Surface and mechanical properties of adhesives with calcium phosphates challenged to different storage media

Abstract

Aim: To evaluate the behavior of experimental dental adhesiveswith hydroxyapatite (HAp), alpha-tricalcium phosphate (α-TCP)or octacalcium phosphate (OCP) after storing them in threedifferent media: dry storage, distilled water, or lactic acid.Methods: An experimental adhesive resin was formulated withbisphenol A glycol dimethacrylate, 2-hydroxyethyl methacrylate,and photoiniciator/co-initiator system. HAp (GHAp), α-TCP(Gα-TCP), or OCP (GOCP) were added to the adhesive resin at 2wt.%, and one group remained without calcium phosphates tobe used as a control (GCtrl). The adhesives were evaluated forsurface roughness, scanning electron microscopy (SEM), andultimate tensile strength (UTS) after storing in distilled water(pH=5.8), lactic acid (pH=4) or dry medium. Results: The initialsurface roughness was not different among groups (p>0.05).GHAp showed increased values after immersion in water(p<0.05) or lactic acid (p<0.05). SEM analysis showed a surfacevariation of the filled adhesives, mainly for Gα-TCP and GHAp. GHApshowed the highest UTS in dry medium (p<0.05), and its valuedecreased after lactic acid storage (p<0.05). Conclusions:The findings of this study showed that HAp, OCP, and α-TCPaffected the physical behavior of the experimental adhesiveresins in different ways. HAp was the calcium phosphatethat most adversely affected the surface roughness and themechanical property of the material, mainly when exposed toan acid medium.

Keywords

• Dentin bonding agents
• Calcium phosphates
• Acids
• Polymers
• Tensile strength