|Year : 2017 | Volume
| Issue : 3 | Page : 177-184
Evaluation of enamel loss with bonding and debonding: A study with profile projector
Juhi Yadav1, Pradeep Raghav2, Munish Reddy3, NK Ahuja4
1 Asst. Prof., Department of Orthodontics, Career Dental College, Meerut, Uttar Pradesh, India
2 Prof. and HOD, Department of Orthodontics, Subharti Dental College, Meerut, Uttar Pradesh, India
3 Prof, Department of Orthodontics, Subharti Dental College, Meerut, Uttar Pradesh, India
4 Department of Orthodontics, Subharti University, Meerut, Uttar Pradesh, India
|Date of Submission||17-Mar-2017|
|Date of Acceptance||07-Jun-2017|
|Date of Web Publication||17-Jul-2017|
Department of Orthodontics, Career Dental College, Lucknow, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
Introduction: Accidental detachment of brackets is a common problem in orthodontic bonding and removal of the residual resin certainly results in some amount of enamel loss. Aims: The present study was undertaken to measure and compare the amount of enamel loss with different prophylactic methods and to check which method results in the least amount of enamel loss. Materials and Methods: One hundred and twenty human premolars extracted for orthodontic treatment purpose were included in the study and divided into three groups of forty samples each: Group 1 (tungsten carbide bur), Group 2 (diamond bur), and Group 3 (soflex disc). The groups were further subdivided into subgroups (a and b) of twenty samples each for different etching times. The enamel loss was measured with profile projector. Results: The mean enamel loss for different subgroups was as follows - subgroup 1a tungsten carbide bur with etching time of 20 s = 69.06 μm and subgroup 1b tungsten carbide bur with etching time of 40 s = 70 μm, subgroup 2a diamond bur with etching time of 20 s = 76 μm and subgroup 2b diamond bur with etching time of 40 s = 76.12 μm, and subgroup 3a soflex disc with etching time of 20 s = 68.32 μm and subgroup 3b soflex disc with etching time of 40 s = 72.24 μm. Statistical Analysis: Analysis of variance showed a significant difference (P < 0.05) in mean enamel loss between three prophylactic methods using different etching times. Unpaired t-test showed no significant difference in mean enamel loss between 20 and 40 s of etching time within groups. Conclusion: It is concluded that tungsten carbide bur resulted in the least amount of enamel loss and gouging and scarring is minimum when viewed with naked eye.
Keywords: Bonding, diamond bur, enamel loss, profile projector, soflex disc, tungsten carbide bur
|How to cite this article:|
Yadav J, Raghav P, Reddy M, Ahuja N K. Evaluation of enamel loss with bonding and debonding: A study with profile projector. J Indian Orthod Soc 2017;51:177-84
|How to cite this URL:|
Yadav J, Raghav P, Reddy M, Ahuja N K. Evaluation of enamel loss with bonding and debonding: A study with profile projector. J Indian Orthod Soc [serial online] 2017 [cited 2019 May 25];51:177-84. Available from: http://www.jios.in/text.asp?2017/51/3/177/210910
| Introduction|| |
Bonding has transformed the tedium of appliance construction into an efficient and pleasant operation for both patients and clinician. The bonding procedure requires debonding at the termination of treatment. The objectives of debonding are to remove the attachments and all adhesive resin from tooth and to restore the surface as closely to its pretreatment condition. To achieve these objectives, correct bonding and debonding techniques are of fundamental importance. There are several factors fundamental for bracket removal, the armamentarium for resin removal, and the type of adhesive used.
The earliest studies relating the effects on the enamel surface when debonding metal brackets were conducted by Newman and Facq 1971. They concluded that removal of the brackets and the adhesive followed by pumicing restored the tooth surface to its original appearance.
Several studies reported on various techniques for the removal of residual resin after debracketing and their effects on enamel surface. All techniques reported produced different degrees of polish and some introduced abrasion anomalies accompanied by a significant loss of enamel. Attempts have been made to separate the enamel loss into its component parts during pumicing, acid etching, debonding, and final cleanup. Many found that a Prophy brush can remove two to four times the amount of enamel as a Prophy cup. The gross removal of residual composite left on the enamel surface after debonding is thought to be best accomplished with a tungsten carbide bur. Retief and Denys  described the removal of bonded attachments and their finishing and concluded that debonding pliers, scalers, and diamond finishing burs should not be used to remove the remaining resin after debonding because they cause deep gouges in the enamel. They recommended using a 12-bladed tungsten carbide bur at high speed with adequate air cooling to remove bulk resin. Many methods have been suggested to measure enamel loss qualitatively and quantitatively after debonding: direct study of the perikymata pattern on the tooth surface,, use of a reference marker inserted in the enamel surface as a point of reference,,, taking impressions and making models of the enamel surface before and after bonding, then measuring the enamel loss with scanning electron microscopy (SEM).
The purpose of the study was to measure and compare the enamel loss in vitro by profile projector caused by different prophylactic methods after repeated debonding.
Aim and objectives
- To evaluate enamel loss using different prophylactic methods after repeated debonding of orthodontic attachments
- First group of forty teeth with tungsten carbide bur and polished
- Second group of forty teeth with diamond bur and polished
- Third group with soflex disc
- To evaluate enamel loss for all groups while etching for 20 or 40 s for similar prophylactic method.
| Materials and Methods|| |
A sample of 120 human premolars freshly extracted for orthodontic purpose was collected. All the teeth had intact enamel with no cracks, no caries, and teeth not subjected to any pretreatment chemical agents. All the collected teeth were cleaned of saliva and blood and stored in distilled water. One hundred and twenty preadjusted stainless steel brackets, Roth prescription, were used. The average base surface area was determined to be 10.25 mm 2 [Roth Prescription American Orthodontics]. Adhesive used was Transbond XT  [Adhesive 3M Unitek Laboratory, Monrovia, CA, USA].
The sample teeth were mounted along their long axis in dental stone exposing their crown portion. All the samples were taken, and holes were made above cervicoenamel junction on each tooth, and a 21-gauge needle was passed through hole and cemented projecting outward the buccal heights of crowns [Needle Dispovan]. This needle acted as a reference marker to determine the enamel loss. Then, for base measurements, reference marker was placed along X axis of profile projector [Profile Projector, Bausch and Lomb US 333] and the length was measured, then the tooth was moved on microstage on Y axis for a distance of 3 mm toward the occlusal side and measurements were made. The difference of both readings recorded was the actual thickness. Measurements were made for each tooth [profile projector table].
The sample was randomly divided into three groups of forty teeth each. These groups were further subdivided into subgroups according to etching time used for conditioning. All the subgroup had twenty samples each.
- Subgroup 1a: Etching time of 20 s
- Subgroup 1b: Etching time of 40 s
- Subgroup 2a: Etching time of 20 s
- Subgroup 2b: Etching time of 40 s
- Subgroup 3a: Etching time of 20 s
- Subgroup 3b: Etching time of 40 s.
The facial surface of each subgroup teeth 1a, 2a, and 3a were conditioned with 37% orthophosphoric acid  for 20 s whereas 1b, 2b, and 3b were conditioned for 40 s with the same strength. They were then rinsed with distilled water for 20 s and dried with moisture and oil-free compressed air until enamel had a frosted appearance. Transbond XT light cure adhesive sealer was applied and then thinned with 2 s air blast. The stainless steel premolar brackets had an 80-gauge foil mesh with surface tooth contact area of 10.25 mm 2. Transbond XT light cure composite resin was applied to each bracket base, and the bracket was then pressed onto the enamel surface. After the excess material was removed, the bracket was aligned on the profile projector with the long axis of tooth and 3 mm to the reference marker. Curing was done for 10 s on each mesial and distal sides [Light Cure 2500, 3M Unitek Laboratory, Monrovia, CA, USA]. Sample was stored in distilled water for 24 h for polymerization. The bonded brackets were removed with the help of Howe pliers [CAT] and clean-up procedures were done,,,,
Group 1 - Finishing with tungsten carbide bur (SS WHITE) and polishing with rubber cup
Group 2 - Finishing with diamond bur (CE) and rubber cup
Group 3 - Finishing with soflex discs (3M ESPE CE).
Clean-up speed was 20,000 rpm  using micromotor with contra-angle handpiece. Cleanup of tooth surface was evaluated with visual and tactile sensation.
After finishing, polishing was done with pumice mixed with water using rubber cup  until shiny surface appeared.
To evaluate enamel loss, all the teeth were measured the same way as previously. Differences of these measurements were then recorded for the enamel loss for each tooth.
Now, the same procedure was repeated once again to evaluate the loss with second debonding.
| Results|| |
The mean enamel loss with different prophylactic methods for etching time of 20 and 40 s is shown in [Table 1].
|Table 1: Mean enamel loss with different prophylactic methods for etching time of 20 and 40 seconds |
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Student's t-test was applied to compare any difference in the values of various subgroups. Unpaired t-test revealed that there was no significant difference between the enamel loss for 20 s and 40 s (P > 0.05) of etching time when the same prophylactic method was used [Table 2].
|Table 2: Unpaired t-test table for 20 and 40 s of etching time in different three groups using same prophylactic method |
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In the tungsten carbide group, the difference in the values of subgroup a and b was not significant (P > 0.05).
In the diamond bur group, there was no significant difference in the values of subgroup a compared with b.
In the soflex disc group, there was no significant difference in the values of subgroup a compared to b.
F-test - to test the significant difference among the three prophylactic methods for 20 s and 40 s of etching time at 5% level of significance, a significant difference was observed for both the time periods (Fcal > Ftab), i.e., P < 0.05 when different prophylactic method was used [Table 3] and [Table 4].
|Table 3: ANOVA table for different groups at etching time of 20 s using different prophylactic methods |
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|Table 4: ANOVA table for different groups at etching time of 40 s using different prophylactic methods |
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| Discussion|| |
In the course of orthodontic therapy, accidental detachment of brackets is a common problem. The bonding procedure requires debonding at the termination of orthodontic treatment. The objectives of debonding are to remove the attachments and all the adhesive resin from tooth surface and to restore the surface as closely as possible to its pretreatment condition. To achieve these objectives, correct bonding and debonding techniques are of fundamental importance. The search for an efficient and safe method of adhesive resin removal following debonding has attracted the interest of many researchers, resulting in introduction of a wide array of instruments and procedures. In spite of substantial increase in the means available for the removal of adhesive resin postdebonding, the methods utilized to investigate the effects of various resin grinding methods have not followed the same pace. Standard microscopic techniques lack a quantitative scale and cannot quantitate the enamel loss. Hence, keeping this in mind the purpose of the study became to measure and compare in vitro enamel loss during different prophylactic methods after debonding.
The profile projector was used to measure the enamel loss consequent to prophylaxis of residual resin after debonding. Although quantification of enamel loss can be done using different techniques requiring the use of SEM namely:
- Indirect technique where impressions are made after bonding and enamel loss measured by SEM.
- Measuring height of perikymata which are subjected to a great deal of natural variation and cannot be very reliable. Whereas profile projector is considered to be more accurate, convenient, and easy to record the measurements as stated by Pus and Way, 1980; Brown and Way, 1978; and Thompson and Way, 1981. Other factors that can affect the enamel loss are taken into consideration so that enamel loss should be minimal. After debonding, residual resin is required to be removed to attain smooth and clear surface. In our study, we had three prophylactic finishing instruments with micromotor for removal of residual resin that is:
- 30-fluted tungsten carbide bur as they are considered efficient for removal of filled resins with least amount of scaling. Other available tungsten carbide burs such as 8-, 12-, 16-fluted are generally used for bulk removal of resin. Since lesser the number of the flutes, more aggressive is the cutting action of the bur 
- Fine diamond burs rather than coarse were chosen for cleanup procedures, as coarser diamond burs produce gouging and more enamel loss 
- Medium grit soflex disc was used in the third group. Super fine and fine discs were not used as they are advocated to be used for polishing procedures.
Most of the published work related to debonding and prophylaxis exists on a qualitative assessment of the enamel surface rather than quantitative enamel loss. Our study is essentially quantitative. It reveals that with first debond, there is 26.61 μm and 28.61 μm of enamel loss with etching times of 20 and 40 s, respectively, whereas Fitzpatrick and Way 1977 in their study recorded a loss of 55.6 μm with first debond using fluted tungsten carbide bur while etching with 30% orthophosphoric acid for a time period of 90 s.
While measuring enamel loss after second debond and using tungsten carbide bur as prophylactic instrument, the loss measured is 69.06 μm and 70 μm against etching time of 20 and 40 s, respectively. Thompson and Way, 1981, study quoted enamel loss of 71.5 μm with third debond using filled resins and 45.4 μm with unfilled resins [Figure 1],[Figure 2],[Figure 3] and [Table 5], [Table 6].
|Figure 3: Tungsten carbide bur group (comparison of 20 and 40 s enamel loss)|
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|Table 5: Enamel loss with tungsten carbide bur with etching time of 20 seconds |
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|Table 6: Enamel loss with tungsten carbide bur with etching time of 40 seconds |
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Enamel assessment surface studies of Campbell 1995, Retief and Denys 1979, and Piacentini and Sfondrini 1996 as such quote that diamond burs cause maximum damage to enamel surface resulting in scarring and gouging. These findings may be due to high hardness of diamond bur and soflex disc in comparison to enamel. Diamond particles have a mho scale of 10 whereas soflex disc which is composed of aluminum oxide have a mho scale of 9 which is quite high compared to enamel (5 mho). Hence diamond and soflex discs are more abrasive to enamel. As per our study, the loss of 76 and 76.12 μm was measured using diamond burs for the etching time of 20 and 40 s, respectively [Figure 4],[Figure 5],[Figure 6] and [Table 7], [Table 8]. The soflex disc group showed enamel loss of 68.32 and 72.24 μm [Figure 7],[Figure 8],[Figure 9] and [Table 9], [Table 10] against etching time of 20 and 40 s which is more in comparison to tungsten carbide burs [Figure 10].
The work of Thompson and Way 1981 and Eversoll and Moore 1988 strongly suggests that the enamel loss is much more with filled resins than unfilled resins; however, the bond strength is lesser with unfilled resins. From the results of the present study, it is quite clear that repeated debonds are very harmful and its results in greater loss of enamel leading to loss of the outermost fluoride layer which can be detrimental to the dentition. Hence, correct bonding is very crucial and important.
| Conclusion|| |
As per the results of our study after repeated debonding, it is concluded that:
- The mean enamel loss of the groups evaluated in the study are as follows-
- Tungsten carbide bur group:
- Subgroup 1a tungsten carbide bur with etching time of 20 s = 69.06 μm
- Subgroup 1b tungsten carbide bur with etching time of 40 s = 70 μm
Diamond bur group:
- Subgroup 2a diamond bur group with etching time of 20 s = 76 μm
- Subgroup 2b diamond bur group with etching time of 40 s = 76.12 μm
Soflex discs group:
- Subgroup 3a soflex disc group with etching time of 20 s = 68.32 μm
- Subgroup 3b soflex disc group with etching time of 40 s = 72.24 μm.
- Tungsten carbide bur group produced least and statistically significant (P < 0.5) amount of enamel loss for both subgroups of etching time. Diamond bur group produced the maximum amount of enamel loss irrespective of the etching time.
Etching time of 20 and 40 s had no significant difference in enamel loss in any group of study for similar prophylactic methods used.
According to our study, the measured enamel loss is the least when tungsten carbide bur is used after repeated debonding, and gouging and scarring is minimum when viewed with naked eyes.
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], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8], [Table 9], [Table 10]