< Second part

Post-extraction implant methods
Post-extraction methods may utilize the pre-existing socket to good advantage. In the maxillary region, as we have seen, the bone has a sparse trabecular structure. In some situations, the bone mineral component is seen only in the areas that we identify radiologically as perpendicular lamina dura. This is another reason why post-extractive implant methods have become increasingly popular. In each clinical situation, we must be able to provide a careful plan, taking into consideration the waiting time between extraction and implant. Wilson and Weber have described the waiting time between extraction and fixture insertion, classifying the sites as: immediate, recent, delayed and mature (18).

Post-extraction delayed implants
The most popular methods have been delayed fixture insertion. A protracted waiting time between the dental extraction and the fixture insertion allows for the socket healing and a good soft tissue recovery. Accordingly, the surgical procedure would be easier.

But, as the time for complete re-ossification inevitably causes a loss of ridge height and thickness, the fixture insertion could become impossible (fig. 21).

Fig. 21

For this reason, we utilize most frequently post-extractive methods with limited time. Early post-extractive delayed methods, usually performed 45 days post-extraction, allow for soft tissue recovery, preventing for the most part the feared process of resorption at the bone ridge level, even if the re-ossification inside the socket is lacking (fig. 22).

Fig. 22

The surgeon must in any case know and implement reliable re-generative techniques, to negotiate the different anatomical situations that can occur in the surgical phase of fixture insertion (fig. 23-24). We must consider that the implant is positioned in an anatomic site with residual signs of the extracted tooth pre-existing endodontic pathology, with a bone contour far from ideal for the standard insertion.

Fig. 23

Fig. 24

It is important to remember that the principles of guided tissue regeneration have been extensively tested and implemented (19). GBR [guided bone regeneration] utilization has become very popular, in association with post-extractive implants, particularly when some of the fixture surface are exposed after the insertion. Whit the occurrence of significant periradicular septic phenomena, the operator is induced - beyond every other consideration - to protract the waiting time following the extraction.

The early fixture insertion in the above-stated cases, could sometimes give origin to an apical peri-implantitis (20) (fig. 25). This pathology may be caused by an iatrogenic dislodgement of the pre-existing bacteria and of their toxins to the apex of the surgically created socket.

Fig. 25

This event could be responsible for delayed infections, which often occur after the completion of the osseointegration and make the case difficult to manage. Only clinical experience supports this procedure at the moment, as unequivocal scientific data are lacking. Anyhow, we have recently reported positive results in the 5 years follow-up of implants, that were inserted on average 45 days after the extraction.

Immediate post-extractive implants
Immediate post-extractive techniques (22) have recently become increasingly popular as, in critical situations, even a minimal waiting time may prevent the possibility of the fixture insertion, if the post-extractive ridge resorption, however slight, becomes an absolute obstacle. Immediate post-extractive procedures present a high rate of success (23). The possibility exists to leave newly inserted implants non-submerged (24). In our opinion, a single surgical act is sufficient to go from a tooth ‘doomed’ to extraction to an implant, ready to be connected with the prosthetic framework (fig. 26).

Fig. 26

The progress at this level seems never to stop, if Salama (25) has already presented the first positive data concerning immediate post-extractive implants with immediate loading on a single tooth. We have also started to implement this procedure, with conical implants, which allow for an optimal sealing of the socket (26). These methods, with their dramatic reduction of the operative time, will become the first line treatment when sustained by long-term results. Therefore, the immediate implant may be considered a predictable operation if we exclude the contraindications of an insufficient bone support for the primary stabilization of the implant or of acute septic events.

Prognosis of post-extractive implants
The prognosis of endodontic retreatment must be compared with the prognosis of implants, inserted in post-extractive conditions, with the frequent aid of regenerative techniques. Even if these techniques have been developed in the last few years, recent studies have evaluated their predictability in time. The rates of success reported in the literature are very high, between 84 % and 100 %. A recent study by Nevins et al. (27) reports long-term rates of success in the highest end of the range. In a 1995 study, on immediate post-extractive implants, Gelb reported success rates of 98 % (28).

Corrente et al. have analyzed the long-term success rates of implants, with regenerative technique, comparing them with implants inserted under standard conditions in patients with similar characteristics. The rates of success were 93.7 % in patients with regenerative technique and 94.9 % in patients without this technique, a difference that was not statistically significant.

Conclusion
The intriguing prospects of implantology must not hide the fact that, under some circumstances, only effective endodontic treatments, even extreme, on terminal teeth, allow for a good mastication, whereas implantology is by no means predictable.

Moreover, it is necessary that both implantology procedures and endodontic ones be performed with the same care on the same patient, to minimize the likelihood of early or late failure (fig. 27).

Fig. 27

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