Insights on Ceramics as Dental Materials. Part II: Chemical Surface Treatments

Abstract

The purpose of surface treatment (conditioning) methods on dental ceramics is to improve the retention and bonding between the enamel or the dentin and ceramic veneer, with the help of resin composite luting cements. These types of surface treatments include chemically altering the surface of ceramics with some specific acidic etchants followed by applying a silane coupling agent (silane). The silane currently used in dentistry is 3-methacryloxypropyltrimethoxysilane, a hybrid organic-inorganic trialkoxy ester monomer, which is diluted in an acidified water-ethanol solvent system. Such silane primers are said to be pre-hydrolyzed. Some oxide ceramics with high crystalline content, such as alumina and zirconia, cannot be easily etched with acid etchants. They should be silica-coated and silanized prior to bonding. A silane coupling agent should be applied after silica-coating to the ceramic surface to achieve chemical bonding and the optimal durable bond strength.

Simplified Classification for Dental Ceramics

“…Then an adhesive or directly resin cement is applied depending on the type of cement. This division provides clinician orientation regarding the indication and way of cementation, with the glass ceramics being used for the more esthetic cases in the anterior region like thinner crowns, veneers, inlays, onlays and the oxide ceramics mainly used for crowns and bridges [8,9] ( Figure 5 and 6). …”

“…Adhesive cementation increases fracture resistance, measured by flexural strength [2]. This can be explained because the chemical and micromechanical bond between the ceramic surface and the tooth microstructure, permits this union to work as a unit [8]. Hydrofluoric acid or the recently introduced amoniumpolyfluoride creates an etching pattern by dissolving the superficial glass layer of mainly feldspathic ceramics, leucite or lithium disilicate reinforced ceramics.…”

“…Hydrofluoric acid or the recently introduced amoniumpolyfluoride creates an etching pattern by dissolving the superficial glass layer of mainly feldspathic ceramics, leucite or lithium disilicate reinforced ceramics. Accordingly, the smaller the glass phase, less effect of acid etching on the ceramic surface, being the case of InCeram ceramics, where Inceram Spinnelis etchable and InCeram Alumina has less interaction with the resin cement [8]. The acid creates pores, cleans the surface and increases the humectability, which allows the silane to infiltrate and create covalent bonding [8,9].…”

“…Accordingly, the smaller the glass phase, less effect of acid etching on the ceramic surface, being the case of InCeram ceramics, where Inceram Spinnelis etchable and InCeram Alumina has less interaction with the resin cement [8]. The acid creates pores, cleans the surface and increases the humectability, which allows the silane to infiltrate and create covalent bonding [8,9]. Silane is a coupling agent that allows two materials of different nature (organic cements with inorganic ceramics) to interact chemically by the creation of a silanol group, creating water as waste of the chemical reaction [2,7].…”

“…Silane is a coupling agent that allows two materials of different nature (organic cements with inorganic ceramics) to interact chemically by the creation of a silanol group, creating water as waste of the chemical reaction [2,7]. There is clear scientific evidence that proves the increase of bond strength between resin cements and ceramics with the use of silanes after the etching with hidrofluoric acid [7,8]. The second group of ceramics, the oxide ceramics, since they do not contain a glass phase, are not etchable and need a sandblasting procedure with aluminium oxide particlesof maximum 40 um at ideally no more than 1 bar of pressure.…”