RU2122365C1 - Method of treating maxillofacial area defects - Google Patents

Abstract

FIELD: stomatology. SUBSTANCE: as polymer material, porous sulfone and octacalcium phosphate-maleic acid composite are used. Composite is capable of maintaining optimum content of calcium and phosphorus in implant structure for a long time and stimulating regeneration processes. EFFECT: stimulated regeneration in adjacent tissues.

Description

 The invention relates to medicine, namely to maxillofacial surgery, and can be used to repair defects of various etiologies and localization.

 In maxillofacial surgery, implants made on the basis of polymer materials are widely used. It is known to use silicone rubber for the manufacture of prostheses when replacing defects in soft tissues of the face [1]. These prostheses have good soft elastic properties, have sufficient mechanical strength, but the implant manufacturing process takes a lot of time, and the prosthesis itself (low molecular weight silicone in a high molecular weight shell) cannot be machined. Moreover, the manufacture of implants to replace defects of small sizes is extremely difficult. Most implants made on the basis of acrylic polymers [2] contain numerous additives that can be irritating.

 Known implants made of metal with a different polymer coating [3]. These prostheses are highly durable, but difficult to manufacture, have a large weight, and in addition, are not subjected to mechanical processing.

 To restore defects in the maxillofacial region, the use of hydroxylapatite implants is known [10]. The disadvantages of this method are the rather labor-intensive manufacturing technology of such prostheses, as well as low mechanical strength.

 In addition, hydroxylapatite in the form of biogenic paste was used to induce regenerative processes of bone tissue in the area of dental implants [6].

 It was also established that hydroxylapatite placed in the hole of the extracted tooth causes an increase in the proliferative activity of connective tissue, bone and bone marrow cell elements [8].

 However, it is known that hydroxylapatite itself is a fairly stable compound and has been utilized in the body for quite a long time. In addition, this compound begins to pass in ionic form at pH <6.0, which may adversely affect the adaptation of endoprostheses in the wound.

The use of the octacalcium phosphate composite compound with organic acid is known [Ca ₈ (PO ₄ ) ₄ (HPO ₄ ) _2-Z (C ₄ H ₂ O ₄ ) _Z mH ₂ O; Z is 0.1; m = 5-7] in order to stimulate reparative ostegenesis in the treatment of bone fractures [4]. When using maleic acid, a crystalline form is formed with the parameters: Z = 0.44; m = 6.5; Ca: P = 1.44; D = 19.2 A ^o . In the postoperative period, the pH of the wound> 7.0, so the wound process will proceed more favorably if lower prostheses are used. The indicated complex easily passes into a more soluble form at pH <7.0, therefore, it is more easily and quickly disposed of by the body. However, the rapid dissolution of its tissue fluid does not allow to prolong this process.

 It is known to use polysulfone in the manufacture of plates in the form of solid cast implants for fixing fragments during the treatment of fractures of long tubular bones [8]. There is evidence of the use of polysulfone to restore the crest of the alveolar ridge in experimental animals [9]. However, in all the above cases, a monolithic polymeric material was used that does not have a volume-porous structure.

 The closest technical solution (prototype) is a medical implant made of silicone elastomer with open cells [4]. This material is obtained by applying a layer of silicone elastomer to the outer surface of the implant. Before the end of polymerization, particles of a certain size and shape are introduced into this layer, which are removed in a subsequent solvent inert with respect to the elastomeric base.

 The disadvantages of this material are a long, multi-stage manufacturing process, requiring a large amount of silicone rubber; impossibility of machining; the presence of open cells only on the surface, which excludes the prosthesis from invading the tissue during implantation. In addition, the use in the manufacturing process of chemical compounds (catalysts and initiators during the polymerization of the surface layer, monomer impurities, solvent), the residual amounts of which may further irritate the surrounding tissues.

 The aim of the present invention is the creation of a biologically inert, porous, light, uniformly dispersed throughout the volume of the implantation material, which could be easily machined, ensured that surrounding tissues can grow into the prosthesis material and has the ability to saturate damaged tissues with calcium and phosphorus ions for a long time and way to stimulate regenerative processes in the surrounding tissues.

 The essence of the invention is the use of a dispersion implant based on polysulfone and a composite compound of octacalcium phosphate with maleic acid (hereinafter the composite), as a regulator of regenerative processes.

The prosthesis material is obtained by foaming a solution of polysulfone in an inert solvent, for example, chloroform and a composite in the form of a 50% additive by weight of the polysulfone by heating at 110-130 ^o C to obtain a uniform porosity and distribution of the composite sample for 60 minutes in the form of a given configuration and volume .

 The choice of components and their ratio are due to the following.

 Polysulfone is a biologically inert material with high chemical resistance and good strength characteristics [8]. The higher content of polysulfone in the composition does not make it possible to obtain a uniformly dispersed structure. A lower concentration of this component leads to the formation of pores with a larger diameter (pore size optimal for germination of 500-600 μm [10]) and a decrease in the strength characteristics of the prosthesis.

 A powdered composite is used to create boiling centers in solution, which creates a uniform dispersion of the resulting structure, as well as to give the implants inductive properties. The specified concentration of filler in the resulting material is optimal to achieve the objective of the invention.

Chloroform upon receipt of this structural composition was used as a solvent having a low boiling point (67 ^° C), which allows it to be completely removed from the implant.

When dissolving polysulfone in chloroform, a movably viscous solution is obtained, after which the required amount of composite powder is added to it and mixed thoroughly in order to obtain a uniform dispersion structure. Then, the resulting mass is folded into the form of a given configuration and volume (the most optimal amount of the introduced solution by volume in comparison with the product is 1: 1 ratio). After foaming at 110-130 ^o for 1 h, the material is divided into implants - blanks of the required size and shape. The result is a prosthesis with a porous structure with a pore size of 500-600 microns. After machining, prostheses can be sterilized by all known methods due to the resistance of the components of the material in aggressive environments [8]. A sterilization method was used in a dry-air cabinet for 1 h at 180 ^° C (polysulfone destruction temperature 400 ^° C).

 Thus, the obtained implantation material has the following advantages.

 1. Due to the bioinertness of polysulfone, implants do not irritate surrounding tissues during implantation.

 2. The material is easy to receive.

 3. Having the necessary strength characteristics, prostheses from this material are easily machined and have a low weight.

 4. The material contains a substance (a composite compound of octalcium phosphate with maleic acid) and allows for a long time to maintain the optimal content of Ca and P in the structure of the implant.

 5. The presence of maleic acid, which is a metabolite of biochemical processes, leads to the release of active forms of Ca and P into the external environment, which activates regenerative processes, in particular osteogenesis.

 6. The porous structure of the material provides the possibility of germination of the prosthesis by surrounding tissues, has a low weight.

 7. Implants well withstand all sterilization modes.

Literature
1. Auth. certificate of the USSR N 1572601 (1990), class. A 61 F 2/02.

 2. Auth. certificate of the USSR N 1651907 (1991), class A 61 K 31/74.

 3. Pat. USA N 4955909 (1992), class. A 61 F 2/02, 2/12.

 4. Pat. U.S. N 5007929 (1991), CL A 61 F 2/10.

 5. Pat. Japan N 60-1189, cl. C 07, F 3/04, C 07, C 57/13 (1985).

 6. S.N. Nazarov, A.S. Grigoryan, E.Ya. Maloryan, V.N. Kopeikin Effect of biogenic paste containing hydroxylapatite on the dynamics of osseointegration of direct implants // Dentistry, 1988, 5, p. 14-16.

 7. M. M. Soloviev, I. N. Ivasenko, T. M. Alekhova and others. The effect of hydroxylapatite on the healing of the tooth socket in the experiment. // Dentistry, 1992, 3-6, p. 51-53.

 8. Hunt MS. Materials Des., 1987, Vol. eight; 47; N2; P. 127-134.

 9. Salama F., Sharawy M. // J. Oral Maxillofac Surg, 1989; Vol. 47; N 11; P. 1169-1176.

 10. Dutton J.J. // Ophthalmology, 1991, Vol. 98; N3; P. 370-377.0

Claims (1)

A method for treating defects of the maxillofacial region using implants based on a polymeric material, characterized in that the porous sulfone and a composite compound of octalcium phosphate with maleic acid are used as the polymeric material
[CA ₈ (PO ₄ ) ₄ (HPO ₄ ) _2-z (C ₄ H ₂ O ₄ ) _z m H ₂ O],
possessing the ability for a long time to maintain the optimal content of Ca and P in the structure of the implant and stimulate regenerative processes.