Papers by Author: M.L. Öveçoğlu

Abstract: There are thousands of land snail species, ranging in size from 1 mm to the Giant African Snail growing up to a foot long. Two species, known as escargot, helix aspersa and helix pomatia, are commercially important. Helix pomatia is abundant in Turkey. Those snails are exported usually without shells. Shells are damped to trash sites or used as substitute food for animals. The shell is rich in calcium carbonate and some other minor minerals. Thus, snails’ shells can be used as a source for bioceramic production. So far, in the literature there are lot of papers about converting calcite and aragonite structures to hydroxyapatite (HA), like corals, sea shells, sea urchin and other sea creatures. However, there is very limited information about converting land snail shells to HA and other bioceramic phases. The aim of this work was to produce various phases of bioceramic materials from land snails’ shells which are left as a residue waste after their export procedures. Empty local land snails’ shells (helix pomatia) were collected in Istanbul. They were washed, dried, crushed and ball milled until a powder of 100 µm particles size was obtained. Raw powders were stirred at 80°C for 15 min on a hotplate. A second part of the raw powder was stirred with an ultrasonic stirrer at 80°C for 15 min in an ultrasonic equipment. Equivalent amount of H₃PO₄ was added drop by drop into the solution. The reaction lasted for 8h. Then, to evaporate the liquid part, the mixtures were put into an incubator at 100°C for 24 h and the resultant dried sediments were collected. The produced powders were analyzed with X-ray diffraction, IR and scanning electron microscope (SEM). The experimental results confirmed the formation of various Ca-phosphates, specifically monetite, fluorapatite and some other minor calcium phosphate phases. Bioceramic production from land snail is a reliable and economic way comparing to other tedious methods of producing synthetic HA and other various bioceramics phases.

Abstract: Hydroxyapatite (HA) is a particularly attractive material for bone and tooth implants since it does not only closely resemble human tooth and bone mineral but it has also biologically proven to be compatible with these tissues. The applications of pure HA are restricted to non load bearing implants due to the poor mechanical properties of HA. Biomaterials of synthetic HA are highly reliable but the synthesis of HA is often complicate and expensive. Bioceramics of naturally derived biological apatites are more economic. Aim of the present work is to introduce sheep teeth dentine HA material as an alternative source of bioactive biomaterials for grafting purposes. The work was started with such a way that extracted sheep teeth were cleaned. The teeth were calcinated at 850°C in air. It was seen that enamel matter was easily separated from dentine after calcination. The collected dentine parts were crushed and ball milled. The powder was pressed between hardened steel dies to produce samples suitable for compression and microhardness tests. The obtained powder compacts were sintered at different temperatures, specifically 1000, 1100, 1200, and 1300°C in air. Results of microhardness and compression strength (along with the statistical analysis of these results) as well as those of SEM and XRD analyses are presented. In the literature, there is very little information about the mechanical properties of dentine and enamel matter derived from sheep, bovine and human. The highest compression strength value in the present study was measured around 146 MPa (from human dentine derived HA the highest value was almost 60 MPa after sintering at 1300°C). The best microhardness in the present study was found as nearly 125 HV. The results of this study showed that the HA material produced from sheep tooth dentine can be qualified as a promising source of HA needed to produce bioactive ceramics.