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Int Poster J Dent Oral Med 3 (2001), No. 4     15. Dec. 2001

Int Poster J Dent Oral Med 2001, Vol 3 No 4, Poster 97

The Physico-Chemical Qualities of ß-Tricalciumphospates

Language: English

Authors:  Prof. Dr. med. dent. Dipl.-Chem. Alfred Johannes Patyk1, Dr. med. dent. Kay Pehrsson2, Prof. Dr. Dr. Alfons Hüls1, Prof. Dr. Dr. Hans Georg Jacobs2
Georg-August-University, 1Dept. of Prosthodontics, 2Dept. of Oral Surgery, Goettingen Germany

Date/Event/Venue: 
27-30 June 2001
79th General Session & Exhibition of the IADR 2001
Chiba, Japan

Introduction

Besides autologous bone, bone substitutes are an important appliance in dentoalveolar implantology of atrophic areas. About twenty years ago, calcium phosphate compounds were first used clinically as bone substitution materials. Because of its high resorption rate in the process of local bone remodelation nowadays mostly the ß-phase is used. The physico-chemical properties of the bone subsitute, such as chemical purity, crystallinity and microstructure are of great significance for the reaction of the embedding bone.


Objective

In this study, three commercial ß-TCP preparations were examined in regard of their physico-chemical properties. The results are fundametal for further investigations of the correlation between pysico-chemical characteristics and biological performance in test animals.


Material and Method

The ß-TCP preparations Cerasorb®, Bio-Resorb® and Biovision® were examined in regard of their crystallinity (Scanning Electron Microscopy), external porosity (Section Preparations) and chemical composition (X-Ray-Diffraction).


Results

Optical- and scaning-electron-microscopic description of the surface

              Original magnification
Biovision Cerasorb Bio-Resorb
  SEM, x 100  
Biovision Cerasorb Bio-Resorb
  SEM, x 1800  
Biovision Cerasorb Bio-Resorb

Clearly visible differences in the crystallinity:

  • compact body in the case of Cerasorb, formed by a scaly take up of crystals without cavities
  • light structure in the case of Bio-Resorb by a kind of sintered conglomeration
  • no distinctive macro-structure in the case of Biovision, loose collection of single crystals and small groups

Compressive strength of the granular powder




The compressive strengths are, compared to human bone, clearly visible lower.


Determination of the external Porosity in selected areas of sections





Biovision Cerasorb Bio Resorb
500-1000 µm
Bio Resorb
1000-2000 µm



A low external porosity defines a high particle density of the material in the osseous defect. The external porosity of all preparations is comparable. It varies in the range between 45 and 53%


X-Ray-Diffraction


Cerasorb
  • Ca3(PO4)2
    Whitlockite syn.
    • CaH2P2O7
      Calcium Hydrogen Phosphate
    • CaH2P2O5
      Calcium Hydrogen Phosphite



Bio-Resorb
  • Ca3(PO4)2
    Whitlockite syn.
    • Ca3(PO4)2xH2O
      Calcium Phosphate Hydrate
    • Ca5(PO4)3(OH)
      Hydroxylfluoroxyapatite syn.
    • Ca2P2O7
      Calcium Phosphate
    • CaHPO4x2H2O
      Brushite



Biovision
  • Ca3(PO4)2
    Whitlockite syn.
    • Ca2P2O7
      Calcium Phosphate
    • Ca5(PO4)3(OH)
      Hydroxylfluoroxyapatite syn.

Chemical purity is a pre-condition for the desired biological reaction of the surrounding human bone. All three preparations contain besides the main phase Whitlockite synthetic several phases as contaminants in different extent. These contaminants are caused by the technology. Presumably a reduction is only possible by improving the parameter of the crystallisation.


The biological valence of the different physico-chemical properties of the tested preparartions have to be established in further studies on animals.



This Poster was submitted by Prof. Dr. med. dent. Dipl.-Chem. Alfred Johannes Patyk.

Correspondence address:
Prof. Dr. med. dent. Dipl.-Chem. Alfred Johannes Patyk
Georg-August-University
Dept. of Prosthodontics
R. Kochstr. 40
37075 Goettingen