Effect of Acidic Solutions on the Surface Degradation of a Micro-Hybrid Composite Resin

Abstract

Composite resins may undergo wear by the action of chemical substances (e.g., saliva, alcohol, bacterial acids) of the oral environment, which may affect the material's structure and surface properties. This study evaluated the effect of acidic substances on the surface properties of a micro-hybrid composite resin (Filtek Z-250). Eighty specimens were prepared, and baseline hardness and surface roughness (KMN0 and Ra0, respectively) were measured. The specimens were subjected to sorption (SO) and solubility (SL) tests according to ISO 4049:2009, but using different storage solutions: deionized water; 75/25 vol% ethanol/water solution; lactic acid; propionic acid; and acetic acid. The acids were used in two concentrations: PA and 0.02 N. pH was measured for all solutions and final hardness (KMN1) and surface roughness (Ra1) were measured. Data were analyzed with paired t-tests and one-way ANOVA and Tukey's test (a=5%). All solutions decreased hardness and increased the Ra values, except for the specimens stored in water and 0.02 N lactic acid, which maintained the hardness. All solutions produced similar SO and SL phenomena, except for the 0.02 N lactic acid, which caused lower solubility than the other solutions. Ethanol showed the highest pH (6.6) and the 0.02 N lactic acid the lowest one (2.5). The solutions affected negatively the surface properties of the composite resin; in addition, an acidic pH did not seem to be a significant factor that intensifies the surface degradation phenomena.

Physicomechanical characterization of polyetheretherketone and current esthetic dental CAD/CAM polymers after aging in different storage media

“…Since the latter cannot absorb water, higher matrix proportions can lead to filler-matrix debonding or even hydrolytic degradation. 4,5,32 In…”

“…[1][2][3] Polymer networks, in particular, tend to absorb water from the surroundings depending on their specific hydrophilicity and on the humidity of the mouth. 4,5 Potential deleterious effects may arise from pH changes due to cariogenic biofilms in the oral ecology, diet intake, and different enzymes. 6 This can lead not only to esthetic problems in terms of water absorption and discoloration but also to the mechanical weakening of the materials and decreased fracture resistance or increased wear.…”

“…These alterations can be explained by fluid absorption in the polymer matrix due to molecule polarity, especially within the first few days, leading to an overall imbalance between the intermolecular forces. 5,28 Martens hardness enables a physicomechanical characterization of the local mechanical properties of materials, including the elastic and plastic parts under different loading regimens. 29,30 Most of the available studies, however, only determined the reduced mechanical properties of resins after aging in artificial saliva, alcohol, and distilled water.…”

Water sorption, solubility and surface roughness of resin surface sealants

“…The increase of surface roughness results from the solubilization process, which in dental composites involves the lixiviation of non-converted monomers, oligomers, catalysts, silane and other by-products [20][21][22] . Furthermore, this process exposes and dislodges filler particles from the material's surface, contributing to a rougher surface in composites 21 .…”

“…Furthermore, this process exposes and dislodges filler particles from the material's surface, contributing to a rougher surface in composites 21 . Table 2.…”