Endosseous single tooth implant for a fixed tooth replacement, with - a substantially cylindrical main body which can be inserted into a bore made in a jawbone and has an annular recess and a bore which is open towards its coronal end and is arranged apically to the annular recess, which has a threading arranged at the apical end in the main body for fixing a retaining screw, wherein the annular recess comprises a guide section, a positive locking section adjoining the guide section coronally and an end section adjoining the positive locking section coronally, - an abutment which can be inserted into the annular recess of the main body, with a guide section, with a positive locking section, with an end section, with a bore for receiving the retaining screw and with a fastening head for the tooth replacement, and - a retaining screw that can be inserted into the bore of the abutment and the main body and passes through it, - wherein the positive locking section of the main body and the positive locking section of the abutment have two to six pairs of positive locking elements (26; 142) in the form of radially inwardly directed webs on the main body, which are coaxial with the longitudinal axis of the main body, and corresponding grooves with slot surfaces and two slot edges on the abutment in the manner of a tongue-and-groove connection, wherein the positive-locking portion of the main body and the positive-locking portion of the abutment have two to six pairs of internal and external edges complementary in shape to one another in the form of internal edge surfaces on the main body and corresponding external edge surfaces on the abutment, which are preferably formed circumferentially alternating with the positive-locking elements in the main body and abutment, - wherein the inner edge surfaces on the main body and the corresponding outer edge surfaces on the abutment at least partially come into contact when the abutment is inserted into the main body. - a substantially cylindrical main body which can be inserted into a bore made in a jawbone and has an annular recess and a bore which is open towards its coronal end and is arranged apically to the annular recess, which has a threading arranged at the apical end in the main body for fixing a retaining screw, wherein the annular recess comprises a guide section, a positive locking section adjoining the guide section coronally and an end section adjoining the positive locking section coronally, - an abutment which can be inserted into the annular recess of the main body, with a guide section, with a positive locking section, with an end section, with a bore for receiving the retaining screw and with a fastening head for the tooth replacement, and - a retaining screw that can be inserted into the bore of the abutment and the main body and passes through it, - wherein the positive locking section of the main body and the positive locking section of the abutment have two to six pairs of positive locking elements (26; 142) in the form of radially inwardly directed webs on the main body, which are coaxial with the longitudinal axis of the main body, and corresponding grooves with slot surfaces and two slot edges on the abutment in the manner of a tongue-and-groove connection, wherein the positive-locking portion of the main body and the positive-locking portion of the abutment have two to six pairs of internal and external edges complementary in shape to one another in the form of internal edge surfaces on the main body and corresponding external edge surfaces on the abutment, which are preferably formed circumferentially alternating with the positive-locking elements in the main body and abutment, - wherein the inner edge surfaces on the main body and the corresponding outer edge surfaces on the abutment at least partially come into contact when the abutment is inserted into the main body.