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Since the 1960s the dental profession has been divided on the issue of dental implants5. Thanks to the osseointegration principle6,7, ideas about suitable interfaces between the bone and the implant have made considerable progress, and it has been shown that it is not desirable to insert fibrous tissue8. The discovery of an osseointegrated implant from a Gallo-Roman population shows that direct contact between the implant and the bone can be obtained using surprisingly basic technology.

The individual in question, a man who was over 30 years old when he died, is dated to the end of the first century ADor the beginning of the second century by associated pottery and radiocarbon dating. There is a piece of metal where the right second upper premolar would have been (Fig. 1a) which has been severely corroded, preventing magnification for the study of the microstructure. The central part, however, has not been affected. X-ray microanalysis (energy dispersive spectroscopy), together with scanning electron microscopy of the apical fragment, identify it as iron or non-alloy steel. The main chemicals are iron and oxygen; nevertheless the presence within a particular section of dark zones — bearing traces of silicon (0.73%) and calcium (0.26%) — and of clear zones shows that some zones are more oxidized than others. This may imply that the metal was given its shape through a hot-hammering and folding process.

Figure 1: Details of the false tooth.
figure 1

a, Antero-lateral view of the skull. The iron-made dental implant is where the right second upper premolar would have been. b, Retro-alveolar X-ray of the right maxilla. The implant was dropped after being handled and it broke near its apical third into two pieces that were then glued together again. The line of breakage is visible on this X-ray picture. The alveolar wall and the pseudo-root fit perfectly together. Only an area one to two millimetres high in contact with the mesial alveolar wall shows an absence of contact between the bone and the implant.

The retro-alveolar X-ray (Fig. 1b) shows that the alveolar wall and the pseudo-root fit perfectly together without peri-implant radiolucent areas, which is considered to be one of the success criteria for the implant of a dental prosthesis9. According to available data5, osseointegration requires a minimum of three to six months. The minor reactions of the periodontium indicate that the subject was probably fitted with his implant more than a year before he died. The osseointegration implies that the man who made the implant used the original tooth as a model. The implant was probably set by impaction soon after the tooth loss. Chance played a part in this success, but the technical choices were, in retrospect, conducive to osseointegration. Furthermore, although iron is surely not the ideal metal for dental implants, its rugged surface must have provided satisfactory adhesion to the bone10.

Because it is osseointegrated and in a good anatomical position, this implant might have been functional. We cannot know why it was inserted. But the early disappearance of the left molars might have given the subject the desire to keep an active right side.

This case, in addition to its exceptional aspect and the technical craft it required, gives remarkable clues about medicine and anatomy in this rural community of the first or second century AD. This implant reflects the potential of early medicine and the validity of the osseointegration principle4,5.