|Year : 2016 | Volume
| Issue : 3 | Page : 88-93
Evaluation of enamel surface after orthodontic debonding and cleanup using different procedures: An in vitro study
Harjoy Khatria1, Rajat Mangla1, Hemant Garg1, Ramandeep Singh Gambhir2
1 Department of Orthodontics, MM College of Dental Sciences and Research, Mullana, Ambala, Haryana, India
2 Department of Public Health Dentistry, Rayat and Bahra Dental College and Hospital, Mohali, Punjab, India
|Date of Web Publication||28-Nov-2016|
Ramandeep Singh Gambhir
Department of Public Health Dentistry, Rayat and Bahra Dental College and Hospital, Mohali, Punjab
Source of Support: None, Conflict of Interest: None
Objectives: The purpose of this in vitro study was to evaluate and compare the efficiency of four protocols of adhesive remnant removal and polishing after bracket debonding on enamel surfaces using scanning electron microscope (SEM) and to compare the time spent to remove resin remnants. Materials and Methods: The present study was a comparative study, in which brackets were bonded on forty freshly extracted human premolar teeth. They were debonded after 24 h and removal of remnant adhesive to as close as possible to the original condition using tungsten carbide burs (TCBs) (30 flutted) with low-speed contra-angle handpiece, Super Snap ® discs (course, medium, fine, and superfine), TCB + Brownie and Greenie (BG) polishers, and TCB + Super Snap ® discs. The surfaces were evaluated under SEM and graded according to the modified surface roughness index. Time taken to remove the residual adhesive was recorded using a stopwatch. Results were subjected to statistical analysis. Results: Super Snap ® discs showed a smooth surface with minimal scratches. TCB resulted in an irregular enamel surface in SEM evaluation, showing horizontal scars with a consistent pattern and left remnants on the enamel surfaces. TCB followed by Super Snap ® discs produced some scratches on the enamel surface. The mean time was significantly higher in Group I than the other three groups (P = 0.000). The mean time was significantly lower in Group II than the other three groups (P = 0.000). TCB took the least amount of time followed by TCB + stainless steel and TCB + BG polishers. Conclusion: Enamel surface was restored as close to the original using the Super Snap ® discs. TCB produced a very rough surface, but it is an efficient and least time-consuming procedure. The resultant enamel surface with enamel scars needs to be finished by other polishing techniques after bulk removal using TCB as the sequential use of Super Snap ® discs and polishers is less aggressive in removing residual bonding resin and results in apparently better surface finish causing less damage to the enamel.
Keywords: Adhesive, bonding, enamel, surface roughness, time
|How to cite this article:|
Khatria H, Mangla R, Garg H, Gambhir RS. Evaluation of enamel surface after orthodontic debonding and cleanup using different procedures: An in vitro study. J Dent Res Rev 2016;3:88-93
|How to cite this URL:|
Khatria H, Mangla R, Garg H, Gambhir RS. Evaluation of enamel surface after orthodontic debonding and cleanup using different procedures: An in vitro study. J Dent Res Rev [serial online] 2016 [cited 2019 Jul 18];3:88-93. Available from: http://www.jdrr.org/text.asp?2016/3/3/88/194832
| Introduction|| |
Debonding is a process of removal of orthodontic attachments along with all the residual adhesives from the enamel surfaces after completion of the treatment. The goal of the orthodontists should be to restore the enamel surface as closely as possible to its pretreatment condition without inducing iatrogenic damage and with minimal enamel loss.  The presence of remnant resin facilitates plaque buildup, possibly leading to the formation of decalcified areas and carious lesions.  Residual adhesive on the enamel surface after debonding can be removed in various ways, including hand instruments (pliers and scalers), various burs, Sof-Lex™ discs, ultrasonic devices, air abrasion units, and lasers, but studies have shown that some recommended modalities damage the enamel surfaces. ,
Tungsten carbide burs (TCBs) have been used as a gold standard for residual resin removal. They have been used as a fast and efficient method of removing the residual adhesive.  TCBs are used at both high (>20,000 rpm) and low (about 2000 rpm) speeds. Some authors preferred TCBs at high speed  while others were of the opinion that TCBs at low speed were most effective in the removal of residual resin. , Aluminum oxide discs including Sof Lex and Super Snap ® discs have been frequently used to remove the residual resin and to provide the highest polish after debonding orthodontic brackets.  However, metal traces along with the increased number of scratches and gouging due to metal centers of mandrel have been observed. ,
Final polishing is important to minimize enamel damage produced during debonding and adhesive remnant removal. , Different polishers such as silicon carbide, silicon dioxide, and diamond particles can be used. Silicon carbide impregnated with one-step OptiShine brush is used, but cause severe roughness with the islets of residual resin remnants on the enamel surface.  Polishing systems (PoGo) with good composite polishing properties leave a lustrous surface. Brownie silicone polisher with grit 35-48 μm and Greenie silicone polisher with grit 6 μm are good polishing instruments.  Visualization of dental structures at the submicron and nanometer levels is essential for understanding the complex surface topography.  The effectiveness of various methods and instruments on the topography and morphology of the tooth surfaces is best examined under scanning electron microscope (SEM).
Thus, in this in vitro study, we aim to evaluate and compare the efficiency of different methods of remnant adhesive removal (including TCB, Super Snap ® discs, Brownie and Greenie (BG) silicon polishers, and their combination) on enamel surface after bracket debonding and also the time spent for the same.
| Materials and Methods|| |
Before the start of the study, ethical approval was sought from the Institutional Review Board for conducting the study. Informed consent was obtained from all the patients before their final recruitment into the study. The present study is a comparative study, in which the method of analysis used is the SEM. The SEM evaluation of an enamel surface is an excellent tool to demonstrate the surface topography.
The sample consisted of forty freshly extracted human premolar teeth which were collected from patients undergoing extractions for the purpose of orthodontic treatment in the Department of Orthodontics and Dentofacial Orthopedics. They were cleaned from any soft tissue remnants using slurry with a brush. Sample size was calculated on the basis of the following formula.
n = 2 (Za + Z1− β) 2σ2, Δ2, where n is the required sample size.
The samples were stored at room temperature for 2 weeks in distilled water containing 0.1% thymol crystals to inhibit bacterial growth. Teeth were selected on the basis of visual observation of the solidity of buccal surfaces and with no hypoplasia of enamel.
A point was marked below the cementoenamel junction. The roots of the teeth were removed below this point by sectioning them using abrasive discs with a straight handpiece. Crowns were embedded in self-cure acrylic resin, with the buccal surface of crown oriented horizontally and about 2 mm above acrylic block. The acrylic blocks were made cubicle. The acrylic blocks were stored in distilled water at room temperature during the study to prevent dehydration. The exposed tooth surface was rinsed with distilled water and air-dried.
Application of adhesive material and bracket cementation
Marking for the attachment of premolar bracket was done on the buccal surface of the tooth by measuring half of the distance mesiodistally as well as occlusogingivally. The buccal enamel of the teeth was etched with 37% orthophosphoric acid (3M ESPE) for 30 s by placing the gel over the area of intended bracket placement. After 15 s, the etchant was removed by rinsing with water for 10 s and air-dried with oil-free compressed air. The buccal surface showed a frosted appearance with assured proper etching. A premolar metal orthodontic MBT bracket (Gemini Twin brackets, 3M Unitek) with 0.022-inch slot was used. Moisture-insensitive primer was brushed onto the mesh of the bracket and cured with a LED-curing light (Gnatus LD Max). Primer was also applied on the tooth surface that was previously etched. Adhesive paste (Transbond XT, 3M Unitek) was applied on the bracket base which was centered on the crown of the tooth mesiodistally on the previously made mark and along the long axis of the tooth. The excess flash was removed with an explorer and was the cured with the LED-curing unit. It was cured from mesial and distal bracket edges for 20 s each. The specimens were kept in distilled water at 37°C for 24 h to allow polymerization of resin.
Debonding of brackets
Brackets were removed using a straight debonding plier by placing the stainless steel blades of the plier in the bracket/adhesive interface, and a traction movement was performed. The brackets were removed, leaving most of the residual adhesive on the enamel surface. The teeth were randomly divided into four groups of ten teeth each and marked on the under surface of mounting for differentiation. The residual adhesive was removed using different methods.
Group 1 (n = 10): 30-fluted TCB with low-speed (2000 rpm) contra-angle handpiece was used in a brush stroke.
Group 2 (n = 10): Aluminum oxide abrasive Super Snap ® discs by Shofu Dental Corp, Kyoto, Japan, with a low-speed (2000 rpm) handpiece was used in a sequence of course, medium, fine, and superfine discs.
Group 3 (n = 10): A combination of 30-fluted TCB followed by a sequence of Super Snap ® discs was used with a low-speed (2000 rpm) hand piece.
Group 4 (n = 10): A combination of 30-fluted TCB followed by BG silicone polisher by Shofu Dental Corp, Kyoto, Japan, was used with a low-speed (2000 rpm) hand piece.
The removal of the remnant adhesive was considered complete when the tooth surface seemed smooth and free of composite to the naked eye under the light of an operative lamp. After the use of each disc, the tooth surfaces were rinsed and dried before proceeding to the next grit. A dry field was maintained for the use of each grit disc. The time taken to clean up the remnant adhesive from the tooth surface was recorded in seconds with the help of a digital stopwatch. The specimens were mounted on aluminum stubs and sputter coated with 15-20 nm of gold-palladium mixture using a JEOL JFC-1600 Auto Fine Coater. The SEM (JSM 6510 LV, JEOL) was used with an accelerating speed of 10 kV. Each image was magnified in ×200. The surfaces were evaluated under SEM and graded according to the modified surface roughness index originally proposed by Howell and Weekes in the form of grades and modified by Hong and Lew [Table 1]. 
The data obtained were subjected to statistical analysis which was performed using SPSS (Statistical Package for Social Science) software version 16.0 for Windows (Chicago, IL, USA). One-way analysis of variance, Chi-square test, Kruskal-Wallis test, and Dunnett test were used for statistical analysis to compare the enamel surface roughness of teeth and the time spent for cleanup of residual resin.
| Results|| |
The photographs obtained under the SEM were graded according to the surface roughness that appeared in all the samples [Figure 1], [Figure 2], [Figure 3] and [Figure 4].
|Figure 1: Score 1 under scanning electron microscope showing acceptable surface, fine scattered scratches|
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|Figure 2: Score 2 under scanning electron microscope showing mildly rough surface, denser fine scratches with some coarser scratches|
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|Figure 3: Score 3 under scanning electron microscope showing rough surface, numerous course scratches over the entire surface|
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|Figure 4: Score 4 under scanning electron microscope showing very rough, deep, very coarse scratches over the entire surface|
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In Group I (Super Snap ® discs), seven samples (70%) had score 1 and three (30%) samples had score 2. In Group II (TCB), four samples (40%) had score 3 and six samples (60%) had score 4. In Group III (TCB + BG silicon polishers), six samples (60%) had score 2 and four samples (40%) had score 3. In Group IV (TCB + Super Snap ® discs), two samples (20%) had score 1 and eight samples (80%) had score 2 [Figure 5].
The median and range for all the groups when plotted on a graph [Graph 1] show that the median score for Group I is lowest at 1 and highest for Group II at 4. The median for Group III and IV is 2. When the time spent for finishing in all the groups was compared, the mean time was lowest for Group II (68.2 s) and highest for Group I (198 s). The minimum time spent was in Group II (62 s) and maximum in Group I (206 s). The range, median, upper boundary, and lower boundary of time taken to clean up for all showed that Group II took the least and Group I took the most amount of time [Table 2].
According to Dunnett T3 test, when the time spent for finishing in groups was compared to each other, there was a significant difference in the mean values of most of the groups. The mean time was significantly higher in Group I than the other three groups (P = 0.000). The mean time was significantly lower in Group II than the other three groups (P = 0.000). The mean times in Group III and Group IV were significantly lower in Group I (P = 0.000) and significantly higher in Group II (P = 0.000). There was no significant difference between the mean time in Group III and Group IV [Table 3].
|Table 3: Intergroup comparison of time spent for finishing in each group|
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| Discussion|| |
Correct bonding and debonding techniques are of fundamental importance. There are several factors involved in this procedure, the most important of which are the type of adhesive used, the instruments used for bracket removal, and the armamentarium for resin removal. 
Some authors found the results of intra-oral sand blasting of debonding to be similar to those with a low-speed handpiece, but it is a highly complex procedure.  Others found that the erbium-doped yttrium-aluminum-garnet laser performed significantly better than the conventional technique in removing composite remnants after the debonding of orthodontic brackets, but it produced a significantly higher amount of enamel loss compared to that observed in the tungsten carbide bur group. 
TCB has been the most recommended instrument for the removal of adhesive remnant, both at low and high speed. ,,, The group using TCB showed that most of the samples had a score of 4 and some had a score of 3, which means that the samples had a very rough surface. The TCB removed the excess resin easily, but produced deep scratches all over the surface of the enamel. This is in accordance with a study done by Pignatta et al. which showed that the TCB produced irregularities on the enamel surface.  Some other authors also found scratches and furrows when using this bur. ,
Discs have been widely used for polishing the enamel surface and have the reputation of providing the highest polish after residual resin removal. , In the present study, the Super Snap ® discs produced a smooth and homogeneous enamel surface with less amount of scratches. The surface, thus produced, was closest to that of the untreated enamel. This was in accordance with a study done by Ulusoy, in which the Super Snap ® discs produced the smoothest surface as compared to TCB and Sof-Lex discs. 
BG polishers have been used for the final finishing of composites. They do not have the ability to remove the bulk of adhesive but can be used subsequently to coarse methods for decreasing the abrasive marks and producing smooth surface after debonding.  Extreme care should be exercised while using these wheels by applying light force.
The group using a combination of TCB (slow speed) and BG silicon polishers showed that most of the samples had a score of 2 and some had a score of 3 [Graph 1] which means that the samples had mild rough to rough surface. The bulk of the remnant resin was removed using TCB which caused irregularities on the surface. These were then polished using the BG polishers. The fine scratches were removed while the coarse deep scratches caused by the TCB remained.
The group using a combination of TCB (slow speed) and Super Snap ® discs showed that most of the samples had a score of 2 and some had a score of 1 [Graph 1], which means that the samples had a mild rough surface. The Super Snap ® discs were used after the bulk of residual resin was removed using TCB. The sequential use of the discs led to the removal of most of the scratches produced by the TCB, but a few deep scratches remained.
Ulusoy  concluded that cleaning the residual adhesive on enamel surfaces after debonding with TCB was found to be the least time-consuming method when compared with polishing discs, PoGo polishers, and Optishine brushes. This finding was in accordance with some other study.  The mean time taken for finishing in Group I (198 s) was significantly higher in Group II (68.2 s). The mean time in Group III (171.6 s) and Group IV (174.8 s) was similar but higher than Group I and lower than Group II.
Therefore, TCB took the least amount of time for cleanup followed by a combination of TCB and BG polishers and a combination of TCB and Super Snap ® discs. The time taken for finishing was highest by Super Snap ® discs.
The present study had some limitations also. Newer methods such as profilometry and atomic force microscopy can be used to get more clear knowledge about the amount of enamel loss caused due to various methods used for the cleanup of residual adhesive.
| Conclusion|| |
The TCB at low speed proved to be fast and efficient in residual resin removal, but caused a significant increase in surface irregularity. The use of Super Snap ® discs or BG polishers, after removal of bulk by TCB, reduced the surface irregularities that were caused by the bur, but the procedure was time-consuming. Super Snap ® discs were least aggressive in removing the residual adhesive. The sequential use of Super Snap ® discs left a lustrous surface, but was more time-consuming. Thus, the protocol causing the least surface roughness after remnant adhesive removal was Super Snap ® discs followed by TCB in combination with Super Snap Discs ® or BG Polishers, and finally, the TCB alone which produced the roughest enamel surface.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3]