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Hydraulic cement compositions with low ph methods, articles and kits

a technology of hydraulic cement and composition, applied in the field of hydraulic cement, can solve the problems of high cost, high cost, and high difficulty in mixing and transferring cement for injection in the operating room, and achieve the effect of fast setting tim

Inactive Publication Date: 2013-03-14
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The invention relates to hydraulic cement compositions that can be easily prepared and delivered to a desired location without excessive material waste. These compositions can also be optimized for improved shelf life. The inclusion of water in the composition can speed up the setting time and allow for the hardening of larger amounts of injected material. Overall, the hydraulic cement compositions of the invention have several advantages over conventional compositions.

Problems solved by technology

However, the methods used for mixing and transfer of cement for injection in the operating room are technically difficult and pose a risk for non-optimal material performance, e.g., early setting renders materials difficult to inject or causes phase separation, so-called filter pressing.
Further, for technical reasons and time constraints, the material is typically mixed with a hydrating liquid in bulk to form a paste and the paste is then transferred to smaller syringes for delivery.
In practice, material is often wasted due to an early setting reaction, i.e., the hydrated material sets to a hardened cement prior to delivery to the desired location, or because more material than is needed is mixed.
However, it is difficult to obtain sufficient shelf life using the described formulations in the prior art, as also noted by Shimada et al, Journal of Research of the National Institute of Standards and Technology “Properties of Injectable Apatite-Forming Premixed Cements,” 115(4): 240 (July-August 2010).
Shelf life is also a problem for reactive Brushite forming cements.
Tests have been performed using monocalcium phosphate anhydrous (MCPA), where difficulties to achieve a rapid setting time resulted when changing from MCPM (monocalcium phosphate monohydrate) to MCPA.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0031]This example shows the effect of the pH of monocalcium phosphate has on the setting properties of the cement formulation.

[0032]Monocalcium phosphate monohydrate and anhydrous from 5 different suppliers were evaluated. When the anhydrous form could not be obtained from the supplier, the MCPM was heated to 120° in order to form MCPA. The particle size of the tested MCPA and MCPM powders was in the range of 10-400 μm. Saturated aqueous solutions of the powders (including glycerol) were prepared (0.1 g / mL). The pH of these solutions was measured using a standard pH meter. The different MCPA and MCPM powders were then used in cement formulations prepared with a powder to liquid ratio of 3.5 g / mL. The cements were evaluated regarding setting time.

Setting Time (ST)

[0033]To evaluate setting time of the cements, they were injected in five cylindrical moulds, diameter 6 mm, height 3 mm. At t=0, the filled moulds were immersed in 37° C. phosphate buffered saline solution (PBS, pH 7.4, Si...

example 2

[0036]This example shows that use of MCPA instead of MCPM increases the shelf life of the cement formulation. The shelf life in room temperature of the cement using MCPA was significantly longer than when using MCPM.

Cement Preparation

[0037]Two cement formulations were evaluated. Cement 1 consisted of monocalcium phosphate hydrate (Alpha Aesar, containing both MCPM and MCPA) and β-tri calcium phosphate (β-TCP, Sigma) in a molar ratio of 1:1. Anhydrous glycerol was used as mixing liquid. Cement 2 consisted of monocalcium phosphate anhydrous (MCPA) and β-tri calcium phosphate (β-TCP) in a molar ratio of 1:1. Anhydrous glycerol was used as mixing liquid. A powder to liquid ratio (P / L) of 4 (g / ml) was used for both cements. The MCPA was produced by heating the monocalcium phosphate hydrate powder to 110° C. for 24 h. A vacuum mixer was used to mix the cements.

Setting Time (ST)

[0038]To evaluate setting time, the cement was injected in four cylindrical moulds, diameter 6 mm, height 3 mm. A...

example 3

[0042]This example shows a number of formulations using MCPA with different particle sizes and powder to liquid ratios. The results show that a larger grain size of the MCPA provides means to control the setting time, injection force and strength of the hardened material.

Cement Preparation

[0043]The cement consisted of monocalcium phosphate anhydrous (MCPA) and β-tri calcium phosphate (β-TCP), in a molar ratio of 1:1. Glycerol (anhydrous) was used as mixing liquid. The MCPA was sieved in order to obtain the following particle sizes: <100 μm, 100-200 μm, 200-400 μm, and 400-600 μm. MCPA was also used as received, containing all the mentioned particle sizes, hereby referred to as ALL. A vacuum mixer was used to mix the cements. All evaluated cement mixtures are listed in the Table 3:

TABLE 3Evaluated CementsParticle size (μm)P / L (g / ml)3.9, 4.2100-2004.0, 4.2200-4004.2400-6004.2, 4.4ALL4.2

Injectability

[0044]The injectability was evaluated by measuring the force needed to inject 2 ml of c...

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Abstract

A non-aqueous hydraulic cement composition comprises a non-aqueous mixture of (a) β-tricalcium phosphate powder, (b) monocalcium phosphate comprising monocalcium phosphate anhydrous (MCPA), monocalcium phosphate monohydrate (MCPM), or a combination thereof, and (c) non-aqueous water-miscible liquid, wherein a 0.1 g / ml saturated aqueous solution of the monocalcium phosphate has a pH less than 3.0. Methods of producing a hardened cement, hardened cements, kits, and articles of manufacture employ such compositions.

Description

FIELD OF THE INVENTION[0001]The present invention is directed to hydraulic cements, and, more particularly, to non-aqueous hydraulic cement compositions or partly aqueous compositions. The hydraulic cement compositions may be formed into hardened cements by contact with a hydration liquid or vapor. In a specific embodiment, the hydraulic cements are suitable for use as biomaterials for in vivo delivery, for example for bone and tooth-root restoration. The invention is also directed to hardened cements formed from such hydraulic cement compositions and to methods of producing hardened cements. The invention is further directed to kits and articles of manufacture including, inter alia, such hydraulic cement compositions.BACKGROUND OF THE INVENTION[0002]Self-hardening calcium phosphate cements (CPC) have been used for bone and tooth restoration and for local drug delivery applications. See, for example, Larsson et al, “Use of injectable calcium phosphate cement for fracture fixation: A...

Claims

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Application Information

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IPC IPC(8): A61B17/58B65D85/84C04B12/02
CPCC04B28/344C04B2111/00836A61B17/56Y10T428/131C04B12/025A61B17/8802C04B22/002C04B24/02C04B38/085C04B40/0625C04B2103/44C04B28/06C04B14/043C04B14/062C04B14/306C04B22/124
Inventor ENGQVIST, HAKANBERG, JONAS
Owner OSSDSIGN
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