DE3024944A1 - 2-Phosphato-ethyl polymethacrylate addn. to dental cement compsn. - increases strength and adhesion to dentine and lowers solubility in water or lactic acid - Google Patents

Abstract

In the prodn. of dental cements, consisting of a mixt. of metal oxides and stirring fluid, 1-15 (2-5)% (2-phosphato-ethyl) poly-methacrylate, (I), is added to the stirring fluid or cement powder. The metal oxides can be ZnO and/or MgO, Al oxide or SiO2. Main stirring fluid component can be H3PO4 or a polycarboxylic acid, e.g. an acrylic acid homo- or copolymer. The dental cements can be used to fix crowns, inlays, as sub-fillings in dental prostheses and as filling material. (I)-addn. improves adhesion to dentine, lowers solubility in water or lactic acid and prevents colouring material- and bacteria penetration in cement. Dental cement compressive- and tensile strength are improved.

Description

The invention relates to a method of manufacture

of dental cements according to the preamble of the claim.

In dentistry there is one for various purposes A range of cements used, for example for fastening crowns and inlays as well as orthodontic appliances as underfilling to protect the tooth pulp against chemical or physical attacks under another filling material or as a filling material for tooth cavities themselves.

The cements usually consist of a mixture of metal oxides, those with a mixing liquid, the main components of which are phosphoric acid or polycarboxylic acid contains, is made to react.

Such cements have been used in dental practice for decades well proven. They are characterized by good processing properties, fast Setting and sufficient strength and often fulfilling years or decades long their task.

However, the disadvantage is that the cements are brittle that they are not Edge strength have that they are damaging to the composition according to their composition Pulp can act so that after some time it is usually removed from the nursing fluids, especially the lactic acid bacteria, are attacked and that they are insufficient Have adhesion to the tooth substance or to the metals to be attached.

The invention is based on the object, the properties of these To improve dental cements.

This object is achieved in that, according to the invention, the dental cement or the mixing liquid 1-15%, preferably 2-5% (2-phosphato-ethyl) polymethacrylate is added.

Have investigations on dental cements produced in this way show that apart from significantly improved compressive and tensile strengths, in particular the adhesion properties to the dentin have been improved or even one in the first place Adhesion has been achieved that the solubility in water or in lactic acid is considerable and prevents the penetration of dyes or bacteria into the cement will.

The invention is to be explained below on the basis of examples.

First, the production of the dental cement according to the invention is described.

The production of the polymer is based on a 2-hydroxyethyl methacrylate. This was with equimolar amounts of phosphorus pentoxide in diethyl ether at 5 to 10 ° C brought to reaction.

After cleaning using conventional methods (repeated Washing with diethyl ether) a viscous colorless liquid was obtained. This Product consisted of a mixture of mono- and diesters of phosphoric acid. To a solution in 0.2% by weight of methyl bis isobutyrate was found in methanol added as a polymerization trigger. The polymerization proceeded over 12 hours 600C. The polymer obtained was precipitated and repeatedly dissolved in diethyl ether and filtered to remove insoluble parts.

To produce the dental cement, 2.5 and 5 g of it were used in each case Polymer dissolved in 100 g of the cement liquid. But the polymer can also be in the form of a salt are mixed with the cement powder. Cement liquid and cement powder are mixed by the dentist in a known manner and used depending on the application.

From the following table 1 it can be seen that with increasing Proportion of the polymer, the properties of the cement are significantly improved.

Table 1 *) Brazil test. Compressive strength, tensile strength, adhesion ability *) on dentine MPa MPa MPa Zinc phosphate cement -. 97.92.6 4.211.25 0.42 0.11 (default) Zinc phosphate cement 110.6 + 2.8 3.60 + 0.84 1.83 + 0.22 (+ 2 1/2% polymer) Zinc phosphate cement (+ 5% polymer) 124.2 + 2.2 5.93 + 2.0 4.35 + 1.20 Carboxylate cement (standard) 78.8 + 5.7 1.8 + 0.76 2.31 + 0.76 Carboxylate cement (+ 2 1/296 polymer) 100.3 + 4.5 2.36 + o.48 2.97 + 0.32 Carboxylate cement (+ 5% polymer) 100.8 + 5.0 4.69 + 1.18t 4.06 + 0.57 Table 2 Zinc phosphate cement zinc phosphate cement (standard) (+ 5% polymer) solubility (7 days: rest. Water 37 0.1% c in% weight loss 0.1% 0% Vulnerable- ability (7 hours in 1/50 N lactic acid in mm depth of erosion - 4.6 + 0.61 0.2 + 0.04 fe

Claims (1)

Dental cement Patent claim Process for the production of dental cements, consisting of a mixture of metal oxides, for example zinc oxide and / or Magnesium oxide Aluminum oxide, silicon oxide and a mixing liquid, their main component either phosphoric acid or a polycarboxylic acid, such as a homopolymer or copolymer of acrylic acid, characterized in that the mixing liquid or the cement powder 1-15%, preferably 2-596 (2-phosphato-ethyl) poly-methacrylate is added.