Microretention
By means of microretention ( Greek μικρός mikrós 'small', Latin retinere ' to hold back') an adhesion of materials for the attachment of tooth restorations ( crowns , fillings ) to the tooth enamel can be created. The bonding of the composite filling material to the tooth enamel can be achieved through the preparatory step of an enamel etching. The process itself is called acid-etching technology (SÄT). Microretention increases the tightness of a filling considerably. It only led to the justifiable use of plastics in restorative dentistry.
Systematics
Microretention is achieved as follows:
- Conditioning with phosphoric acid : Etching the tooth enamel for 30–60 seconds with 30–40% phosphoric acid creates an ideal surface morphology , which is created by the different acid solubility of the enamel prisms in the center and in the periphery of the tooth. The etching process irreversibly removes approx. 10 μm of the enamel surface and creates a surface roughness of up to 50 μm underneath , the so-called etching pattern, which is characterized by a high surface energy and thus increases the wettability of the enamel.
- Wetting : Because the composite material to be applied is very viscous due to the high filler content, it is necessary to coat the surface roughened by the acid with a thin, unfilled or low-filled monomer mixture beforehand. These monomers get more easily into the etched pattern, "wedge" themselves there as a result of the subsequent polymerisation and thus enable an intimate interlocking of polymer and tooth enamel.
- Melt bond : The actual melt bond (polymerization) is achieved using functional adhesives, for example with monomers based on bisphenol glycidyl methacrylate ( BisGMA ), possibly diluted with triethylene glycol dimethacrylate ( TEGDMA ). The adhesion is built up via so-called tags (plastic pins) and intergranular retention.
- Oxygen inhibition : Due to the diffusion of oxygen molecules react in the uppermost layer of enamel adhesives radicals that would be required for the polymerization of the enamel adhesives, with the oxygen atoms . As a result, the top layer is only partially cured and what is known as an oxygen inhibition layer remains on the surface of the enamel adhesive . This layer enables the filling composites to create a chemical bond with the enamel adhesive, since when the composites harden, radicals diffuse into the oxygen inhibition layer of the enamel adhesives and also lead to polymerization of the remaining monomers.
Due to the process, draining, rinsing and drying are among the necessary work steps before the actual composite filling can be placed. The polymerization takes place by light curing using a polymerization lamp . If necessary, a dentine-adhesive cementation should also be carried out.
See also
Individual evidence
- ↑ MG Buonocore: A simple method of increasing the adhesion of acrylic filling materials to enamel surfaces. In: Journal of dental research. Volume 34, Number 6, December 1955, pp. 849-853, PMID 13271655 .
- ↑ Stephan Hinz, Comparison of the marginal qualities of composite fillings, inserts and adhesive inlays in extensive posterior tooth cavities before and after stress tests , dissertation 2006. P. 21. Accessed on August 4, 2015.
- ↑ L. Castagnola, J. Wirz and R. Garberoglio: Enamel etching for conservative dental treatment. In: Swiss monthly journal for dentistry = Revue mensuelle suisse d'odonto-stomatologie / SSO. Volume 85, Number 10, October 1975, pp. 975-1011, PMID 1103283 .
- ^ R. Frankenberger, D. Heidemann, HJ Staehle, E. Hellwig, U. Blunck and R. Hickel, DGZ expert opinion on adhesive technology , German Dental Association . Retrieved August 4, 2015.
- ↑ Karl-Heinz Kunzelmann, composite restorations in the anterior tooth area ( memento of the original from September 23, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. . Retrieved August 4, 2015.
