Influence of the Number of Layers of a One Bottle Adhesive on the Longevity of Composite Restorations in Primary Molars

• Survival rate [ Time Frame: 06, 12, 18, 24, 30 and 36 months ] [ Designated as safety issue: No ]
  Survival rate considering failure of restorations due: partial or complete loss of restorative material; marginal ditching; superficial or marginal discoloration; secondary caries; pulpal complications; wear of restorative material; tooth fracture.
  
  

• Marginal adaptation [ Time Frame: 06, 12, 18, 24, 30 and 36 months ] [ Designated as safety issue: No ]
  Evaluation of resin replicas of restored teeth on scanning electron microscopy (SEM)
  
  

Adhesive systems based on total etch technique remains the most popular products among dental practitioners. These systems are based on the use of an acid conditioner to remove the smear layer and demineralize the enamel and dentin. After the removal of the conditioner by rinsing, a mixture containing the primer and adhesive - i.e. one bottle adhesives - is applicated over the demineralized tissues. The polymerization of the adhesive monomers into microporosities created by acid conditioning forms the structure knowing as hybrid layer or resin-dentin interdifusion zone. A common problem related to total etch technique is the incomplete infiltration of adhesive monomers through demineralized dentin, resulting in the presence of a zone of unprotected collagen fibrils beneath the hybrid layer that is prone to enzymatic degradation. According to some laboratory studies, consecutive application of multiple adhesive coats results in quantitative and qualitative improvements in dental adhesion. In addition to increasing the values of bond strength to dentin, consecutive application of multiple adhesive layers enhances the infiltration of adehesive monomers through demineralized dentin, resulting in a more homogenous hybrid layer.