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      Effect of Er:YAG and Er,Cr:YSGG Lasers on Ceramic Bracket Debonding from Composite Blocks


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          This study aimed to assess the effect of erbium-doped yttrium aluminum garnet (Er:YAG) and erbium, chromium: yttrium, scandium, gallium, garnet (Er,Cr:YSGG) lasers on the shear bond strength (SBS) of ceramic brackets debonding from the surface of composite blocks.

          Materials and Methods:

          Thirty-six composite blocks were fabricated using Filtek Z250 light-cure composite. Block surfaces were etched with 37% phosphoric acid for 30 seconds and then rinsed with water for 20 seconds and dried. Maxillary right central incisor ceramic orthodontic brackets were bonded to the surfaces of composite blocks using Transbond XT adhesive and were cured for 40 seconds. Twelve samples were irradiated with Er:YAG laser, while 12 samples were irradiated with Er,Cr:YSGG laser, and the brackets were then debonded using a universal testing machine. Twelve samples served as controls (debonding using the universal testing machine without using a laser). The adhesive remnant index (ARI) score and bracket or composite cracks were evaluated under a stereomicroscope. One-way analysis of variance (ANOVA) was used for the comparison of the three groups. Kruskal-Wallis test was used to compare the ARI scores.


          The mean SBS was 17.01±5.22 MPa with Er:YAG laser, 18.03±6.46 MPa with Er,Cr:YSGG laser, and 16.61±6.73 MPa in the control group; the difference of the three groups was not significant (P=0.835). The difference in the ARI scores and enamel and composite cracks was not significant either (P>0.05).


          This study did not show any reduction in the bond strength of ceramic bracket to composite blocks after Er:YAG and Er,Cr:YSGG laser irradiation.

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          Most cited references 29

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          Experimental studies of the application of the Er:YAG laser on dental hard substances: I. Measurement of the ablation rate.

           R Hibst,  U. Keller (1988)
          Up to now lasers have not achieved any practical importance in dentistry for drilling teeth because of considerable damage to the surrounding tissue. We studied the application of pulsed 2.94 microns Er:YAG laser radiation in vitro on extracted teeth to remove enamel, dentin, and carious lesions. The depth and diameter of laser-drilled holes were measured as a function of pulse number and radiant exposure. The tissue removal is very effective both for dentin and enamel.
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            The inappropriateness of conventional orthodontic bond strength assessment protocols.

            The purpose of this article is to examine the soundness of conventional orthodontic bonding assessment methods. A classification of bond strength studies is proposed with the testing environment (in vivo, in vitro, and ex vivo), loading mode (shear, tensile, and torsion), and bonding substrate (enamel, restorative, and prosthetic materials) serving as discriminating variables. Inconsistencies throughout the various stages of research protocols are analysed. These include the following: tooth selection, storage, and preparation; bonding; testing; and data analysis with regard to the clinical applicability of the reported information, as well as the scientific integrity of the testing procedure. Contradictory models may partially account for the considerable variability noted for reported bond strength values of different orthodontic bonding systems. Such discrepancies may also explain the conflicting evidence reported on the failure characteristics of the components of the bonding system in different trials examining the efficacy of nominally identical materials. A novel approach to study the fatigue life of materials is proposed to understand the processes occurring prior to bond failure. Mock research data manipulation is also utilized to illustrate the correct statistical treatment of findings, and recommendations for future research are made to ensure scientific soundness and clinical applicability of data.
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              Bond strengths of orthodontic bracket after acid-etched, Er:YAG laser-irradiated and combined treatment on enamel surface.

              Laser ablation has been proposed as an alternative method to acid etching: however, previous studies have obtained contrasting results. The purpose of this study was to compare the bond strengths after acid etching, laser ablation, acid etching followed by laser ablation, and laser ablation followed by acid etching. Forty specimens were randomly assigned to one of the four groups. Two more specimens in each group did not undergo bond test and were prepared for observation with scanning electron microscope (SEM) after the four kinds of surface treatment. After the bond test, all specimens were inspected under the digital stereomicroscope and SEM to record the bond failure mode. Student's t-test results showed that the mean bond strength (13.0 +/- 2.4 N) of the laser group was not significantly different from that of the acid-etched group (11.8 +/- 1.8 N) (P > .05). However, this strength was significantly higher than that of the acid-etched then laser-ablated group (10.4 +/- 1.4 N) or that of the laser-ablated then acid-etched group (9.1 +/- 1.8 N). The failure modes occurred predominantly at the bracket-resin interface. Er:YAG laser ablation consumed less time compared with the acid-etching technique. Therefore, Er:YAG laser ablation can be an alternative tool to conventional acid etching.

                Author and article information

                Front Dent
                Front Dent
                Frontiers in Dentistry
                Tehran University of Medical Sciences
                Mar-Apr 2019
                30 April 2019
                : 16
                : 2
                : 88-95
                [1. ] Department of Orthodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran
                [2. ] Laser Research Center of Dentistry, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran
                [3. ] Department of Periodontics, Dental Branch, Islamic Azad University, Tehran, Iran
                [4. ] Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran
                Author notes
                [* ] Corresponding author: Department of Orthodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran, Email: drabolghasemb@ 123456gmail.com
                Copyright© Dental Research Center, Tehran University of Medical Sciences

                This work is published as an open access article distributed under the terms of the Creative Commons Attribution 4.0 License ( http://creativecommons.org/licenses/by-nc/4). Non-commercial uses of the work are permitted, provided the original work is properly cited.

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