Spontaneous early exposure of submerged endosseous implants resulting increstal bone loss : a clinical evaluation between stage 1 and stage 2 surgery

Aim of the study

To study the effect of spontaneous exposure of submerged implants during the period of osseointegration, especially with respect to the possible relationship between the amount of bone loss and the degree of exposure.

Materials and methods

Two hundred and six Steri-oss^® implants in 64 patients were studied during osseointegration and the amount of exposure was assessed at 6 weeks to 8 weeks (Tal, 1999) :

- class 0 = no exposure ;

- class 1 = operculum present (detected by probe) ;

- class 2 = operculum present (visible) ;

- class 3 = partial exposure of a thread involving part of the periphery ;

- class 4 = total exposure of a thread. The amount of bone loss was assessed at stage 2 and comparisons between patients were undertaken when at least two different classes are present.

Conclusion

As the amount of bone loss increased, so did the amount of exposure (Class 0 = 0.0123 mm, Class 1 = 0.403 mm, Class 2 = 0.856 mm, Class 3 = 0.776 mm) but Class 4 lost very little bone (0.375 mm).

Also, the differences in bone loss between two classes in the same patient were more marked between classes 1 and 2 and 0 and 3.

The greatest amount of bone loss (> 4 mm) occurred in Class 2.

Finally, it was the buccal aspect that suffered most exposure.

Commentary

According to these data, it seems that the best results are obtained when implants are fully submerged or totally… non-submerged !

However, this study only provides mean values between patients as well as between sites. This masks certain differences or extreme values that could be linked to other factors, eg. tobacco use, standard of oral hygiene.