An implantable bone replacement material (body) based on completely or partially resorbable particles incorporated in a matrix material. The particles are composed of bioactive sintered calcium phosphate ceramic material having a CaO:P.sub.2 O.sub.5 composition ratio between 3:1 and 4:1. The replacement material (body) consists of a metal containing calcium phosphate ceramic material in the form of a monolayer of particles in the peripheral areas of the material (body) which serve as interfaces to the body tissue. The metal is compatible with body tissue. The ceramic particles have a size range between about 500 .mu.m and a few millimeters. The calcium phosphate particles are located so that they lie exposed on the upper surface of the material (body). Other embodiments and processes are also disclosed.