Abstract:
The present study aimed at developing a novel zinc phosphate based dental cement by
adding Pentacalcium hydroxide triphosphate (hydroxyapatite) as a reinforcing filler to
investigate the mechanical and elution properties of the prepared specimens. Here waste
oyster shells of Crassostrea madrasensis were calcined to obtain Oxocalcium. The
Calcium dihydroxide precursor for the synthesis of hydroxyapatite by wet precipitation
method at room temperature was prepared by dissolving Oxocalcium in water.
Synthesized hydroxyapatite was added into zinc phosphate powder in seven different
ratios and specimens were fabricated. X-ray fluorescence spectroscopy results of oyster
shells showed that Oxocalcium (88.5%) was the major oxide while Silicon dioxide and
Iron (Ⅲ) oxide were present in trivial amounts. The stoichiometric calcium/phosphorus
ratio of synthesized hydroxyapatite was close to 1.7. Both Fourier Transform Infrared
spectroscopy and X-ray Diffraction results of unsintered and sintered hydroxyapatite were
compatible with the results of the commercial compound. The particle size of the sintered
hydroxyapatite was 1.518×10-6 m. Zinc phosphate cement with 10% hydroxyapatite was
identified as the ideal percentage that showed the best mechanical and chemical
properties with the highest compressive and diametral tensile strengths which were
66.85×106 Nm-2
are 18.88 Nm-2
respectively. Further, it showed the lowest elution
percentage in pH 3 and 5 aqueous 2-Hydroxypropanoic acid and water. Hence
hydroxyapatite synthesized from waste can be used as reinforcing filler in zinc phosphate
dental cement.
Keywords: Zinc phospate dental cement, Hydroxyapatite, Crassostrea madrasensis,
oysters
