No abstract

All biomaterials examined resulted in being biocompatible and seemed to improve new bone formation in maxillary sinus lift. No signs of inflammation were present. The data are very encouraging because of the high number of successfully treated patients and the good quality of bone found in the retrieved specimens.

In our specimens, the inflammatory infiltrate was mostly present in the titanium specimens. Their extension was much larger than that of the zirconium oxide specimens. Higher values of MVD were observed in the titanium specimens (29.1 versus 15.8). In addition, a higher expression of VEGF intensity was observed in the peri-implant tissues of titanium healing caps, whereas predominantly lower expressions of VEGF intensity were noted around the zirconium oxide healing caps. The Ki-67 expression was higher in the titanium specimens. All these data revealed that the tissues around titanium healing caps underwent a higher rate of inflammation-associated processes, most probably correlated to the higher inflammation processes observed in these tissues. A higher intensity expression of NOS1 and NOS3 was recorded in the tissues around titanium, whereas, on the contrary, a lower intensity of expression was found in the tissues around zirconium oxide specimens. These latter data indicate that the higher expression of these two mediators could be correlated to the higher amount of bacteria present around the titanium samples.

Biological interactions occurring at the bone-biomaterial interface are critical for long-term clinical success. Bio-Oss is a deproteinized, sterilized bovine bone that has been extensively used in bone regeneration procedures. The aim of the present study was a comparative light, scanning, and electron microscopy evaluation of the interface between Bio-Oss and bone in specimens retrieved after sinus augmentation procedures. Under light microscopy, most of the particles were surrounded by newly formed bone, while in a few cases, at the interface of some particles it was possible to observe marrow spaces and biological fluids. Under scanning electron microscopy, in most cases, the particle perimeter appeared lined by bone that was tightly adherent to the biomaterial surface. Transmission electron microscopy showed that the bone tissue around the biomaterial showed all the phases of the bone healing process. In some areas, randomly organized collagen fibers were present, while in other areas, newly formed compact bone was present. In the first bone lamella collagen fibers contacting the Bio-Oss surface were oriented at 243.73 +/- 7.12 degrees (mean +/- SD), while in the rest of the lamella they were oriented at 288.05 +/- 4.86 degrees (mean +/- SD) with a statistically significant difference of 44.32 degrees (p < 0.001). In the same areas the intensity of gray value was 172.56 +/- 18.15 (mean +/- SD) near the biomaterial surface and 158.71 +/- 21.95 (mean +/- SD) in the other part of the lamella with an unstatistically significant difference of 13.79 (p = 0.071). At the bone-biomaterial interface there was also an electron-dense layer similar to cement lines. This layer had a variable morphology being, in some areas, a thin line, and in other areas, a thick irregular band. The analyses showed that Bio-Oss particles do not interfere with the normal osseous healing process after sinus lift procedures and promote new bone formation. In conclusion, this study serves as a better understanding of the morphologic characteristics of Bio-Oss and its interaction with the surrounding tissues.

The non-removal of an abutment placed at the time of surgery results in a statistically significant reduction of the horizontal bone remodeling around the immediately restored, subcrestally placed, tapered implant in cases of partial posterior mandibular edentulism.

Immediate functional and non-functional loading seems to be a technique that gives satisfactory results in selected cases.

Recently, several experimental and clinical investigations found that immediately loaded implants obtained satisfactory levels of osseointegration with high success percentages. Only a few long-term studies of immediately loaded implants have been reported in the literature. The aim of this study was a 7-year clinical and radiographic follow-up of 93 immediately loaded dental implants in human patients. Eleven patients were consecutively enrolled in this study. A total of 7 full and 9 partial edentulous arches were rehabilitated. Patients presented a completely edentulous mandible (n=6), a completely edentulous maxilla (n=1), mandibular posterior edentulous areas (n=5), or a posterior maxillary edentulous area (n=1). Patients were rehabilitated with a bar and an overdenture (n=4), a provisional prosthesis of 3 to 12 elements (n=11), or a metal-ceramic bridge of 10 elements (n=1). A total of 93 implants were inserted and loaded within a 24-hour time frame. Six implants failed in the first year after loading. No more failures were observed in the following 6 years, and all the other implants were well integrated from a clinical and radiographic point of view. The cumulative success rate at 7 years was 93.5%, and the prostheses survival rate was 98.5%. The mean marginal bone loss was 0.6 mm after the first year and 1.1 mm at the 7-year evaluation. Primary stability is one of the most important parameters in immediately loaded implants because it avoids micromotion at the bone-implant interface. Four of the 6 failures in our patients occurred in partially edentulous patients; an excessive load applied to these small bridges could be the reason for the failure. Also, the bone quality is important, for 3 of our failed implants had been inserted in D3 bone. Our clinical and radiographic results have shown that these immediately loaded implants have remained osseointegrated for a long period. Our results point to the possibility of using the immediate loading technique in selected and well-informed cases.

Abutments smaller than the diameter of the implant body (platform switching) in combination with an absence of micromovement and microgap may protect the peri-implant soft and mineralized tissues, explaining the observed absence of bone resorption. Immediate loading did not interfere with bone formation and did not have adverse effects on osseointegration.