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| ORIGINAL ARTICLE |
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| Year : 2023 | Volume
: 12
| Issue : 1 | Page : 7 |
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Effect of ER, CR: YSGG laser debonding on enamel surface changes in stainless steel and ceramic brackets – An in-vitro study
Aravindaksha Rao1, P Deenadayalan1, C Deepak1, Dhivya Dilipkumar1, Nidhi Angrish1, Suhani S Shetty2
1 Department of Orthodontics and Dentofacial Orthopaedics, SRMKDC and H, Chennai, Tamil Nadu, India
2 Private Practitioner, Bangalore, Karnataka, India
| Date of Submission | 17-Jun-2022 |
| Date of Decision | 25-Jul-2022 |
| Date of Acceptance | 10-Aug-2022 |
| Date of Web Publication | 18-Mar-2023 |
Correspondence Address:
Aravindaksha Rao
Post Graduate Student, Department of Orthodontics and Dentofacial Orthopaedics, SRMKDC and H, Chennai, Tamil Nadu
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/jos.jos_52_22
AIM: The aim of this in-vitro study was to observe and analyze the various enamel surface changes that occur due to laser debonding of metal and ceramic brackets, done by means of Er, Cr:YSGG laser.
MATERIALS AND METHODS: 90 extracted premolars were randomly allocated into one of six groups with 15 teeth each. The groups represent metal brackets (Groups A1, A2, A3) and ceramic brackets (Groups B1, B2, B3). Each sub-group represents the mode of debonding used in the study. Debonded teeth were analyzed under scanning electron microscopy (SEM) at 80X and at 1000X magnification at three sites. The adhesive remnant index (ARI) scores were analyzed and the presence of enamel damage was observed.
RESULT: ARI showed high score in Groups A1 and B1. SEM images of large composite remnants at the site of bracket in Groups A1 and B1 at the site of bracket and multiple enamel microcracks and fractures at interface and enamel adjacent to bracket in Groups A1 and B1. SEM images of minimal composite remnants at the site of bracket in Groups A2, A3, B2, and B3 and little to no presence of enamel microcracks or fractures at interface and enamel adjacent to bracket in Groups A2, A3, B2, and B3.
CONCLUSION: The use of Er, Cr:YSGG laser in orthodontic practice, especially in the debonding procedures of orthodontic brackets provide quality care to patient with minimal post-treatment damages.
Keywords: Ceramic brackets, debonding, Er, Cr:YSGG, laser debonding, metal brackets
How to cite this article:
Rao A, Deenadayalan P, Deepak C, Dilipkumar D, Angrish N, Shetty SS. Effect of ER, CR: YSGG laser debonding on enamel surface changes in stainless steel and ceramic brackets – An in-vitro study. J Orthodont Sci 2023;12:7 |
How to cite this URL:
Rao A, Deenadayalan P, Deepak C, Dilipkumar D, Angrish N, Shetty SS. Effect of ER, CR: YSGG laser debonding on enamel surface changes in stainless steel and ceramic brackets – An in-vitro study. J Orthodont Sci [serial online] 2023 [cited 2023 Mar 25];12:7. Available from: https://www.jorthodsci.org/text.asp?2023/12/1/7/371969 |
| Introduction | |  |
Modern physics has given rise to various forms of technology of which Laser technology is one of the most widely used and accepted forms. The term LASER is the acronym of “Light Amplification by Stimulated Emission of Radiation” which accurately describes the functioning of device as a whole. Since the creation and subsequent development in various fields, many forms have been introduced, but only a few have withstood the test of time.
Theodore Maiman, in the year 1960 was one of the first scientists, who created a laser made of Aluminium oxide, that showcased the function of lasers. This laser emitted a red colored beam and thus it was called “Ruby Laser”.[1] After the invention of Ruby lasers, the various potentials of lasers were investigated by dental researchers like CO2 laser,[2] Neodinium Yttrium Aluminium Granet (Nd:YAG) pulsed laser,[3] Erbium: Yttrium Aluminium Garnet (Er:YAG 2940 nm).[4],[5]
Erbium, Chromium:Yttrium Scandinium Gallium Garnet (2780 nm) is Er, Cr: YSGG (2780 nm) which has an “active medium of a solid crystal of yttrium scandium gallium garnet doped with erbium and chromium”. This family of lasers has proven to be an effective tool in the restorative as well as etching procedures.[5] The Erbium family of lasers has been gathering attention due to its safe and effective use in various fields of dentistry, thus the use of Er, Cr:YSGG has been advocated in the following study for Laser debonding of orthodontic brackets.
The aim of this in vitro study was to observe and analyze the various enamel surface changes that occur due to laser debonding of metal and ceramic brackets, done by means of Er, Cr:YSGG laser. The surface changes were observed under scanning electron microscopy (SEM) and the adhesive remnant index (ARI) scores are measured.
| Materials and Methods | | |
The extracted teeth were collected from patients who reported to the department of Orthodontics and dentofacial orthopedics. Patients who were recommended for orthodontic extraction of 1st or 2nd premolars as part of treatment protocol were selected to be part of the study.Ethical clearance was obtained from the college, ethical clearance number was 1486/IEC/2018and was approved on 26th October 2018.
The sample size was determined by means of convenience sampling. Inclusion criteria was 1st or 2nd premolar extraction as part of orthodontic treatment protocol and clinically sound teeth. Exclusion criteria was enamel hypoplasia, enamel fluorosis, previously bonded teeth, fractured enamel, and restored teeth.
The teeth were randomly allocated into one of six groups, A1, A2, A3, B1, B2, B3, respectively. Each group contained 15 teeth each. The groups represent metal brackets (Groups A1, A2, A3) and ceramic brackets (Groups B1, B2, B3). Each sub-group represents the mode of debonding used in the study, Groups A1 and B1 represents the control group which used conventional debonding by means of debonding pliers. Groups A2 and B2 represents laser debonding by means of Er, Cr:YSGG laser at 4.5W and Group A3 and B3 represents Laser debonding by means of Er, Cr:YSGG laser at 6W.
The extracted premolars were washed to remove any blood stains and remnant PDL structures. Following tooth collection, auto polymerizing acrylic was placed in the silicone mold, the root surface of extracted teeth was covered in a thin layer of light body impression material, to simulate PDL, and tooth was immersed in the acrylic till the level of CEJ.
The mounted teeth were placed in jars of distilled water for 24 hours to preserve the water content in the teeth. The mounted teeth were removed from distilled water after a period of 24 hrs, the tooth surface was conditioned by means of prophylactic paste and rubber cups and prophy brush. The tooth surface was air dried by means of chip blower for 15 sec.
The conditioned teeth were etched by means of 37% orthophosphoric acid for 20 sec, washed and dried by means of three-way syringe for 20 sec. 3M UnitekTransbond XT bonding agent was applied by means of applicator tip and mildly air dried to evenly spread the agent.
Bonding agent was cured by Light Cure unit for 20 sec. 3M UnitekTransbond XT adhesive was applied to bracket base and positioned on tooth surface at the mid-point of clinical crown face, bracket was pressed against tooth surface and flash was removed by means of probe. Light Cure unit was used to cure the bracket against the tooth surface for 40 sec.
The teeth were placed in containers of distilled water for 48 hours to allow complete polymerization of composite.
Conventional debonding of brackets were done by means of debonding pliers, following the manufacturer's instructions, the pliers were placed on the lateral wings of the brackets and torsional force was applied to debond the bracket from the tooth surface.
Laser debonding was done by Er, Cr:YSGG laser with 2780 nm wavelength (Waterlase I plus, Biolase, India) at the following settings for the various groups.
The laser tip was positioned parallel with 1 mm distance from the bracket. Laser light was irradiated on the labial surface at speed of 2 mm/sec, the light was irradiated around the bracket, from mesial, to gingival, to distal, to occlusal sides of the bracket. The procedure was repeated twice around the bracket base.
Following laser irradiation, the brackets were removed as per the manufacturer's instructions.
Debonded teeth were analyzed under SEM at 80X to view the debonded surface and at 1000X magnification at three sites: the enamel surface, the bonded surface, the interface between the bracket, and tooth surface. The ARI scores were analyzed and the presence of enamel damage was observed.
Statistical analysis
The output of the data was collected and statistically estimated by the software package R Studio 1.3.1073 and SPSS 16. Data was presented using a non-parametric Friedman ANOVA test was used to determine any variance between the measurements (p < 0.05). Post-hoc pair-wise comparisons between measurements were calculated by using the Wilcoxon-signed rank test. Statistical significance was defined as P < 0.05.
| Results | | |
ARI scores of samples revealed the amount of composite remaining on the tooth surface after debonding had been completed. The scores of each sample were assessed as shown in [Table 1], it was observed that samples in the Group A1 showed scores ranging from 1 to 3, with 5 samples of score 1 (33%), 6 samples of score 2 (40%), and 4 samples of score 3 (27%). The high scores seen in Group A1 are indicative of excessive adhesive remnants on the tooth surface after conventional debonding by means of debonding plier, this is suggestive of excess force propagation on the tooth surface, and requires post-debonding cleaning procedures to be employed. Samples in Groups A2, A3 showed scores ranging from 0 to 3, with 1 sample of score 0 (7%), 7 samples of score 1 (47%), 5 samples of score 2 (33%), 2 samples of score 3 (13%) in Group A2 and 2 samples of score 0 (13%), 9 samples of score 1 (60%), 3 samples of score 2 (20%), 1 sample of score 3 (7%) in Group A3 after laser debonding by Er, Cr:YSGG laser. These scores are indicative of multiple samples with minimal to no presence of adhesive remnants, and only few samples with very high scores. Thus, the procedures employed for post-debonding cleaning of enamel surface is minimal.
The scores of each sample were assessed as shown in [Table 2], it was observed that samples in the Group B1 showed scores ranging from 1 to 3, with 3 samples of score 1 (20%), 7 samples of score 2 (47%), and 5 samples of score 3 (33%). The high scores seen in Group B1 are indicative of excessive adhesive remnants on the tooth surface after conventional debonding by means of debonding plier, this is suggestive of excess force propagation on the tooth surface, and requires post debonding cleaning procedures to be employed. Samples in Groups B2, B3 showed scores ranging from 0 to 2, with 1 sample of score 0 (7%), 8 samples of score 1 (53%), 6 samples of score 2 (40%), in Group B2 and 2 samples of score 0 (13%), 10 samples of score 1 (67%), 3 samples of score 2 (20%) in Group B3 after laser debonding by Er, Cr:YSGG laser. These scores are indicative of multiple samples with minimal to no presence of adhesive remnants, and none of the samples presented with a score of 3, which suggests that laser debonding of ceramic brackets is effective and the adhesive remnants is minimal after debonding.
Temperature changes were measured as shown in [Table 3] during the course of laser debonding in samples of Group A2, A3; B2, B3. The changes were measured by means of thermocouple with a multimeter to estimate the rise in temperature. The readings in the multimeter were noted and were analyzed. The temperature change observed was 1–2oC in samples of all four groups. The rise in temperature was noted to be well within the acceptable temperature range of 5.5o C. Thus, the laser debonding procedure can be considered safe to use in patient.
The SEM analysis of samples was conducted. The samples were processed by air drying them 48 hours prior to SEM (acceleration 10 kV, spot size 40, and 50 nm) analysis. The samples were analyzed in Apreo 2 SEM (Thermo Fisher Scientific) using Microscope version 13.9.0 software.
SEM images of samples from Group A1 reveal areas of large composite remnants at the site of bracket. [Figure 1]a The interface region and the enamel adjacent to the bracket reveal multiple enamel microcracks and fractures [Figure 2]a, [Figure 3]a | Figure 1: SEM image at site of bracket (a) Group A1 (b) Group A2 (c) Group A3 (d) Group B1 (e) Group B2 (f) Group B3
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 | Figure 2: SEM image at site of enamel bracket interface (a) Group A1 (b) Group A2 (c) Group A3 (d) Group B1 (e) Group B2 (f) Group B3
Click here to view |
 | Figure 3: SEM image at site of enamel adjacent to bracket (a) Group A1 (b) Group A2 (c) Group A3 (d) Group B1 (e) Group B2 (f) Group B3
Click here to view |
SEM images of samples from Group A2 reveal areas of minimal composite remnants at the site of bracket. [Figure 1]b The interface region and the enamel adjacent to the bracket reveal little to no presence of enamel microcracks or fractures [Figure 2]b, [Figure 3]b.
SEM images of samples from Group A3 reveal areas of minimal composite remnants at the site of bracket. [Figure 1]c The interface region and the enamel adjacent to the bracket reveal little to no presence of enamel microcracks or fractures, certain samples even showed the presence of only enamel etching pattern [Figure 2]c, [Figure 3]c
SEM images of samples from Group B1 reveal areas of large composite remnants at the site of bracket. [Figure 1]d The interface region and the enamel adjacent to the bracket reveal multiple enamel microcracks and fractures [Figure 2]d, [Figure 3]d.
SEM images of samples from Group B2 reveal areas of minimal composite remnants at the site of bracket. [Figure 1]e The interface region and the enamel adjacent to the bracket reveal little to no presence of enamel microcracks or fractures [Figure 2]e, [Figure3]e.
SEM images of samples from Group B3 reveal areas of minimal composite remnants at the site of bracket. [Figure 1]f The interface region and the enamel adjacent to the bracket reveal little to no presence of enamel microcracks or fractures, certain samples even showed the presence of only enamel etching pattern [Figure 2]f, [Figure 3]f.
| Discussion | | |
The use of lasers became active in the field of dentistry only by the year 1989. This was largely because of the activities of Dr. Terry Myers who developed and marketed the Nd: YAG laser.[6] Although the laser was dedicated for dental use, it had a low power which made it ineffective for dental use.
In 2010, in a study conducted by Paul J. Feldon,[7] the effectiveness of diode laser for the debonding of ceramic brackets. Based on the findings, they concluded that the use of diode laser had significant effect on the shear bond strength of the bracket after irradiation. The use of Er:YAG laser has been extensively studied by various authors.[7],[8] Both studies revealed a decrease in the shear bond strength of the composite used which was a result of thermal softening. This allowed for easier removal of brackets after laser irradiation.[7],[8]
The erbium family of lasers includes Er, Cr:YSGG and Er:YAG lasers with 2780 and 2940 nm wavelengths, respectively. Recent studies revealed that Er, Cr:YSGG laser has three times less water sorption than Er:YAG laser. Thus, it has three times more absorption depth.[9],[10] Dostalova et al.[11] showed that Er:YAG laser decreased the enamel damage following debonding. Nonetheless, the efficacy of Er, Cr:YSGG laser for metal and ceramic bracket debonding has not been investigated and compared before.
The ARI scores of both groups were noted to be significantly increased as compared to the other study groups with the minimum value being 1.0 and a maximum value of 3.0. Group A1 showed a mean ARI score of 1.93 ± 0.79 and Group B1 showed a mean ARI score of 2.13 ± 0.74. Study by Youssef Sedky et al.[12] and Navid Naseri et al.[10] revealed similar findings of decreased ARI scores in the laser irradiation groups as compared to conventional debonding procedures.
Laser debonding by Er, Cr:YSGG laser was carried out on the study groups with an alteration in the laser power: 4.5 W was examined in study Groups A2 and B2; 6 W was examined in study Groups A3 and B3. The ARI scores recorded in the study groups were assessed and it was observed that the values ranged from 0.0 to 3.0. The current results revealed an increased risk of enamel damage during debonding of ceramic and metal brackets by means of conventional debonding.
Laser debonding by Er, Cr:YSGG laser was carried out on the study groups with an alteration in the laser power: 4.5 W was examined in study Groups A2 and B2; 6 W was examined in study Groups A3 and B3. The ARI scores recorded in the study groups were assessed and it was observed that the values ranged from 0.0 to 3.0. The mean values of ARI scores were 1.53 ± 0.83 in Group A2; 1.33 ± 0.61 in Group B2 and 1.20 ± 0.77 in Group A3; 1.06 ± 0.59 in Group B3. Based on these statistics we can see a stark difference in the ARI scores between the control groups and study groups, where the ARI scores are statistically significant (p ≤ 0.05) in the metal brackets and they are seen to be highly significant (p ≤ 0.001) in the ceramic bracket group. As observed in the variations of the ARI scores we can conclude that the use of Er, Cr:YSGG laser is a better alternative to conventional debonding procedures, especially when utilized for the purpose of debonding ceramic brackets. These findings are in agreement with the findings of Youssef Sedky et al.[12]; Navid Naseri et al.,[10] who reported that debonding of chemically retained metal and ceramic brackets can cause significant damage to the enamel surface, that is, increased number of enamel cracks and microfractures.
SEM analysis of the various samples reveals the absence of cracks or fractures in all the samples in the laser debonding groups, whereas pronounced cracks or fractures were seen in both groups of metal and ceramic brackets which were debonded in the conventional method. The observations of the SEM analysis are similar to those seen in the samples debonded by means of Er:YAG laser in the study conducted by Grzech-Leśniak et al.[13]
Aside from all the positive properties of laser irradiation, one important concern in laser-assisted debonding is pulpal temperature rise during laser irradiation. Evidence shows that temperature rises over 5.5°C can be harmful to the dental pulp.[14] In the present study, the temperature rise was measured to be1.2oC in metal bracket group and 1.3oC in the ceramic group at 4.5 W and 1.6oC for metal brackets and 1.3oC for ceramic brackets at 6 W during laser debonding. The current results showed that this temperature rise was below the critical threshold that would damage the pulp.
Our study has revealed that the use of laser, especially Er, Cr:YSGG in the routine practices of an orthodontist is highly beneficial to both patient and doctor. The use of the laser has been revealed to have multiple significant and positive outcomes, but the drawbacks in the use of laser also are equally high. The cost of installation, the knowledge and skill required to operate the laser become a key aspect. The future of laser in dentistry will depend on the technological advances that allow for cheaper and more user-friendly equipment to be designed that can be applied to every aspect of orthodontic treatment.
| Conclusion | | |
The use of Er, Cr:YSGG laser in orthodontic practice, especially in the debonding procedures of orthodontic brackets is slowly gathering momentum in the field of dentistry and following this trend would be an advisable course of action, if we wish to provide quality care to patient with minimal post-treatment damages.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
| References | | |
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| 2. | Thomas G, Isaacs R. Basic principles of lasers. Anaesth Intensive Care Med 2011;12:574-7. |
| 3. | Yamamoto H. Prevention of dental caries by Nd: YAG laser irradiation. J Dent Res 1980;59:2171-7. |
| 4. | Frentzen M, Hoort HJ. The effect of Er: YAG irradiation on enamel and dentin. J Dent Res 1992;71:571. |
| 5. | Pogrel MA, Muff DF, Marshall GW. Structural changes in dental enamel induced by high energy continuous wave carbon dioxide laser. Lasers Surg Med 1993;13:89-96. |
| 6. | Myers TD, Myers WD, Stone RM. First soft tissue study utilising a pulsed Nd YAG dental laser. Northwest Dent 1989;68:14-7. |
| 7. | Feldon PJ, Murray PE, Burch JG, Meister M, Freedman MA. Diode laser debonding of ceramic brackets. Am J Orthod Dentofacial Orthop 2010;138:458-62. |
| 8. | 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. |
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| 10. | Naseri N, Ghasemi N, Baherimoghadam T, Azmi A. Efficacy of Er, Cr: YSGG laser for debonding of ceramic brackets and prevention of enamel damage and intrapulpal temperature change. Lasers Dent Sci 2020;4:157-63. |
| 11. | Dostalova T, Jelinkova H, Remes M, Šulc J, Němec M. The use of the Er: YAG laser for bracket debonding and its effect on enamel damage. Photomedicine and laser surgery. 2016 Sep 1;34(9):394-9. |
| 12. | Rodríguez-Chávez JA, Arenas-Alatorre J, Belio-Reyes IA. Comparative study of dental enamel loss after debonding braces by analytical scanning electron microscopy (SEM). Microscopy Research and Technique. 2017 Jul; 80(7):680-6. |
| 13. | Grzech-Leśniak K, Matys J, Żmuda-Stawowiak D, Mroczka K, Dominiak M, Brugnera Junior A, et al. Er: YAG laser for metal and ceramic bracket debonding: An in vitro study on intrapulpal temperature, SEM, and EDS analysis. Photomed Laser Surg 2018;36:595-600. |
| 14. | Zach L, Cohen G. Pulp response to externally applied heat. Oral Surg Oral Med Oral Pathol 1965;19:515–30. |
[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]
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