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This study reports the clinical use of a bioactive bone graft material, PerioGlas, in the treatment of dental extraction sites before dental implant placement, to effect bone regeneration and to give early fixation to the implant.PerioGlas, granules, ranging from 90 to 710 mm, are implanted after tooth extraction in three patients; after 6 months bone biopsies were performed in the site of the glass implantation and observed under Electron Scanning Microscopy. All the granules showed a biodegradation involving precipitation of calcium phosphate that worked as a scaffold for osteoblasts colonization. All cases examined showed the bioactivity of PerioGlas granules resulting in new bone formation and biodegradation of the glass. After a two-year clinical follow-up all the implants were successfully loaded and appeared stable.

Nano-sized particles of ceramic and metallic materials are generated by high-tech industrial activities, and can be generated from worn-out replacement and prosthetic implants. The interaction with the human body of such nanoparticles has been investigated, with a particular emphasis on innate defence mechanisms. Human macrophages (PMA-differentiated myelomonocytic U-937 cells) were exposed in vitro to non-toxic concentrations of TiO(2), SiO(2), ZrO(2), or Co nanoparticles, and their inflammatory response (expression of TLR receptors and co-receptors, and cytokine production) was examined. Expression of TLR receptors was generally unaffected by exposure to the different nanoparticles, except for some notable cases. Exposure to nanoparticles of ZrO(2) (and to a lesser extent TiO(2)), upregulated expression of viral TLR receptors TLR3 and TLR7. Expression of TLR10 was also increased by TiO(2) and ZrO(2) nanoparticles. On the other hand, TLR9 expression was decreased by SiO(2) nano-particles, and expression of the co-receptor CD14 was inhibited by Co nanoparticles. Basal and LPS-induced production of cytokines IL-1beta, TNF-alpha, and IL-1Ra was examined in macrophages exposed to nanoparticles. SiO(2) nanoparticles strongly biased naive macrophages towards inflammation (M1 polarisation), by selectively inducing production of inflammatory cytokines IL-1beta and TNF-alpha. SiO(2) nanoparticles also significantly amplified the inflammatory phenotype of LPS-polarised M1 macrophages. Other ceramic nanoparticles had little influence on cytokine production, either in resting macrophages, or in LPS-activated cells. Generally, Co nanoparticles had an overall pro-inflammatory effect on naive macrophages, by reducing anti-inflammatory IL-1Ra and inducing inflammatory TNF-alpha. However, Co nanoparticles reduced production of IL-1beta and IL-1Ra, but not TNF-alpha, in LPS-polarised M1 macrophages. Thus, exposure to different nanoparticles can modulate, in different ways, the defence/inflammatory capacities of macrophages. A thorough analysis of these biasing effects may shed light on the mechanisms of pathogenesis of several diseases based on dysregulation of the immune response (allergies, autoimmunity, tumours).

The bioactivity of two similar vitreous materials used in the form of granules of 'critical' size was investigated in bone defects in jaws of two sheep. The granules consisted of Hench's Bioglass and another glass with the same chemical composition made in Italy. Two months after implantation, the sheep were killed and elemental analyses carried out on sections of the embedded jaws. The microanalyses for both the glasses showed a diffusion from the granules towards the surrounding tissue of silicon and sodium, and an inverse diffusion (from the surrounding tissue towards the granules) of calcium and phosphorus. The degradation for the Italian glass was slower than for the Bioglass. No significant osteoinduction was seen after that time at the interface of the glass granules or in the bone pocket.

Granules of a glass (A) prepared according to Hench's formula and a new vitreous material for biological applications (AKRA 15) were used for repair of bone defects in the dental field. The behaviour of these materials implanted in holes drilled in sheep's mandibular bone was examined 4, 8, 12 month after implantation. Microradiographic analyses, optical and scanning electron microscopic observations, and X-ray microprobe evaluations were carried out using undecalcified, methacrylate-embedded sections of the jaw containing the granules. After one year the granules of A disappeared, but not important bone growth was observed also in the holes containing AKRA 15. SEM and microprobe showed: disappearance of Na and Si ions at different stages; increase of P and Ca up to 4 month and then decrease, but in different ways in the two glasses; unexpected appearance of K ions after 4 month only in AKRA 15.

Aim of this work is the evaluation of "in situ" implants in an animal model to study the interfaces that some ceramic materials for dental bone defects develop with bone and to check which material is more osteoconductive. In a sheep's jaw, eight holes were drilled and filled with six ceramic materials in granular shape. Two bilateral holes were left empty as reference. The ceramic materials were: porous tricalcium phosphate (TCP), porous hydroxylapatite (HA) and four bioactive glasses. The glasses differ for doping agents that affect the velocity of biodegradation in the living body. Monthly radiographs were taken and the X-ray pictures analyzed by means of a Video Display Computer in order to quantify the optical density changes occurred in the holes. After 4 months implantation, the segments of the jaw containing the materials were fixed in paraformaldehyde, embedded in methylmethacrylate and sectioned. The results obtained under the microradiograph, the SEM and the X-ray microprobe showed a good bone repair only with TCP granules. A great degradation was seen in HA granules and particularly in glasses. The degradation modified the structure and the composition of the glass granules, but it was not followed by a consequent bone deposition.