Etching Patterns of Self-Etching Primers in Relation to Shear Bond Strength on Unground Enamel Samples.

Lorenz Brauchli,Markus Steineck

doi:10.3390/dj9110138

Abstract

It was the intention of the study to evaluate the etching effects of several self-etching primers on unground enamel and their relevance for shear bond strength testing. Seven self-etching primers (Clearfil SE, Futurabond NR, M-Bond, One Coat, Optibond, Transbond SEP+, Xeno III) and a conventional 35% phosphoric gel acid were applied to bovine incisors according to the manufacturer’s instructions. All specimens were analyzed by electron microscopy. A visual four-step grading was used for the characterization of the macroscopic (5000×) and microscopic (20,000×) etching patterns. In addition, shear bond strength for all the products was tested with an Instron 3344 after 1000 thermocycles between 5 °C and 55 °C. Statistical analysis was carried out using Kruskal–Wallis with Dunn’s post-test and Pearson’s correlation coefficient. Very strong etching patterns with well-defined prisms were found for the conventional etching, Transbond SEP+, and to a lesser degree, for Xeno III. Clearfil SE and Futurabond NR revealed moderate etching patterns, and M-Bond, One Coat, and Optibond revealed very weak etching patterns. The bond strength correlated well with the etching patterns. The highest shear strength was obtained with conventional etching and Transbond SEP+, followed by Clearfil SE. Moderate shear bond strengths were found for Xeno III, Futurabond NR, One Coat, and M-Bond, and the lowest were found with Optibond.

Highlights

Since its introduction in orthodontic practice by Newman in 1965 [1], adhesive technologies today are essential in orthodontic therapy
Very strong etching patterns with well-defined prisms were found for the conventional etching, Transbond SEP+, and to a lesser degree, for Xeno III
It has been documented that conventional etching with a 35% phosphoric acid for 15–60 s leads to a well-defined etching pattern with dissolution of interprismatic material [5]

Summary

Introduction

Since its introduction in orthodontic practice by Newman in 1965 [1], adhesive technologies today are essential in orthodontic therapy. Since the mechanical interlocking of the bonding monomers to the enamel surface plays a major role in determining adhesive strength [2,3,4], etching is a crucial stage in the bonding procedure. Self-etching primers on the other hand react differently. They dissolve the enamel, and simultaneously, the monomer penetrates the retentive relief to the same depth. The etching is buffered by the dissolved substrate. This method is a simplified technique with a reduced potential for contamination. There is no consensus on the suitability of self-etching primers for the use on unground enamel

Methods

Results

Discussion

Conclusion