Dental Tribune United Kingdom Edition

About the author Georgi Tomov, Department of Opera- tive dentistry and endodontic, Faculty of Dental Medicine, Medical Univer- sity, Plovdiv, Bulgaria. Assist. Prof. Dr. Georgi Tomov, Faculty of Dental Medi- cine, Department of Operative dentist- ry and endodontic, 3 Hristo Botev str, 4000 Plovdiv, Bulgaria e-mail: stoma- tolog79@ abv.bg 27ClinicalFebruary 14-20, 2011United Kingdom Edition on Er: YAG lasers 9 , 10 , but with- out thermic degenerated surfac- es, areas of extensive recrystalli- sation, melted surfaces or cracks in the dentin, as described in some in vitro studies.3,4,5 It is also reported for better opportunities for adhesive bonding,11 faster ablation of enamel and dentin compared with rotating burs 12 and an increase in dentinal mi- crohardness after treatment with Er: YAG pulsed lasers. 13 The lat- ter statement is not confirmed by other studies. The marked surface irregularities and lack of smear layer observed in the recent study, noted also in other researches 14, 15 provide a solid evidence for the physical mecha- nism of bonding with composite materials after laser treatment.11 This fact is not yet fully explored as a possible opportunity to elim- inate acid etching of hard dental tissues and its related adverse effects on the underlying dentin and pulp. The results of some contem- porary studies showed that de- spite of the differences between individual authors, generally the amount of smear layer after treatment with Er: YAG laser in all cases is less than that after conventional rotating instru- ments, and surface changes are characterised by markedly rug- ged topography.2, 3, 12, 15 The morphological fea- tures of hard dental tissues ob- served in our study suggested us to generalise that cavity prep- aration with Er: YAG laser is consistent with the principles of minimally invasive prepara- tion, leaving clean surfaces and strong microretentions suit- able for adhesive restorations. These assumptions about the benefits of alternative techniques for minimally invasive prepara- tion of dental tissues for adhe- sive restorations should be con- firmed in future clinical studies. Conclusion SEM analysis of hard dental tis- sues treated with steel and dia- mond burs showed surfaces cov- ered with a thick layer of debris, which could compromise the ad- hesion of filling materials. Den- tal tubules orifices are obturated with debris, with exception the areas under water turbulence where the debris is partially re- moved. All laser-treated samples showed no evidence of thermal damageorsignsofcarbonification and melting. The SEM exami- nation revealed characteristic micro-irregularities of the lased dentin surface without smear layer, and opened dentinal tu- bules. Intertubul dentin is ablated more than peritubu- lar dentin and that made the dentinal tubules appearance more prominent. Er:YAG laser ablated enamel effectively and remained exposed enamel prisms without debris. The sur- faces are very retentive. The author declares not hav- ing any financial interest in a company (or its competitor) that makes a product discussed in the article or any conflicts of interest. DT References: 1. Banerjee, A. Watson TF, Kidd EA. Dentine caries excavation: a review of current clinical techniques. Br Dent J 2000;188(9):476-82. 2. Yazici, A.R. Ozgunaltay, G. Dayangac, B. A scanning electron microscopic study of different caries removal techniques on human dentin. Operative Dentistry 2002;27:360–6. 3. Stefanovic, M. Skenirasch electronically - mikroskopski analysis Efektim from vzdeystvieto on Er: YAG laser and konventsionalniya method vrhu dentin. KFOR and the NUS 2005; 4(1): 153 – 156 4. McCormack, S.M. et al. Scanning electron microscope observations of CO2 laser effects on dental enamel. J Dent Res 1995;74:1702–8 5. Palamara, J. et al. The effect on the ultrastructure of dental enamel of excimerdye, argonion and CO2 lasers. Scanning Microsc 1992; 6:1061–71 6. Li, Z.Z. Code, J.E. Van De Merwe, W.P. Er:YAG laser ablation of enamel and dentin of human teeth: determination of ablation rates at various fluences and pulse repetition rates. Lasers Surg Med 1992;12:625–30 7. Park, N.S. Changes in Intrapulpal Temperature After Er:YAG Laser Irradiation. Photomedicine and Laser Surgery. 2007, 25:229-232 8. Eguro, T. et al. Energy output reduction and surface alteration of quartz and sapphire tips following Er:YAG laser contact irradiation for tooth enamel ablation. Lasers in Surgery and Medicine. 2009; 41:595-604 9. Eberhard, J. et al. Cavity size difference after caries removal by a fluorescence-controlled Er:YAG laser and by conventional bur treat- ment. Clin Oral Investig 2008;12(4):311-8. 10. Matsumoto, M. et al. Morphological and Compositional Changes of Human Dentin after Er:YAG Laser Irradiation. J Oral Laser Applications 2003; 3:12 – 20 11. Ceballos, L. et al. Bonding to Er-YAG-laser-treated dentin. J Dent Res 2002;81(2):119-22. 12. Baraba, A. et al. Ablative Potential of the Erbium–Doped Yttrium Aluminium Garnet Laser and Conventional Handpieces: A Comparative Study. Photomedicine and Laser Surgery. 2009, 11:465-504 13. Chinelatti, MA. et al. Effect of erbium:yttrium– aluminum–garnet laser energies on superficial and deep dentin microhardness. Lasers Med Sci. 2008, 34:135-140 14. Raucci-Neto, W. Chinelatti, MA. Palma-Dibb, R.G. Ablation Rate and Morphology of Superficial and Deep Dentin Irradiated with Different Er:YAG Laser Energy Levels. Photomedicine and Laser Surgery. 2008, 26:523-529 15. Kinoshita, J. Kimura, Y. Matsumoto, K.Comparative study of cari- ous dentin removal by Er,Cr:YSGG laser and Carisolv. J Clin Laser Med Surg. 2003 21:307-15. 16. Banerjee, A. Kidd, E.A.M. Watson, T.F. Scanning electron microscopic observations of human dentine after mechanical caries excavation. Journal of Dentistry 2000;28:179–86. Figs 2 a, b: Laser treated dentin. The surface is clean and free from debris, all dentinal tubules were found open. The surface is irregular, rough, which creates strong retentions. At greater magnification more effective removal of intertubular dentin is seen, and that makes dentinal tubules orifices to appear convex (Magnification x 500, 2000). 2a 2b Fig 2 c: Enamel treated with Er: YAG laser revealed characteristic surface which is very retentive and free from contaminants and smear layer (Magnification x 2000). Figs 3 a, b: Smooth and thin smear layer covers tooth surfaces prepared with diamond burs and air turbine. In the area of water turbulence partially removed contaminants and single dentinal tubules lumena were observed. (Magnification x 500, 2000). 3a 3b 4a 4a Figs 4 a, b: SEM photomicrographies of tooth surfaces prepared with steel burs. The sur- face is covered with a layer of debris, dentinal tubules orifices are not visible. (Magnifica- tion x 500, 2000)