Articles
Total Impaction of Deciduous Maxillary Molars: Two Case Reports

Introduction

Dental adhesives have been used in several clinical conditions especially to improve the retention strength of restorations and to prevent microleakage. Initially multi-bottle, total-etch adhesive systems were used. Now simplified adhesive systems, such as total-etch and self-etch systems, have been introduced.1-5

The adhesive luting of prefabricated fiber-reinforced composite (FRC) posts has been considered mandatory in order to optimize the pull-out strength of these posts. The clinical performance of a prosthetic restoration with a fiber post depends on several factors6 such as: the type of the post material, shape, dimension, and length;7-10 the quality and quantity of remaining dentin;11-12 the type of adhesive and cement used; and the adaptation of the post inside the root canal.13-14

However, the resin bond to root dentin is problematic as the bond strength can be affected by some factors as follows:

  1. The dentin substrate provides a lower hybridization potential.15,16
  2. There is a higher configuration factor in root canals (high polymerization stress of resin cements),17,18 and the bond to root canal dentin appears to be attributed to friction resistance.19
  3. It is difficult to perform light curing inside the root canal.14,20
  4. There may be chemical incompatibility between the adhesive system and resin cement.21-27

Some studies have indicated a probable chemical incompatibility between adhesive systems with low pH and resinous materials of chemical- and dual-polymerization.21-27 A correlation was observed between the decline in microtensile bond strengths of chemical-cured composites coupled to bonded dentin and the acidity of these adhesives.23 Another study21 evaluated the experimental application of an additional hydrophobic adhesive layer on the crown dentin after a self-etching primer was used for adhesive luting. The authors noted this additional resin layer significantly improved the bond strength by 35%, mainly due to the decrease in the pH of the surface contacting the resin cement.

Thus, the aim of this study was to evaluate the push-out bond strengths of a multi-bottle and three simplified adhesive systems to bovine root dentin. The hypothesis was the experimental application of an additional layer of a non-acidic low-viscosity hydrophobic bonding resin improves the bond strength of the all-in-one adhesive.