Basic Properties of Self- and Total-Etch Adhesives

Author : Dental Product Shopper
Published Date 09/21/2011
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Basic Properties of Self- and Total-Etch Adhesives

Selective etch technique enables esthetic restorations

While total-etch adhesive systems have a track record of more than 12 years,1,2 self-etch adhesives have won favor with many dentists due to their simple technique and reduced risk of post-operative sensitivity. Some data show that self-etch systems produce just half as much post-operative sensitivity as total-etch products, although data suggest that the sensitivity seen with total-etch adhesives, which involve multiple steps, depends on clinical technique3,4,5,6 Thus, while total-etch systems have accumulated more years of data, self-etch adhesives offer a compelling, patient-friendly advantage.

To understand why this is, a review of the properties of both types of systems is necessary. Total-etch systems use a phosphoric acid step to demineralize tooth surfaces. The acid helps create porosities in enamel, into which the adhesive can penetrate. On dentin, the acid etch removes the smear layer and exposes collagen fibers, allowing the adhesive to penetrate and interlock with the fibers. However, when using total-etch systems, dentists must take care not to over-dry the surface, which causes the collagen fibers to collapse. If primer and adhesive are applied to these collapsed fibers, instead of infiltrating into upright collagen fibers, the result can be poor adhesion and post-operative sensitivity.7

Due to the fact that self-etch adhesives simultaneously etch and prime, there is a reduced risk of these problems. The material is designed to surround the collagen fibers in the dentin, enabling it to create a hybrid layer on wet or dry surfaces. One-bottle self-etch systems typically combine hydrophilic and hydrophobic agents in the same bottle, with pH levels ranging from 1.0 to 2.7.8 The lower acidity seen with self-etch adhesives works well in the case of restorations on dentin, as it reduces the risk of over-etching and post-operative sensitivity. However, the performance of these adhesives on enamel can be less impressive. Due to this, selectively etching enamel surfaces is recommended when using 7th generation materials on uncut enamel surfaces. Many dentists also utilize this technique on prepared enamel surfaces.

By first applying a 35% phosphoric acid to enamel margins, clinicians can help create a stronger bond to the enamel when using a self-etch material. Applying the etchant only to the enamel areas results in a localized deep etch, allowing the dentist to maintain the benefits of the self-etch adhesive on dentin. Furthermore, this technique can also help create a more natural looking, discreet enamel margin for the restoration.

Fig. 1: Tooth presenting with a fractured amalgam restoration on the first molar.
Fig. 2: The tooth was isolated and prepared.
Fig. 3: Phosphoric acid was applied to the enamel margins for 15 seconds.
Fig. 4: The phosphoric acid was rinsed off and the tooth dried, leaving etched enamel margins.
Fig. 5: 3M? ESPE? Adper? Easy Bond Self-Etch Adhesive was brushed on all surfaces for 20 seconds and gently air dried for 15 seconds.
Fig. 6: The adhesive was light cured with the 3M? ESPE? Elipar? Freelight 2 LED Curing Light for 10 seconds.
Fig. 7: 3M? ESPE? Filtek? Supreme Plus Universal Restorative was placed in 2mm increments, with each increment light cured for 20 seconds.
Fig. 8: The final restoration: immediately after placement.
Fig. 9: Three years following its initial placement, the restoration continued to show natural esthetics and an imperceptible margin.

This article was written  by Dr. Cristiana Godoy Sartori Azevedo and Dr. Mario Fernando de Goes of the Dental School of Piracicaba ? University of Campinas, São Paulo, Brazil.



1. Wilder A.D., Jr., et. al. A 12-Year Clinical Evaluation of a Three-Step Dentin Adhesive in Noncarious Cervical Lesions. J Am Dent Assoc. 2009 140(5): 526-535.

2. van Dijken J. W. V.; et. al. Clinical long-term retention of etch-and-rinse and self-etch adhesive systems in non-carious cervical lesions: A 13 years evaluation. Den Mater 2007; 23(9):1101-7. CRA Foundation. Self-etch primer (SEP) adhesives update.

3. CRA Foundation Newsletter. 2003;27(11/12):1-5.

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5. Perdigão J, Geraldeli S, Hodges JS. Total etch versus self-etch adhesive: effect on postoperative sensitivity. JADA 2003;134:1621-9.

6. Swift EJ Jr. Dentin bonding: what is the state of the art? Compend Contin Educ Dent. 2001;22(12 supplement):4-7.

7. Perdigão J.; Carmo A. R. P.; Geraldeli S. Eighteen-month clinical evaluation of two dentin adhesives applied on dry vs moist dentin. J Adhes Dent. 2005;7(3):253-8.

8. Feuerstein O, Matalon S, Slutzky H, Weiss EI. Antibacterial properties of self-etching dental adhesive systems. JADA. 2007; Vol. 138: 349-354.