Adhesive Restorations and the Oral Environmental Behaviour

Abstract

Adhesive restorations are based on the use of materials, which have the capacity to bond tooth effectively. This is possible due to a polymerizing hybrid layer interface created by the use of the Etch&Rinse (ERAs) and self-etching adhesives (SEAs). Bonding using ERAs include the acid-etching removal of the mineral phase from the substrates of enamel and dentine. A hybrid layer results by filling the voids left by minerals by means of adhesive monomers. However, etching dentine may result in too much demineralization and wetness with discrepancies in reinforcement at the bottom of hybrid layer. SEAs avoid the separate etching phase of ERAs using acidic functional monomers. In the two-step SEAs, hybridization is created by the application of a primer of different pH acidity, followed by an adhesive resin. In the 'One-Step SEAs', acidic and adhesive monomers are mixed in the same bottle thereby causing hybridization at the same time. 10-MDP mild SEAs represent the better bonding technology in dentistry due to the ability to form a strong chemical bond in tooth tissue. However, adhesive restorations have high vulnerability in the oral environment, which have been attributed to the esterase activity of Streptococcus mutans and hydrolysis by matrix metalloproteinase.Despite the great evolution, dental adhesive restorations need to be improved in an effort to obtain stable restorations within the oral environment.Even if, enamel etching by ERAs can represent the gold standard in enamel bond strength, at the same time, etching dentine may leave exposed and non-reinforced fibrils with all the consequences related to.The 10 MDP technology of mild SEAs has been suggested as the better bonding technology due to the capacity of increasing the resistance to biological breakdown of adhesion.However, modification of the resin materials is necessary to antagonize infiltration of salivary fluids and proteins, which are the causes of hydrolysis, particularly by the esterase activities of S. mutans and by MMPs.

Efficiency of desensitizing materials in xerostomic patients with head and neck cancer: a comparative clinical study

“…It can be assumed that the generally more aggressive oral environment in xerostomic patients may influence the clinical effectiveness of all desensitizing agents, though to a different extent and in different ways. This assumption can be related to the demineralizing effect produced by the acidic biofilm at the gingival margin between the restoration and the tooth [13],…”

“…Although this reaction is expected to be relatively slow at neutral pH values, variations in pH may lead to transient acid or base catalysis [45]. It may be possible that the acidic environment in group A may have caused faster degradation of local domains of the methacrylate network by S. mutans [13] in the acidic biofilm with the release of esterase enzymes, which greatly accelerate ester bond hydrolysis [47,48]. These events may have led to on-going destruction of the sealing capacity of VF in Group A, which compared with the normal-salivary group B, had higher recurrent sensitivity at POST-3 and POST-4.…”

“…The health-associated microbial population is significantly altered, and a more acidogenic and cariog e n i c p o p u l a t i o n o f S t re p t o c o c c us m u t a n s a n d Lactobacillus spp., in addition to Candida albicans, arises [3,9]. In such a situation, S. mutans is particularly aggressive, leading to severe and recurrent caries [10,11] due to the bacterial ability to attack the vulnerable resin interface between a restoration and the tooth, as well as esterase activities [12,13]. Xerostomic patients may also experience dental hypersensitivity (DH).…”

Long-term water sorption/solubility of two dental bonding agents containing a colloidal dispersion of TiO2

“…While solubility of dental bonding agents is defined as the hydrolytic degradation of bonding agents' monomers in the presence of water, which is caused by a chemical reaction with water that can break the covalent bonds between polymer networks, resulting in the loss of monomer mass, which has an adverse effect on the mechanical properties and stability of the resin polymer network. 5 Titanium dioxide (TiO2) is a trace element with a high refractive index. TiO2 is also a chemically resistant substance that is thermally stable.…”

Long-term water sorption/solubility of two dental bonding agents containing a colloidal dispersion of titanium dioxide

“…While solubility of dental bonding agents is elucidated as the hydrolytic degradation of bonding agents' monomers in the presence of water, which is caused by a chemical reaction with water that can break the covalent bonds between polymer networks, resulting in the loss of monomer mass, which has an adverse impact on the mechanical characteristics and stability of the resin polymer network. [ 5 ]…”