide bur system showed significantly reduced surface roughness as compared with untouched enamel
No seemingly obvious groves were evident in the enamel surface finished by the aluminum oxide disks.

These findings suggest that aluminum oxide disks (Shofu, Super-Snap Kit) were comparatively more efficient than 30-fluted tungsten carbide bur for obtaining a smooth and polished surface of enamel. We suggest that further research needs to be done using with additional investigations for assessing the retention of biofilm and enamel brightness to clinically validate our results.

Ethical clearance

Institutional review board of PDM Dental College and Research Institute.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1.	Ulusoy C. Comparison of finishing and polishing systems for residual resin removal after debonding. J Appl Oral Sci 2009;17:209-15.
2.	Eliades T, Gioka C, Eliades G, Makou M. Enamel surface roughness following debonding using two resin grinding methods. Eur J Orthod 2004;26:333-8.
3.	Uçtaşli MB, Arisu HD, Omürlü H, Eligüzeloğlu E, Ozcan S, Ergun G. The effect of different finishing and polishing systems on the surface roughness of different composite restorative materials. J Contemp Dent Pract 2007;8:89-96.
4.	Campbell PM. Enamel surfaces after orthodontic bracket debonding. Angle Orthod 1995;65:103-10.
5.	Faria-Júnior ÉM, Guiraldo RD, Berger SB, Correr AB, Correr-Sobrinho L, Contreras EF, et al. In-vivo evaluation of the surface roughness and morphology of enamel after bracket removal and polishing by different techniques. Am J Orthod Dentofacial Orthop 2015;147:324-9.
6.	Karan S, Kircelli BH, Tasdelen B. Enamel surface roughness after debonding. Angle Orthod 2010;80:1081-8.
7.	Rouleau BD Jr., Marshall GW Jr., Cooley RO. Enamel surface evaluations after clinical treatment and removal of orthodontic brackets. Am J Orthod 1982;81:423-6.
8.	Brauchli LM, Baumgartner EM, Ball J, Wichelhaus A. Roughness of enamel surfaces after different bonding and debonding procedures: An in vitro study. J Orofac Orthop 2011;72:61-7.
9.	Zarrinnia K, Eid NM, Kehoe MJ. The effect of different debonding techniques on the enamel surface: An in vitro qualitative study. Am J Orthod Dentofacial Orthop 1995;108:284-93.
10.	Vieira AC, Pinto RA, Chevitarese O, Almeida MA. Polishing after debracketing: Its influence upon enamel surface. J Clin Pediatr Dent 1993;18:7-11.
11.	Goel A, Singh A, Gupta T, Gambhir RS. Evaluation of surface roughness of enamel after various bonding and clean-up procedures on enamel bonded with three different bonding agents: An in-vitro study. J Clin Exp Dent 2017;9:608-16.
12.	Sharma S, Cross SE, Hsueh C, Wali RP, Stieg AZ, Gimzewski JK. Nanocharacterization in dentistry. Int J Mol Sci 2010;11:2523-45.
13.	Hasanreisoglu U, Berksun S, Aras K, Arslan I. An analysis of maxillary anterior teeth: facial and dental proportions. J Prosthet Dent 2005;94:530-8.
14.	Eminkahyagil N, Arman A, Cetinşahin A, Karabulut E. Effect of resin-removal methods on enamel and shear bond strength of rebonded brackets. Angle Orthod 2006;76:314-21.
15.	Pont HB, Özcan M, Bagis B, Ren Y. Loss of surface enamel after bracket debonding: An in-vivo and ex-vivo evaluation. Am J Orthod Dentofacial Orthop 2010;138:387.e1- 387.e9.
16.	Ferreira FG, Nouer DF, Silva NP, Garbui IU, Correr-Sobrinho L, Nouer PR. Qualitative and quantitative evaluation of human dental enamel after bracket debonding: A noncontact three-dimensional optical profilometry analysis. Clin Oral Investig 2014;18:1853-64.
17.	Bishara SE, Trulove TS. Comparisons of different debonding techniques for ceramic brackets: An in vitro study. Part I. Background and methods. Am J Orthod Dentofacial Orthop 1990;98:145-53.
18.	Lombardi RE. The principles of visual perception and their clinical application to denture esthetics. J Prosthet Dent 1973;29:358-82.
19.	Rosenstiel SF, Ward DH, Rashid RG. Dentists' preferences of anterior tooth proportion – A web-based study. J Prosthodont 2000;9:123-36.
20.	Wolfart S, Quaas AC, Freitag S, Kropp P, Gerber WD, Kern M. Subjective and objective perception of upper incisors. J Oral Rehabil 2006;33:489-95.
21.	Fan XC, Chen L, Huang XF. Effect of various debonding and adhesive clearance methods on enamel surface: An in-vitro study. BMC Oral Health 2017;17:58.
22.	Arman A, Cehreli SB, Ozel E, Arhun N, Cetinşahin A, Soyman M. Qualitative and quantitative evaluation of enamel after various stripping methods. Am J Orthod Dentofacial Orthop 2006;130: 14.e7-14.
23.	Joseph VP, Rossouw PE, Basson NJ. Orthodontic microabrasive reproximation. Am J Orthod Dentofacial Orthop 1992;102:351-9.
24.	Radlanski RJ, Jäger A, Schwestka R, Bertzbach F. Plaque accumulations caused by interdental stripping. Am J Orthod Dentofacial Orthop 1988;94:416-20.
25.	Segura A, Donly KJ, Wefel JS, Drake D. Effect of enamel microabrasion on bacterial colonization. Am J Dent 1997;10:272-4.
26.	Zachrisson BU, Arthun J. Enamel surface appearance after various debonding techniques. Am J Orthod 1979;75:121-7.
27.	Retief DH, Denys FR. Finishing of enamel surfaces after debonding of orthodontic attachments. Angle Orthod 1979;49:1-10.