< First part

Results
At the second surgical stage, 6 implants inserted with bone regeneration procedures(4 with Biocoral Gel,1 with Biocoral Gel and Tissucol, 1 with TCP) and 1 implant inserted in standard conditions were not osseointegrated (Tab.1).

Table 1

Among the 75 osseointegrated implants with bone regeneration, 11 implants(14.6%) showed an incomplete bone defects filling(6 with Biocoral Gel, 1 with autologous bone,1 with Biofix and autologous bone, 3 with Gore-Tex). After the second surgical stage implants with GBR had a mean follow-up of 23.08±8.07 months (min 13-max 47) and standard implants had a mean follow-up of 26.14± 9.04 months (min 19-max 53).

During the follow-up period , 5 GBR and 4 standard implants were unsuccessfull, hereby the success rate of implants inserted with bone regeneration procedures was 93.3% while the success rate of implants inserted in standard conditions was 95.6%. The difference between the two rates wasn’t of statistical value (P=0.732)(Tab.2).

Table 2

Among the implants with regenerative procedures, in those that reached a complete bone defects filling only one unsuccess(with TCP) was registered (success rate of 98.4%) while in those that had an incomplete bone defects filling 4 unsuccess were registered (success rate of 63.6%).The difference between the two groups was of statistical value (P=0.001)(Tab.3).

Table 3

The comparison, during the follow-up period, among the various regenerative procedures showed no differences of statistical value(P=0.171)(Tab.4).

Table 4

Discussione e conclusioni
Various authors reported long-term predictability of implants inserted in adequate bone volume [15] [16] [17] [18] [19].

In the same way , periimplant regenerative techniques are able to recreate a suitable bone volume for implant insertion [20][21][22][23]. In the present study the stability of bone regenerated in periimplant.

In the present study the stability of bone regenerated in periimplant sites and its possibility to affect the long-term success of osseointegrated implants have been evaluated.

In a mean follow-up of about two years, results show no difference about the predictability of implants inserted in preexisting bone and in newly formed bone obtained by means of various augmentation procedures, after osseointegration has been obtained.

Such a predictability shows no difference in relation to the use of vatious regenerative techniques : so it’s possible to day that ,in the long -term maintenance of the results, techniques with or without membranes are equally of confidence: this confirm that the biological principle and not the kind of material used is the basis for success.

On the contrary,the difference between implants in which regenerative techniques allowed a complete bone defect filling and implants with an incomplete bone defect filling at the second surgical stage was of statistical value.

Hereby it is possible to confirm the great impact that regenerative procedures can have today in order to extend the possibilities of using dental implants, also when the preexisting bone volume won’t allow the insertion of the fixture, with a long-term predictability, once osseointegration and periimplant bone defect filling have been obtained, absolutly equal to that of implants inserted in standard conditions.

Bibliografy

1. Brånemark PI,Breine U,Adell R et al.Intraosseous anchorage of dental prostheses.I.Experimental studies. Scand J Plast Surg 1969;3:81
2. Schroeder A,Pohler O,Sutter F. Gewebsereaktion auf ein Titan-Hohlzylinderimplantat mit Titan-Spritzschichtoberflache. Schweiz Monatsschr Zahnheielk 1976;86:713
3. Nyman S,Lang NP,Buser D et al.Bone regeneration adjacent to titanium implants using guided tissue regeneration:a report of two cases. Int J Oral Maxillofac Implants 1990;5:9-14
4. Seibert J,Nyman S.Localized ridge augmentation in dogs.A pilot study using membranes and hydroxyapatite. J Periodontol 1990;61:157
5. Buser D,Bragger U,Lang NP et al.Regeneration and enlarjament of jaw bone using guided tissue regeneration. Clin Oral Impl Res 1990;1:22-32
6. Dahlin C,Lekholm U,Linde A.Membrane induced bone augmentation at titanium implants. Int J Periodont Rest Dent 1991;11:273-282
7. Murray G,Holden R,Roachlau W.Experimental and clinical study of new growth of bone in a cavity. Am J Surg 1957;93:385
8. Hurley AL,Stinchfield FE et al. The role of soft tissues in osteogenesis. J Bone Joint Surg 1959;41a:1243
9. Nyman S,Gottlow J,Karring T et al. The regenerative potential of the periodontal ligament. J Clin Periodontol 1982;9:257-265
10. Nyman S,Lindhe J,Karring T et al. New attachment following surgical treatment of human periodontal disease. J Clin Periodontol 1982;9:290-296
11. Becker W,Becker BE,Prichard JF et al.Root isolation for new attachment procedures:a surgical and suturing method.Three case reports. J Periodontol 1987;58:819-826
12. Pontoriero R,Nyman S,Lindhe J et al.Guided tissue regeneration in the treatment of furcations defects in man. J Clin Periodontol 1987;14:618-620
13. Gottlow J,Nyman S,Lindhe J et al. New attachment formation in the human periodontium by guided tissue regeneration.Case reports. J Clin Periodontol 1986;13:604-616
14. Albrektsson T,Zarb C et al. The long term efficacy of currently used dental implants:a review and proposed criteria of success. Int J Oral Maxillofac Implants 1986;1:11-25
15. Albrektsson T,Dahl E et al. Osseointegrated oral implants.A swedish multicenter study of 8139 consecutively inserted Nobelpharma implants. I Periodontol 1988;59:287-296
16. Albrektsson T,Bergmann B et al. A multicenter study of osseointegrated oral implants. J Prosthetic Dent 1988;60:75-84
17. Adell R,Eriksson B et al. Studio con un lungo follow-up su impianti osteointegrati per la ricostruzione delle mascelle completamente edentule. Quintessence International 1992;3:235-247
18. Brånemark PI,Svensson B et al. Ten-year survival rates of fixed prostheses on four or six implants ad modum Brånemark in full edentulism. Clin Oral Impl Res 1995;6:227-231
19. Spiekermann H,Jansen VK et al. Uno studio con un follow-up di dieci anni su impianti IMZ e TPS nella ricostruzione della mandibola edentula con sovraprotesi su barra. Quintessence International 1995;12:793-804
20. Dahlin C,Lekholm U et al.Treatment of fenestration and dehiscence bone defects around oral implants using the guided tissue regeneration technique: a prospective multicenter study. Int J Oral Maxillofac Implants 1995;10:312-318
21. Dahlin C,Lekholm U,Linde A. Aumento dell’osso indotto dalla membrana a livello di impianti in titanio. Rapporto su dieci impianti seguiti da 1 a 3 anni dopo il carico. Riv Int Parod Od Ricostr 1991;11:273-281
22. Gelb DA.Intervento d’impianto immediato: valutazione retrospettiva nell’arco di tre anni di 50 casi consecutivi. Quintessence International 1995;2:137-148
23. Buser D,Dula K et al. Long-term stability of osseointegrated implants in bone regenerated with the membrane technique.5-year results of a prospective study with 12 implants. Clin Oral Impl Res 1996;7:175-183