< First part

Removing the post may cause root fracture, whose likelihood is higher if the post is longer and more retentive and if the canal walls are very thin (fig. 11).

Fig. 11

We must also consider the need to position a new post at the end of the treatment, a procedure which presents some long-term risks. We must not ignore the growing diffusion of vertical root fractures. If one is detected, it represents a sure indication for extraction (fig. 12).

Fig. 12

It must be noted, though, that the diagnosis of root fracture is difficult and dubious. This is the reason why, in some cases, the choice to retreat becomes an explorative operation, whose outcome is uncertain. The periodontal situation of the tooth under treatment may be a negative prognostic indicator. Pockets and dehiscences may compromise the permanence of the tooth in the mouth. Moreover, bacteria in the periodontal pocket, in case of alteration of the root cement, may colonize the dentinal tubules. The bacterial colonization of the dentinal tubules makes the root a favorable ground for a retrograde periodontitis (9). The prognosis is more negative. We must not forget the tooth strategic position and the prosthetic concerns. The tooth frequently constitutes the terminal abutment in an expensive fixed prosthesis rehabilitation.

Osseointegrated implantology
Is it possible to consider implantology as a valuable alternative in the seriously compromised dental situations we have seen (fig. 13-14)

Fig. 13

Fig. 14

The answer seems to be positive and both literature and clinical practice consider it possible to substitute teeth, no more susceptible of endodontic treatment, and therefore candidates for extraction, with endosseous implants. Nowadays, the substitution of a single tooth by conventional prosthetic interventions, with loss of healthy dental tissue from adjacent teeth, is considered a makeshift solution. The utilization of osseointegrated implants is fully accepted in the treatment plan of partial or total edentulous patients. Case reports presented by Branemark and colleagues (10, 11) (fig 15) show excellent success rates, but they analyze a series of prosthetic rehabilitations, very different from the ones we have considered.

Fig. 15

In following years, other authors have presented other cases, with different methodological approaches and prosthetic solutions, always with outstanding rates of success (12).

Monoimplants, the possible therapeutic answer in the cases we have considered, for many years have been labeled as unfavorable, from a bio-mechanical standpoint. But nowadays, the literature data about the success rates of this operation are reassuring (13).

Several studies, from the more recent literature, support the value and sometimes the primary indication for the implants, in specific clinical situations.

Clinical pre-implant considerations
There are some pre-operative clinical considerations, that can determine the choice between an endodontic treatment and an extraction, with implant rehabilitation.

We must remember the different bone structure in different areas of the both maxilla and mandible (14): in the inter-foraminal area we have an excellent quality bone, whereas in the posterior areas of the maxilla, next to the maxillary sinus, the bone trabecular structure is thinner; therefore it is more difficult to achieve a sufficient primary stability and a good osseointegration, as we can see from the literature data about the so-called type 4-bone (fig. 16).

Fig. 16

Especially in these areas there is often a conditioning anatomical variable: a reduced vertical bone availability. In some cases, the implant could be inserted only by advanced surgical techniques, with a high elevation of the maxillary sinus floor (fig. 17).

Fig. 17

Until now we cannot consider these procedures like a routine practice. But even in these areas, the progress of the techniques and knowledge has extended and above all simplified our field of action. The use of Summers’ osteotomes, instead of burs, allows compacting the bone thin trabecular structure, enhancing the implant primary stability, sometimes in association with parceling elevations of the sinus floor (15) (fig. 18-19).

Fig. 18

Fig. 19

Such procedure allows a clearer indication of an implant success, thanks to the positive operation on the bone quality and on the vertical bone dimension (the site of the implant) without being invasive or traumatic.

The implant length has been considered as a second variable which can predict the prognosis: implants whose length was less than 8 mm had a more negative prognosis in the first follow-up studies.

Nonetheless, where the techniques to increase the vertical bone availability are not possible, even short implants, if properly used, may be effective in borderline situations.

Recently, Ten Bruggenkate et al. have reported high rates of success for 6 mm long TPS implants (16).

In a research study, now under way, by Corrente et al. (17), the success rates of patients with a serious periodontal condition and an unfavorable crown-root ratio were not statistically different from standard patients’ rates, with positive outcome at 5 years (88 %), and implant lengths between 7 and 9 mm (fig. 20).

Fig. 20

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