title: Shear bond strength of orthodontic brackets after acid-etched and erbium-doped yttrium aluminum garnet laser-etched.
abstract: BACKGROUND
  Laser ablation has been suggested as an alternative method to acid etching; however, previous studies have obtained contrasting results. The purpose of this study was to compare the shear bond strength (SBS) and fracture mode of orthodontic brackets that are bonded to enamel etched with acid and erbium-doped yttrium aluminum garnet (Er:YAG) laser.
  
  
  METHODS
  In this experimental in vitro study, buccal surfaces of 15 non-carious human premolars were divided into mesial and distal regions. Randomly, one of the regions was etched with 37% phosphoric acid for 15 s and another region irradiated with Er:YAG laser at 100 mJ energy and 20 Hz frequency for 20 s. Stainless steel brackets were then bonded using Transbond XT, following which all the samples were stored in distilled water for 24 h and then subjected to 500 thermal cycles. SBS was tested by a chisel edge, mounted on the crosshead of universal testing machine. After debonding, the teeth were examined under ×10 magnification and adhesive remnant index (ARI) score determined. SBS and ARI scores of the two groups were then compared using t-test and Mann-Whitney U test. Significant level was set at P < 0.05.
  
  
  RESULTS
  The mean SBS of the laser group (16.61 ± 7.7 MPa) was not significantly different from that of the acid-etched group (18.86 ± 6.09 MPa) (P = 0.41). There was no significant difference in the ARI scores between two groups (P = 0.08). However, in the laser group, more adhesive remained on the brackets, which is not suitable for orthodontic purposes.
  
  
  CONCLUSIONS
  Laser etching at 100 mJ energy produced bond strength similar to acid etching. Therefore, Er:YAG laser may be an alternative method for conventional acid-etching.
authors.affiliation: Dental Materials Research Center and Department of Orthodontics, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Shiva
authors.initials: S
authors.lastname: Alavi
authors.affiliation: Torabinejad Dental Research Center and Department of Periodontics, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Birang
authors.affiliation: Department of Orthodontics, School of Dentistry, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Hajizadeh
keywords: Bond strength; dental acid etching; erbium-doped yttrium aluminum garnet laser; orthodontic bracket
references.citation: Lasers Med Sci. 2008 Apr;23(2):141-7
references.pmid: 17899311
references.citation: Am J Orthod Dentofacial Orthop. 2002 Dec;122(6):649-56
references.pmid: 12490877
references.citation: Dtsch Zahnarztl Z. 1991 Feb;46(2):158-60
references.pmid: 1814713
references.citation: Angle Orthod. 2003 Oct;73(5):565-70
references.pmid: 14580025
references.citation: J Biomech. 2002 Jul;35(7):995-8
references.pmid: 12052404
references.citation: Eur J Orthod. 2008 Apr;30(2):183-9
references.pmid: 18263892
references.citation: Lasers Med Sci. 2002;17(4):246-52
references.pmid: 12417978
references.citation: Caries Res. 1990;24(2):86-92
references.pmid: 2160327
references.citation: Am J Orthod. 1984 Apr;85(4):333-40
references.pmid: 6231863
references.citation: Angle Orthod. 2006 Nov;76(6):1052-6
references.pmid: 17090176
references.citation: J Clin Laser Med Surg. 2003 Aug;21(4):197-201
references.pmid: 13678456
references.citation: Angle Orthod. 2007 Jan;77(1):117-23
references.pmid: 17029548
references.citation: Angle Orthod. 1993 Spring;63(1):73-6
references.pmid: 8507035
references.citation: J Periodontal Res. 2000 Oct;35(5):266-77
references.pmid: 11005154
references.citation: Lasers Surg Med. 2000;26(3):262-9
references.pmid: 10738288
references.citation: J Biomech. 2005 Nov;38(11):2204-11
references.pmid: 16154407
references.citation: Dent Mater. 1997 Jan;13(1):51-5
references.pmid: 9467323
references.citation: Dent Mater. 1994 May;10(3):162-6
references.pmid: 7758858
references.citation: Aust Dent J. 1997 Apr;42(2):81-4
references.pmid: 9153834
references.citation: Lasers Surg Med. 2005 Dec;37(5):366-72
references.pmid: 16240417
references.citation: J Biomed Mater Res. 1979 Nov;13(6):975-85
references.pmid: 389927
references.citation: Am J Orthod Dentofacial Orthop. 2001 Jun;119(6):621-4
references.pmid: 11395706
references.citation: J Am Dent Assoc. 1997 Jun;128(6):732-7
references.pmid: 9188230
references.citation: Lasers Surg Med. 1992;12(6):625-30
references.pmid: 1453865
references.citation: J Prosthet Dent. 2000 Sep;84(3):280-8
references.pmid: 11005900
references.citation: Caries Res. 2005 Jan-Feb;39(1):65-70
references.pmid: 15591737
references.citation: Lasers Surg Med. 1995;16(2):103-33
references.pmid: 7769957
references.citation: Am J Orthod Dentofacial Orthop. 2008 Aug;134(2):193-7
references.pmid: 18675199
references.citation: Lasers Med Sci. 2011 Mar;26(2):149-56
references.pmid: 20151169
references.citation: Oper Dent. 1992 Nov-Dec;17(6):229-42
references.pmid: 1303516
references.citation: Eur J Orthod. 1999 Feb;21(1):71-7
references.pmid: 10191580
references.citation: Lasers Surg Med. 1984;4(4):323-7
references.pmid: 6394935
references.citation: J Dent Res. 1955 Dec;34(6):849-53
references.pmid: 13271655
references.citation: Int Dent J. 1977 Dec;27(4):317-23
references.pmid: 338496
references.citation: Dent Res J (Isfahan). 2012 May;9(3):288-93
references.pmid: 23087733
references.citation: J Prosthet Dent. 1992 Mar;67(3):307-12
references.pmid: 1507090