1、Designation: F 1926/F 1926M 08Standard Test Method forEvaluation of the Environmental Stability of CalciumPhosphate Granules, Fabricated Forms, and Coatings1This standard is issued under the fixed designation F 1926/F 1926M; the number immediately following the designation indicates theyear of origi
2、nal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers calcium phosphate materialsintended for
3、use in surgical implant applications.1.2 Aspects of the biological response to calcium phosphatematerials in soft tissue and bone have been reported fromlaboratory studies and clinical use (1-10).21.3 The requirements of this specification apply to calciumphosphate materials such as calcium hydroxya
4、patite (seeSpecification F 1185), beta-tricalcium phosphate (see Specifi-cation F 1088), and biphasic mixtures thereof with or withoutintentional addition of other minor components (10 %).1.4 The material(s) shall be representative of that producedfor sale. It shall have been produced and processed
5、understandard manufacturing conditions.1.5 The materials may be in the form of powders, granules,fabricated forms or coatings; and may be porous, nonporous,textured, and other implantable topographical substrate formrepresentative of the end-use product.1.6 The calcium phosphate material may constit
6、ute the onlymaterial in a substrate or it may be one of multiple materials solong as all other materials present do not dissolve under the testconditions described in this test method.1.7 This test method is limited to the laboratory evaluationof the dissolution rate of a calcium phosphate material.
7、 Nocorrelation of the results to in vivo performance is implied.1.8 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combini
8、ngvalues from the two systems may result in non-conformancewith the standard.1.9 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determ
9、ine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodF 1088 Specification for Beta-Tricalcium Phosphate forSurgical ImplantationF 1185 Specification fo
10、r Composition of Hydroxylapatitefor Surgical Implants3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 calcium phosphateany one of a number of inorganicchemical compounds containing calcium and phosphate ions asits principal constituents.3.1.2 coatinga layer of material mechanic
11、ally or chemi-cally adhering to the surface of a substrate.4. Dissolution Media4.1 Water used for preparing reagents or dissolution mediashall be degassed carbon dioxide free deionized or distilledwater and have less than 0.1 ppm of residual Ca+ion.4.2 Unbuffered Water MediaDeionized or distilled wa
12、tercontaining 8 3 105M NaCl, 8 3 105M CaCl2, and 5 3 105MK3(PO4).4.3 pH 5.5 MES Buffer Media1.0 M MES, 2-(N-morphplino)ethanesulfonic acid having a pH of 5.5 at 37 60.5C and containing 8 3 105M NaCl, 8 3 105M CaCl2, and53 105MK3(PO4).4.3.1 A buffer concentration of 1.0 M will usually providesufficie
13、nt buffer capacity to keep the solution within 60.1 pHunits of the initial value. If this is not the case, the buffercapacity should be adjusted accordingly.4.3.2 The pH must be adjusted to 5.5 at 37 6 0.5C usingHCl or NaOH solutions.4.4 pH 7.4 TRIS Buffer Media1.0 M TRIS, Tris(hy-droxymethyl)aminom
14、ethane having a pH of 7.4 at 37 6 0.5Cand containing 8 3 105M NaCl, 8 3 105M CaCl2, and 5 3105MK3(PO4).1This test method is under the jurisdiction of ASTM Committee F04 onMedicaland Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.13 on Ceramic Materials.Current edi
15、tion approved Oct. 1, 2008. Published October 2008. Originallypublished in 1998. Last previous edition approved in 2003 as F 1926 03.2The boldface numbers given in parentheses refer to a list of references at theend of the text.3For referenced ASTM standards, visit the ASTM website, www.astm.org, or
16、contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.4.1 A buffer con
17、centration of 1.0 M will usually providesufficient buffer capacity to keep the solution within 6 0.1 pHunits of the initial value. If this is not the case, the buffercapacity should be adjusted accordingly.4.4.2 The pH must be adjusted to 7.4 at 37 6 0.5C usingHCl or NaOH solutions.5. Analytical Par
18、ameters5.1 The following procedure should be performed with eachof the media listed:5.1.1 The dissolution rate shall be measured under theconditions of a constant ratio of initial material mass (mg) tototal dissolution media volume (mL). The ratio of test materialmass to dissolution media shall typi
19、cally be between 0.005 and0.01 mg/mL.5.1.2 The dissolved Ca+ concentration (61 ppm) shall bemeasured as soon as practical after the start of the experimentand at appropriate time intervals thereafter to allow thedetermination of their changes with time.6. Analytical Procedures6.1 Make pH measurement
20、s with an appropriately cali-brated pH meter and probe.6.2 Measure the Ca+ concentrations potentiometrically.Other methods (for example, colorimetrically, atomic absorp-tion (AA), inductively coupled plasma (ICP) spectroscopy, orinductively coupled plasma mass spectroscopy (ICP/MS) maybe used if equ
21、ivalency can be demonstrated.6.3 An appropriate bacteriostat (for example, 0.1 v/v %Hibiclens or 0.1 w/v % sodium azide) may be added to thedissolution media prior to the start of an experiment.7. Dissolution Apparatus7.1 The dissolution vessel shall be of such design to easilyaccommodate the test s
22、pecimen, the magnetic stirrer bar, andthe specific ion-electrode and reference electrode assemblies. Itshall also be isolated from the atmosphere by an oxygen andcarbon dioxide free inert gas purge.7.1.1 A convenient apparatus (see Fig. 1) is a 100 mLjacketed beaker with circulating water from a the
23、rmostaticallycontrolled vessel. A flat piece of polyethylene, or other inertplastic, with appropriate holes drilled to accommodate theprobes, sample holder, and purge gas tube can serve as a lid.7.2 It shall be of appropriate dimensions to contain therequired volume of dissolution media at a level t
24、o keep the testmaterial completely submerged during the test and facilitatesufficient stirring action from the magnetic stirrer bar.7.3 The stirrer assembly shall be capable of maintaining aconstant stirring rate of 100 6 20 rpm.7.3.1 Magnetic stirrer bar(0.31 in. (8 mm) diameter, 2 in.(51 mm) lengt
25、h, polytetrafluoroethylene (PTFE)-coated).7.3.2 A different type of stirrer design and stirring rate maybe used provided equivalence in experimental results can bedemonstrated.7.4 The dissolution vessel shall be thermostatically con-trolled at 37 6 0.5 C.7.5 The dissolution apparatus may include var
26、ious datarecording and storage devices, strip chart recorders, computers,and so forth, to facilitate continuous monitoring throughout theduration of the experiment.8. Preparation of Test Specimens8.1 Coatings:8.1.1 The standard test specimen for evaluating coatingmaterials is defined in Fig. 2.8.1.2
27、 The test specimen shall be manufactured from thesame materials and processes as substrates produced for sale.8.1.3 The test specimen shall have the upper shank threadedso as to mate with an appropriate supporting shaft as describedin Fig. 1.8.1.4 By appropriate masking, or other techniques, thecoat
28、ing shall be applied only to the central 0.5 6 0.005 in. ofthe test specimen.8.1.5 The coating shall be applied to the test specimen andreceive the same processing steps as the actual product.8.2 Fabricated FormsThe standard test specimen forevaluating fabricated forms is a cylinder 9.53 mm (0.375 i
29、n.) indiameter and 12.70 mm (0.500 in.) in length. This cylinderFIG. 1 Dissolution ApparatusF 1926/F 1926M 082shall be attached (threaded into or glued unto) an appropriatesupporting shaft as described in Fig. 1.8.3 Powders and GranulesPowders and granules shall beenclosed in an inert porous contain
30、er capable of retainingundissolved material, preventing it from being impelled by themagnetic stirrer bar and allowing easy circulation of the testmedia through out. Containers fabricated from polymeric orstainless steel mesh materials may be useful.9. Procedure for Monitoring Changes in pH and Calc
31、iumConcentrations9.1 Prepare the test specimen as described in Section 8.9.2 Procure the appropriate volume of dissolution medianeeded for the experiment and equilibrate at 37 6 0.5C.9.3 Calibrate the pH probe and any other analytical instru-mentation to be used immediately before starting the exper
32、i-ment or use as recommended by the manufacturers.9.4 Calibrate the calcium specific ion electrode as recom-mended by the manufacturer except use the same test media aswill be used in the experiment for preparing the calibrationstandards.9.5 Adjust the stirrer assembly to 100 6 20 rpm.9.6 Assemble t
33、he dissolution apparatus (see Fig. 1). Thedissolution media, all calibrated sensing electrodes, and thestirrer should be in place and operating. However, do notinclude the test specimen. Then equilibrate this assembly at 376 0.5 C.9.7 Record the initial pH of the test media.9.8 Set the experiment ti
34、ming device to zero.9.9 When ready to begin the experiment, add the testspecimen to the dissolution vessel and make any necessaryadjustments to the equipment.9.10 As soon as practical after the introduction of the testspecimen to the dissolution media, record the initial pH and thedissolved Ca+ conc
35、entration.9.11 Repeat the measurement of the dissolved Ca+ con-centration at appropriate time intervals to define the dissolutionrate curve.9.11.1 A typical initial sampling rate is every three minutesor more frequently for the first 15 min. More frequent samplingmay be necessary for some materials
36、in order to accuratelydetermine the slope of the initial linear portion of the dissolu-tion curve.9.11.2 A typical sampling rate for the remainder of the testis every hour or more frequently and then every 10 min for thelast hour of the experiment.9.12 The duration of a typical experiment shall be a
37、t least 24h. Longer times may be needed for some materials if theirmeasured concentrations of dissolved Ca+continue to changeby more than 10 % overa1hperiod.9.13 Record the final pH of the test media. If the final pHdiffers by more than 0.2 pH units from the initial value, thisentire experiment shou
38、ld be considered invalid. Determine andcorrect the cause of the change in the pH of the buffered mediaand repeat the test.10. Report10.1 Report the following results for each of the mediasystems used:10.1.1 All procedural details that differ from those describedin this test method.10.1.2 The mass to
39、 dissolution volume ratio of the test.10.1.3 The identity of the dissolution media, the substratematerial(s).10.1.4 The pH and concentration of dissolved Ca+re-corded at the start of the experiment (see 9.10).10.1.5 The pH and concentration of dissolved Ca at the endof the experiment (see 9.13).10.1
40、.6 Plots of the concentrations of total dissolved Ca+versus time data for the duration of the experiment.10.1.7 The calculated initial dissolution rates as follows:10.1.7.1 Calcium phosphates typically display two quasi-linear regions in their dissolution rate curves. The initialdissolution rate is
41、usually distinguished from the final dissolu-tion rate by a significantly higher rate of increase in theconcentrations of dissolved Ca+. The final dissolution rate isthat rate observed in the quasi-equilibrium state obtainedimmediately prior to the termination of the experiment.10.1.7.2 The initial
42、dissolution rate (Ri) is expressed interms of the initial changes in total Ca+concentration withtime. (Ri)Ca= initial slope of the Ca+concentration versus timecurve expressed in terms of the total dissolved Ca+(in mg) permg of material per mL of dissolution media per hour.10.1.8 The final dissolutio
43、n rates (Rf) is expressed in termsof the final changes in total Ca+concentration with time.(Rf)Ca= final slope of the Ca+concentration versus time curveexpressed in terms of the total dissolved Ca+(in mg) per mg ofmaterial per mL of dissolution media per hour.11. Precision and Bias11.1 Precision and
44、 bias of this test method will be deter-mined after interlaboratory tests are carried out and the resultstabulated. The interlaboratory tests will be carried out follow-ing Practice E 691.12. Keywords12.1 calcium-phosphate; coating; dissolution rate; environ-mental stability; fabricated form; granul
45、eFIG. 2 Test Specimen and CoatingF 1926/F 1926M 083APPENDIX(Nonmandatory Information)X1. RATIONALEX1.1 Certain concentrations of TRIS have been reported tointerfere with the performance of some Ca+2ion specificelectrodes. In order to minimize or eliminate this potentialinterference, it is important
46、for the user of this test method toconduct all Ca+2ion concentration measurements on calibra-tion standard solutions and working solutions that have equiva-lent TRIS concentrations.X1.2 Although this test method does not require themeasurement, control, or reporting of the calcium phosphatematerials
47、 surface area, porosity, coating thickness, or coatingdeposition method, all these parameters are known to affect itsmeasured dissolution rate. Therefore, the user must carefullyconsider these parameters when attempting to comparingdifferent calcium phosphate materials.REFERENCES(1) Cranin, A. N., T
48、obin, G., Gelbman, J., and Varjan, R., Trans. Soc.Biomaterials, 1986.(2) Kent, J. N., Quinn, J. H., Zide, M. F., Guerra, L. R., and Boyne, P., J.Oral and Maxillofacial Surg., Vol 41, No. 10, 1983.(3) Yukna, R.A., Mayer, E. T., and Brite, D. V., J. Periodontology, Vol 55,No. 11, 1984.(4) Jarcho, M. P
49、., Kay, J. F., Gumaer, K. I., Doremus, R. H., and Drobeck,H. P., J. Bioengineering, Vol 1, 1977.(5) Drobeck, H. P., Rothstein, S. S., Gumaer, K. I., Sherer, A. D., andSlighter, R. G., J. Oral and Maxillofacial Surg., Vol 42, 1984.(6) Tracy, B. M. and Doremus, R. H., J. Biomedical Materials Research,Vol 18, 1984.(7) Cook, S. D., Kay, J. F., Thomas, K. A., and Jarcho, M., Clin. Orthop.,Vol 230, 1988.(8) Kay, J. F., Golec, T. S., and Riley, R. L., J. Prosthet. Dent., Vol 58,1987.(9) Jarcho, M., Clin. Orthop., Vol 157, 1981.(10) Sendax, V.,
