Biomedical subjects

B Assenza

Publications and source records attributed to B Assenza.

4 recordsLinked to original sources

PubMed2001

Localized ridge augmentation using titanium micromesh.

Guided bone regeneration (GBR) has been used recently for the regeneration of bone in conjunction with the placement of dental implants, for augmentation of resorbed alveolar crests, and to treat localized ridge deformities. Twenty-two patients with alveolar crest defects or peri-implant dehiscences participated in this study. Titanium implants were inserted, and the defects were covered with a titanium micromesh, above which was positioned an e-PTFE membrane. After healing, the 2 membranes were removed and a small specimen of the underlying tissues was retrieved with a small trephine. The postoperative healing was mostly uneventful, and only a few dehiscences with membrane exposure were observed. The space under the membranes was, in all patients, filled by a tissue with the macroscopic features of newly formed bone. No residual bone defects were observed and an increase of the alveolar width or height was observed. No untoward effects on bone regeneration were observed in the cases with membrane exposure. Histology showed that the underlying regenerated tissues were composed, in all cases, by newly formed bone. In conclusion, our results show that very satisfactory results concerning GBR techniques can be obtained even without the use of grafts under barrier membranes.

Adult↗

PubMed2001

Fluids and microbial penetration in the internal part of cement-retained versus screw-retained implant-abutment connections.

BACKGROUND: It has been recently observed that in implants with screw-retained abutments, in in vitro as well as in vivo conditions, bacteria can penetrate inside the internal cavity of the implant as a consequence of leakage at the implant-abutment interface. An alternative to screw-retained abutments is represented by implants that can receive cemented abutments. In this case, the abutment goes through a transmucosal friction implant extension (collar) and is cemented inside the internal hexagonal portion of the implant. The aim of the present research was to compare fluids and bacterial penetration in 2 different implant systems, one with cement-retained abutments (CRA) and the other with screw-retained abutments (SRA). METHODS: Twelve CRA dental implants and 12 SRA implants were used in this study. The research was done in 3 steps: scanning electron microscopic (SEM) analysis, fluid penetration analysis, and bacterial penetration analysis. RESULTS: 1) Under SEM it was possible to observe in the SRA implants a mean 2 to 7 micron gap between implant and abutment, while in the CRA implants, the gap was 7 micron. In the latter group, however, the gap was always completely filled by the fixation cement. All the spaces between abutment and implant were filled by the cement. 2) With SRA implants, it was possible to observe the presence of toluidine blue at the level of the fixture-abutment interface and the internal threads; the absorbent paper was stained in all cases. With CRA implants, the absorbent paper inside the hollow portion of the implants was never stained by toluidine blue. No penetration of toluidine blue was observed at the implant-abutment interface and inside the hollow portion of the implants. 3) In all the SRA implant assemblies, bacterial penetration was observed at the implant-abutment interface. No bacteria were detected in the hollow portion of the CRA implants. CONCLUSION: On the basis of the results obtained in the present study using 2 different implant systems, we conclude that CRA implants offer better results relating to fluid and bacterial permeability compared to SRA implants.

Cementation↗

PubMed1999

Guided bone regeneration using titanium grids: report of 10 cases.

In order to ensure an adequate space where new bone can be formed in guided bone regeneration (GBR), most surgeons fill bone defects with biomaterials. In this work we evaluated new bone regeneration in 10 patients using only a blood clot protected with titanium grids and non-resorbable membranes, without any filling material. A manual measurement of the size of the bone defect, using a plastic probe, was performed at 2 surgical steps. After 5 months of treatment, a biopsy was taken from each patient, fixed and embedded in PMMA, examined microradiographically and morphologically to evaluate the newly-formed bone. Our results showed a good repair of the defects by bone regeneration (about 85% overall), high mineral density of new bone around the implants after 5 months, and steady state deposition processes. These results in GBR, without filling material, appear very promising for implantology and reconstructive odontostomatology practice.

Adult↗

PubMedDate not supplied

Surface analysis of machined versus sandblasted and acid-etched titanium implants.

Initially, implant surface analyses were performed on 10 machined implants and on 10 sandblasted and acid-etched implants. Subsequently, sandblasted and acid-etched implant cytotoxicity (using L929 mouse fibroblasts), morphologic differences between cells (osteoblast-like cells MG63) adhering to the machined implant surfaces, and cell anchorage to sandblasted and acid-etched implant surfaces were evaluated. Results indicated that acid etching with 1% hydrofluoric acid/30% nitric acid after sandblasting eliminated residual alumina particles. The average roughness (Ra) of sandblasted and acid-etched surfaces was about 2.15 microns. Cytotoxicity tests showed that sandblasted and acid-etched implants had non-cytotoxic cellular effects and appeared to be biocompatible. Scanning electron microscopic examination showed that the surface roughness produced by sandblasting and acid etching could affect cell adhesion mechanisms. Osteoblast-like cells adhering to the machined implants presented a very flat configuration, while the same cells adhering to the sandblasted and acid-etched surfaces showed an irregular morphology and many pseudopodi. These morphologic irregularities could improve initial cell anchorage, providing better osseointegration for sandblasted and acid-etched implants.

Acid Etching, Dental↗