SLEPOCHNY MATERIALS — the supporting materials applied in orthopedic stomatology to receiving molds, i.e. negative display of a prosthetic bed (teeth and jaws). Sometimes molds call prints, and materials — impression. On a mold afterwards create model (positive display of a prosthetic bed), with the help make a cut dentures (see).
Accuracy of a mold depends generally on quality of slepochny material, to-ry shall have the following properties: small shrinkage, plasticity at the time of introduction to an oral cavity to harden in an oral cavity in the conditions of the increased humidity and temperature, it is easy to be entered into an oral cavity and to be removed from it, to precisely reproduce a surface of a prosthetic bed and not to be deformed at removal of a mold from an oral cavity, not to make harmful effects on a mucous membrane of an oral cavity, and also not to have off-flavor and taste, to keep the main properties at sterilization, it is easy to separate from material, from to-rogo make models, not to change the qualities at long-term storage.
Attempts of creation of universal S. of the m meeting all listed requirements were not crowned with success. Therefore for receiving qualitative molds it is necessary to have the sufficient range of sle-pochny materials, it is correct to choose and apply them in each case.
Distinguish hard, elastic and thermoplastic slepochny materials.
Hard slepochny materials
carry To them gypsum (see) and dentol. Gypsum is used for receiving molds at production of crowns, an intermediate part of bridge-like, byugelny, plastinochny prostheses at a partial and full edentia, etc. However molds from gypsum have a number of shortcomings: at removal of a mold from an oral cavity it should be broken then it is not always possible to compare fragments precisely; there is a danger of aspiration of pieces of gypsum, especially in pediatric practice; at removal of a plaster cast together with it removal of mobile teeth is possible. All this limits use of gypsum as S. to m
Dentol represents high-quality S. of m on the basis of a tsin-koksidevgenol or guaiacol. It is almost nonshrinking material, at removal from an oral cavity is not deformed, is harmless. Thanks to these properties of a dentol with its help it is possible to remove very exact molds not only from teeth, but also from soft tissues. Dentol apply to receiving molds from toothless jaws. The quality mold from a dentol can be received only on rigid individual slepochny spoons at a small thickness (2 — 3 mm) of S.'s layer of m. The mold hardens in an oral cavity within 2 — 5 min. then it is deleted. If repeatedly to apply paste on a surface of the hardened mold, then during the hardening she well unites to an initial layer that allows to make a repeated mold for the purpose of correction. The mold can be stored a long time, without changing the volume and a configuration. In the USSR was widely used ^слепоч-ный material on the basis of a tsinko-ksidevgenol — Repin, released in ChSSR.
Elastic slepochny materials
carry hydrocolloid, alginate, silicone and thiokol S. To them of m. Hydrocolloid S. m represent elastic compositions on the basis of an agar. For giving of bigger durability enter fillers into structure of slepochny weight. During the heating hydrocolloid S. m become plastic, and during the cooling gain elastic properties again. They accurately recreate a relief of a surface of a prosthetic bed, but because of a number of negative properties (long preparation for use, big shrinkage) of a wide spread occurance did not find. They are applied, generally at duplication of the models used for production of byugelny prostheses.
M receive alginate S. on the basis of sodium alginate. Treat them algelast, stomalgin, novalgin. Alginate S. in m have high elasticity, well reproduce a relief of a surface of a prosthetic bed, are simple in use. M do molds for production of prostheses at a partial edentia of alginate S., in the presence of mobile teeth, etc. The mold is received on a perforated spoon since slepochny weight lags behind a usual spoon. Alginate S. m give big shrinkage therefore models need to be cast not later than in 15 min. after receiving a mold. The alginate mold very easily separates from model. Pages of m on the basis of sodium alginate gained distribution in many countries: in ChSSR release an elastic, in GDR — kaltsinat etc.
Silicone S. m represent liquid polymer, to-ry during the mixing with the corresponding catalyst (hardener) turns into elastic rubber. Treat them sielast PS, sielast 03. M apply silicone S. at production of porcelain crowns, tselnolity bridge-like, byugelny, ceramic-metal prostheses, and also during creation of plastinochny prostheses at a full secondary edentia. They are used also for receiving the so-called two-layer molds which are well reproducing a relief of fabrics of a prosthetic bed. Silicone S. of m shrink in 3 hours therefore the model needs to be cast no later than this time. Molds from model are removed easily.
M receive thiokol S. on the basis of thiokol polymers, they are used in the same cases, as by silicone S. of m. Thiokol S.' representative of m is tio-dent — almost nonshrinking material. Qualitative molds from a tiodent turn out only with a sufficient pressure therefore apply rigid individual spoons and take a small amount of S. of m
Thermoplastic slepochny materials
carry To them stens, akrodent, thermoplastic masses No. 1, 2, 3, 4, 5, hundred-maplast, an ortokor, dentafol, having various softening point. M before the use soften thermoplastic S. in hot water. All thermoplastic S. of m during the cooling shrink, and at removal from an oral cavity are deformed. Besides, thermoplastic S. m change the qualities over time. Stens and akrodent found the greatest application in pediatric practice. Masses No. 1, 2, 3, 4, 5 uses for receiving non-working models, primary molds for production of individual slepochny spoons, tabs, portion crowns.
Ortokor — the slepochny material which is not hardening in an oral cavity. It is applied to specification of borders of prostheses top and bottom toothless jaws, and also to receiving functionally sticking molds at the expressed atrophy of alveolar shoots. Molds from orthobark receive under the influence of force developed by masseters. This material is used also at production of two-layer prostheses. The two-layer basis differs from usual in the fact that its surface, adjacent to a prosthetic bed, is made of the elastic material covering basis from hard plastics.
Dentafol — composition on the basis of vegetable pitches. It is intended for receiving functionally sticking molds at a full edentia. The prostheses made on such molds have expanded borders and are well fixed on a jaw.
See also Polymeric materials .
Bibliography: Gerner M. M., etc. Fundamentals of materials science on stomatology, M., 1969; N ap ad M. A. and Sapozhnikov A. JI. Prosthetics of patients with total absence of teeth, page 90, 149, Kiev, 1972; Napadovm. And., Sapozhnikov A. L. and I" e district of e r M. M. Materials for prosthetics in stomatology, Kiev, 1978; The Guide to orthopedic stomatology, under the editorship of A. I. Evdokimov, page 76, M., 1974; Anderson J. N. Applied dental materials, Oxford a. o., 1976; Goldberg A. J. Viscoelastic properties of silicone, polysulfide, and polyether impression materials, J. dent. Res., v. 53, No. 5, pt 1, p. 1033, 1974; Stomatologische Werk-stoffkunde, hrsg. v. A. Breustedt u. E. Lenz, Lpz., 1978; Von Fraunhofer J. A. Scientific aspects of dental materials, L. — Boston, 1975.
A. P. Voronov.