Comparison of Enamel Morphologic Characteristics after Conditioning with Various Combinations of Acid Etchant and Er:YAG Laser in Bonding and Rebonding Procedures: A SEM Analysis
Objectives: Many studies have evaluated re-etched enamel by using scanning electron microscopy (SEM); however, there is no evidence regarding the use of Erbium-doped yttrium aluminium garnet (Er:YAG) laser at primary and secondary bonding instead of acid etching with regards to enamel surface changes. The purpose of the present study was to determine that whether or not the methods of primary and secondary enamel preparation affect enamel characteristics after rebonding, by using SEM analysis.
Materials and Methods: Twelve freshly extracted premolars were divided into 4 groups. The samples in each group were conditioned by acid etchant or Er:YAG laser at primary conditioning, according to the instructions. Afterwards, they were bonded with orthodontic brackets. After debonding, the samples were prepared for second conditioning. Also, two samples were conditioned only once with acid etchant or laser, to compare enamel morphology changes with those after re-etching. Finally, buccal enamel surfaces were evaluated using SEM.
Results: Enamel etching patterns were observed in the samples which had been acid-conditioned at first or at both conditionings. The samples irradiated by Er:YAG laser showed amorphous and irregular surfaces, with no signs of typical etching patterns. A large deep gap was seen in one of the samples irradiated with laser at primary and secondary conditionings, which might have penetrated the underling layers of enamel and dentin.
Conclusions: Enamel surface preparation with Er:YAG laser produces irregular and indistinct morphologic changes, completely different from those produced after acid etching at both conditioning and reconditioning. Therefore, it is recommended to use this laser with caution to avoid permanent enamel damage.
- Brauchli LM, Schramm A, Senn C, Ball J, Wichelhaus A. Laser conditioning of enamel with the Erbium YAG and the CO2 laser. Bond strength and surface structure. Dentistry. 2011 Oct; 1(2):106-10.
- Silverstone LM, Saxton CA, Dogon IL, Feierskov O. Variation in pattern of acid etching of human dental enamel examined by scanning electron microscopy. Caries Res. 1975;9(5):373-87.
- Bader C, Krejci I. Indications and limitations of Er:YAG laser applications in dentistry. Am J Dent. 2006 Jun;19(3):178-86.
- Attrill DC, Farrar SR, King TA, Dickinson MR, Davies RM, Blinkhorn AS. Er:YAG (λ= 2.94 µm) laser etching of dental enamel as an alternative to acid etching. Lasers Med Sci. 2000 Sep:15(3):154–61.
- Lee BS, Hsieh TT, Lee YL, Lan WH, Hsu YJ, Wen PH, et al. Bond strengths of orthodontic bracket after acid-etched, Er:YAG laser-irradiated and combined treatment on enamel surface. Angle Orthod. 2003 Oct;73(5):565-70.
- Basaran G, Hamamci N, Akkurt A. Shear bond strength of bonding to enamel with different laser irradiation distances. Lasers Med Sci. 2011 Mar;26(2):149-56.
- Walsh LJ, Abood D, Brockhurst PJ. Bonding of resin composite to carbon dioxide laser-modified human enamel. Dent Mater. 1994 May;10(3):162-6.
- Ozer T, Başaran G, Berk N. Laser etching of enamel for orthodontic bonding. Am J Orthod Dentofacial Orthop. 2008 Aug;134(2):193-7.
- Türköz C, Ulusoy C. Evaluation of different enamel conditioning techniques for orthodontic bonding. Korean J Orthod. 2012 Feb;42(1):32-8.
- Von Fraunhofer JA, Allen DJ, Orbell GM. Laser etching of enamel for direct bonding. Angle Orthod. 1993 Spring;63(1):73-6.
- Üşümez S, Orhan M, Üşümez A. Laser etching of enamel for direct bonding with an Er,Cr:YSGG hydrokinetic laser system. Am J Orthod Dentofacial Orthop. 2002 Dec;122(6):649-56.
- Roberts-Harry DP. Laser etching of teeth for orthodontic bracket placement: a preliminary clinical study. Lasers Surg Med. 1992;12(5):467-70.
- Martínez-Insua A, Da Silva Dominguez L, Rivera FG, Santana-Penín UA. Differences in bonding to acid-etched or Er:YAG-laser-treated enamel and dentin surfaces. J Prosthet Dent. 2000 Sep;84(3):280-8.
- Dunn WJ, Davis JT, Bush AC. Shear bond strength and SEM evaluation of composite bonded to Er:YAG laser prepared dentin and enamel. Dent Mater. 2005 Jul;21(7):616-24.
- Sawan MN, Hussain N, Alkurdi MM. Etching of enamel by laser energy for direct bonding of orthodontic appliance and evaluation of shear bond strength. Energy Procedia. 2015 Aug;74:1452–1458.
- Keller U, Hibst R. Experimental studies of the application of the Er:YAG laser on dental hard substances: II. Light microscopic and SEM investigations. Lasers Surg Med. 1989;9(4):345-51.
- Hess JA. Scanning electron microscopic study of laser-induced morphologic changes of a coated enamel surface. Lasers Surg Med. 1990;10(5):458-462.
- Sasaki LH, Lobo PD, Moriyama Y, Watanabe IS, Villaverde AB, Tanaka CS, et al. Tensile bond strength and SEM analysis of enamel etched with Er:YAG laser and phosphoric acid: a comparative study in vitro. Braz Dent J. 2008;19(1):57-61.