Flexible materials "permanent" total prosthesis in which indications?

To forget the underside of a denture by means of a flexible material is an idea that seems sensible face some difficult clinical situations of total toothless. Indeed, it seems logical not to compress the lining between two hard structures, the prosthesis and the bone [1]. These flexible materials have been and are still subject to many misunderstandings, because if one side, they seem to solve, by their mere presence, most of the problems, on the other hand, some of their caractéristiquesireprésentent constraints that , if she is not taken into account, can lead to treatment failure. The purpose of this study is to fairele information on the use of these materials and possibly rehabilitate lesibases soft denture by demystifying. We propose a course of action (regardless of thetype of flexible base "always" used) both in terms of achieving that level of prosthetic laimaintenance and hygiene, eniessayant to have a more rational approach and most effective, because the most important is not to allow patients to recover a relevant social and personal life more harmonious?

the materials

The subject of this article concerneque flexible bases so-called "permanent" and in any case, the resins

Hydrocast delayed type-setting, Fitt ... The list of soft materials utilisésdans this study is not exhaustive but covers the four main families of products in the trade. Are:

Acrylic resins

These are polymethyl methacrylate "classic" soft parl'adjonction made of a plasticizer. It seems that this plasticizer evaporates and causes a hardening of the soft material in the short term [2]. However, these resins bind very well to the resin based rigid prosthetic since they are the same chemical nature. The implementation of the laboratory is easy. In this family, we find the Vertex (1), thermal polymerization, and Perform Soft (2), which is light-cured.

silicones

They are flexible in their chemical nature. They have non-stick properties vis-à-vis micro-organisms, but in return it is necessary to use an adhesive and a metal casting interface (mechanical connection) pourrelier the flexible material to the resin base: were used the Lutemoll (3), which is pressed and cured at high temperature (nearly 200 ° C), and Permaflex (4), which is pressed and cured at about 100 ° C.

Ethylene vinyl acetate (EVA)

They are thermoplastic materials containing antibacterial substances. They are flexible in

(1) Odoncia, 3, rue Michelet, 94853 Ivry-surSeine Cedex. Tel. : 01 46 58 06 96. Fax: 01 14 4672 81.

(2) Coltene Whaledent, 16, rue Louis Blanc, 93585 Saint-Ouen Cedex. Tel. : 01 40 November 02 47.Fax: 01 40 10 99 80.

(3) Bisico France, Opera, PO Box 60, 13680Lançon-de-Provence. Tel. : 04 90 42 92 92.Fax: 04 90 42 92 61.

(4) Kohler-Medizintechnik GmbH and Co KG, Danningen, 9, 78579 Neuhasem, Germany.

(5) Laboratories Mazeau Sari, France. (6) Hygienic Eudident-SA, PO Box 38, 95270Luzarches.

their chemical nature. Their connection to the rigid resin is reinforced by the use of an adhesive. The Flexital Plastulène (5) is the most famous member of this family. Its implementation requires specific equipment and technique (it is injected, hot, in press). It comes as a cartridge ready for use.

the fluoroelastomer

The fluoroelastomer, represented Novus speaks (6), is a semi-organic, it is the only one that is radiopaque. It contains fungicide and bacteriostatic substances. Binding to the rigid base is correct, but requires the addition of an adhesive for safety. This product is packaged as a pre-mixed. It is heat curable and requires the purchase of any new laboratory technique.

All these materials have similar mechanical descaractéristiques: they are flexible and all have a modulus of 4.2 MPa and a coefficient of 0.47 Poissonde [3]. This means they make in every case a shock absorber to reduce the energy from the shock of masticatory forces [4] and can, as D. Buch [5], considered "solutionsanti-trauma."

In all cases, the flexible material ideal does not exist, know their strengths and weaknesses will take Lemeilleur party (or least bad) of such material.

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