applied to the alveolar bone portion is reduced application_number US 84421086 A description fig3 shows artificial tooth root 20 according to an embodiment of the invention implanted in alveolar bone portion 2 and fig4 is an external side view of tooth root body 30 of artificial tooth root 20 recess 24 is left in alveolar bone portion 2 in the location where a natural tooth has been extracted artificial tooth root 20 includes root holder 32 which is inserted into recess 24 and tooth root body 30 which is inserted into a receiving recess 36 formed in root holder 32 impact reducing member 34 is fitted between tooth root body 30 and the walls of the root holder deining the receiving recess 36 root holder 32 is formed of high strength ceramics al 2 o 3 zro 2 y 2 o 3 and is covered by a biologically activated layer 38 which is made of u03b2 tcp tricalcium phosphate u03b2 ca 3 po 4 2 hydroxyapacite ca 10 po 4 6 oh 2 or a compound thereof root holder 32 is implanted in recess 24 formed in alveolar bone portion 2 biologically activated layer 38 is formed as follows when apatite or u03b2 tcp is formed on the surface water soluble calcium chloride calcium nitrate etc calcium complexing agent ethylene jamin four vinegar chloride ammonium chloride and water soluble phosphate chloride hydrogen phosphate 2 ammonium is mixed at a mole fraction of 1 1.