Scanning electron microscopy evaluation of the effect of etching agents on human enamel surface

Acid etching promotes microporosities on enamel surface, which provide a better bonding surface to adhesive materials. The purpose of this study was to comparatively analyze the microstructure of enamel surface after etching with 37% phosphoric acid or with two self-etching primers, Non-rinse conditioner (NRC) and Clearfil SE Bond (CSEB) using scanning electron microscopy. Thirty sound premolars were divided into 3 groups with ten teeth each: Group 1: the buccal surface was etched with 37% phosphoric acid for 15 seconds; Group 2: the buccal surface was etched with NRC for 20 sec-onds; Group 3: the buccal surface was etched with CSEB for 20 seconds. Teeth from Group 1 were rinsed with water; teeth from all groups were air-dried for 15 seconds. After that, all specimens were processed for scanning electron microscopy and analyzed in a Jeol 6100 SEM. The results showed deeper etching when the enamel surface was etched with 37% phosphoric acid, followed by NRC and CSEB. It is concluded that 37% phosphoric acid is still the best agent for a most effective enamel etch-ing.

1. Buonocore MG. A simple method of increasing the adhesion of acrylic filling materials to enamel surfaces. J Dent Res 34:849–53, 1955.

2. Kugel G, Ferrari M. The science of bonding: from first to sixth generation. J Am Dent Assoc 131:20–5, 2000.

3. Nakabayashi N, Pashley DH. Hybridization of Dental Hard Tissues. Quintessence Publishing Co Ltd., Tokyo, 1998

4. Swift Junior EJ, Perdigão J, Heymann HO. Bonding to enamel and dentin: a brief history and state of the art. Quintessence Int 26:95–110, 1995.

5. Silverstone LM. Variation in the pattern of acid etching of human dental enamel examined by scanning electron microscopy. Caries Res 9:373–87, 1975.

6. Gwinnett AJ. Histologic changes in human enamel following treatment with acidic adhesive conditioning agents. Arch Oral Biol 16: 731–8, 1971.

7. Miyazaki M, Hirohata N, Takagaki K, Onose H, Moore, BK. Influence of self-etching primer drying time on enamel bond strength of resin composites. J Dent 27:203–7, 1999.

8. VanMeerbeek B, De Munk J, Yoshida Y, Inoue S, Vargas M, Vijay P, Van Landuyt K, Lambrechts P, Vanherle G. Buonocore memo-rial lecture. Adhesion to enamel and dentin: current status and future challenges. Oper Dent 28:215–31, 2003.

9. Kanca III J. A method for bonding to tooth structure using phos-phoric acid as a dentin-enamel conditioner. Quintessence Int 22:285–90,1991.

10. Glasspoole EA, Erickson RL, Davidson CL. Effect of enamel pretreatments on bond strength of compomer. Dent Mater 17:402–8, 2001.

11. Toledano M, Osorio R, De Leonardi G, Rosales-Leal JI, Ceballos L, Cabrerizo-Vilchez MA. Influence of self-etching primer primer on the resin adhesion to enamel and dentin. Am J Dent 14:205–10, 2001.

12. Arana-Chavez VE, Massa LF. Odontoblasts: the cells forming and maintaining dentine. Int J Biochem Cell Biol 46:1367–1373, 2004.